Environmental degradation

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Environmental_degradation

More than eighty years after the abandonment of Wallaroo Mines (Kadina, South Australia), mosses remain the only vegetation in some areas of the site's grounds.

Environmental degradation is the deterioration of the environment through depletion of resources such as quality of air, water and soil; the destruction of ecosystems; habitat destruction; the extinction of wildlife; and pollution. It is defined as any change or disturbance to the environment perceived to be deleterious or undesirable. The environmental degradation process amplifies the impact of environmental issues which leave lasting impacts on the environment.

Environmental degradation is one of the ten threats officially cautioned by the High-level Panel on Threats, Challenges and Change of the United Nations. The United Nations International Strategy for Disaster Reduction defines environmental degradation as "the reduction of the capacity of the environment to meet social and ecological objectives, and needs".

Environmental degradation comes in many types. When natural habitats are destroyed or natural resources are depleted, the environment is degraded; direct environmental degradation, such as deforestation, which is readily visible; this can be caused by more indirect process, such as the build up of plastic pollution over time or the buildup of greenhouse gases that causes tipping points in the climate system. Efforts to counteract this problem include environmental protection and environmental resources management. Mismanagement that leads to degradation can also lead to environmental conflict where communities organize in opposition to the forces that mismanaged the environment.

Biodiversity loss

See also: Biodiversity loss, Defaunation, and Holocene extinction

Deforestation in Europe, 2018. Almost all of Europe's original forests have been destroyed.

Scientists assert that human activity has pushed the earth into a sixth mass extinction event. The loss of biodiversity has been attributed in particular to human overpopulation, continued human population growth and overconsumption of natural resources by the world's wealthy. A 2020 report by the World Wildlife Fund found that human activity – specifically overconsumption, population growth and intensive farming – has destroyed 68% of vertebrate wildlife since 1970. The Global Assessment Report on Biodiversity and Ecosystem Services, published by the United Nation's IPBES in 2019, posits that roughly one million species of plants and animals face extinction from anthropogenic causes, such as expanding human land use for industrial agriculture and livestock rearing, along with overfishing.

Since the establishment of agriculture over 11,000 years ago, humans have altered roughly 70% of the Earth's land surface, with the global biomass of vegetation being reduced by half, and terrestrial animal communities seeing a decline in biodiversity greater than 20% on average. A 2021 study says that just 3% of the planet's terrestrial surface is ecologically and faunally intact, meaning areas with healthy populations of native animal species and little to no human footprint. Many of these intact ecosystems were in areas inhabited by indigenous peoples. With 3.2 billion people affected globally, degradation affects over 30% of the world's land area and 40% of land in developing countries.

The implications of these losses for human livelihoods and wellbeing have raised serious concerns. With regard to the agriculture sector for example, The State of the World's Biodiversity for Food and Agriculture, published by the Food and Agriculture Organization of the United Nations in 2019, states that "countries report that many species that contribute to vital ecosystem services, including pollinators, the natural enemies of pests, soil organisms and wild food species, are in decline as a consequence of the destruction and degradation of habitats, overexploitation, pollution and other threats" and that "key ecosystems that deliver numerous services essential to food and agriculture, including supply of freshwater, protection against hazards and provision of habitat for species such as fish and pollinators, are declining."

Impacts of environmental degradation on women's livelihoods

On the way biodiversity loss and ecosystem degradation impact livelihoods, the Food and Agriculture Organization of the United Nations finds also that in contexts of degraded lands and ecosystems in rural areas, both girls and women bear heavier workloads.

Women's livelihoods, health, food and nutrition security, access to water and energy, and coping abilities are all disproportionately affected by environmental degradation. Environmental pressures and shocks, particularly in rural areas, force women to deal with the aftermath, greatly increasing their load of unpaid care work. Also, as limited natural resources grow even scarcer due to climate change, women and girls must also walk further to collect food, water or firewood, which heightens their risk of being subjected to gender-based violence.

This implies, for example, longer journeys to get primary necessities and greater exposure to the risks of human trafficking, rape, and sexual violence.

Water degradation

See also: water scarcity and water cycle

Ethiopia's move to fill the Grand Ethiopian Renaissance Dam's reservoir could reduce Nile flows by as much as 25% and devastate Egyptian farmlands.

One major component of environmental degradation is the depletion of the resource of fresh water on Earth. Approximately only 2.5% of all of the water on Earth is fresh water, with the rest being salt water. 69% of fresh water is frozen in ice caps located on Antarctica and Greenland, so only 30% of the 2.5% of fresh water is available for consumption. Fresh water is an exceptionally important resource, since life on Earth is ultimately dependent on it. Water transports nutrients, minerals and chemicals within the biosphere to all forms of life, sustains both plants and animals, and moulds the surface of the Earth with transportation and deposition of materials.

The current top three uses of fresh water account for 95% of its consumption; approximately 85% is used for irrigation of farmland, golf courses, and parks, 6% is used for domestic purposes such as indoor bathing uses and outdoor garden and lawn use, and 4% is used for industrial purposes such as processing, washing, and cooling in manufacturing centres. It is estimated that one in three people over the entire globe are already facing water shortages, almost one-fifth of the world population live in areas of physical water scarcity, and almost one quarter of the world's population live in a developing country that lacks the necessary infrastructure to use water from available rivers and aquifers. Water scarcity is an increasing problem due to many foreseen issues in the future including population growth, increased urbanization, higher standards of living, and climate change.

Industrial and domestic sewage, pesticides, fertilizers, plankton blooms, silt, oils, chemical residues, radioactive material, and other pollutants are some of the most frequent water pollutants. These have a huge negative impact on the water and can cause degradation in various levels.

Climate change and temperature

Climate change affects the Earth's water supply in a large number of ways. It is predicted that the mean global temperature will rise in the coming years due to a number of forces affecting the climate. The amount of atmospheric carbon dioxide (CO₂) will rise, and both of these will influence water resources; evaporation depends strongly on temperature and moisture availability which can ultimately affect the amount of water available to replenish groundwater supplies.

Transpiration from plants can be affected by a rise in atmospheric CO₂, which can decrease their use of water, but can also raise their use of water from possible increases of leaf area. Temperature rise can reduce the snow season in the winter and increase the intensity of the melting snow leading to peak runoff of this, affecting soil moisture, flood and drought risks, and storage capacities depending on the area.

