Ape

From Wikipedia, the free encyclopedia

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

 

Hominoids or apes Temporal range: Miocene-Holocene
Sumatran orangutan (Pongo abelli)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Primates
Suborder:	Haplorhini
Infraorder:	Simiiformes
Parvorder:	Catarrhini
Superfamily:	Hominoidea Gray, 1825
Type species
Homo sapiens Linnaeus, 1758
Families
†Proconsulidae †Afropithecidae †Pliobatidae †Dendropithecidae Hylobatidae Hominidae sister: Cercopithecoidea

Apes (collectively Hominoidea /hɒmɪˈnɔɪdi.ə/) are a clade of Old World simians native to sub-Saharan Africa and Southeast Asia (though they were more widespread in Africa, most of Asia, and as well as Europe in prehistory), which together with its sister group Cercopithecidae form the catarrhine clade, cladistically making them monkeys. Apes do not have tails due to a mutation of the TBXT gene. In traditional and non-scientific use, the term "ape" can include tailless primates taxonomically considered Cercopithecidae (such as the Barbary ape and black ape), and is thus not equivalent to the scientific taxon Hominoidea. There are two extant branches of the superfamily Hominoidea: the gibbons, or lesser apes; and the hominids, or great apes.

• The family Hylobatidae, the lesser apes, include four genera and a total of 20 species of gibbon, including the lar gibbon and the siamang, all native to Asia. They are highly arboreal and bipedal on the ground. They have lighter bodies and smaller social groups than great apes.
• The family Hominidae (hominids), the great apes, include four genera comprising three extant species of orangutans and their subspecies, two extant species of gorillas and their subspecies, two extant species of panins (bonobos and chimpanzees) and their subspecies, and humans in a single extant subspecies.

Except for gorillas and humans, hominoids are agile climbers of trees. Apes eat a variety of plant and animal foods, with the majority of food being plant foods, which can include fruits, leaves, stalks, roots and seeds, including nuts and grass seeds. Human diets are sometimes substantially different from that of other hominoids due in part to the development of technology and a wide range of habitation. Humans are by far the most numerous of the hominoid species, in fact outnumbering all other primates by a factor of several thousand to one.

All non-human hominoids are rare and threatened with extinction. The eastern hoolock gibbon is the least threatened, only being vulnerable to extinction. Five gibbon species are critically endangered, as are all species of orangutan and gorilla. The remaining species of gibbon, the bonobo, and all four species of chimpanzees are endangered. The chief threat to most of the endangered species is loss of tropical rainforest habitat, though some populations are further imperiled by hunting for bushmeat. The great apes of Africa are also facing threat from the Ebola virus. Currently considered to be the greatest threat to survival of African apes, Ebola infection is responsible for the death of at least one third of all gorillas and chimpanzees since 1990.

Name and terminology

Hominin timeline
−10 — – −9 — – −8 — – −7 — – −6 — – −5 — – −4 — – −3 — – −2 — – −1 — – 0 —	Miocene Pliocene Pleistocene Hominini Nakalipithecus Ouranopithecus Oreopithecus Sahelanthropus Orrorin Ardipithecus Australopithecus H. habilis H. erectus H. heidelbergensis Homo sapiens Neanderthals Denisovans	← Earlier apes ← Gorilla split ← Chimpanzee split ← Earliest bipedal ← Earliest stone tools ← Dispersal beyond Africa ← Earliest fire / cooking ← Earliest rock art ← Earliest clothes ← Modern humans H o m i n i d s
(million years ago)

"Ape", from Old English apa, is a word of uncertain origin. The term has a history of rather imprecise usage—and of comedic or punning usage in the vernacular. Its earliest meaning was generally of any non-human anthropoid primate, as is still the case for its cognates in other Germanic languages. Later, after the term "monkey" had been introduced into English, "ape" was specialized to refer to a tailless (therefore exceptionally human-like) primate. Thus, the term "ape" obtained two different meanings, as shown in the 1911 Encyclopædia Britannica entry: it could be used as a synonym for "monkey" and it could denote the tailless human-like primate in particular.

Some, or recently all, hominoids are also called "apes", but the term is used broadly and has several different senses within both popular and scientific settings. "Ape" has been used as a synonym for "monkey" or for naming any primate with a human-like appearance, particularly those without a tail. Biologists have traditionally used the term "ape" to mean a member of the superfamily Hominoidea other than humans, but more recently to mean all members of Hominoidea. So "ape"—not to be confused with "great ape"—now becomes another word for hominoid including humans.

The taxonomic term hominoid is derived from, and intended as encompassing, the hominids, the family of great apes. Both terms were introduced by Gray (1825). The term hominins is also due to Gray (1824), intended as including the human lineage (see also Hominidae#Terminology, Human taxonomy).

The distinction between apes and monkeys is complicated by the traditional paraphyly of monkeys: Apes emerged as a sister group of Old World Monkeys in the catarrhines, which are a sister group of New World Monkeys. Therefore, cladistically, apes, catarrhines and related contemporary extinct groups such as Parapithecidaea are monkeys as well, for any consistent definition of "monkey". "Old World Monkey" may also legitimately be taken to be meant to include all the catarrhines, including apes and extinct species such as Aegyptopithecus, in which case the apes, Cercopithecoidea and Aegyptopithecus emerged within the Old World Monkeys.

The primates called "apes" today became known to Europeans after the 18th century. As zoological knowledge developed, it became clear that taillessness occurred in a number of different and otherwise distantly related species. Sir Wilfrid Le Gros Clark was one of those primatologists who developed the idea that there were trends in primate evolution and that the extant members of the order could be arranged in an ".. ascending series", leading from "monkeys" to "apes" to humans. Within this tradition "ape" came to refer to all members of the superfamily Hominoidea except humans. As such, this use of "apes" represented a paraphyletic grouping, meaning that, even though all species of apes were descended from a common ancestor, this grouping did not include all the descendant species, because humans were excluded from being among the apes.

Traditionally, the English-language vernacular name "apes" does not include humans, but phylogenetically, humans (Homo) form part of the family Hominidae within Hominoidea. Thus, there are at least three common, or traditional, uses of the term "ape": non-specialists may not distinguish between "monkeys" and "apes", that is, they may use the two terms interchangeably; or they may use "ape" for any tailless monkey or non-human hominoid; or they may use the term "ape" to just mean the non-human hominoids.

Modern taxonomy aims for the use of monophyletic groups for taxonomic classification; Some literature may now use the common name "ape" to mean all members of the superfamily Hominoidea, including humans. For example, in his 2005 book, Benton wrote "The apes, Hominoidea, today include the gibbons and orang-utan ... the gorilla and chimpanzee ... and humans". Modern biologists and primatologists refer to apes that are not human as "non-human" apes. Scientists broadly, other than paleoanthropologists, may use the term "hominin" to identify the human clade, replacing the term "hominid". See terminology of primate names.

See below, History of hominoid taxonomy, for a discussion of changes in scientific classification and terminology regarding hominoids.

