Mars habitability analogue environments on Earth

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Mars_habitability_analogue_environments_on_Earth

Mars habitability analogue environments on Earth are environments that share potentially relevant astrobiological conditions with Mars. These include sites that are analogues of potential subsurface habitats, and deep subsurface habitats.

A few places on Earth, such as the hyper-arid core of the high Atacama Desert and the McMurdo Dry Valleys in Antarctica approach the dryness of current Mars surface conditions. In some parts of Antarctica, the only water available is in films of brine on salt / ice interfaces. There is life there, but it is rare, in low numbers, and often hidden below the surface of rocks (endoliths), making the life hard to detect. Indeed, these sites are used for testing sensitivity of future life detection instruments for Mars, furthering the study of astrobiology, for instance, as a location to test microbes for their ability to survive on Mars, and as a way to study how Earth life copes in conditions that resemble conditions on Mars.

Other analogues duplicate some of the conditions that may occur in particular locations on Mars. These include ice caves, the icy fumaroles of Mount Erebus, hot springs, or the sulfur rich mineral deposits of the Rio Tinto region in Spain. Other analogues include regions of deep permafrost and high alpine regions with plants and microbes adapted to aridity, cold and UV radiation with similarities to Mars conditions.

Precision of analogues

Mars surface conditions are not reproduced anywhere on Earth, so Earth surface analogues for Mars are necessarily partial analogues. Laboratory simulations show that whenever multiple lethal factors are combined, the survival rates plummet quickly. There are no full-Mars simulations published yet that include all of the biocidal factors combined.

• Ionizing radiation. Curiosity rover measured levels on Mars similar to the interior of the International Space Station (ISS), which is far higher than surface Earth levels.
• Atmosphere. The Martian atmosphere is a near vacuum while Earth's is not. Through desiccation resistance, some life forms can withstand the vacuum of space in dormant state.
• UV levels. UV levels on Mars are much higher than on Earth. Experiments show that a thin layer of dust is enough to protect microorganisms from UV radiation.
• Oxidizing surface. Mars has a surface layer which is highly oxidizing (toxic) because it contains salts such as perchlorates, chlorates, cholorites, and sulfates pervasive in the soil and dust, and hydrogen peroxide throughout the atmosphere. Earth does have some areas that are highly oxidizing, such as the soda lakes, and though not direct analogues, they have conditions that may be duplicated in thin films of brines on Mars.
• Temperature. Nowhere on Earth reproduces the extreme changes in temperature that happen within a single day on Mars.
• Dry ice. The Mars surface consists of dry ice (CO₂ ice) in many areas. Even in equatorial regions, dry ice mixed with water forms frosts for about 100 days of the year. On Earth, although temperatures on Earth briefly get cold enough for dry ice to form in the Antarctic interior at high altitudes, the partial pressure of carbon dioxide in Earth's atmosphere is too low for dry ice to form because the depositional temperature for dry ice on Earth under 1 bar of pressure is −140 °C (−220 °F) and the lowest temperature recorded in Antarctica is −94.7 °C (−138.5 °F), recorded in 2010 by satellite.

These partial analogues are useful, for instance for:

• Testing life detection equipment which may one day be sent to Mars
• Studying conditions for preservation of past life on Mars (biosignatures)
• Studying adaptations to conditions similar to those that may occur on Mars
• As a source of microbes, lichens etc. that can be studied as they may exhibit resistance to some conditions present on Mars.

Atacama Desert

The Atacama Desert plateau lies at an altitude of 3,000 meters and lies between the Pacific and the Andes mountains. Its Mars-like features include

• Hyper arid conditions
• Cold compared to most arid deserts because of the altitude
• High levels of UV light (because it is relatively cloudless, also the higher altitude means less air to filter the UV out, and the ozone layer is somewhat thinner above sites in the southern hemisphere than above corresponding sites in the northern hemisphere)
• Salt basins, which also include perchlorates making them the closest analogues to Martian salts on Earth.

Yungay area

Atacama Desert

Atacama Desert (South America)

The Yungay area at the core of the Atacama Desert used to be considered the driest area on Earth for more than a decade, until the discovery in 2015 that Maria Elena South is drier. It can go centuries without rainfall, and parts of it have been hyper-arid for 150 million years. The older regions in this area have salts that are amongst the closest analogues of salts on Mars because these regions have nitrate deposits that contain not only the usual chlorides, but also sulfates, chlorates, chromates, iodates, and perchlorates. The infrared spectra are similar to the spectra of bright soil regions of Mars.

The Yungay area has been used for testing instruments intended for future life detection missions on Mars, such as the Sample Analysis at Mars instruments for Curiosity, the Mars Organic Analyzer for ExoMars, and Solid3 for Icebreaker Life, which in 2011, in a test of its capabilities, was able to find a new "microbial oasis" for life two meters below the surface of the Atacama desert. It is the current testing site for the Atacama Rover Astrobiology Drilling Studies (ARADS) project to improve technology and strategies for life detection on Mars.

Experiments conducted on Mars have also been successfully repeated in this region. In 2003, a group led by Chris McKay repeated the Viking Lander experiments in this region and got the same results as those of the Viking landers on Mars: decomposition of the organics by non-biological processes. The samples had trace elements of organics, no DNA was recovered, and extremely low levels of culturable bacteria. This led to increased interest in the site as a Mars analogue.

Although hardly any life, including plant or animal life, exists in this area, the Yungay area does have some microbial life, including cyanobacteria, both in salt pillars, as a green layer below the surface of rocks, and beneath translucent rocks such as quartz. The cyanobacteria in the salt pillars have the ability to take advantage of the moisture in the air at low relative humidities. They begin to photosynthesize when the relative humidity rises above the deliquescence relative humidity of salt, at 75%, presumably making use of deliquescence of the salts. Researchers have also found that cyanobacteria in these salt pillars can photosynthesize when the external relative humidity is well below this level, taking advantage of micropores in the salt pillars which raise the internal relative humidity above the external levels^.

Maria Elena South

This site is even drier than the Yungay area. It was found through a systematic search for drier regions than Yungay in the Atacama Desert, using relative humidity data loggers set up from 2008 to 2012, with the results published in 2015. The relative humidity is the same as the lowest relative humidity measured by Curiosity rover.

A 2015 paper reported  an average atmospheric relative humidity 17.3%, and soils relative humidity a constant 14% at depth of 1 meter, which corresponds to the lowest humidity measured by Curiosity rover on Mars. This region's maximum atmospheric relative humidity is 54.7% compared with 86.8% for the Yungay region.

The following living organisms were also found in this region:

• Actinomycetota: Actinobacterium, Aciditerrmonas, and Geodermatophilus
• Pseudomonadota: Caulobacter and Sphingomonas
• Bacillota: Clostridiales
• Acidobacteriota: Acidobacterium
• 16 new species of Streptomyces, 5 of Bacillus and 1 of Geodermatophilus.

There was no decrease in the numbers of species as the soil depth increased down to a depth of one meter, although different microbes inhabited different soil depths. There was no colonization of gypsum, showing the extreme dryness of the site.

No archaea was detected in this region using the same methods that detected archaea in other regions of the Atacama Desert. The researchers said that if this is confirmed in studies of similarly dry sites, it could mean that "there may be a dry limit for this domain of life on Earth."