Warmer winter temperatures cause a decrease in snowpack, which can result in diminished water resources during summer. This is especially important at mid-latitudes and in mountain regions that depend on glacial runoff to replenish their river systems and groundwater supplies, making these areas increasingly vulnerable to water shortages over time; an increase in temperature will initially result in a rapid rise in water melting from glaciers in the summer, followed by a retreat in glaciers and a decrease in the melt and consequently the water supply every year as the size of these glaciers get smaller and smaller.

Thermal expansion of water and increased melting of oceanic glaciers from an increase in temperature gives way to a rise in sea level. This can affect the freshwater supply to coastal areas as well. As river mouths and deltas with higher salinity get pushed further inland, an intrusion of saltwater results in an increase of salinity in reservoirs and aquifers. Sea-level rise may also consequently be caused by a depletion of groundwater, as climate change can affect the hydrologic cycle in a number of ways. Uneven distributions of increased temperatures and increased precipitation around the globe results in water surpluses and deficits, but a global decrease in groundwater suggests a rise in sea level, even after meltwater and thermal expansion were accounted for, which can provide a positive feedback to the problems sea-level rise causes to fresh-water supply.

A rise in air temperature results in a rise in water temperature, which is also very significant in water degradation as the water would become more susceptible to bacterial growth. An increase in water temperature can also affect ecosystems greatly because of a species' sensitivity to temperature, and also by inducing changes in a body of water's self-purification system from decreased amounts of dissolved oxygen in the water due to rises in temperature.

Climate change and precipitation

A rise in global temperatures is also predicted to correlate with an increase in global precipitation but because of increased runoff, floods, increased rates of soil erosion, and mass movement of land, a decline in water quality is probable, because while water will carry more nutrients it will also carry more contaminants. While most of the attention about climate change is directed towards global warming and greenhouse effect, some of the most severe effects of climate change are likely to be from changes in precipitation, evapotranspiration, runoff, and soil moisture. It is generally expected that, on average, global precipitation will increase, with some areas receiving increases and some decreases.

Climate models show that while some regions should expect an increase in precipitation, such as in the tropics and higher latitudes, other areas are expected to see a decrease, such as in the subtropics. This will ultimately cause a latitudinal variation in water distribution. The areas receiving more precipitation are also expected to receive this increase during their winter and actually become drier during their summer, creating even more of a variation of precipitation distribution. Naturally, the distribution of precipitation across the planet is very uneven, causing constant variations in water availability in respective locations.

Changes in precipitation affect the timing and magnitude of floods and droughts, shift runoff processes, and alter groundwater recharge rates. Vegetation patterns and growth rates will be directly affected by shifts in precipitation amount and distribution, which will in turn affect agriculture as well as natural ecosystems. Decreased precipitation will deprive areas of water causing water tables to fall and reservoirs of wetlands, rivers, and lakes to empty. In addition, a possible increase in evaporation and evapotranspiration will result, depending on the accompanied rise in temperature. Groundwater reserves will be depleted, and the remaining water has a greater chance of being of poor quality from saline or contaminants on the land surface.

Climate change is resulting into a very high rate of land degradation causing enhanced desertification and nutrient deficient soils. The menace of land degradation is increasing by the day and has been characterized as a major global threat. According to Global Assessment of Land Degradation and Improvement (GLADA) a quarter of land area around the globe can now be marked as degraded. Land degradation is supposed to influence lives of 1.5 billion people and 15 billion tons of fertile soil is lost every year due to anthropogenic activities and climate change.

Population growth

Graph of human population from 10,000 BCE to 2000 CE. It shows sevenfold rise in world population that has taken place since the end of the seventeenth century.

Main articles: Human overpopulation and Population growth

The human population on Earth is expanding rapidly, which together with even more rapid economic growth is the main cause of the degradation of the environment. Humanity's appetite for resources is disrupting the environment's natural equilibrium. Production industries are venting smoke into the atmosphere and discharging chemicals that are polluting water resources. The smoke includes detrimental gases such as carbon monoxide and sulphur dioxide. The high levels of pollution in the atmosphere form layers that are eventually absorbed into the atmosphere. Organic compounds such as chlorofluorocarbons (CFCs) have generated an opening in the ozone layer, which admits higher levels of ultraviolet radiation, putting the globe at risk.

The available fresh water being affected by the climate is also being stretched across an ever-increasing global population. It is estimated that almost a quarter of the global population is living in an area that is using more than 20% of their renewable water supply; water use will rise with population while the water supply is also being aggravated by decreases in streamflow and groundwater caused by climate change. Even though some areas may see an increase in freshwater supply from an uneven distribution of precipitation increase, an increased use of water supply is expected.

An increased population means increased withdrawals from the water supply for domestic, agricultural, and industrial uses, the largest of these being agriculture, believed to be the major non-climate driver of environmental change and water deterioration. The next 50 years will likely be the last period of rapid agricultural expansion, but the larger and wealthier population over this time will demand more agriculture.

Population increase over the last two decades, at least in the United States, has also been accompanied by a shift to an increase in urban areas from rural areas, which concentrates the demand for water into certain areas, and puts stress on the fresh water supply from industrial and human contaminants. Urbanization causes overcrowding and increasingly unsanitary living conditions, especially in developing countries, which in turn exposes an increasingly number of people to disease. About 79% of the world's population is in developing countries, which lack access to sanitary water and sewer systems, giving rises to disease and deaths from contaminated water and increased numbers of disease-carrying insects.

Agriculture

The rate of global tree cover loss has approximately doubled since 2001, to an annual loss approaching an area the size of Italy.

Water pollution due to dairy farming in the Wairarapa in New Zealand

Agriculture is dependent on available soil moisture, which is directly affected by climate dynamics, with precipitation being the input in this system and various processes being the output, such as evapotranspiration, surface runoff, drainage, and percolation into groundwater. Changes in climate, especially the changes in precipitation and evapotranspiration predicted by climate models, will directly affect soil moisture, surface runoff, and groundwater recharge.

In areas with decreasing precipitation as predicted by the climate models, soil moisture may be substantially reduced. With this in mind, agriculture in most areas already needs irrigation, which depletes fresh water supplies both by the physical use of the water and the degradation agriculture causes to the water. Irrigation increases salt and nutrient content in areas that would not normally be affected, and damages streams and rivers from damming and removal of water. Fertilizer enters both human and livestock waste streams that eventually enter groundwater, while nitrogen, phosphorus, and other chemicals from fertilizer can acidify both soils and water. Certain agricultural demands may increase more than others with an increasingly wealthier global population, and meat is one commodity expected to double global food demand by 2050, which directly affects the global supply of fresh water. Cows need water to drink, more if the temperature is high and humidity is low, and more if the production system the cow is in is extensive, since finding food takes more effort. Water is needed in the processing of the meat, and also in the production of feed for the livestock. Manure can contaminate bodies of freshwater, and slaughterhouses, depending on how well they are managed, contribute waste such as blood, fat, hair, and other bodily contents to supplies of fresh water.