Evolution

Although the hominoid fossil record is still incomplete and fragmentary, there is now enough evidence to provide an outline of the evolutionary history of humans. Previously, the divergence between humans and other extant hominoids was thought to have occurred 15 to 20 million years ago, and several species of that time period, such as Ramapithecus, were once thought to be hominins and possible ancestors of humans. But, later fossil finds indicated that Ramapithecus was more closely related to the orangutan; and new biochemical evidence indicates that the last common ancestor of humans and non-hominins (that is, the chimpanzees) occurred between 5 and 10 million years ago, and probably nearer the lower end of that range (more recent); see Chimpanzee–human last common ancestor (CHLCA).

Taxonomic classification and phylogeny

Genetic analysis combined with fossil evidence indicates that hominoids diverged from the Old World monkeys about 25 million years ago (mya), near the Oligocene–Miocene boundary. The gibbons split from the rest about 18 mya, and the hominid splits happened 14 mya (Pongo), 7 mya (Gorilla), and 3–5 mya (Homo & Pan). In 2015, a new genus and species were described, Pliobates cataloniae, which lived 11.6 mya, and appears to predate the split between Hominidae and Hylobatidae.

Skeletons of members of the ape superfamily, Hominoidea. There are two extant families: Hominidae, the "great apes"; and Hylobatidae, the gibbons, or "lesser apes".

From left: Comparison of size of gibbon, human, chimpanzee, gorilla and orangutan. Non-human hominoids do not stand upright as their normal posture.

The families, and extant genera and species of hominoids are:

• Superfamily Hominoidea
  • Family Hominidae: hominids ("great apes")
    • Genus Pongo: orangutans
      • Bornean orangutan, P. pygmaeus
      • Sumatran orangutan, P. abelii
      • Tapanuli orangutan, P. tapanuliensis
    • Genus Gorilla: gorillas
      • Western gorilla, G. gorilla
      • Eastern gorilla, G. beringei
    • Genus Homo: humans
      • Human, H. sapiens
    • Genus Pan: chimpanzees
      • Chimpanzee, P. troglodytes
      • Bonobo, P. paniscus
  • Family Hylobatidae: gibbons ("lesser apes")
    • Genus Hylobates
      • Lar gibbon or white-handed gibbon, H. lar
      • Bornean white-bearded gibbon, H. albibarbis
      • Agile gibbon or black-handed gibbon, H. agilis
      • Western grey gibbon or Abbott's grey gibbon, H. abbotti
      • Eastern grey gibbon or northern grey gibbon, H. funereus
      • Müller's gibbon or southern grey gibbon, H. muelleri
      • Silvery gibbon, H. moloch
      • Pileated gibbon or capped gibbon, H. pileatus
      • Kloss's gibbon or Mentawai gibbon or bilou, H. klossii
    • Genus Hoolock
      • Western hoolock gibbon, H. hoolock
      • Eastern hoolock gibbon, H. leuconedys
      • Skywalker hoolock gibbon, H. tianxing
    • Genus Symphalangus
      • Siamang, S. syndactylus
    • Genus Nomascus
      • Northern buffed-cheeked gibbon, N. annamensis
      • Black crested gibbon, N. concolor
      • Eastern black crested gibbon, N. nasutus
      • Hainan black crested gibbon, N. hainanus
      • Southern white-cheeked gibbon N. siki
      • White-cheeked crested gibbon, N. leucogenys
      • Yellow-cheeked gibbon, N. gabriellae

History of hominoid taxonomy

Further information: Human taxonomy § History

The history of hominoid taxonomy is complex and somewhat confusing. Recent evidence has changed our understanding of the relationships between the hominoids, especially regarding the human lineage; and the traditionally used terms have become somewhat confused. Competing approaches to methodology and terminology are found among current scientific sources. Over time, authorities have changed the names and the meanings of names of groups and subgroups as new evidence — that is, new discoveries of fossils and tools and of observations in the field, plus continual comparisons of anatomy and DNA sequences — has changed the understanding of relationships between hominoids. There has been a gradual demotion of humans from being 'special' in the taxonomy to being one branch among many. This recent turmoil (of history) illustrates the growing influence on all taxonomy of cladistics, the science of classifying living things strictly according to their lines of descent.

Today, there are eight extant genera of hominoids. They are the four genera in the family Hominidae, namely Homo, Pan, Gorilla, and Pongo; plus four genera in the family Hylobatidae (gibbons): Hylobates, Hoolock, Nomascus and Symphalangus. (The two subspecies of hoolock gibbons were recently moved from the genus Bunopithecus to the new genus Hoolock and re-ranked as species; a third species was described in January 2017).

In 1758, Carl Linnaeus, relying on second- or third-hand accounts, placed a second species in Homo along with H. sapiens: Homo troglodytes ("cave-dwelling man"). Although the term "Orang Outang" is listed as a variety – Homo sylvestris – under this species, it is nevertheless not clear to which animal this name refers, as Linnaeus had no specimen to refer to, hence no precise description. Linnaeus may have based Homo troglodytes on reports of mythical creatures, then-unidentified simians, or Asian natives dressed in animal skins. Linnaeus named the orangutan Simia satyrus ("satyr monkey"). He placed the three genera Homo, Simia and Lemur in the order of Primates.

The troglodytes name was used for the chimpanzee by Blumenbach in 1775, but moved to the genus Simia. The orangutan was moved to the genus Pongo in 1799 by Lacépède.

Linnaeus's inclusion of humans in the primates with monkeys and apes was troubling for people who denied a close relationship between humans and the rest of the animal kingdom. Linnaeus's Lutheran archbishop had accused him of "impiety". In a letter to Johann Georg Gmelin dated 25 February 1747, Linnaeus wrote:

It is not pleasing to me that I must place humans among the primates, but man is intimately familiar with himself. Let's not quibble over words. It will be the same to me whatever name is applied. But I desperately seek from you and from the whole world a general difference between men and simians from the principles of Natural History. I certainly know of none. If only someone might tell me one! If I called man a simian or vice versa I would bring together all the theologians against me. Perhaps I ought to, in accordance with the law of Natural History.

Accordingly, Johann Friedrich Blumenbach in the first edition of his Manual of Natural History (1779), proposed that the primates be divided into the Quadrumana (four-handed, i.e. apes and monkeys) and Bimana (two-handed, i.e. humans). This distinction was taken up by other naturalists, most notably Georges Cuvier. Some elevated the distinction to the level of order.

However, the many affinities between humans and other primates – and especially the "great apes" – made it clear that the distinction made no scientific sense. In his 1871 book The Descent of Man, and Selection in Relation to Sex, Charles Darwin wrote:

The greater number of naturalists who have taken into consideration the whole structure of man, including his mental faculties, have followed Blumenbach and Cuvier, and have placed man in a separate Order, under the title of the Bimana, and therefore on an equality with the orders of the Quadrumana, Carnivora, etc. Recently many of our best naturalists have recurred to the view first propounded by Linnaeus, so remarkable for his sagacity, and have placed man in the same Order with the Quadrumana, under the title of the Primates. The justice of this conclusion will be admitted: for in the first place, we must bear in mind the comparative insignificance for classification of the great development of the brain in man, and that the strongly marked differences between the skulls of man and the Quadrumana (lately insisted upon by Bischoff, Aeby, and others) apparently follow from their differently developed brains. In the second place, we must remember that nearly all the other and more important differences between man and the Quadrumana are manifestly adaptive in their nature, and relate chiefly to the erect position of man; such as the structure of his hand, foot, and pelvis, the curvature of his spine, and the position of his head.