McMurdo Dry Valleys in Antarctica

Researchers scout out field sites in Antarctica's Beacon Valley, one of McMurdo Dry Valleys, is one of the most Mars-like places on Earth in terms of cold and dryness.

These valleys lie on the edge of the Antarctic plateau. They are kept clear of ice and snow by fast katabatic winds that blow from the plateau down through the valleys. As a result, they are amongst the coldest and driest areas in the world.

The central region of Beacon Valley is considered to be one of the best terrestrial analogues for the current conditions on Mars. There is snowdrift and limited melting around the edges and occasionally in the central region, but for the most part, moisture is only found as thin films of brine around permafrost structures. It has slightly alkaline salt rich soil.

Don Juan Pond

Don Juan Pond is a small pond in Antarctica, 100 meters by 300 meters, and 10 cm deep, that is of great interest for studying the limits of habitability in general. Research using a time-lapse camera shows that it is partly fed by deliquescing salts. The salts absorb water by deliquescence only, at times of high humidity, then flows down the slope as salty brines. These then mix with snow melt, which feeds the lake. The first part of this process may be related to the processes that form the Recurring Slope Lineae (RSLs) on Mars.

This valley has an exceptionally low water activity (a_w) of 0.3 to 0.6. Though microbes have been retrieved from it, they have not been shown to be able to reproduce in the salty conditions present in the lake, and it is possible that they only got there through being washed in by the rare occasions of snow melt feeding the lake.

Blood Falls

Blood Falls seeps from the end of the Taylor Glacier into Lake Bonney. The tent at left provides a sense of scale

A schematic cross-section of Blood Falls showing how subglacial microbial communities have survived in cold, darkness, and absence of oxygen for a million years in brine water below Taylor Glacier.

This unusual flow of melt water from below the glacier gives scientists access to an environment they could otherwise only explore by drilling (which would also risk contaminating it). The melt water source is a subglacial pool of unknown size which sometimes overflows. Biogeochemical analysis shows that the water is marine in source originally. One hypothesis is that the source may be the remains of an ancient fjord that occupied the Taylor valley in the tertiary period. The ferrous iron dissolved in the water oxidizes as the water reaches the surface, turning the water red.

Its autotrophic bacteria metabolize sulfate and ferric ions. According to geomicrobiologist Jill Mikucki at the University of Tennessee, water samples from Blood Falls contained at least 17 different types of microbes and almost no oxygen. An explanation may be that the microbes use sulfate as a catalyst to respire with ferric ions and metabolize the trace levels of organic matter trapped with them. Such a metabolic process had never before been observed in nature. This process is of astrobiological importance as an analogue for environments below the Glaciers on Mars, if there is any liquid water there, for instance through hydrothermal melting (though none such has been discovered yet). This process is also an analogue for cryovolcanism in icy moons such as Enceladus.

Subglacial environments in Antarctica need similar protection protocols to interplanetary missions.

"7. Exploration protocols should also assume that the subglacial aquatic environments contain living organisms, and precautions should be adopted to prevent any permanent alteration of the biology (including introduction of alien species) or habitat properties of these environments.

28. Drilling fluids and equipment that will enter the subglacial aquatic environment should be cleaned to the extent practicable, and records should be maintained of sterility tests (e.g., bacterial counts by fluorescence microscopy at the drilling site). As a provisional guideline for general cleanliness, these objects should not contain more microbes than are present in an equivalent volume of the ice that is being drilled through to reach the subglacial environment. This standard should be re-evaluated when new data on subglacial aquatic microbial populations become available".

Blood Falls was used as the target for testing IceMole in November 2014. This is being developed in connection with the Enceladus Explorer (EnEx) project by a team from the FH Aachen in Germany. The test returned a clean subglacial sample from the outflow channel from Blood Falls. Ice Mole navigates through the ice by melting it, also using a driving ice screw, and using differential melting to navigate and for hazard avoidance. It is designed for autonomous navigation to avoid obstacles such as cavities and embedded meteorites, so that it can be deployed remotely on Encladus. It uses no drilling fluids, and can be sterilized to suit the planetary protection requirements as well as the requirements for subglacial exploration. The probe was sterilized to these protocols using hydrogen peroxide and UV sterilization. Also, only the tip of the probe samples the liquid water directly.

Qaidam Basin

David Rubin of the USGS Pacific Coastal and Marine Science Center at Qaidam Basin

At 4,500 metres (14,800 ft), Qaidam Basin is the plateau with highest average elevation on the Earth. The atmospheric pressure is 50% - 60% of sea level pressures, and as a result of the thin atmosphere it has high levels of UV radiation, and large temperature swings from day to night. Also, the Himalayas to the South block humid air from India, making it hyper arid.

In the most ancient playas (Da Langtang) at the north west of the plateau, the evaporated salts are magnesium sulfates (sulfates are common on Mars). This, combined with the cold and dryness conditions make it an interesting analogue of the Martian salts and salty regolith. An expedition found eight strains of Haloarchaea inhabiting the salts, similar to some species of Virgibacillus, Oceanobacillus, Halobacillus, and Ter-ribacillus.

Mojave Desert

Mojave Desert map

The Mojave Desert is a desert within the United States that is often used for testing Mars rovers. It also has useful biological analogues for Mars.

• Some arid conditions and chemical processes are similar to Mars.
• Has extremophiles within the soils.
• Desert varnish similar to Mars.
• Carbonate rocks with iron oxide coatings similar to Mars - niche for microbes inside and underneath the rocks, protected from the sun by the iron oxide coating, if microbes existed or exist on Mars they could be protected similarly by the iron oxide coating of rocks there.

Other analogue deserts

• Namib Desert - oldest desert, life with limited water and high temperatures, large dunes and wind features
• Ibn Battuta Centre Sites, Morocco - several sites in the Sahara desert that are analogues of some of the conditions on present day Mars, and used for testing of ESA rovers and astrobiological studies.

Axel Heiberg Island (Canada)

Two sites of special interest: Colour Peak and Gypsum Hill, two sets of cold saline springs on Axel Heiberg Island that flow with almost constant temperature and flow rate throughout the year. The air temperatures are comparable to the McMurdo Dry Valleys, range -15 °C to -20 °C (for the McMurdo Dry Valleys -15 °C to -40 °C). The island is an area of thick permafrost with low precipitation, leading to desert conditions. The water from the springs has a temperature of between -4 °C and 7 °C. A variety of minerals precipitate out of the springs including gypsum, and at Colour Peak crystals of the metastable mineral ikaite (CaCO
₃·6H
₂O) which decomposes rapidly when removed from freezing water.

"At these sites permafrost, frigid winter temperatures, and arid atmospheric conditions approximate conditions of present-day, as well as past, Mars. Mineralogy of the three springs is dominated by halite (NaCl), calcite (CaCO
₃), gypsum (CaSO
₄·2 H₂O), thenardite (Na
₂SO
₄), mirabilite (Na
₂SO
₄·10H
₂O), and elemental sulfur (S°).

Some of the extremophiles from these two sites have been cultured in simulated Martian environment, and it is thought that they may be able to survive in a Martian cold saline spring, if such exist.