The transfer of water from agricultural to urban and suburban use raises concerns about agricultural sustainability, rural socioeconomic decline, food security, an increased carbon footprint from imported food, and decreased foreign trade balance. The depletion of fresh water, as applied to more specific and populated areas, increases fresh water scarcity among the population and also makes populations susceptible to economic, social, and political conflict in a number of ways; rising sea levels forces migration from coastal areas to other areas farther inland, pushing populations closer together breaching borders and other geographical patterns, and agricultural surpluses and deficits from the availability of water induce trade problems and economies of certain areas. Climate change is an important cause of involuntary migration and forced displacement According to the Food and Agriculture Organization of the United Nations, global greenhouse gas emissions from animal agriculture exceeds that of transportation.

Water management

A stream in the town of Amlwch, Anglesey, which is contaminated by acid mine drainage from the former copper mine at nearby Parys Mountain

Water management is the process of planning, developing, and managing water resources across all water applications, in terms of both quantity and quality." Water management is supported and guided by institutions, infrastructure, incentives, and information systems

The issue of the depletion of fresh water has stimulated increased efforts in water management. While water management systems are often flexible, adaptation to new hydrologic conditions may be very costly. Preventative approaches are necessary to avoid high costs of inefficiency and the need for rehabilitation of water supplies, and innovations to decrease overall demand may be important in planning water sustainability.

Water supply systems, as they exist now, were based on the assumptions of the current climate, and built to accommodate existing river flows and flood frequencies. Reservoirs are operated based on past hydrologic records, and irrigation systems on historical temperature, water availability, and crop water requirements; these may not be a reliable guide to the future. Re-examining engineering designs, operations, optimizations, and planning, as well as re-evaluating legal, technical, and economic approaches to manage water resources are very important for the future of water management in response to water degradation. Another approach is water privatization; despite its economic and cultural effects, service quality and overall quality of the water can be more easily controlled and distributed. Rationality and sustainability is appropriate, and requires limits to overexploitation and pollution and efforts in conservation.

Consumption increases

As the world's population increases, it is accompanied by an increase in population demand for natural resources. With the need for more production increases comes more damage to the environments and ecosystems in which those resources are housed. According to United Nations' population growth predictions, there could be up to 170 million more births by 2070. The need for more fuel, energy, food, buildings, and water sources grows with the number of people on the planet.

However, the scale of environmental degradation is not only determined by population growth but also by consumption patterns and resource efficiency. Industrialized nations, with higher per capita consumption rates, often have a disproportionately large environmental footprint compared to less developed regions. Efforts to adopt sustainable development practices, including renewable energy, recycling, and waste reduction, could mitigate some of the environmental impacts of increased consumption. Furthermore, promoting circular economies and transitioning to low-impact technologies are critical.

Deforestation

As the need for new agricultural areas and road construction increases, the deforestation processes stay in effect. Deforestation is the "removal of forest or stand of trees from land that is converted to non-forest use." (Wikipedia-Deforestation). Since the 1960s, nearly 50% of tropical forests have been destroyed, but this process is not limited to tropical forest areas. Europe's forests are also destroyed by livestock, insects, diseases, invasive species, and other human activities. Many of the world's terrestrial biodiversity can be found living in the different types of forests. Tearing down these areas for increased consumption directly decreases the world's biodiversity of plant and animal species native to those areas.

Along with destroying habitats and ecosystems, decreasing the world's forest contributes to the amount of CO₂ in the atmosphere. By taking away forested areas, we are limiting the amount of carbon reservoirs, limiting it to the largest ones: the atmosphere and oceans. While one of the biggest reasons for deforestation is agriculture use for the world's food supply, removing trees from landscapes also increases erosion rates in areas, making it harder to produce crops in those soil types.

Methylation

From Wikipedia, the free encyclopedia

Methylation, in the chemical sciences, is the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These terms are commonly used in chemistry, biochemistry, soil science, and biology.

In biological systems, methylation is catalyzed by enzymes; such methylation can be involved in modification of heavy metals, regulation of gene expression, regulation of protein function, and RNA processing. In vitro methylation of tissue samples is also a way to reduce some histological staining artifacts. The reverse of methylation is demethylation.

In biology

In biological systems, methylation is accomplished by enzymes. Methylation can modify heavy metals and can regulate gene expression, RNA processing, and protein function. It is a key process underlying epigenetics. Sources of methyl groups include S-methylmethionine, methyl folate, methyl B12.

Methanogenesis

Methanogenesis, the process that generates methane from CO₂, involves a series of methylation reactions. These reactions are caused by a set of enzymes harbored by a family of anaerobic microbes.

Cycle for methanogenesis, showing intermediates

In reverse methanogenesis, methane is the methylating agent.

O-methyltransferases

Main article: O-methyltransferase

A wide variety of phenols undergo O-methylation to give anisole derivatives. This process, catalyzed by such enzymes as caffeoyl-CoA O-methyltransferase, is a key reaction in the biosynthesis of lignols, percursors to lignin, a major structural component of plants.

Plants produce flavonoids and isoflavones with methylations on hydroxyl groups, i.e. methoxy bonds. This 5-O-methylation affects the flavonoid's water solubility. Examples are 5-O-methylgenistein, 5-O-methylmyricetin, and 5-O-methylquercetin (azaleatin).

Proteins

Along with ubiquitination and phosphorylation, methylation is a major biochemical process for modifying protein function. The most prevalent protein methylations affect arginine and lysine residue of specific histones. Otherwise histidine, glutamate, asparagine, cysteine are susceptible to methylation. Some of these products include S-methylcysteine, two isomers of N-methylhistidine, and two isomers of N-methylarginine.

Methionine synthase

The methylation reaction catalyzed by methionine synthase

Methionine synthase regenerates methionine (Met) from homocysteine (Hcy). The overall reaction transforms 5-methyltetrahydrofolate (N⁵-MeTHF) into tetrahydrofolate (THF) while transferring a methyl group to Hcy to form Met. Methionine Syntheses can be cobalamin-dependent and cobalamin-independent: Plants have both, animals depend on the methylcobalamin-dependent form.