Changes in taxonomy and terminology

See also: Hominidae and Human taxonomy

 

Humans the non-apes: Until about 1960, taxonomists typically divided the superfamily Hominoidea into two families. The science community treated humans and their extinct relatives as the outgroup within the superfamily; that is, humans were considered as quite distant from kinship with the "apes". Humans were classified as the family Hominidae and were known as the "hominids". All other hominoids were known as "apes" and were referred to the family Pongidae.
The "great apes" in Pongidae: The 1960s saw the methodologies of molecular biology applied to primate taxonomy. Goodman's 1964 immunological study of serum proteins led to re-classifying the hominoids into three families: the humans in Hominidae; the great apes in Pongidae; and the "lesser apes" (gibbons) in Hylobatidae. However, this arrangement had two trichotomies: Pan, Gorilla, and Pongo of the "great apes" in Pongidae, and Hominidae, Pongidae, and Hylobatidae in Hominoidea. These presented a puzzle; scientists wanted to know which genus speciated first from the common hominoid ancestor.
Gibbons the outgroup: New studies indicated that gibbons, not humans, are the outgroup within the superfamily Hominoidea, meaning: the rest of the hominoids are more closely related to each other than (any of them) are to the gibbons. With this splitting, the gibbons (Hylobates, et al.) were isolated after moving the great apes into the same family as humans. Now the term "hominid" encompassed a larger collective taxa within the family Hominidae. With the family trichotomy settled, scientists could now work to learn which genus is 'least' related to the others in the subfamily Ponginae.
Orangutans the outgroup: Investigations comparing humans and the three other hominid genera disclosed that the African apes (chimpanzees and gorillas) and humans are more closely related to each other than any of them are to the Asian orangutans (Pongo); that is, the orangutans, not humans, are the outgroup within the family Hominidae. This led to reassigning the African apes to the subfamily Homininae with humans—which presented a new three-way split: Homo, Pan, and Gorilla.
Hominins: In an effort to resolve the trichotomy, while preserving the nostalgic "outgroup" status of humans, the subfamily Homininae was divided into two tribes: Gorillini, comprising genus Pan and genus Gorilla; and Hominini, comprising genus Homo (the humans). Humans and close relatives now began to be known as "hominins", that is, of the tribe Hominini. Thus, the term "hominin" succeeded to the previous use of "hominid", which meaning had changed with changes in Hominidae (see above: 3rd graphic, "Gibbons the outgroup").
Gorillas the outgroup: New DNA comparisons now provided evidence that gorillas, not humans, are the outgroup in the subfamily Homininae; this suggested that chimpanzees should be grouped with humans in the tribe Hominini, but in separate subtribes. Now the name "hominin" delineated Homo plus those earliest Homo relatives and ancestors that arose after the divergence from the chimpanzees. (Humans are no longer classified as an outgroup, but are a branch, deep in the tree of the pre-1960s ape group).
Speciation of gibbons: Later DNA comparisons disclosed previously unknown speciation of genus Hylobates (gibbons) into four genera: Hylobates, Hoolock, Nomascus, and Symphalangus. The ordering of speciation of these four genera are being investigated as of 2022.

Characteristics

Like those of the orangutan, the shoulder joints of hominoids are adapted to brachiation, or movement by swinging in tree branches.

The lesser apes are the gibbon family, Hylobatidae, of sixteen species; all are native to Asia. Their major differentiating characteristic is their long arms, which they use to brachiate through trees. Their wrists are ball and socket joints as an evolutionary adaptation to their arboreal lifestyle. Generally smaller than the African apes, the largest gibbon, the siamang, weighs up to 14 kg (31 lb); in comparison, the smallest "great ape", the bonobo, is 34 to 60 kg (75 to 132 lb).

The superfamily Hominoidea falls within the parvorder Catarrhini, which also includes the Old World monkeys of Africa and Eurasia. Within this grouping, the two families Hylobatidae and Hominidae can be distinguished from Old World monkeys by the number of cusps on their molars; hominoids have five in the "Y-5" molar pattern, whereas Old World monkeys have only four in a bilophodont pattern.

Further, in comparison with Old World monkeys, hominoids are noted for: more mobile shoulder joints and arms due to the dorsal position of the scapula; broader ribcages that are flatter front-to-back; and a shorter, less mobile spine, with greatly reduced caudal (tail) vertebrae—resulting in complete loss of the tail in extant hominoid species. These are anatomical adaptations, first, to vertical hanging and swinging locomotion (brachiation) and, later, to developing balance in a bipedal pose. Note there are primates in other families that also lack tails, and at least one, the pig-tailed langur, is known to walk significant distances bipedally. The front of the ape skull is characterised by its sinuses, fusion of the frontal bone, and by post-orbital constriction.

Distinction from monkeys

See also: Monkey § Historical and modern terminology

Cladistically, apes, catarrhines, and extinct species such as Aegyptopithecus and Parapithecidaea, are monkeys, so one can only specify ape features not present in other monkeys.

Unlike most monkeys, apes do not possess a tail. Monkeys are more likely to be in trees and use their tails for balance. While the great apes are considerably larger than monkeys, gibbons (lesser apes) are smaller than some monkeys. Apes are considered to be more intelligent than monkeys, which are considered to have more primitive brains.

The enzyme urate oxidase has become inactive in all apes, its function having been lost in two primate lineages during the middle Miocene; first in the common ancestors of Hominidae, and later in the common ancestor of Hylobatidae. It has been hypothesized that in both incidents it was a mutation that occurred in apes living in Europe when the climate was getting colder, leading to starvation during winter. The mutation changed the biochemistry of the apes and made it easier to accumulate fat, which allowed the animals to survive longer periods of starvation. When they migrated to Asia and Africa, this genetic trait remained.

Behaviour

Major studies of behaviour in the field were completed on the three better-known "great apes", for example by Jane Goodall, Dian Fossey and Birute Galdikas. These studies have shown that in their natural environments, the non-human hominoids show sharply varying social structure: gibbons are monogamous, territorial pair-bonders, orangutans are solitary, gorillas live in small troops with a single adult male leader, while chimpanzees live in larger troops with bonobos exhibiting promiscuous sexual behaviour. Their diets also vary; gorillas are foliovores, while the others are all primarily frugivores, although the common chimpanzee hunts for meat. Foraging behaviour is correspondingly variable.

Diet

Apart from humans and gorillas, apes eat a predominantly frugivorous diet, mostly fruit, but supplemented with a variety of other foods. Gorillas are predominately folivorous, eating mostly stalks, shoots, roots and leaves with some fruit and other foods. Non-human apes usually eat a small amount of raw animal foods such as insects or eggs. In the case of humans, migration and the invention of hunting tools and cooking has led to an even wider variety of foods and diets, with many human diets including large amounts of cooked tubers (roots) or legumes. Other food production and processing methods including animal husbandry and industrial refining and processing have further changed human diets. Humans and other apes occasionally eat other primates. Some of these primates are now close to extinction with habitat loss being the underlying cause.