Colour Lake Fen

This is another Mars analogue habitat in Axel Heiberg Island close to Colour Peak and Gypsum Hill. The frozen soil and permafrost hosts many microbial communities that are tolerant of anoxic, acid, saline and cold conditions. Most are in survival rather than colony forming mode. Colour Lake Fen is a good terrestrial analogue of the saline acidic brines that once existed in the Meridani Planum region of Mars and may possibly still exist on the martian surface. Some of the microbes found there are able to survive in Mars-like conditions.

"A martian soil survey in the Meridiani Planum region found minerals indicative of saline acidic brines. Therefore acidic cryosol/permafrost habitats may have once existed and are perhaps still extant on the martian surface. This site comprises a terrestrial analogue for these environments and hosts microbes capable of survival under these Mars-like conditions"

Rio Tinto, Spain

Rio Tinto is the largest known sulfide deposit in the world, and it is located in the Iberian Pyrite Belt. (IPB).

Riotintoagua

Many of the extremophiles that live in these deposits are thought to survive independently of the Sun. This area is rich in iron and sulfur minerals such as

• hematite (Fe
  ₂O
  ₃) which is common in the Meridiani Planum area of Mars explored by Opportunity rover and thought to be signs of ancient hot springs on Mars.

Jarosite, on quartz

• jarosite (KFe³⁺
  ₃(OH)
  ₆(SO
  ₄)
  ₂), discovered on Mars by Opportunity and on Earth forms either in acid mine drainage, during oxidation of sulphide minerals, and during alteration of volcanic rocks by acidic, sulphur-rich fluids near volcanic vents.

Permafrost soils

Much of the water on Mars is permanently frozen, mixed with the rocks. So terrestrial permafrosts are a good analogue. And some of the Carnobacterium species isolated from permafrosts have the ability to survive under the conditions of the low atmospheric pressures, low temperatures and CO
₂ dominated anoxic atmosphere of Mars.

Ice caves

Ice caves, or ice preserved under the surface in cave systems protected from the surface conditions, may exist on Mars. The ice caves near the summit of Mount Erebus in Antarctica, are associated with fumaroles in a polar alpine environments starved in organics and with oxygenated hydrothermal circulation in highly reducing host rock.

Cave systems

Mines on Earth give access to deep subsurface environments which turn out to be inhabited, and deep caves may possibly exist on Mars, although without the benefits of an atmosphere.

Basaltic lava tubes

The only caves found so far on Mars are lava tubes. These are insulated to some extent from surface conditions and may retain ice also when there is none left on the surface, and may have access to chemicals such as hydrogen from serpentization to fuel chemosynthetic life. Lava tubes on Earth have microbial mats, and mineral deposits inhabited by microbes. These are being studied to help with identification of life on Mars if any of the lava tubes there are inhabited.

Lechuguilla Cave

Further information: Lechuguilla Cave

First of the terrestrial sulfur caves to be investigated as a Mars analogue for sulfur based ecosystems that could possibly exist underground also on Mars. On Earth, these form when hydrogen sulfide from below the cave meets the surface oxygenated zone. As it does so, sulfuric acid forms, and microbes accelerate the process.

The high abundance of sulfur on Mars combined with presence of ice, and trace detection of methane suggest the possibility of sulfur caves below the surface of Mars like this.

Cueva de Villa Luz

The Snottites in the toxic sulfur cave Cueva de Villa Luz flourish on Hydrogen Sulfide gas and though some are aerobes (though only needing low levels of oxygen), some of these species (e.g. Acidianus), like those that live around hydrothermal vents, are able to survive independent of a source of oxygen. So the caves may give insight into subsurface thermal systems on Mars, where caves similar to the Cueva de Villa Luz could occur.

Movile Cave

Further information: Movile Cave

• Movile Cave is thought to have been isolated from the atmosphere and sunlight for 5.5 million years.
• Atmosphere rich in H
  ₂S and CO
  ₂ with 1% - 2% CH
  ₄ (methane)
• It does have some oxygen, 7-10% O
  ₂ in the cave atmosphere, compared to 21% O
  ₂ in the air
• Microbes rely mainly on sulfide and methane oxidation.
• Has 33 vertebrates and a wide range of indigenous microbes.

Magnesium sulfate lakes

Spotted Lake in British Columbia, Canada. Its sulfate concentrations are amongst the highest in the world. Every summer the water evaporated to form this pattern of interconnected brine pools separated by salt crusts.

Crystals of Meridianiite, formula Magnesium sulfate 11 hydrate MgSO
₄·11H
₂O. Evidence from orbital measurements show that this is the phase of Magnesium sulfate which would be in equilibrium with the ice in the Martian polar and sub polar regions It also occurs on the Earth, for instance in Basque Lake 2 in Western Columbia, which may give an analogue for Mars habitats.

Vugs on Mars which may be voids left by Meridianiite when it dissolved or dehydrated

Opportunity found evidence for magnesium sulfates on Mars (one form of it is epsomite, or "Epsom salts"), in 2004. Curiosity rover has detected calcium sulfates on Mars. Orbital maps also suggest that hydrated sulfates may be common on Mars. The orbital observations are consistent with iron sulfate or a mixture of calcium and magnesium sulfate.

Magnesium sulfate is a likely component of cold brines on Mars, especially with the limited availability of subsurface ice. Terrestrial magnesium sulfate lakes have similar chemical and physical properties. They also have a wide range of halophilic organisms, in all the three Kingdoms of life (Archaea, Bacteria and Eukaryota), in the surface and near subsurface. With the abundance of algae and bacteria, in alkaline hypersaline conditions, they are of astrobiological interest for both past and present life on Mars.

These lakes are most common in western Canada, and the northern part of Washington state, USA. One of the examples, is Basque Lake 2 in Western Canada, which is highly concentrated in magnesium sulfate. In summer it deposits epsomite ("Epsom salts"). In winter, it deposits meridianiite. This is named after Meridiani Planum where Opportunity rover found crystal molds in sulfate deposits (Vugs) which are thought to be remains of this mineral which have since been dissolved or dehydrated. It is preferentially formed at subzero temperatures, and is only stable below 2 °C, while Epsomite (MgSO
₄·7H
₂O) is favored at higher temperatures.

Another example is Spotted Lake, which shows a wide variety of minerals, most of them sulfates, with sodium, magnesium and calcium as cations.

"Dominant minerals included blöedite Na
₂Mg(SO
₄)
₂·4H
₂O, konyaite Na
₂Mg(SO
₄)
₂·5H
₂O, epsomite MgSO
₄·7H
₂O, and gypsumCaSO
₄·2H
₂O, with minor eugsterite, picromerite, syngenite, halite, and sylvite",

Some of the microbes isolated have been able to survive the high concentrations of magnesium sulfates found in Martian soils, also at low temperatures that may be found on Mars.

Sulfates (for instance of sodium, magnesium and calcium) are also common in other continental evaporates (such as the salars of the Atacama Desert), as distinct from salt beds associated with marine deposits which tend to consist mainly of halites (chlorides).

Subglacial lakes

Lake Vostok drill 2011

Subglacial lakes such as Lake Vostok may give analogues of Mars habitats beneath ice sheets. Sub glacial lakes are kept liquid partly by the pressure of the depth of ice, but that contributes only a few degrees of temperature rise. The main effect that keeps them liquid is the insulation of the ice blocking escape of heat from the interior of the Earth, similarly to the insulating effect of deep layers of rock. As for deep rock layers, they don't require extra geothermal heating below a certain depth.