In methylcobalamin-dependent forms of the enzyme, the reaction proceeds by two steps in a ping-pong reaction. The enzyme is initially primed into a reactive state by the transfer of a methyl group from N⁵-MeTHF to Co(I) in enzyme-bound cobalamin ((Cob), also known as vitamine B12)) , , forming methyl-cobalamin(Me-Cob) that now contains Me-Co(III) and activating the enzyme. Then, a Hcy that has coordinated to an enzyme-bound zinc to form a reactive thiolate reacts with the Me-Cob. The activated methyl group is transferred from Me-Cob to the Hcy thiolate, which regenerates Co(I) in Cob, and Met is released from the enzyme.

Heavy metals: arsenic, mercury, cadmium

Biomethylation is the pathway for converting some heavy elements into more mobile or more lethal derivatives that can enter the food chain. The biomethylation of arsenic compounds starts with the formation of methanearsonates. Thus, trivalent inorganic arsenic compounds are methylated to give methanearsonate. S-adenosylmethionine is the methyl donor. The methanearsonates are the precursors to dimethylarsonates, again by the cycle of reduction (to methylarsonous acid) followed by a second methylation. Related pathways are found in the microbial methylation of mercury to methylmercury.

Epigenetic methylation

DNA methylation

DNA methylation is the conversion of the cytosine to 5-methylcytosine. The formation of Me-CpG is catalyzed by the enzyme DNA methyltransferase. In vertebrates, DNA methylation typically occurs at CpG sites (cytosine-phosphate-guanine sites—that is, sites where a cytosine is directly followed by a guanine in the DNA sequence). In mammals, DNA methylation is common in body cells, and methylation of CpG sites seems to be the default. Human DNA has about 80–90% of CpG sites methylated, but there are certain areas, known as CpG islands, that are CG-rich (high cytosine and guanine content, made up of about 65% CG residues), wherein none is methylated. These are associated with the promoters of 56% of mammalian genes, including all ubiquitously expressed genes. One to two percent of the human genome are CpG clusters, and there is an inverse relationship between CpG methylation and transcriptional activity. Methylation contributing to epigenetic inheritance can occur through either DNA methylation or protein methylation. Improper methylations of human genes can lead to disease development, including cancer.

In honey bees, DNA methylation is associated with alternative splicing and gene regulation based on functional genomic research published in 2013. In addition, DNA methylation is associated with expression changes in immune genes when honey bees were under lethal viral infection. Several review papers have been published on the topics of DNA methylation in social insects.

RNA methylation

RNA methylation occurs in different RNA species viz. tRNA, rRNA, mRNA, tmRNA, snRNA, snoRNA, miRNA, and viral RNA. Different catalytic strategies are employed for RNA methylation by a variety of RNA-methyltransferases. RNA methylation is thought to have existed before DNA methylation in the early forms of life evolving on earth.

N6-methyladenosine (m6A) is the most common and abundant methylation modification in RNA molecules (mRNA) present in eukaryotes. 5-methylcytosine (5-mC) also commonly occurs in various RNA molecules. Recent data strongly suggest that m6A and 5-mC RNA methylation affects the regulation of various biological processes such as RNA stability and mRNA translation, and that abnormal RNA methylation contributes to etiology of human diseases.

In social insects such as honey bees, RNA methylation is studied as a possible epigenetic mechanism underlying aggression via reciprocal crosses.

Protein methylation

Protein methylation typically takes place on arginine or lysine amino acid residues in the protein sequence. Arginine can be methylated once (monomethylated arginine) or twice, with either both methyl groups on one terminal nitrogen (asymmetric dimethylarginine) or one on both nitrogens (symmetric dimethylarginine), by protein arginine methyltransferases (PRMTs). Lysine can be methylated once, twice, or three times by lysine methyltransferases. Protein methylation has been most studied in the histones. The transfer of methyl groups from S-adenosyl methionine to histones is catalyzed by enzymes known as histone methyltransferases. Histones that are methylated on certain residues can act epigenetically to repress or activate gene expression. Protein methylation is one type of post-translational modification.

Evolution

Methyl metabolism is very ancient and can be found in all organisms on earth, from bacteria to humans, indicating the importance of methyl metabolism for physiology. Indeed, pharmacological inhibition of global methylation in species ranging from human, mouse, fish, fly, roundworm, plant, algae, and cyanobacteria causes the same effects on their biological rhythms, demonstrating conserved physiological roles of methylation during evolution.

In chemistry

The term methylation in organic chemistry refers to the alkylation process used to describe the delivery of a CH₃ group.

Electrophilic methylation

Methylations are commonly performed using electrophilic methyl sources such as iodomethane, dimethyl sulfate, dimethyl carbonate, or tetramethylammonium chloride. Less common but more powerful (and more dangerous) methylating reagents include methyl triflate, diazomethane, and methyl fluorosulfonate (magic methyl). These reagents all react via S_N2 nucleophilic substitutions. For example, a carboxylate may be methylated on oxygen to give a methyl ester; an alkoxide salt RO⁻ may be likewise methylated to give an ether, ROCH₃; or a ketone enolate may be methylated on carbon to produce a new ketone.

The Purdie methylation is a specific for the methylation at oxygen of carbohydrates using iodomethane and silver oxide.

Eschweiler–Clarke methylation

The Eschweiler–Clarke reaction is a method for methylation of amines. This method avoids the risk of quaternization, which occurs when amines are methylated with methyl halides.

Diazomethane and trimethylsilyldiazomethane

Diazomethane and the safer analogue trimethylsilyldiazomethane methylate carboxylic acids, phenols, and even alcohols:

${\displaystyle {\text{RCO}}_2^{}\text{H}+{\text{tmsCHN}}_2^{}+{\text{CH}}_3^{}\text{OH}⟶{\text{RCO}}_2^{}{\text{CH}}_3^{}+{\text{CH}}_3^{}\text{Otms}+{\text{N}}_2^{}}$

The method offers the advantage that the side products are easily removed from the product mixture.

Nucleophilic methylation

Methylation sometimes involve use of nucleophilic methyl reagents. Strongly nucleophilic methylating agents include methyllithium (CH₃Li) or Grignard reagents such as methylmagnesium bromide (CH₃MgX). For example, CH₃Li will add methyl groups to the carbonyl (C=O) of ketones and aldehyde.:

Milder methylating agents include tetramethyltin, dimethylzinc, and trimethylaluminium.