Cognition

A series of images showing a gorilla utilizing a small tree trunk as a tool to maintain balance as she fished for aquatic herbs

All the non-human hominoids are generally thought of as highly intelligent, and scientific study has broadly confirmed that they perform very well on a wide range of cognitive tests—though there is relatively little data on gibbon cognition. The early studies by Wolfgang Köhler demonstrated exceptional problem-solving abilities in chimpanzees, which Köhler attributed to insight. The use of tools has been repeatedly demonstrated; more recently, the manufacture of tools has been documented, both in the wild and in laboratory tests. Imitation is much more easily demonstrated in "great apes" than in other primate species. Almost all the studies in animal language acquisition have been done with "great apes", and though there is continuing dispute as to whether they demonstrate real language abilities, there is no doubt that they involve significant feats of learning. Chimpanzees in different parts of Africa have developed tools that are used in food acquisition, demonstrating a form of animal culture.

Monkey

From Wikipedia, the free encyclopedia

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

Monkeys Temporal range: Late Eocene–Present PreꞒ Ꞓ O S D C P T J K Pg N
Bonnet macaque Macaca radiata Mangaon, Maharashtra, India
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Primates
Suborder:	Haplorhini
Infraorder:	Simiiformes
Groups included
Platyrrhini Cercopithecidae †Parapithecidae
Cladistically included but traditionally excluded taxa
Hominoidea

Monkey is a common name that may refer to most mammals of the infraorder Simiiformes, also known as the simians. Traditionally, all animals in the group now known as simians are counted as monkeys except the apes, which constitutes an incomplete paraphyletic grouping; however, in the broader sense based on cladistics, apes (Hominoidea) are also included, making the terms monkeys and simians synonyms in regards to their scope.

In 1812, Geoffroy grouped the apes and the Cercopithecidae group of monkeys together and established the name Catarrhini, "Old World monkeys", ("singes de l'Ancien Monde" in French). The extant sister of the Catarrhini in the monkey ("singes") group is the Platyrrhini (New World monkeys). Some nine million years before the divergence between the Cercopithecidae and the apes, the Platyrrhini emerged within "monkeys" by migration to South America from Afro-Arabia (the Old World), likely by ocean.  Apes are thus deep in the tree of extant and extinct monkeys, and any of the apes is distinctly closer related to the Cercopithecidae than the Platyrrhini are.

Many monkey species are tree-dwelling (arboreal), although there are species that live primarily on the ground, such as baboons. Most species are mainly active during the day (diurnal). Monkeys are generally considered to be intelligent, especially the Old World monkeys.

Within suborder Haplorhini, the simians are a sister group to the tarsiers – the two members diverged some 70 million years ago. New World monkeys and catarrhine monkeys emerged within the simians roughly 35 million years ago. Old World monkeys and apes emerged within the catarrhine monkeys about 25 million years ago. Extinct basal simians such as Aegyptopithecus or Parapithecus (35–32 million years ago) are also considered monkeys by primatologists.

Lemurs, lorises, and galagos are not monkeys, but strepsirrhine primates (suborder Strepsirrhini). The simians' sister group, the tarsiers, are also haplorhine primates; however, they are also not monkeys.

Apes emerged within monkeys as sister of the Cercopithecidae in the Catarrhini, so cladistically they are monkeys as well. However, there has been resistance to directly designate apes (and thus humans) as monkeys, so "Old World monkey" may be taken to mean either the Cercopithecoidea (not including apes) or the Catarrhini (including apes). That apes are monkeys was already realized by Georges-Louis Leclerc, Comte de Buffon in the 18th century. Linnaeus placed this group in 1758 together with the tarsiers, in a single genus "Simia" (sans Homo), an ensemble now recognised as the Haplorhini.

Monkeys, including apes, can be distinguished from other primates by having only two pectoral nipples, a pendulous penis, and a lack of sensory whiskers.

Historical and modern terminology

The Barbary macaque is also known as the Barbary ape.

According to the Online Etymology Dictionary, the word "monkey" may originate in a German version of the Reynard the Fox fable, published c. 1580. In this version of the fable, a character named Moneke is the son of Martin the Ape.^[29] In English, no clear distinction was originally made between "ape" and "monkey"; thus the 1911 Encyclopædia Britannica entry for "ape" notes that it is either a synonym for "monkey" or is used to mean a tailless humanlike primate. Colloquially, the terms "monkey" and "ape" are widely used interchangeably. Also, a few monkey species have the word "ape" in their common name, such as the Barbary ape.

Later in the first half of the 20th century, the idea developed that there were trends in primate evolution and that the living members of the order could be arranged in a series, leading through "monkeys" and "apes" to humans. Monkeys thus constituted a "grade" on the path to humans and were distinguished from "apes".

Scientific classifications are now more often based on monophyletic groups, that is groups consisting of all the descendants of a common ancestor. The New World monkeys and the Old World monkeys are each monophyletic groups, but their combination was not, since it excluded hominoids (apes and humans). Thus, the term "monkey" no longer referred to a recognized scientific taxon. The smallest accepted taxon which contains all the monkeys is the infraorder Simiiformes, or simians. However this also contains the hominoids, so that monkeys are, in terms of currently recognized taxa, non-hominoid simians. Colloquially and pop-culturally, the term is ambiguous and sometimes monkey includes non-human hominoids. In addition, frequent arguments are made for a monophyletic usage of the word "monkey" from the perspective that usage should reflect cladistics.

A group of monkeys may be commonly referred to as a tribe or a troop.

Two separate groups of primates are referred to as "monkeys": New World monkeys (platyrrhines) from South and Central America and Old World monkeys (catarrhines in the superfamily Cercopithecoidea) from Africa and Asia. Apes (hominoids)—consisting of gibbons, orangutans, gorillas, chimpanzees and bonobos, and humans—are also catarrhines but were classically distinguished from monkeys. Tailless monkeys may be called "apes", incorrectly according to modern usage; thus the tailless Barbary macaque is historically called the "Barbary ape".

Description

As apes have emerged in the monkey group as sister of the old world monkeys, characteristics that describe monkeys are generally shared by apes as well. Williams et al. outlined evolutionary features, including in stem groupings, contrasted against the other primates such as the tarsiers and the lemuriformes.

Monkeys range in size from the pygmy marmoset, which can be as small as 117 mm (4+5⁄8 in) with a 172 mm (6+3⁄4 in) tail and just over 100 g (3+1⁄2 oz) in weight, to the male mandrill, almost 1 m (3 ft 3 in) long and weighing up to 36 kg (79 lb). Some are arboreal (living in trees) while others live on the savanna; diets differ among the various species but may contain any of the following: fruit, leaves, seeds, nuts, flowers, eggs and small animals (including insects and spiders).

Some characteristics are shared among the groups; most New World monkeys have long tails, with those in the Atelidae family being prehensile, while Old World monkeys have non-prehensile tails or no visible tail at all. Old World monkeys have trichromatic color vision like that of humans, while New World monkeys may be trichromatic, dichromatic, or—as in the owl monkeys and greater galagos—monochromatic. Although both the New and Old World monkeys, like the apes, have forward-facing eyes, the faces of Old World and New World monkeys look very different, though again, each group shares some features such as the types of noses, cheeks and rumps.