In the case of Mars, the depth needed for geothermal melting of the basal area of a sheet of ice is 4-6 kilometers. The ice layers are probably only 3.4 to 4.2 km in thickness for the north polar cap. However, it was shown that the situation is different when considering a lake that is already melted. When they applied their model to Mars, they showed that a liquid layer, once melted (initially open to the surface of the ice), could remain stable at any depth over 600 meters even in absence of extra geothermal heating. According to their model, if the polar regions had a subsurface lake perhaps formed originally through friction as a subglacial lake at times of favourable axial tilt, then supplied by accumulating layers of snow on top as the ice sheets thickened, they suggest that it could still be there. If so, it could be occupied by similar life forms to those that could survive in Lake Vostok.

Ground penetrating radar could detect these lakes because of the high radar contrast between water and ice or rock. MARSIS, the ground penetrating radar on ESA's Mars Express detected a subglacial lake in Mars near the south pole.

Subsurface life kilometers below the surface

Investigations of life in deep mines, and drilling beneath the ocean depths may give an insight into possibilities for life in the Mars hydrosphere and other deep subsurface habitats, if they exist.

Mponeng gold mine in South Africa

Further information: Mponeng

• bacteria obtain their energy from hydrogen oxidation linked to sulfate reduction, living independent of the surface
• nematodes feeding on those bacteria, again living independent of the surface.
• 3 to 4 km depth

Boulby Mine on the edge of the Yorkshire moors

Further information: Boulby Mine

• 250 million year halite (chloride) and sulfate salts
• High salinity and low water activity
• 1.1. km depth
• Anaerobic microbes that could survive cut off from the atmosphere

Alpine and permafrost lichens

In high alpine and polar regions, lichens have to cope with conditions of high UV fluxes low temperatures and arid environments. This is especially so when the two factors, polar regions and high altitudes are combined. These conditions occur in the high mountains of Antarctica, where lichens grow at altitudes up to 2,000 meters with no liquid water, just snow and ice. Researchers described this as the most Mars-like environment on the Earth.

Genetic diversity

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Genetic_diversity 

A graphical representation of the typical human karyotype.

Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species, it ranges widely from the number of species to differences within species and can be attributed to the span of survival for a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary.

Genetic diversity serves as a way for populations to adapt to changing environments. With more variation, it is more likely that some individuals in a population will possess variations of alleles that are suited for the environment. Those individuals are more likely to survive to produce offspring bearing that allele. The population will continue for more generations because of the success of these individuals.

The academic field of population genetics includes several hypotheses and theories regarding genetic diversity. The neutral theory of evolution proposes that diversity is the result of the accumulation of neutral substitutions. Diversifying selection is the hypothesis that two subpopulations of a species live in different environments that select for different alleles at a particular locus. This may occur, for instance, if a species has a large range relative to the mobility of individuals within it. Frequency-dependent selection is the hypothesis that as alleles become more common, they become more vulnerable. This occurs in host–pathogen interactions, where a high frequency of a defensive allele among the host means that it is more likely that a pathogen will spread if it is able to overcome that allele.

Within-species diversity

Varieties of maize in the office of the Russian plant geneticist Nikolai Vavilov

A study conducted by the National Science Foundation in 2007 found that genetic diversity (within-species diversity) and biodiversity are dependent upon each other — i.e. that diversity within a species is necessary to maintain diversity among species, and vice versa. According to the lead researcher in the study, Dr. Richard Lankau, "If any one type is removed from the system, the cycle can break down, and the community becomes dominated by a single species." Genotypic and phenotypic diversity have been found in all species at the protein, DNA, and organismal levels; in nature, this diversity is nonrandom, heavily structured, and correlated with environmental variation and stress.

The interdependence between genetic and species diversity is delicate. Changes in species diversity lead to changes in the environment, leading to adaptation of the remaining species. Changes in genetic diversity, such as in loss of species, leads to a loss of biological diversity. Loss of genetic diversity in domestic animal populations has also been studied and attributed to the extension of markets and economic globalization.

Neutral and adaptive genetic diversity

Neutral genetic diversity consists of genes that do not increase fitness and are not responsible for adaptability. Natural selection does not act on these neutral genes. Adaptive genetic diversity consists of genes that increase fitness and are responsible for adaptability to changes in the environment. Adaptive genes are responsible for ecological, morphological, and behavioral traits. Natural selection acts on adaptive genes which allows the organisms to evolve. The rate of evolution on adaptive genes is greater than on neutral genes due to the influence of selection. However, it has been difficult to identify alleles for adaptive genes and thus adaptive genetic diversity is most often measured indirectly. For example, heritability can be measured as ${\displaystyle h^2=V_A/V_P}$ or adaptive population differentiation can be measured as ${\displaystyle Q_{ST}=V_G/(V_G+2V_A)}$. It may be possible to identify adaptive genes through genome-wide association studies by analyzing genomic data at the population level.

Identifying adaptive genetic diversity is important for conservation because the adaptive potential of a species may dictate whether it survives or becomes extinct, especially as the climate changes. This is magnified by a lack of understanding whether low neutral genetic diversity is correlated with high genetic drift and high mutation load. In a review of current research, Teixeira and Huber (2021), discovered some species, such as those in the genus Arabidopsis, appear to have high adaptive potential despite suffering from low genetic diversity overall due to severe bottlenecks. Therefore species with low neutral genetic diversity may possess high adaptive genetic diversity, but since it is difficult to identify adaptive genes, a measurement of overall genetic diversity is important for planning conservation efforts and a species that has experienced a rapid decline in genetic diversity may be highly susceptible to extinction.

Evolutionary importance of genetic diversity

Adaptation

Variation in the populations gene pool allows natural selection to act upon traits that allow the population to adapt to changing environments. Selection for or against a trait can occur with changing environment – resulting in an increase in genetic diversity (if a new mutation is selected for and maintained) or a decrease in genetic diversity (if a disadvantageous allele is selected against). Hence, genetic diversity plays an important role in the survival and adaptability of a species. The capability of the population to adapt to the changing environment will depend on the presence of the necessary genetic diversity The more genetic diversity a population has, the more likelihood the population will be able to adapt and survive. Conversely, the vulnerability of a population to changes, such as climate change or novel diseases will increase with reduction in genetic diversity. For example, the inability of koalas to adapt to fight Chlamydia and the koala retrovirus (KoRV) has been linked to the koala's low genetic diversity. This low genetic diversity also has geneticists concerned for the koalas' ability to adapt to climate change and human-induced environmental changes in the future.

Small populations

Large populations are more likely to maintain genetic material and thus generally have higher genetic diversity. Small populations are more likely to experience the loss of diversity over time by random chance, which is an example of genetic drift. When an allele (variant of a gene) drifts to fixation, the other allele at the same locus is lost, resulting in a loss in genetic diversity. In small population sizes, inbreeding, or mating between individuals with similar genetic makeup, is more likely to occur, thus perpetuating more common alleles to the point of fixation, thus decreasing genetic diversity. Concerns about genetic diversity are therefore especially important with large mammals due to their small population size and high levels of human-caused population effects.