Natural capital

From Wikipedia, the free encyclopedia

Mangrove swamp at Iriomote Island, Japan, providing beneficial services of sediment accumulation, coastal protection, nursery and fish-spawning grounds which may in turn support coastal fishing communities. At least 35% of the world's stock of mangrove swamps has been destroyed in just 20 years

Remarks from 1937 by FDR on "natural capital" and "balancing the budget of our resources"

Honeybee (Apis mellifera) pollinating an Avocado crop. Healthy stocks of wild and cultivated pollinator species are important to support the farming industry and help ensure food security.

Aerial view of the Amazon Rainforest. Looked at as a natural capital asset, rainforests provide air and water regulation services, potential sources of new medicines and natural carbon sequestration.

Fires along the Rio Xingu, Brazil – NASA Earth Observatory. Loss of natural capital assets may have significant impact on local and global economies, as well as on the climate.

The many components of natural capital can be viewed as providing essential goods and ecosystem services which underpin some of our key global issues, such as food and water supply, minimising climate change and meeting energy needs.

Natural capital is the world's stock of natural resources, which includes geology, soils, air, water and all living organisms. Some natural capital assets provide people with free goods and services, often called ecosystem services. All of these underpin our economy and society, and thus make human life possible.

It is an extension of the economic notion of capital (resources which enable the production of more resources) to goods and services provided by the natural environment. For example, a well-maintained forest or river may provide an indefinitely sustainable flow of new trees or fish, whereas over-use of those resources may lead to a permanent decline in timber availability or fish stocks. Natural capital also provides people with essential services, like water catchment, erosion control and crop pollination by insects, which in turn ensure the long-term viability of other natural resources. Since the continuous supply of services from the available natural capital assets is dependent upon a healthy, functioning environment, the structure and diversity of habitats and ecosystems are important components of natural capital. Methods, called 'natural capital asset checks', help decision-makers understand how changes in the current and future performance of natural capital assets will impact human well-being and the economy. Unpriced natural capital is what we refer to when businesses or individuals exploit or abuse nature without being held accountable, which can harm ecosystems and the environment. 

History of the concept

The term 'natural capital' was first used in 1973 by E. F. Schumacher in his book Small Is Beautiful and was developed further by Herman Daly, Robert Costanza, and other founders of the science of Ecological Economics, as part of a comprehensive critique of the shortcomings of conventional economics. Natural capital is a concept central to economic assessment ecosystem services valuation which revolves around the idea, that non-human life produces goods and services that are essential to life. Thus, natural capital is essential to the sustainability of the economy.

In a traditional economic analysis of the factors of production, natural capital would usually be classified as "land" distinct from traditional "capital". The historical distinction between "land" and "capital" defined "land" as naturally occurring with a fixed supply, whereas "capital", as originally defined referred only to man-made goods. (e.g., Georgism) It is, however, misleading to view "land" as if its productive capacity is fixed, because natural capital can be improved or degraded by the actions of man over time (see Environmental degradation). Moreover, natural capital yields benefits and goods, such as timber or food, which can be harvested by humans. These benefits are similar to those realized by owners of infrastructural capital which yields more goods, such as a factory that produces automobiles just as an apple tree produces apples.

Ecologists are teaming up with economists to measure and express values of the wealth of ecosystems as a way of finding solutions to the biodiversity crisis. Some researchers have attempted to place a dollar figure on ecosystem services such as the value that the Canadian boreal forest's contribution to global ecosystem services. If ecologically intact, the boreal forest has an estimated value of US$3.7 trillion. The boreal forest ecosystem is one of the planet's great atmospheric regulators and it stores more carbon than any other biome on the planet. The annual value for ecological services of the Boreal Forest is estimated at US$93.2 billion, or 2.5 greater than the annual value of resource extraction.

The economic value of 17 ecosystem services for the entire biosphere (calculated in 1997) has an estimated average value of US$33 trillion per year. These ecological economic values are not currently included in calculations of national income accounts, the GDP and they have no price attributes because they exist mostly outside of the global markets. The loss of natural capital continues to accelerate and goes undetected or ignored by mainstream monetary analysis.

Within the international community the basic principle is not controversial, although much uncertainty exists over how best to value different aspects of ecological health, natural capital and ecosystem services. Full-cost accounting, triple bottom line, measuring well-being and other proposals for accounting reform often include suggestions to measure an "ecological deficit" or "natural deficit" alongside a social and financial deficit. It is difficult to measure such a deficit without some agreement on methods of valuation and auditing of at least the global forms of natural capital (e.g. value of air, water, soil).

All uses of the term currently differentiate natural from man-made or infrastructural capital in some way. Indicators adopted by United Nations Environment Programme's World Conservation Monitoring Centre and the Organisation for Economic Co-operation and Development (OECD) to measure natural biodiversity use the term in a slightly more specific way. According to the OECD, natural capital is "natural assets in their role of providing natural resource inputs and environmental services for economic production" and is "generally considered to comprise three principal categories: natural resources stocks, land, and ecosystems."

The concept of "natural capital" has also been used by the Biosphere 2 project, and the Natural Capitalism economic model of Paul Hawken, Amory Lovins, and Hunter Lovins. Recently, it has begun to be used by politicians, notably Ralph Nader, Paul Martin Jr., and agencies of the UK government, including its Natural Capital Committee and the London Health Observatory.

In Natural Capitalism: Creating the Next Industrial Revolution the author claims that the "next industrial revolution" depends on the espousal of four central strategies: "the conservation of resources through more effective manufacturing processes, the reuse of materials as found in natural systems, a change in values from quantity to quality, and investing in natural capital, or restoring and sustaining natural resources."

Natural capital declaration

In June 2012 a 'natural capital declaration' (NCD) was launched at the Rio+20 summit held in Brazil. An initiative of the global finance sector, it was signed by 40 CEOs to 'integrate natural capital considerations into loans, equity, fixed income and insurance products, as well as in accounting, disclosure and reporting frameworks.' They worked with supporting organisations to develop tools and metrics to integrate natural capital factors into existing business structures.

In summary, its four key aims are to:

• Increase understanding of business dependency on natural capital assets;
• Support development of tools to integrate natural capital considerations into the decision-making process of all financial products and services;
• Help build a global consensus on integrating natural capital into private sector accounting and decision-making;
• Encourage a consensus on integrated reporting to include natural capital as one of the key components of an organisation's success.