Classification

The following list shows where the various monkey families (bolded) are placed in the classification of living (extant) primates.

• Order Primates
  • Suborder Strepsirrhini: lemurs, lorises, and galagos
  • Suborder Haplorhini: tarsiers, monkeys, and apes
    • Infraorder Tarsiiformes
      • Family Tarsiidae: tarsiers
    • Infraorder Simiiformes: simians
      • Parvorder Platyrrhini: New World monkeys
        • Family Callitrichidae: marmosets and tamarins (42 species)
        • Family Cebidae: capuchins and squirrel monkeys (14 species)
        • Family Aotidae: night monkeys (11 species)
        • Family Pitheciidae: titis, sakis, and uakaris (41 species)
        • Family Atelidae: howler, spider, and woolly monkeys (24 species)
      • Parvorder Catarrhini
        • Superfamily Cercopithecoidea
          • Family Cercopithecidae: Old World monkeys (135 species)
        • Superfamily Hominoidea: apes
          • Family Hylobatidae: gibbons ("lesser apes") (20 species)
          • Family Hominidae: great apes (including humans, gorillas, chimpanzees, and orangutans) (8 species)

Cladogram with extinct families

Generally, extinct non-hominoid simians, including early catarrhines are discussed as monkeys as well as simians or anthropoids, which cladistically means that Hominoidea are monkeys as well, restoring monkeys as a single grouping. It is indicated approximately how many million years ago (Mya) the clades diverged into newer clades. It is thought the New World monkeys started as a drifted "Old World monkey" group from the Old World (probably Africa) to the New World (South America).

Relationship with humans

Macaque on a "Please do not feed monkeys" sign in Ko Chang, Thailand.

 

Sign at a store in Swyambhunath, Bagmati, Nepal, which reads "Monkey's Food is Available here". Some places use their monkey population as a tourist attraction.

The many species of monkey have varied relationships with humans. Some are kept as pets, others used as model organisms in laboratories or in space missions. They may be killed in monkey drives (when they threaten agriculture) or used as service animals for the disabled.

In some areas, some species of monkey are considered agricultural pests, and can cause extensive damage to commercial and subsistence crops. This can have important implications for the conservation of endangered species, which may be subject to persecution. In some instances farmers' perceptions of the damage may exceed the actual damage. Monkeys that have become habituated to human presence in tourist locations may also be considered pests, attacking tourists.

As service animals for disabled people

See also: Service animal § Helper monkey

Some organizations train capuchin monkeys as service animals to assist quadriplegics and other people with severe spinal cord injuries or mobility impairments. After being socialized in a human home as infants, the monkeys undergo extensive training before being placed with disabled people. Around the house, the monkeys assist with daily tasks such as feeding, fetching, manipulating objects, and personal care.

Helper monkeys are usually trained in schools by private organizations, taking seven years to train, and are able to serve 25–30 years (two to three times longer than a guide dog).

In 2010, the U.S. federal government revised its definition of service animal under the Americans with Disabilities Act (ADA). Non-human primates are no longer recognized as service animals under the ADA. The American Veterinary Medical Association does not support the use of non-human primates as assistance animals because of animal welfare concerns, the potential for serious injury to people, and risks that primates may transfer dangerous diseases to humans.

In experiments

Main article: Animal testing on non-human primates

The most common monkey species found in animal research are the grivet, the rhesus macaque, and the crab-eating macaque, which are either wild-caught or purpose-bred. They are used primarily because of their relative ease of handling, their fast reproductive cycle (compared to apes) and their psychological and physical similarity to humans. Worldwide, it is thought that between 100,000 and 200,000 non-human primates are used in research each year, 64.7% of which are Old World monkeys, and 5.5% New World monkeys. This number makes a very small fraction of all animals used in research. Between 1994 and 2004 the United States has used an average of 54,000 non-human primates, while around 10,000 non-human primates were used in the European Union in 2002.

In space

Sam, a rhesus macaque, was flown to a height of 88,500 m (290,400 ft) by NASA in 1959

 

Main article: Monkeys and apes in space

A number of countries have used monkeys as part of their space exploration programmes, including the United States and France. The first monkey in space was Albert II, who flew in the US-launched V-2 rocket on June 14, 1949.

As food

Main article: Monkey meat

Monkey brains are eaten as a delicacy in parts of South Asia, Africa and China. Monkeys are sometimes eaten in parts of Africa, where they can be sold as "bushmeat". In traditional Islamic dietary laws, the eating of monkeys is forbidden.

Literature

Illustration of Indian monkeys known as bandar from the illuminated manuscript Baburnama (Memoirs of Babur)

Sun Wukong (the "Monkey King"), a character who figures prominently in Chinese mythology, is the protagonist in the classic comic Chinese novel Journey to the West.

Monkeys are prevalent in numerous books, television programs, and movies. The television series Monkey and the literary characters Monsieur Eek and Curious George are all examples.

Informally, "monkey" may refer to apes, particularly chimpanzees, gibbons, and gorillas. Author Terry Pratchett alludes to this difference in usage in his Discworld novels, in which the Librarian of the Unseen University is an orangutan who gets very violent if referred to as a monkey. Another example is the use of Simians in Chinese poetry.

The winged monkeys are prominent characters in L. Frank Baum's Wizard of Oz books and in the 1939 film based on Baum's 1900 novel The Wonderful Wizard of Oz.

Religion and worship

Abhinandananatha with his symbol of monkey below his idol

Monkey is the symbol of fourth Tirthankara in Jainism, Abhinandananatha.

Hanuman, a prominent deity in Hinduism, is a human-like monkey god who is believed to bestow courage, strength and longevity to the person who thinks about him or Rama.

In Buddhism, the monkey is an early incarnation of Buddha but may also represent trickery and ugliness. The Chinese Buddhist "mind monkey" metaphor refers to the unsettled, restless state of human mind. Monkey is also one of the Three Senseless Creatures, symbolizing greed, with the tiger representing anger and the deer lovesickness.

The Sanzaru, or three wise monkeys, are revered in Japanese folklore; together they embody the proverbial principle to "see no evil, hear no evil, speak no evil".

The Moche people of ancient Peru worshipped nature. They placed emphasis on animals and often depicted monkeys in their art.

The Tzeltal people of Mexico worshipped monkeys as incarnations of their dead ancestors.

Zodiac

Monkeys as Judges of Art, an ironical 1889 painting by Gabriel von Max.

The Monkey (猴) is the ninth in the twelve-year cycle of animals which appear in the Chinese zodiac related to the Chinese calendar. The next time that the monkey will appear as the zodiac sign will be in the year 2028.

Natural reservoir

From Wikipedia, the free encyclopedia

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

 

Cows are natural reservoirs of African trypanosomiasis

In infectious disease ecology and epidemiology, a natural reservoir, also known as a disease reservoir or a reservoir of infection, is the population of organisms or the specific environment in which an infectious pathogen naturally lives and reproduces, or upon which the pathogen primarily depends for its survival. A reservoir is usually a living host of a certain species, such as an animal or a plant, inside of which a pathogen survives, often (though not always) without causing disease for the reservoir itself. By some definitions a reservoir may also be an environment external to an organism, such as a volume of contaminated air or water.