A genetic bottleneck can occur when a population goes through a period of low number of individuals, resulting in a rapid decrease in genetic diversity. Even with an increase in population size, the genetic diversity often continues to be low if the entire species began with a small population, since beneficial mutations (see below) are rare, and the gene pool is limited by the small starting population. This is an important consideration in the area of conservation genetics, when working toward a rescued population or species that is genetically healthy.

Mutation

Random mutations consistently generate genetic variation. A mutation will increase genetic diversity in the short term, as a new gene is introduced to the gene pool. However, the persistence of this gene is dependent of drift and selection (see above). Most new mutations either have a neutral or negative effect on fitness, while some have a positive effect. A beneficial mutation is more likely to persist and thus have a long-term positive effect on genetic diversity. Mutation rates differ across the genome, and larger populations have greater mutation rates. In smaller populations a mutation is less likely to persist because it is more likely to be eliminated by drift.

Gene flow

Gene flow, often by migration, is the movement of genetic material (for example by pollen in the wind, or the migration of a bird). Gene flow can introduce novel alleles to a population. These alleles can be integrated into the population, thus increasing genetic diversity.

For example, an insecticide-resistant mutation arose in Anopheles gambiae African mosquitoes. Migration of some A. gambiae mosquitoes to a population of Anopheles coluzziin mosquitoes resulted in a transfer of the beneficial resistance gene from one species to the other. The genetic diversity was increased in A. gambiae by mutation and in A. coluzziin by gene flow.

In agriculture

In crops

When humans initially started farming, they used selective breeding to pass on desirable traits of the crops while omitting the undesirable ones. Selective breeding leads to monocultures: entire farms of nearly genetically identical plants. Little to no genetic diversity makes crops extremely susceptible to widespread disease; bacteria morph and change constantly and when a disease-causing bacterium changes to attack a specific genetic variation, it can easily wipe out vast quantities of the species. If the genetic variation that the bacterium is best at attacking happens to be that which humans have selectively bred to use for harvest, the entire crop will be wiped out.

The nineteenth-century Great Famine in Ireland was caused in part by a lack of biodiversity. Since new potato plants do not come as a result of reproduction, but rather from pieces of the parent plant, no genetic diversity is developed, and the entire crop is essentially a clone of one potato, it is especially susceptible to an epidemic. In the 1840s, much of Ireland's population depended on potatoes for food. They planted namely the "lumper" variety of potato, which was susceptible to a rot-causing oomycete called Phytophthora infestans. The fungus destroyed the vast majority of the potato crop, and left one million people to starve to death.

Genetic diversity in agriculture does not only relate to disease, but also herbivores. Similarly, to the above example, monoculture agriculture selects for traits that are uniform throughout the plot. If this genotype is susceptible to certain herbivores, this could result in the loss of a large portion of the crop. One way farmers get around this is through inter-cropping. By planting rows of unrelated, or genetically distinct crops as barriers between herbivores and their preferred host plant, the farmer effectively reduces the ability of the herbivore to spread throughout the entire plot.

In livestock

The genetic diversity of livestock species permits animal husbandry in a range of environments and with a range of different objectives. It provides the raw material for selective breeding programmes and allows livestock populations to adapt as environmental conditions change.

Livestock biodiversity can be lost as a result of breed extinctions and other forms of genetic erosion. As of June 2014, among the 8,774 breeds recorded in the Domestic Animal Diversity Information System (DAD-IS), operated by the Food and Agriculture Organization of the United Nations (FAO), 17 percent were classified as being at risk of extinction and 7 percent already extinct. There is now a Global Plan of Action for Animal Genetic Resources that was developed under the auspices of the Commission on Genetic Resources for Food and Agriculture in 2007, that provides a framework and guidelines for the management of animal genetic resources.

Awareness of the importance of maintaining animal genetic resources has increased over time. FAO has published two reports on the state of the world's animal genetic resources for food and agriculture, which cover detailed analyses of our global livestock diversity and ability to manage and conserve them.

Viral implications

High genetic diversity in viruses must be considered when designing vaccinations. High genetic diversity results in difficulty in designing targeted vaccines, and allows for viruses to quickly evolve to resist vaccination lethality. For example, malaria vaccinations are impacted by high levels of genetic diversity in the protein antigens. In addition, HIV-1 genetic diversity limits the use of currently available viral load and resistance tests.

Coronavirus populations have considerable evolutionary diversity due to mutation and homologous recombination. For example, the sequencing of 86 SARS-CoV-2 coronavirus samples obtained from infected patients revealed 93 mutations indicating the presence of considerable genetic diversity. Replication of the coronavirus RNA genome is catalyzed by an RNA-dependent RNA polymerase. During replication this polymerase may undergo template switching, a form of homologous recombination. This process which also generates genetic diversity appears to be an adaptation for coping with RNA genome damage.

Coping with low genetic diversity

A Tanzanian cheetah.

Natural

Photomontage of planktonic organisms.

The natural world has several ways of preserving or increasing genetic diversity. Among oceanic plankton, viruses aid in the genetic shifting process. Ocean viruses, which infect the plankton, carry genes of other organisms in addition to their own. When a virus containing the genes of one cell infects another, the genetic makeup of the latter changes. This constant shift of genetic makeup helps to maintain a healthy population of plankton despite complex and unpredictable environmental changes.

Cheetahs are a threatened species. Low genetic diversity and resulting poor sperm quality has made breeding and survivorship difficult for cheetahs. Moreover, only about 5% of cheetahs survive to adulthood However, it has been recently discovered that female cheetahs can mate with more than one male per litter of cubs. They undergo induced ovulation, which means that a new egg is produced every time a female mates. By mating with multiple males, the mother increases the genetic diversity within a single litter of cubs.

Human intervention

Attempts to increase the viability of a species by increasing genetic diversity is called genetic rescue. For example, eight panthers from Texas were introduced to the Florida panther population, which was declining and suffering from inbreeding depression. Genetic variation was thus increased and resulted in a significant increase in population growth of the Florida Panther. Creating or maintaining high genetic diversity is an important consideration in species rescue efforts, in order to ensure the longevity of a population.

Measures

Genetic diversity of a population can be assessed by some simple measures.

• Gene diversity is the proportion of polymorphic loci across the genome.
• Heterozygosity is the fraction of individuals in a population that are heterozygous for a particular locus.
• Alleles per locus is also used to demonstrate variability.
• Nucleotide diversity is the extent of nucleotide polymorphisms within a population, and is commonly measured through molecular markers such as micro- and minisatellite sequences, mitochondrial DNA, and single-nucleotide polymorphisms (SNPs).

Furthermore, stochastic simulation software is commonly used to predict the future of a population given measures such as allele frequency and population size.

Genetic diversity can also be measured. The various recorded ways of measuring genetic diversity include:

• Species richness is a measure of the number of species
• Species abundance a relative measure of the abundance of species
• Species density an evaluation of the total number of species per unit area

Wolf reintroduction

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Wolf_reintroduction

Wolf #10, a male, in the Rose Creek acclimation pen, Yellowstone National Park

Wolf reintroduction involves the reintroduction of a portion of grey wolves in areas where native wolves have been extirpated. More than 30 subspecies of Canis lupus have been recognized, and grey wolves, as colloquially understood, comprise nondomestic/feral subspecies. Reintroduction is only considered where large tracts of suitable wilderness still exist and where certain prey species are abundant enough to support a predetermined wolf population.