Natural Capital Protocol

In July 2016, the Natural Capital Coalition (now known as Capitals Coalition) released the Natural Capital Protocol. The Protocol provides a standardised framework for organisations to identify, measure and value their direct and indirect impacts and dependencies on natural capital. The Protocol harmonises existing tools and methodologies, and guides organisations towards the information they need to make strategic and operational decisions that include impacts and dependencies on natural capital.

The Protocol was developed in a unique collaboration between 38 organisations who signed voluntary, pre-competitive contracts. This collaboration was led by Mark Gough, who is now the CEO of the Capitals Coalition.

The Protocol is available on a creative commons license and is free for organisations to apply.

Internationally agreed standard

Environmental-economic accounts provide the conceptual framework for integrated statistics on the environment and its relationship with the economy, including the impacts of the economy on the environment and the contribution of the environment to the economy. A coherent set of indicators and descriptive statistics can be derived from the accounts that inform a wide range of policies.

These include, but are not limited to:

• Green economy/green growth
• Natural resource management
• Sustainable development

The System of Integrated Environmental and Economic Accounting (SEEA) contains the internationally agreed standard concepts, definitions, classifications, accounting rules and tables for producing internationally comparable statistics on the environment and its relationship with the economy. The SEEA is a flexible system in the sense that its implementation can be adapted to countries' specific situations and priorities. Coordination of the implementation of the SEEA and ongoing work on new methodological developments is managed and supervised by the UN Committee of Experts on Environmental-Economic Accounting (UNCEEA). The final, official version of the SEEA Central Framework was published in February 2014.

In March 2021, the United Nations Statistical Commission adopted the SEEA Ecosystem Accounting (SEEA EA) standard at its 52nd session. The SEEA EA is a statistical framework that provides a coherent accounting approach to the measurement of ecosystems. Ecosystem accounts enable the presentation of data and indicators of ecosystem extent, ecosystem condition, and ecosystem services in both physical and monetary terms in a spatially explicit way. Following its adoption, the Statistics Division of the United Nations Department of Economic and Social Affairs (UN DESA) in collaboration with the United Nations Environment Programme (UNEP) and the Basque Centre for Climate Change (BC3) released the ARIES for SEEA Explorer in April 2021, an artificial intelligence-powered tool based on the Artificial Intelligence for Environment and Sustainability (ARIES) platform for rapid, standardized and customizable natural capital accounting. The ARIES for SEEA Explorer was made available on the UN Global Platform in order to accelerate SEEA's implementation worldwide.

Private sector approaches

Some studies envisage a private sector natural capital 'ecosystem', including investors, assets and regulators.

Criticism

Whilst measuring the components of natural capital in any region is a relatively straightforward process, both the task and the rationale of putting a monetary valuation on them, or on the value of the goods and services they freely give us, has proved more contentious. Within the UK, Guardian columnist, George Monbiot, has been critical of the work of the government's Natural Capital Committee and of other attempts to place any sort of monetary value on natural capital assets, or on the free ecosystem services they provide us with. In a speech referring to a report to government which suggested that better protection of the UK's freshwater ecosystems would yield an enhancement in aesthetic value of £700m, he derided attempts 'to compare things which cannot be directly compared'. He went on to say:

These figures, ladies and gentlemen, are marmalade. They are finely shredded, boiled to a pulp, heavily sweetened ... and still indigestible. In other words they are total gibberish.

— G. Monbiot

Others have defended efforts to integrate the valuation of natural capital into local and national economic decision-making, arguing that it puts the environment on a more balanced footing when weighed against other commercial pressures, and that 'valuation' of those assets is not the same as monetisation.

Developmental plasticity

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Developmental_plasticity

Developmental plasticity refers to changes in neural connections during growth, influenced by environmental interactions and learning. Similar to brain plasticity, it specifically involves how neurons and synapses adapt during development. Most of these connections form from birth to early childhood, following three main processes, with critical periods determining lasting changes. The term can also describe how an embryo or larva adjusts its traits based on the environment. Unlike phenotypic plasticity, which can be reversible in adulthood, developmental plasticity shapes traits early in life that usually remain permanent.

Mechanisms

During development, the central nervous system acquires information via endogenous or exogenous factors as well as learning experiences. In acquiring and storing such information, the plastic nature of the central nervous system allows for the adaptation of existing neural connections in order to accommodate new information and experiences, resulting in developmental plasticity. According to Turrigiano (2012), this form of plasticity that occurs during development is the result of three predominant mechanisms: synaptic and homeostatic plasticity, and learning. When brain areas are impaired, remaining circuits can reorganize to compensate for lost functions. Additionally, adult neuroplasticity allows for continuous learning and memory formation. Factors such as age, environment, and experience influence the extent of plasticity, with enriched environments enhancing cognitive function. These changes are driven by mechanisms like synaptic plasticity, which strengthens or weakens synapses based on activity, homeostatic plasticity, which maintains neural stability, and learning-induced plasticity, which adapts neural circuits in response to new experiences.

Synaptic plasticity

Phenotypic plasticity is the ability of an organism to change its physical traits, behavior, or physiology in response to environmental conditions. This adaptability allows a single genotype to produce different phenotypes depending on the environment, helping organisms survive and reproduce in varying or changing habitats. For example, some plants can grow taller in low-light conditions to reach sunlight, while certain animals may change their coloration with the seasons for better camouflage. Phenotypic plasticity plays a crucial role in evolution and ecological interactions.

Synaptic plasticity

The underlying principle of synaptic plasticity is that synapses undergo an activity-dependent and selective strengthening or weakening so that new information can be stored. Synaptic plasticity depends on numerous factors including the threshold of the presynaptic stimulus in addition to the relative concentrations of neurotransmitter molecules. Synaptic plasticity has long been implicated for its role in memory storage and is thought to play a key role in learning. However, during developmental periods, synaptic plasticity is of particular importance, as changes in the network of synaptic connections can ultimately lead to changes in developmental milestones. For instance, the initial overproduction of synapses during development is key to plasticity that occurs in the visual and auditory cortices. In experiments conducted by Hubel and Wiesel, the visual cortex of kittens exhibits synaptic plasticity in the refinement of neural connections following visual inputs. Correspondingly, in the absence of such inputs during development, the visual field fails to develop properly and can lead to abnormal structures and behavior. Furthermore, research suggests that this initial overproduction of synapses during developmental periods provides the foundation by which many synaptic connections can be formed, thus resulting in more synaptic plasticity. In the same way that synapses are abundant during development, there are also refining mechanisms that assist in the maturation of synapses in neural circuits. This regulatory process allows the strengthening of important or frequently used synaptic connections while reducing the amount of weak connections.