Because of the enormous variety of infectious microorganisms capable of causing disease, precise definitions for what constitutes a natural reservoir are numerous, various, and often conflicting. The reservoir concept applies only for pathogens capable of infecting more than one host population and only with respect to a defined target population – the population of organisms in which the pathogen causes disease. The reservoir is any population of organisms (or any environment) which harbors the pathogen and transmits it to the target population. Reservoirs may comprise one or more different species, may be the same or a different species as the target, and, in the broadest sense, may include vector species, which are otherwise distinct from natural reservoirs. Significantly, species considered reservoirs for a given pathogen may not experience symptoms of disease when infected by the pathogen.

Identifying the natural reservoirs of infectious pathogens has proven useful in treating and preventing large outbreaks of disease in humans and domestic animals, especially those diseases for which no vaccine exists. In principle, zoonotic diseases can be controlled by isolating or destroying the pathogen's reservoirs of infection. The mass culling of animals confirmed or suspected as reservoirs for human pathogens, such as birds that harbor avian influenza, has been effective at containing possible epidemics in many parts of the world; for other pathogens, such as the ebolaviruses, the identity of the presumed natural reservoir remains obscure.

Definition and terminology

The great diversity of infectious pathogens, their possible hosts, and the ways in which their hosts respond to infection has resulted in multiple definitions for "natural reservoir", many of which are conflicting or incomplete. In a 2002 conceptual exploration published in the CDC's Emerging Infectious Diseases, the natural reservoir of a given pathogen is defined as "one or more epidemiologically connected populations or environments in which the pathogen can be permanently maintained and from which infection is transmitted to the defined target population." The target population is the population or species in which the pathogen causes disease; it is the population of interest because it has disease when infected by the pathogen (for example, humans are the target population in most medical epidemiological studies).

A common criterion in other definitions distinguishes reservoirs from non-reservoirs by the degree to which the infected host shows symptoms of disease. By these definitions, a reservoir is a host that does not experience the symptoms of disease when infected by the pathogen, whereas non-reservoirs show symptoms of the disease. The pathogen still feeds, grows, and reproduces inside a reservoir host, but otherwise does not significantly affect its health; the relationship between pathogen and reservoir is more or less commensal, whereas in susceptible hosts that do develop disease caused by the pathogen, the pathogen is considered parasitic.

What further defines a reservoir for a specific pathogen is where it can be maintained and from where it can be transmitted. A "multi-host" organism is capable of having more than one natural reservoir.

Types of reservoirs

Natural reservoirs can be divided into three main types: human, animal (non-human), and environmental.

Human reservoirs

Human reservoirs are human beings infected by pathogens that exist on or within the human body. Infections like poliomyelitis and smallpox, which exist exclusively within a human reservoir, are sometimes known as anthroponoses. Humans can act as reservoirs for sexually transmitted diseases, measles, mumps, streptococcal infection, various respiratory pathogens, and the smallpox virus.

Bushmeat being prepared for cooking in Ghana, 2013. Human consumption of animals as bushmeat in equatorial Africa has caused the transmission of diseases, including Ebola, to people.

Animal reservoirs

Animal (non-human) reservoirs consist of domesticated and wild animals infected by pathogens. For example, the bacterium Vibrio cholerae, which causes cholera in humans, has natural reservoirs in copepods, zooplankton, and shellfish. Parasitic blood-flukes of the genus Schistosoma, responsible for schistosomiasis, spend part of their lives inside freshwater snails before completing their life cycles in vertebrate hosts. Viruses of the taxon Ebolavirus, which causes Ebola virus disease, are thought to have a natural reservoir in bats or other animals exposed to the virus. Other zoonotic diseases that have been transmitted from animals to humans include: rabies, blastomycosis, psittacosis, trichinosis, cat-scratch disease, histoplasmosis, coccidiomycosis and salmonella.

Common animal reservoirs include: bats, rodents, cows, pigs, sheep, swine, rabbits, raccoons, dogs, other mammals.

Common animal reservoirs

Bats

Further information: Bat-borne virus

Numerous zoonotic diseases have been traced back to bats. There is a couple of theories that serve as possible explanations as to why bats carry so many viruses. One proposed theory is that there exist so many bat-borne illnesses because there exist a large number of bat species and individuals. The second possibility is that something about bats' physiology makes them especially good reservoir hosts. Perhaps bats' "food choices, population structure, ability to fly, seasonal migration and daily movement patterns, torpor and hibernation, life span, and roosting behaviors" are responsible for making them especially suitable reservoir hosts. Lyssaviruses (including the Rabies virus), Henipaviruses, Menangle and Tioman viruses, SARS-CoV-Like Viruses, and Ebola viruses have all been traced back to different species of bats. Fruit bats in particular serve as the reservoir host for Nipah virus (NiV).

Rats

Rats are known to be the reservoir hosts for a number of zoonotic diseases. Norway rats were found to be infested with the Lyme disease spirochetes. In Mexico rats are known carriers of Trypanosoma cruzi, which causes Chagas disease.

Mice

White-footed mice (Peromyscus leucopus) are one of the most important animal reservoirs for the Lyme disease spirochete (Borrelia burgdorferi). Deer mice serve as reservoir hosts for Sin Nombre virus, which causes hantavirus pulmonary syndrome (HPS).

Monkeys

The Zika virus originated from monkeys in Africa. In São José do Rio Preto and Belo Horizonte, Brazil the zika virus has been found in dead monkeys. Genome sequencing has revealed the virus to be very similar to the type that infects humans.

Environmental reservoirs

Environmental reservoirs include living and non-living reservoirs that harbor infectious pathogens outside the bodies of animals. These reservoirs may exist on land (plants and soil), in water, or in the air. Pathogens found in these reservoirs are sometimes free-living. The bacteria Legionella pneumophila, a facultative intracellular parasite which causes Legionnaires' disease, and Vibrio cholerae, which causes cholera, can both exist as free-living parasites in certain water sources as well as in invertebrate animal hosts.

Disease transmission

A disease reservoir acts as a transmission point between a pathogen and a susceptible host. Transmission can occur directly or indirectly.

Direct transmission

Direct transmission can occur from direct contact or direct droplet spread. Direct contact transmission between two people can happen through skin contact, kissing, and sexual contact. Humans serving as disease reservoirs can be symptomatic (showing illness) or asymptomatic (not showing illness), act as disease carriers, and often spread illness unknowingly. Human carriers commonly transmit disease because they do not realize they are infected, and consequently take no special precautions to prevent transmission. Symptomatic persons who are aware of their illness are not as likely to transmit infection because they take precautions to reduce possible transmission of the disease and/or seek out treatment to prevent the spread of the disease. Direct droplet spread is due to solid particles or liquid droplet suspended in air for some time. Droplet spread is considered the transmission of the pathogen to a susceptible host within a meter of distance; said droplet spread can occur from coughing, sneezing, and/or just by talking.

• Neisseria gonorrhoeae (Gonorrhea) is transmitted by sexual contact involving the penis, vagina, mouth, and anus through direct contact transmission.
• Bordetella pertussis (Pertussis) is transmitted by cough from human reservoir to susceptible host through direct droplet spread.