United States

Arizona and New Mexico

Captive-bred Mexican wolf in pen, Sevilleta National Wildlife Refuge

Further information: Mexican wolf

The five last known wild Mexican gray wolves were captured in 1980 in accordance with an agreement between the United States and Mexico intended to save the critically endangered subspecies. Between 1982 and 1998, a comprehensive captive-breeding program brought Mexican wolves back from the brink of extinction. Over 300 captive Mexican wolves were part of the recovery program.

The ultimate goal for these wolves is to reintroduce them to areas of their former range. In March 1998, this reintroduction campaign began with the releasing of three packs into the Apache-Sitgreaves National Forest in Arizona, and 11 wolves into the Blue Range Wilderness Area of New Mexico. By 2014, as many as 100 wild Mexican wolves were in Arizona and New Mexico. The final goal for Mexican wolf recovery is a wild, self-sustaining population of at least 300 individuals. In 2021, 186 wolves were counted in the annual survey, of which 114 wolves were spotted in New Mexico and the other 72 in Arizona. This shows a steady growth throughout the last 5 years.

Distribution and population

As of March 2024, there were at least 257 wild Mexican wolves in the United States: 144 in New Mexico (36 packs), and 113 in Arizona (20 packs). This represents 8 years of consecutive population growth. The total captive Mexican wolf population is 380 individuals, across over 60 facilities.

Colorado

Further information: Repopulation of wolves in Colorado

Wolves traversed a Rocky Mountain pathway from Canada to Mexico until the 1940s. They are seen by wildlife experts as essential to the native balance of species, species interactions, and ecosystem health. Colorado Parks and Wildlife (CPW) created a multidisciplinary working group that drafted a wolf management plan for possible reintroduction. The Colorado Wildlife Commission approved the plan in May 2005.

Proposition 114, a ballot initiative to introduce wolves on the Western Slope by 2023, was narrowly approved by voters in November 2020. The Colorado Parks and Wildlife Commission was tasked with preparing a plan.

In late December 2023, the first wolves were released onto public land in Summit and Grand counties. The 10 wolves were translocated from Oregon. The group consisted of two adult male, two juvenile males, and six juvenile females.

Northern Rocky Mountains

See also: History of wolves in Yellowstone

Map showing wolf packs in the Greater Yellowstone Ecosystem as of 2002.

Grey wolf packs were reintroduced to Yellowstone National Park and Idaho starting in 1995. These wolves were considered as “experimental, nonessential” populations per article 10(j) of the Endangered Species Act (ESA). Such classification gave government officials greater leeway in managing wolves to protect livestock, which was considered one of a series of compromises wolf reintroduction proponents made with concerned local ranchers.

Local industry and environmental groups battled for decades over the Yellowstone and Idaho wolf reintroduction effort. The idea of wolf reintroduction was first brought to Congress in 1966 by biologists who were concerned with the critically high elk populations in Yellowstone and the ecological damages to the land from excessively large herds. Officially, 1926 was when the last wolves were killed within Yellowstone’s boundaries. When the wolves were eradicated and hunting eliminated, the elk population boomed. Over the succeeding decades, elk populations grew so large that they unbalanced the local ecosystem. The number of elk and other large prey animals increased to the point that they gathered in large herds along valley bottoms and meadows, overgrazing new-growth vegetation. Because of overgrazing, deciduous woody plant species, such as upland aspen and riparian cottonwood, became seriously diminished. So, because the keystone predators, the wolves, had been removed from the Yellowstone-Idaho ecosystem, the ecosystem changed. This change affected other species as well. Coyotes filled in the niche left by wolves, but could not control the large ungulate populations. Booming coyote numbers, furthermore, also had a negative effect on other species, particularly the red fox, pronghorn, and domestic sheep. Ranchers, though, remained steadfastly opposed to reintroducing a species of animal that they considered to be analogous to a plague, citing the hardships that would ensue with the potential loss of stock caused by wolves.

The government, which was charged with creating, implementing, and enforcing a compromise, struggled for over two decades to find middle ground. A wolf recovery team was appointed in 1974, and the first official recovery plan was released for public comment in 1982. General public apprehension regarding wolf recovery forced the U.S. Fish and Wildlife Service to revise their plan to implement more control for local and state governments, so a second recovery plan was released for public comment in 1985. That same year, a poll conducted at Yellowstone National Park showed that 74% of visitors thought wolves would improve the park, while 60% favored reintroducing them. The preparation of an environmental impact statement (EIS), the last critical step before reintroduction could be approved, was halted when Congress insisted that further research be done before an EIS was to be funded.

People look on as the grey wolves are trucked through Roosevelt Arch, Yellowstone National Park, January 1995.

In 1987, in an effort to shift the burden of financial responsibility from ranchers to the proponents of wolf reintroduction, Defenders of Wildlife set up a "wolf compensation fund" that would use donations to pay ranchers market value for any stock that was lost to wolf depredation. That same year, a final recovery plan was released. Following a long period of research, public education, and public commenting, a draft EIS was released for public review in 1993, and it received over 150,000 comments from interested parties. It was finalized in May 1994, and included a clause that specified that all wolves reintroduced to the recovery zones would be classified under the "experimental, nonessential" provision of the ESA. Though the original plan called for three recovery zones – one in Idaho, another in Montana, and a final one in the greater Yellowstone area – the Montana recovery zone was eliminated from the final EIS after it had been proven that a small, but breeding population had already established itself in the northwestern part of the state. The plan stipulated that each of the three recovery areas must have 10 breeding pairs of wolves successfully rearing two or more pups for three consecutive years before the minimum recovery goals would be reached.

Reintroduced wolves being carried to acclimation pens, Yellowstone National Park, January 1995

Two lawsuits filed in late 1994 put the recovery plan in jeopardy. While one of the lawsuits was filed by the Wyoming Farm Bureau, the other was filed by a coalition of concerned environmental groups including the Idaho Conservation League and Audubon Society. The latter group pointed to unofficial wolf sightings as proof that wolves had already migrated down to Yellowstone from the north, which, they argued, made the plan to reintroduce an experimental population in the same area unlawful. According to their argument, if wolves were already present in Yellowstone, they should rightfully be afforded full protection under the ESA, which, they reasoned, was preferable to the limited "experimental" classification that would be given to any reintroduced wolves.

Nevertheless, both cases were thrown out on January 3, 1995. Adolescent members from packs of Mackenzie Valley wolves in Alberta, Canada, were tranquilized and carted down to the recovery zones later that week, but a last-minute court order delayed the planned releases. The stay came from an appellate court in Denver, and was instigated by the Wyoming Farm Bureau. After spending an additional 36 hours in transport cages in Idaho and in their holding pens in Yellowstone, the wolves were finally released following official judicial sanction. Yellowstone's wolves stayed in acclimation pens for two more months before being released into the wild. Idaho's wolves, conversely, were given a hard (or immediate) release. Sixty-six wolves were released to the two areas in this manner in January 1995 and January 1996.