Homeostatic plasticity

In order to maintain balance, homeostatic controls exist to regulate the overall activity of neural circuits, specifically by regulating the destabilizing effects of developmental and learning processes that result in changes of synaptic strength. Homeostatic plasticity also helps regulate prolonged excitatory responses, which lead to a reduction in all of a neuron's synaptic responses. Numerous pathways have recently been associated with homeostatic plasticity, though there is still no clear molecular mechanism. Synaptic scaling is one method that serves as a type of autoregulation, as neurons can recognize their own firing rates and notice when there are alterations; calcium-dependent signals control the levels of glutamate receptors at synaptic sites in response. Homeostatic mechanisms may be local or network-wide.

Learning

While synaptic plasticity is considered to be a by-product of learning, learning involves interaction with the environment to acquire the new information or behavior; synaptic plasticity merely represents the change in strength or configuration of neural circuits. Learning is crucial, as there is considerable interaction with the environment, which is when the potential for acquiring new information is greatest. By depending largely upon selective experiences, neural connections are altered and strengthened in a manner that is unique to those experiences. Experimentally, this can be seen when rats are raised in an environment that allows ample social interaction, resulting in increased brain weight and cortical thickness. In contrast, the inverse is seen following rearing in an environment devoid of interaction. Also, learning plays a considerable role in the selective acquisition of information and is markedly demonstrated when children develop one language instead of another. Another example of such experience-dependent plasticity that is critical during development is the occurrence of imprinting. This occurs as a result of a young child or animal being exposed to a novel stimulus and rapidly implementing a certain behavior in response.

Neural development

The formation of the nervous system is one of the most crucial events in the developing embryo. The differentiation of stem cell precursors into specialized neurons gives rise to the formation of synapses and neural circuits, which is key to the principle of plasticity. During this pivotal point in development, consequent developmental processes like the differentiation and specialization of neurons are highly sensitive to exogenous and endogenous factors. For example, in utero exposure to nicotine has been linked to adverse effects, such as severe physical and cognitive deficits, due to the impediment of the normal acetylcholine receptor activation. In a recent study, the connection between such nicotine exposure and prenatal development was assessed. It was determined that nicotine exposure in early development can have a lasting and encompassing effect on neuronal structures, underlying the behavioral and cognitive defects observed in exposed humans and animals. Additionally, when proper synaptic function is disrupted through nicotine exposure, the overall circuit may become less sensitive and responsive to stimuli, resulting in compensatory developmental plasticity. It is for this reason that exposure to various environmental factors during developmental periods can cause profound effects on subsequent neural functioning.

Neural refinement and connectivity

Initial stages of neural development begin early on in the fetus with spontaneous firing of the developing neuron. These early connections are weak and often overlap at the terminal ends of the arbors. The young neurons have complete potential of changing morphology during a time span classified as the critical period to achieve strengthened and refined synaptic connections. It is during this time that damaged neuronal connections can become functionally recovered. Large alterations in length and location of these neurons can occur until synaptic circuitry is further defined. Although organization of neural connections begins at the earliest stages of development, activity-driven refinement only begins at birth when the individual neurons can be recognized as separate entities and start to enhance in specificity. The gradual pruning of the initially blurry axonal branching occurs via competitive and facilitative mechanisms, relying on electrical activity at the synapses; axons that fire independently of each other tend to compete for territory, whereas axons that synchronously fire mutually amplify connections. Until this architecture has been established, retinal focus remains diffuse. Perpetuation of these newly formed connections or the lack thereof depends on maintenance of electrical activities at the synapses. Upon refinement, the elaborate connections narrow and strengthen to fire only in response to specific stimuli to optimize visual acuity. These mechanisms can malfunction with the introduction of toxins, which bind to sodium channels and suppress action potentials and consequently electrical activity between synapses.

Quantification of synaptic networks has primarily been through retinal wave detection using Ca²⁺ fluorescent indicators. Prior to birth, retinal waves are seen to originate as clusters that propagate through the refractory region. These assays have been shown to provide spatiotemporal data on the random bursts of action potentials produced in a refractory period. Another assay recently developed to assess the depth of neuronal connections utilizes the trans-neuronal spread of rabies. This method of tracing employs the migration of a neurotropic virus through tightly interconnected neurons and specific site labeling of distinct connections. Patch-clamping experiments and calcium imaging are often conducted based on preliminary results from this assay in order to detect spontaneous neuronal activity. A method for in vitro synaptic quantification has been developed that uses immunofluorescence to measure synaptic density in different cell cultures.

Critical period

The concept of critical periods is a widely accepted and prominent theme in development, with strong implications for developmental plasticity. Critical periods establish a time frame in which the shaping of neural networks can be carried out. During these critical periods in development, plasticity occurs as a result of changes in the structure or function of developing neural circuits. Such critical periods can also be experience-dependent, in the instance of learning via new experiences, or can be independent of the environmental experience and rely on biological mechanisms including endogenous or exogenous factors. Another notable example includes the development of sensory systems, which also undergo plastic changes during critical time periods. A lesser known example, however, remains the critical development of respiratory control during developmental periods. At birth, the development of respiratory control neural circuits is incomplete, requiring complex interactions from both the environment and intrinsic factors. Experimentally exposing two-week-old kittens and rats to hyperoxic conditions completely eliminates the carotid chemoreceptor response to hypoxia, resulting in respiratory impairment. This has remarkable clinical significance, as newborn infants are often supplemented with considerable amounts of oxygen, which could detrimentally affect the way in which neural circuits for respiratory control develop during the critical period. When stimuli appear or experiences occur outside of the critical period, any potential outcome is typically not long-lasting.

Spontaneous network activity

Another lesser known element of developmental plasticity includes spontaneous bursts of action potentials in developing neural circuits, also referred to as spontaneous network activity. During the early development of neural connections, excitatory synapses undergo spontaneous activation, resulting in elevated intracellular calcium levels that signal the onset of numerous signaling cascades and developmental processes. For example, prior to birth, neural circuits in the retina undergo spontaneous network activity, which has been found to elicit the formation of retinogeniculate connections. Developmental spontaneous network activity is also exhibited in the proper formation of neuromuscular circuits. It is believed that spontaneous network activity establishes a scaffold for subsequent learning and information acquisition following the initial establishment of synaptic connections during development.