Indirect transmission

Indirect transmission can occur by airborne transmission, by vehicles (including fomites), and by vectors.

Airborne transmission is different from direct droplet spread as it is defined as disease transmission that takes place over a distance larger than a meter. Pathogens that can be transmitted through airborne sources are carried by particles such as dust or dried residue (referred to as droplet nuclei).

Vehicles such as food, water, blood and fomites can act as passive transmission points between reservoirs and susceptible hosts. Fomites are inanimate objects (doorknobs, medical equipment, etc.) that become contaminated by a reservoir source or someone/something that is a carrier. A vehicle, like a reservoir, may also be a favorable environment for the growth of an infectious agent, as coming into contact with a vehicle leads to its transmission.

Vector transmission occurs most often from insect bites from mosquitoes, flies, fleas, and ticks. There are two sub-categories of vectors: mechanical (an insect transmits the pathogen to a host without the insect itself being affected) and biological (reproduction of the pathogen occurs within the vector before the pathogen is transmitted to a host). To give a few examples, Morbillivirus (measles) is transmitted from an infected human host to a susceptible host as they are transmitted by respiration through airborne transmission. Campylobacter (campylobacteriosis) is a common bacterial infection that is spread from human or non-human reservoirs by vehicles such as contaminated food and water. Plasmodium falciparum (malaria) can be transmitted from an infected mosquito, an animal (non-human) reservoir, to human host by biological vector transmission.

Implications for public health

LH Taylor found that 61% of all human pathogens are classified as zoonotic. Thus, the identification of the natural reservoirs of pathogens prior to zoonosis would be incredibly useful from a public health standpoint. Preventive measures can be taken to lessen the frequency of outbreaks, such as vaccinating the animal sources of disease or preventing contact with reservoir host animals. In an effort to predict and prevent future outbreaks of zoonotic diseases, the U.S. Agency for International Development started the Emerging Pandemic Threats initiative in 2009. In alliance with University of California-Davis, EcoHealth Alliance, Metabiota Inc., Smithsonian Institution, and Wildlife Conservation Society with support from Columbia and Harvard universities, the members of the PREDICT project are focusing on the "detection and discovery of zoonotic diseases at the wildlife-human interface." There are numerous other organizations around the world experimenting with different methods to predict and identify reservoir hosts. Researchers at the University of Glasgow created a machine learning algorithm that is designed to use "viral genome sequences to predict the likely natural host for a broad spectrum of RNA viruses, the viral group that most often jumps from animals to humans."

Disease ecology

From Wikipedia, the free encyclopedia

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

Disease ecology is a sub-discipline of ecology concerned with the mechanisms, patterns, and effects of host-pathogen interactions, particularly those of infectious diseases. example, it examines how parasites spread through and influence wildlife populations and communities. By studying the flow of diseases within the natural environment, scientists seek to better understand how changes within our environment can shape how pathogens, and other diseases, travel. Therefore, diseases ecology seeks to understand the links between ecological interactions and disease evolution. New emerging and re-emerging infectious diseases (infecting both wildlife and humans) are increasing at unprecedented rates which can have lasting impacts on public health, ecosystem health, and biodiversity.

Factors affecting spread of diseases

Parasitic infections, along with certain transmitted diseases, are present in wildlife which can have severe health effects on particular individuals and populations. Constant host-parasite interactions make disease ecology critical in conservation ecology.

Ecological factors

Ecological factors that can determine the persistence and the spread of diseases are population size, density, and composition. Host population size is important in the context of host-parasite interactions since the spread of diseases needs a host population large enough to sustain parasitic interactions. The health of the overall population (and the size of the weakened population members) will also influence the way that parasites and diseases will transmit among members. Additionally, competition and predation dynamics in the ecosystem can influence the density of potential hosts which can either propagate or limit the spread of diseases.

Predator-prey interactions

In some cases when a parasite has weakened an animal it will become easier prey for a predator species. Occasionally predators will prefer feeding on the sick or infected prey even though they carry a parasite because of the opportunity weak prey present. Without the presence of a predator species the prey species would likely exceed manageable numbers therefore leading to the rapid spread of pathogens throughout the prey population. Available host numbers increased when the infected individuals are not removed due to low predation. However, there are some situations where predator feeding can disturb a pathogen that previously was dormant leading to an epidemic that otherwise would not have occurred. Some parasites are able to survive when their host species is consumed leading to the parasite being distributed in the waste of the predator which can continue the spread of disease.

Parasitism

Parasitism in disease ecology is important because it can shape the way many habitats function because they are disease carriers. These diseases can alter the timing of events, biogeochemical cycles, and even the flow of energy in a habitat. Parasites are able to limit population growth and reproduction of species which may lead to a shift in the balance of an ecosystem. Other ways parasites impact systems are through nutrient cycles. Parasites are able to create imbalances of the elements in a system through the relationship they have with a host and the host's diet.

Biological factors

Biological factors that can determine the persistence of diseases include parameters pertaining at the level of the individual within the population (one single organism). Sex differences are found to be prevalent in disease transmission. For example, male American minks are larger and travel wider distances, making them more prone to come into contact with parasites and diseases. The host species age may additionally affect the rate in which diseases are transmitted. Younger members of populations have yet to acquire herd immunity and are therefore more susceptible to parasitic infections.

Anthropogenic factors

Anthropogenic factors of disease spread can be through the introduction or translocation of wildlife for conservation purposes by humans. Additionally, human activity is changing the way in which diseases move through the natural environment.

In relation to anthropogenic factors

Humans are strongly impacting how diseases spread by creating what is known as "novel species associations". Globalization, mainly through world travel and trade, has created a system in which pathogens, and other species, are more in contact with one another than before. Ecological disruption, including habitat fragmentation and road construction, degrade natural landscapes and have been studied as drivers of recent emergence and re-emergence of infectious diseases worldwide. Scientists have speculated that habitat destruction and biodiversity loss are some of the main reasons influencing the rapid spread of non-human, disease carrying vectors. The loss of predators, that mitigate the ability for pathogen transmission, can increase the rate of disease transmission. Human anthropogenic induced climate change is becoming problematic, as parasites and their associated diseases, can move to higher latitudes with increasing global temperatures. New diseases can therefore infect populations that were previously never in contact with certain pathogens.

Urbanization and biodiversity loss

Urban sprawl of Toronto, Canada, viewed from the CN Tower

Urbanization is considered one of the main land-use changes, defined as the growth in the area and number of people inhabiting cities and creates artificial landscapes of built-up structures for human use. With over 65% of the global human population living in cities by 2025, ecological impacts of urbanization focuses mainly on biodiversity loss defined as the decline in species richness. With empirical evidence, scientists are understanding that biodiversity loss is associated with increased disease transmission and worsening of disease severity for humans, wildlife, and certain plant species. As biodiversity is lost worldwide, it is oftentimes the larger, slower reproducing animal species that will go extinct first. This leaves smaller, more adaptable, fast reproducing species abundant. Research has shown that these smaller species are more likely the ones to carry and transmit pathogens (key examples include bats, rats, and mice).