The 2005 estimates of wolf populations in the two recovery zones reflect the success the species has had in both areas:

• Greater Yellowstone area: 325
• Central Idaho: 565

These numbers, added with the estimated number of wolves in northwestern Montana (130), puts the total number of wolves in the Northern Rocky Mountains recovery area at over 1000 individuals. This includes about 134 packs (two or more wolves traveling together) and 71 breeding pairs (male and female that successfully rear a litter of at least two until Dec. 31). The recovery goal for the area was revised to 30 breeding pairs total, and this number has been surpassed for some time.

Current wolf population statistics can be found at http://www.fws.gov/mountain-prairie/species/mammals/wolf/

Over the decades since wolves have been present in the region, hundreds of incidents of livestock depredation have been confirmed, though such predation represents a minute proportion of a wolf's diet on a per-wolf basis. While the majority of wolves ignore livestock entirely, a few wolves or wolf packs become chronic livestock hunters, and most of these have been killed to protect livestock. Since the year Defenders of Wildlife implemented their compensation fund, they have allocated over $1,400,000 to private owners for proven and probable livestock depredation by wolves. Opponents argue that the Yellowstone reintroductions were unnecessary, as American wolves were never in danger of biological extinction, since wolves still persisted in Canada. Opponents have also stated that wolves are of little commercial benefit, as cost estimates on wolf recovery are from $200,000 to $1 million per wolf. The Lamar Valley is one of the best places in the world to observe wolves, though, and tourism based on wolves is booming. The growing wolf-viewing outfitting trend contrasts with declines for big-game hunters. National Park Service Biologist Wayne Brewster informed guides and outfitters living north of Yellowstone National Park, to expect a 50% drop in harvestable game when wolves were reintroduced to Yellowstone National Park. This was confirmed when in 2006, the Yellowstone elk herd had in fact shrunk to 50% since the mid 1990s, though researchers documented that most of the elk that fell prey to wolves were very old, diseased, or very young. Two 30-day periods of tracking radio-collared wolves showed that 77–97% of prey species documented by wolves in the park were elk. Outside the park, numerous hunting outfitters have closed due to the concomitant 90% reduction in elk permits. Defenders of Wildlife transitioned from paying compensation to helping ranchers use nonlethal methods to better protect livestock from wolf predation. These methods include carcass removal to reduce attractants to scavengers, increased human presence near livestock, lighting, herd management, livestock guard dogs, and other measures (see http://www.defenders.org/sites/default/files/publications/livestock_and_wolves.pdf for more information).

The reintroduction of wolves, an apex predator, has had important impacts on biodiversity within Yellowstone National Park. Through predation of elk populations, wolf reintroduction has coincided with an increase of new-growth vegetation among certain plants, such as aspen and willow trees, which elk previously grazed upon at unsustainable levels. Presence of wolves has even changed behavioral patterns of other animals. Elk have quit venturing into deeper thickets, out of fear of being attacked by wolves in an area of such low visibility. Elk have also begun avoiding open areas such as valley bottoms and open meadows, where prior to wolf introduction, the elk grazed collectively and avoided predation from mountain lions and bears. This process of top predators regulating the lower sections of the trophic pyramid was dubbed, "the ecology of fear" by William J. Ripple and Robert L. Bestcha In addition to the restoration of vegetation several important species, such as the beaver (which also became extinct in the park) and red fox have also recovered, probably due to the wolves keeping coyote populations under control.

The Idaho state government opposed the reintroduction of wolves into the state, and many ranchers and hunters there feel as if the wolves were forced onto the state by the federal government. The state's wolf management plan is prefaced by the legislature's memorial declaring that the official position of the state is the removal of all wolves by any means necessary. Because of the state of Idaho's refusal to participate in wolf restoration, the US Fish and Wildlife Service (FWS) and the Nez Perce tribe initially managed the wolf population there since the reintroduction. During that time, the Idaho wolf population had made the most remarkable comeback in the region, with its abundant federal lands and wilderness areas peaking at nearly 900 wolves (almost half of the regional wolf population) in 2009. However, the wolves have increasingly been blamed for livestock and hunting opportunity losses. The FWS attempted twice to delist wolves from federal protection and turn them over to state management, but both of those attempts were found unlawful by the federal court in Missoula, Montana. To quell the political battle between the ranchers, hunters, and conservationists, members of Congress removed Endangered Species Act protection from wolves in 2011 and gave wolf management to the states of Idaho and Montana under state wolf management plans. Since that time, the FWS has also delisted wolves from federal protection in Wyoming, and the state now has authority over wolf management there, as well. This decision is also being challenged as unlawful in court in 2013.

Despite being approved by the FWS, Idaho’s proposed management plan is still shrouded in controversy. The plan calls for 10 breeding pairs in Idaho or 100 to 150 wolves. Compared with the state's other wildlife numbers (e.g. 2000-3000 mountain lions, 20,000 American black bears, 100,000 elk, and several hundred thousand mule deer), conservationists are concerned that too few wolves are protected under the plan. According to the FWS guidelines, the Idaho wolf population needs to stay above 100 individuals for the species to stay off the endangered species list and remain a viable, self-sustaining population, but much evidence shows that a much larger wolf population can survive in Idaho without having major impacts on livestock and hunting opportunities.

In adjacent Washington, wolves were not reintroduced, but populations have been re-established through the natural expansion of the Idaho population. By 2008, wolves had established a permanent toehold in Washington, and have increased their number every year since. The Washington Department of Fish and Wildlife tracks the "minimum numbers" of wolves. This number only counts wolves in known packs that den inside the state. Lone wolves, suspected packs, and packs that range into the state but den outside it are not counted. In 2008, this "minimum number" was five; by the end of 2014, it was 68. Known wolf packs are concentrated in the northeastern corner of the state, but packs occur also in the central Cascades. In 2015, a wolf was killed on Interstate 90, about 10 mi west of the Snoqualmie Pass, proving the wolves are expanding westward.

Current Distribution and Population

As of March 2023, the Northern Rocky Mountains gray wolf population is now distributed across western Montana (1,100 wolves), western Wyoming (311 wolves), Idaho (1,337 wolves), eastern Washington (206 wolves), and Eastern Oregon (175 wolves). There is a small presence in northern California (30 wolves) and in December 2023, a small population was released in northern Colorado to complement the small number of wolves that had naturally dispersed into the state (16 wolves).

Great Smoky Mountains National Park

Red wolves were once native to the Southeastern United States, but the last wolf seen in the vicinity of the park was in 1905. In 1991, two pairs were reintroduced into the Great Smoky Mountains National Park. Despite some early success, the program was cancelled in 1998 due to the death of wolf pups from malnutrition and disease, and the wolves roaming beyond the boundaries of the park. The wolves were relocated to North Carolina in 1998, ending the effort to reintroduce the species to the park.