Phenotypic plasticity

Reaction norms

Graphical representation of a reaction norm, which determines distribution of potential phenotypes.

The norm of reaction, or reaction norm, is a pattern of phenotypic plasticity that describes how a single genotype can produce an array of different phenotypes in response to different environmental conditions. Furthermore, a reaction norm can be a graphical representation of organismal variation in phenotype in response to numerous environmental circumstances. The graphical representation of reaction norms is commonly parabolic in shape, which represents the variation in plasticity across a population. Additionally, reaction norms allow organisms to evaluate the need for various phenotypes in response to the magnitude of the environmental signal.

Polyphenisms

Example of phenotypic plasticity in the desert locust Schistocerca gregaria. The green pigment locust (top) has miniature wings that result from a low-density population. The deep pigmentation locust (bottom) has leg and wing development suitable for migration, which arose due to a high-density environment.

Polyphenism refers to the ability of a single genotype to produce a variety of phenotypes. In contrast to reaction norms, which produce a continuous range of phenotypes, polyphenisms allow a distinct phenotype to arise from altering environmental conditions. Polyphenisms occur in a wide range of organisms, including both vertebrates and invertebrates. A specific example of a polyphenism can be seen in the Florida carpenter ant, Camponotus floridanus. For a developing ant embryo, a multitude of environmental signals–such as the temperature surrounding the developing embryo, or the nutrition and chemicals provided to the larvae–can ultimately determine the adult ant's morphology and placement within the caste system. For Florida carpenter ants, the end phenotype and behavior are determined by the morphology; developing ants can become minor workers, major workers, or queen ants. An example of the anatomical differences seen in this species of ant is the presence or absence of wings and the size differences between male ants. Although the polyphenism of the ants has been documented, research is still needed to determine the molecular mechanisms for the induction of each unique phenotype. Another example of a polyphenism is temperature-dependent sex determination (TSD). This process occurs when variations in the external temperature surrounding eggs influence the development of reproductive organs within the embryo. TSD can be observed in crocodiles because they lack specialized sex chromosomes. Male crocodiles develop when temperatures stay neutral, between 31–32°C (87.8–89.6°F), whereas female crocodiles develop when the eggs experience a more extreme rise or fall in temperature. Polyphenism and its genomic pathways are not yet fully understood, and future research into the genetic aspects among various organisms could provide better insight into how different phenotypes arise.

Environmental cues

Environmental cues in either the maternal or the embryonic environment can result in changes in the embryo. Embryonic development is a sensitive process and can be impacted by cues from predators,^[42] light, and/or temperature. For example, in Daphnia, neonates exposed to predator cues displayed higher expression of genes related to digestion, reproductive function, and defense. It was hypothesized that this increase in gene expression would allow the Daphnia to defend themselves and that an increase in growth would result in a larger investment in future offspring. Subsequent generations exhibited a similar pattern, despite not being exposed to any predator cues, suggesting an inheritance of epigenetic expression factors. An organism's sensitivity to light during development could be useful in predicting what phenotype may be the most beneficial in the future based on the foliage of the mature organism.

Plants

In one study, the mechanisms of signaling certain triggers and responses in plants is studied. These networks function in providing the plants with a sort of cushion to environmental changes. Just like animals, plants know when or when not to produce flowers or fruit based on environmental changes.

A prime example of phenotypic plasticity in seeds is the size of the seed based on environmental conditions, as researched in Darwin's studies on Galapagos finches regarding beak size to seed size coevolution.

Since plants are immobile, they have to develop these systems of recognizing certain cues in order to provide a response that works in relation to their fitness and even more so their survival. Plants have a certain sensitivity about them, and this is exactly why it is needed. One study describes how canalization is the driving factor of the developing genetic plasticity in plants. It also discusses how the vernalization2 gene controls the epigenetic regulation of vernalization in one species known as Arabidopsis. As fluctuations in temperature and light can impact the health of the plant, the organism confers with its intricate network of a buffer to produce the best response in terms of survival and flourishment.

Peppered Moths

Since we are speaking of cues, the adult peppered moth's melanism is primarily a genetic adaptation driven by natural selection which is applied through environmental cues. The question is why?

This is a picture of a melanistic female after the adaptive switch due to environmental pressures.

During the Industrial Revolution, air pollution caused a change in the moth population, with an increase in dark-colored moths due to industrial melanism.^[47] The caterpillars of the peppered moth have demonstrated the ability to change their coloration to match the color of the twigs they rest on. This is a prime example of phenotypic plasticity, where an organism's phenotype (observable characteristics) changes in response to environmental cues. The primary environmental cue that causes the larval color change, is visual information, gathered through the skin of the larvae. Studies have shown that even when blindfolded, the caterpillars can still sense and react to the color of their environment, indicating that they possess extraocular photoreception (light sensing through their skin). This shows that the light wavelengths that are being reflected off of the twigs, is the environmental cue causing the color change. This color plasticity is crucial for the larvae's survival.

Limb Morphology

Research has shown that Anolis lizard (anole) limb morphology can be influenced by the environment during development. Specifically, studies have demonstrated that the length of their hind limbs can vary depending on the substrate they experience as hatchlings. For example, Anolis lizards raised on broad surfaces tend to develop relatively longer hind limbs, while those raised on narrow surfaces develop relatively shorter hind limbs. This adaptation is thought to be related to their ability to move efficiently in their respective environments.

This is a great example of developmental plasticity, because the environment experienced during the early stages of life, effects the physical development of the animal.

Ecological relevance

Developmental plasticity seen here is ecologically relevant because it allows Anolis lizards to fine-tune their locomotor abilities to match their specific habitat. A benefit, yes, because it can enhance their survival and reproductive success. Moreover, this is especially important when considering the vast amount of different microhabitats that Anolis lizards occupy. Furthermore, research indicates that while plasticity is present, it does not fully explain all of the morphological differences observed in Anolis lizards. Evolutionary adaptation, through genetic changes, also plays a large role. In all, Anolis lizards demonstrate developmental plasticity, particularly through limb morphology, allowing them to adapt to different environmental conditions during their early development.

Temperature Sex Determination

Several species, including alligators and tortoises, have temperature-dependent sex determination, where the sex of the organism is dependent on the environmental temperature during a crucial thermosensitive period. An active area of research involves the mechanisms of temperature sex determination, which have been hypothesized to be associated with the methylation of specific genes.