Invasive species

Globalization, especially world trade and travel, has facilitated the spread of non-native species worldwide. Newly introduced invasive species have the ability to alter ecological dynamics through local and regional extinction of native species. This can promote changes to the ecosystem including the shift in abundance and richness of native species. New invasive species, and the diseases they potentially carry, can escape into the environment and alter the existing natural ecosystems and the ecosystem services that people are dependent upon, including water quality and nutrient availability.

Habitat fragmentation

Highways can cause habitat fragmentation which increases edge effects and promotes disease spread.

Encroachment on natural ecosystems and wildlife with rapid urbanization exposes humans to a wide variety of disease carrying animals. Habitat fragmentation leads to increased edge effects and increases the contact between different communities, vectors, and pathogens which can increase disease transmission. It is argued that between 2013 and 2015, the Ebola virus disease (EDB) outbreak in West Africa began due to deforestation and habitat degradation. In this case, frugivorous and insectivorous bat species had less forest serving as a barrier between them and dense human settlements. Transmission of the Ebola virus is believed to have occurred through direct contact with bat species carrying the pathogen and humans, encroaching on natural ecosystems.

Climate change

Further information: Climate change and infectious diseases

Scientists have deemed vector borne diseases to be sensitive to changes in weather and climate. The abundance of disease carrying vectors in the environment depends on multiple factors, including temperature, relative humidity, and water availability, all factors necessary for the reproductive processes and success of disease carrying vectors. Climate change predictions include rising temperatures and changes in rainfall pattern which can create suitable habitats and increases the overall survival rate and fitness of pathogen carrying species. With a warming climate, pathogens and parasites can begin shifting their native geographic ranges to higher latitudes and infect host species in which they have no prior interaction with. The shift in rainfall patterns can additionally indicate the presence of disease carrying vectors. For example, mosquitos spread diseases such as malaria and lymphatic filariasis. The distribution of lymphatic filariasis via mosquitos can be determined by looking at soil moisture content, an indicator of viable mosquito breeding habitat (as mosquito larvae need shallow, stagnant water to survive). As temperature and precipitation patterns change, so will soil moisture levels and the corresponding mosquito populations.

As climate change continues to disrupt ecosystems around the world it can make both human and non-human populations more or less vulnerable to disease depending on the specific effects of climate change on the disease. The subject of climate change and its impact on disease is increasingly attracting the attention of health professionals and climate-change scientists, particularly with respect to malaria and other vector-transmitted human diseases. More specifically, climate change can impact malaria transmissions by extending the season of transmission and creating more breeding sites due to increasing temperatures and rainfall, respectively. Increases in malaria transmissions and other vector-transmitted human diseases can have a devastating impact on communities that do not receive appropriate medical care and on people who have not had exposure to these diseases.

In relation to tropical, northern temperate zones, and the Arctic

It is thought that the effects of climate change on temperature will increase with latitude. This means that northern temperate zones will experience more temperature changes than tropical zones. Tropical zones experience less climate variability, so organisms in tropical zones have adjusted to a continuous climate. Therefore, slight disruptions in climate can dramatically affect the organisms in tropical zones. Climate change can affect organisms by elongating their reproductive cycles. In addition to this, climate change allows for pathogens to expand beyond tropical zones, dramatically impacting species because of the introduction of new pathogens. These impacted species include humans and human livestock.

Changes in northern temperate zones and the Arctic are also expected. More specifically, the effects of climate change on temperature increase with latitude, so the temperature in northern temperate zones is projected to increase and the temperature in the Arctic is projected to increase even more. Like tropical zones, climate change in northern temperate zones and the Arctic can also cause species to move beyond their original niche. For example, climate change has allowed elk to move north in areas that overlap with other species such as caribou. When the elk move, they introduce new pathogens into the area, thus harming the caribou.

Models and predicting disease ecology

There are numerous approaches when predicting the impacts of climate change on diseases. Static approaches use reproduction rates to find how climate change will affect vectors. An example of the use of static approaches is a process-based model called MIASMA. This model explores the relationship between different climate change scenarios and the reproduction rate of vectors. This model has been used specifically to look at mosquitoes in African highlands to make predictions about the future of the development and feeding of mosquitoes. Additionally, this model can be used to find the population of mosquitoes that bite, allowing predictions of diseases such as dengue fever.

Another approach includes statistical based models, which relies on observations unlike process-based models. An example of this type of model is CLIMEX, which maps vector species over geographical locations while accounting for climate factors. It is important to note that this approach does have limitations. CLIMEX does not include all factors that impact vector species.

Time-series models can also be used to find how climate change will modify disease dynamics. However this approach has a downside; only a limited number of locations and pathogens can be looked at simultaneously using time-series models.

Predictions of ENSO (El Niño Southern Oscillation) can also help predict diseases. ENSO events can create cooler temperatures in the Western Tropical Pacific and warmer temperatures in the Central and Eastern Tropical Pacific leading to intense precipitation and storms. Changes in climate due to ENSO can affect the dynamics of diseases and can affect the water sources humans use. For example, in 1991, cholera reappeared in Peru around the same time as an el Niño event occurred. ENSO events can be anticipated early on, and therefore by predicting ENSO, predictions about disease transmission peaks can be made up to two months before they occur.

Notable examples in disease ecology

Ticks are a vector for Lyme disease.

 

Barn owls are a host species for West Nile virus.

Malaria

Malaria is a disease transferred by the female Anopheles mosquito, located predominantly in sub-Saharan Africa and is a long withstanding public health issue. It is a disease that is strongly regulated by climate factors and therefore climate change will have a notable impact on the transmission of the disease. As temperatures warm, the reproductive phase of the Plasmodium parasite, within the gut of the female mosquito, will undergo completion. This will ensure that the female mosquito becomes infective before the end of its lifespan. Precipitation is also a critical factor for the breeding and the transmission of malaria and with climate change influencing regular precipitation patterns, studies are finding that mosquito breeding potential can increase as a direct result of climate change.

Lyme disease

Lyme disease is the most common tickborne disease throughout the United States and Europe with an estimated 476,000 cases in Europe and 200,000 cases in the United States per year. Recently, studies have concluded that there is an increased risk of Lyme disease in Southern Canada due to the home range expansion of the tick vector Ixodes scapularis, which is responsible for carrying the disease. Climate change creates milder winters and extended Spring and Autumn seasons. This creates hospitable habitats for ticks thrive at higher latitudes (where they are normally not found). Human infections of Lyme disease have been increasingly prominent in certain southern parts of Canadian provinces such as Ontario, Quebec, Manitoba, and Nova Scotia. According to Canadian published studies, other environmental factors are contributing to the expansion of the Ixodes scapularis home range which include the introduction of the vector through migratory birds and density of deer populations.

West Nile virus

West Nile virus is transferred between mosquitos and birds of prey including eagles, hawks, falcons, and owls. In the United States, West Nile Virus is being increasingly studied in New York and Connecticut due to the effects of climate change on two disease carrying vectors. Climate change is promoting the hybridization amongst two mosquito vectors (C. pipiens and C. quinquefasciatus) which can have an effect on the genetic composition of the hybrid allowing it to become more effective at transmitting diseases and increases its adaptability to different climactic conditions.