North and South Carolina

Canis rufus walking in a forest

Further information: Red wolf

In December 1976, two red wolves were released onto Cape Romain National Wildlife Refuge's Bulls Island in South Carolina with the intent of testing and honing reintroduction methods. They were not released with the intent of beginning a permanent population on the island. The first experimental translocation lasted for 11 days, during which a mated pair of red wolves was monitored day and night with remote telemetry. A second experimental translocation was tried in 1978, with a different mated pair, and they were allowed to remain on the island for close to 9 months. After that, a larger project was executed in 1987 to reintroduce a permanent population of red wolves back to the wild in the Alligator River National Wildlife Refuge (ARNWR) on the eastern coast of North Carolina. Also in 1987, Bulls Island became the first island breeding site. Pups were raised on the island and relocated to North Carolina until 2005.

In September 1987, four pairs of red wolves were released in ARNWR in northeastern North Carolina and designated as an experimental population. Since then, the experimental population has grown and the recovery area expanded to include four national wildlife refuges, a Department of Defense bombing range, state-owned lands, and private lands, encompassing about 1,700,000 acres (6,900 km²).

According to the Red Wolf Recovery Program First Quarter Report (October–December 2010), the FWS estimated that 110-130 red wolves were in the Red Wolf Recovery Area in North Carolina, but since not all of the newly bred-in-the-wild red wolves have radio collars, they can only confirm a total of 70 "known" individuals, 26 packs, 11 breeding pairs, and 9 additional individuals not associated with a pack.

Interbreeding with the coyote has been recognized as a threat affecting the restoration of red wolves. Currently, adaptive management efforts are making progress in reducing the threat of coyotes to the red wolf population in northeastern North Carolina. Other threats, such as habitat fragmentation, disease, and anthropogenic mortality, are of concern in their restoration. Efforts to reduce the threats are presently being explored.

Over 30 facilities participate in the red wolf Species Survival Plan, and oversee the breeding and reintroduction of over 150 wolves.

However, relaxed protections and a halt of reintroductions in the early 2010s led to a plummet in the population due to poaching and vehicle collisions. The wild population declined from approximately 130 individuals in 2010 to less than 10 individuals by 2021. No wild litters were born between 2019 and 2021.

Under pressure from conservation groups, the US Fish and Wildlife Service resumed reintroductions and increased protection. Reintroductions resumed in 2021. In 2022, the first wild litter was born since 2018. As of 2023, there are between 15 and 17 wild red wolves in ARNWR.

Gulf Coast

In 1989, the second island propagation project was initiated with release of a population of red wolves on Horn Island off the Mississippi coast. This population was removed in 1998 because of a likelihood of encounters with humans. The third island propagation project introduced a population on St. Vincent Island, Florida, offshore between Cape San Blas and Apalachicola, Florida, in 1990, and in 1997, the fourth island propagation program introduced a population to Cape St. George Island, Florida, south of Apalachicola.

New York

An official analysis of wolves in New York by the New York State Department of Environmental Conservation (DEC) stated that, due to the adaptability of wolves to different habitats, there exists a significant amount of area (about 6,000 square miles (16,000 km²) of the Adirondacks) in the state suitable for wolves, and that the best course of action for the organization would be to reintroduce the species. Despite no confirmed breeding population, wolves are still listed as Endangered in the state, and are a protected species under Environmental Conservation Law (ECL) section 11-0535. An interview with DEC biologists in 2015 explained that three extirpated carnivores (wolves, cougars, and Canada lynx) were removed from the state's proposed list of Species of Greatest Conservation Need in order to focus on extant species within the state, and that there were no plans by the DEC to reintroduce wolves, citing a lack of public and state support, funding, and personnel. They also highlighted that, even with all these factors, the type of wolves that would be brought in would be unknown, since records cite both the eastern wolf and red wolf as present in the state; the two canines have ongoing taxonomic discussions.

DNA results of a canid killed near Cherry Valley in 2021 initially pointed to it being an eastern coyote, but a recent statement by the DEC confirms the animal was a wolf, with most of its ancestry matching wolves in Michigan; the DEC also has not confirmed or denied a breeding population within the state. Certain proponents of wolf recolonization state that wolves are already established in New York and New England, and have naturally dispersed from Canada by crossing the frozen St. Lawrence River.

Mexico

Further information: Mexican wolf

Sonora and Chihuahua

On October 11, 2011, 5 Mexican wolves (2 males and 3 females) were released into Sonora's Madrean Sky Islands. Since then, Mexico's National Commission of Natural Protected Areas (CONANP) has facilitated 19 wolf releases into the country.

On March 9, 2022, two new breeding pairs of Mexican gray wolves were released into the wild in the state of Chihuahua in northern Mexico, bringing the total number of Mexican gray wolves in the country to around 45 wild individuals.

Europe

Northern Europe

In Sweden and Norway, a long and ongoing conflict is happening between some groups whose belief it is that wolves have no place in human-inhabited areas and those who wish the wolf to be allowed to expand out into more of the area’s vast boreal forests. The former mostly consists of members of the rural working class who fear competition for certain large ungulate species (roe deer, moose, etc.), and who consider the wolf to be a foreign element. They argue that modern Scandinavian wolves are actually recent migrants from Russia and not the remnants of old native wolf packs.

Scandinavian wolves had been nearly completely eliminated from the range due to extirpation campaigns in the 19th and 20th centuries, and were considered to be gone from the area by the 1960s. In the early 1980s, however, a single breeding pack was discovered in southern Sweden, over 1000 km away from the nearest known population in Russia or eastern Finland. The pack was small, about 10 animals, and it stayed that way for many years until its population began to noticeably increase starting in 1991. Prior to 1991, the small population lacked ideal genetic diversity, and inbreeding had been occurring to a potentially dangerous degree. Furthermore, low birth rates suggested that the wolves were apprehensive to mate with each other, which was most likely due to their close relation. Genetic data suggest that in 1991, a lone immigrant wolf from Russia migrated to the area and single-handedly restored genetic diversity to the population. A study showed that of the 72 wolves born between 1993 and 2001, 68 of them could trace their genetic heritage to this lone migrant wolf. Today, over 100 individuals range across this southern area of Scandinavia. The population remains genetically isolated, however, which is a cause of concern for some, but reason to believe exists that as the number of wolves living in this area increases, the boundaries of the population's range will creep towards the ranges of other, separate populations in Finland, thus promoting dispersal. Direct reintroduction remains an intriguing option to foster genetic diversity in the Scandinavian population in the meantime.

Speculation arose as to how the original population came to be in the early 1980s. Some believe that they might be a native species – remnants of a population that somehow survived persecution. Much genetic research has been performed on this population, however, and this particular theory is not supported by the findings. Genetic analysis seems to support the idea that the wolves were immigrants that had traveled over 1000 km from Russia to southern Scandinavia along one of several possible dispersal routes. Conspiracy theorists claim that they were artificially reintroduced by some secret agenda of the Swedish government.

Central and Western Europe

Further information: Wolves in Great Britain and Wolves in Ireland

In several areas in Europe, reintroduction of wolves to areas where they have become extinct is being actively considered. Charities in many European countries, including Denmark, Germany, Italy, Ireland, and the United Kingdom, are also advocating the reintroduction of wolves to specific rural and forested areas. Most plans have been met with a mixture of enthusiasm and unease by different population groups. Opponents fear the loss of livestock that may result from their reintroduction. In several countries, charity-based compensation plans (similar to those that operate in the USA) have been proposed.

The reintroduction of wolves to Scotland and England is currently being considered, along with bears and lynxes, as part of a larger effort to reintroduce native species to the country.