Wild ancestor

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Wild ancestors are the original species from which domesticated plants and animals are derived. Examples include dogs which are derived from wolves and flax which is derived from Linum bienne . In most cases the wild ancestor species still exists, but some domesticated species, such as camels, have no surviving wild relatives. In many cases there is considerable debate in the scientific community about the identity of the wild ancestor or ancestors, as the process of domestication involves natural selection, artificial selection, and hybridization.

Contents

Wild ancestors have gone through genetic changes to achieve biological mutualism with humans. This is due to humans selectively breeding those species.

 Theory

All living creatures are derived from a common wild ancestor. With time and the help of humans or nature, living beings adapt to their surroundings by gradual changes whether visible or not. According to Darwin, there are two different categories that may cause wild ancestors to change to their modern or domesticated counterparts: natural selection and artificial selection. Natural selection, as the name suggests, is environmentally driven; this occurs when more advantageous traits are passed down ensuring survival of the fittest, whereas artificial selection occurs through humans intentionally breeding creatures to attain desirable traits. Both of these allow the wild ancestors to evolve. [1]

Ancestors of two different species may overlap. A term for this is concestorcoined by Nicky Warren—from the book The Ancestor's Tale by Richard Dawkins.

Generally, wild ancestors have a similar genetic code to their descendants, although different or additional gene mutations are found in their modern counterparts.

Wild ancestors in animals

The red junglefowl (Gallus gallus), often believed to be an ancestor of the domestic chicken. Red Junglefowl hen India.jpg
The red junglefowl (Gallus gallus), often believed to be an ancestor of the domestic chicken.

Most animals are tuned to modern life by artificial selection. This is either due to the pressure of early hunter-gatherers' attempts to stabilise the food supply, which resulted in the existence of domesticated farm animals, or domestication of pets which are useful to humans. [2] Different animal species undergo different pathways of domestication although they almost always result in one common trait, which is tolerance of proximity to humans or lack of fear of humans and increased reproductivity. [3]

An example of the wild ancestor of an animal bred as a food source is in chickens. The ancestor of the domesticated chicken, the red junglefowl, is believed to have an origin in parts of South and Southeast Asia. [4] Around 8,000 years ago humans started to breed this species for food. A study has shown that the act of domestication for the chickens caused the gene mutation involving a gene known as TSHR, which was found only in domestic populations. This implied that this gene in particular may have some involvement in the domestication of bird species.

The domestication of the wolf is a different process altogether as it is the result of two interwoven processes which happened during the nomadic period of hunter-gatherers in humans. [1] The process started by less fearful wolves scavenging in human settlements and the humans utilising their presence as an alarm, which may warn humans of invaders whether it be humans or predatory animals approaching at night (Lindsay, 2000). Afterwards, the process of self-domestication of the wolves began. Wolves with friendly traits have a higher chance of survival as conflicts with humans are lessened. As friendlier wolves bred together for generations, they gradually evolved into the modern domestic dog. In this case of domestication, the phases of natural and artificial selection were blended together.

In other cases, animals adapt to their ecology, and since the environment continuously differs, they continually adapt and change as well. They may also migrate and branch off and evolve into a new species.

Wild ancestors in plants

A species of wild banana, the appearance and taste of which differ from that of cultivated bananas. Inside a wild-type banana.jpg
A species of wild banana, the appearance and taste of which differ from that of cultivated bananas.

Thousands of years ago, humans started to settle and grow crops. This change in human behaviour from nomadic to sedentary marked the start of the domestication process of plants. Many wild ancestors of plants still coexist with the modern domesticated crops; these are called crop wild relatives. [5] A lot of crop plants were also moved into human-managed conditions which caused the selection pressures to differ from the plants in their normal environment creating a significant difference in traits, life cycle and appearance compared to the original predecessor.

Many significant changes can be seen in modern cultivated watermelons ( Citrullus lanatus ), which are believed to have derived from Citrullus colocynthis after being domesticated as a water and food source in northeastern Africa over 4000 years ago. [6] Citrullus colocynthis, which now still exists as a crop wild relative known as the desert gourd or thorny apple, were small, bitter in taste and yellow or green inside, while modern watermelons are mainly large, red or yellow in color and sweet tasting. The same goes for other common crops cultivated nowadays; most of them have evolved to be suited to the human palate.

Wild ancestors and their domesticated counterparts

Differences

Compared to their wild ancestors, the domesticated counterparts of living creatures underwent several changes depending on various factors and pathways of evolution.

Physical appearance

Domestic animals show differences in physical appearance in comparison to their wild ancestors as they underwent some changes such as having floppier ears, bigger skulls, curlier tail and changes in coat colour or pattern, as noted in domestications of dogs and the experimental domesticated red fox in Russia by Dmitry Belyayev. [7] Changes in physical appearance which are caused by selective breeding can be seen in pets such as koi fish and betta fish which are bred for aesthetic purposes or dogs bred for extreme physical appearances (e.g. extremely short snouts in pugs or bulldogs, short limbs on dachshunds, extremely small sizes in "teacup dogs"). Extreme physical appearances in selectively bred animals may cause health problems, which may cause wild ancestors to have longer natural lifespans.

Behavior

Behavioral differences in wild ancestors were caused by differences in brain structures compared to their domesticated counterparts. An example of this can be seen when comparing wild and domestic rabbits. Wild rabbits have a larger ratio of brain-to-body size, while domestic rabbits have a smaller amygdala and larger medial prefrontal cortex and also reduced white matter. This causes domestic rabbits to have a decreased fight-or-flight response and thus domesticated rabbits show less indication of fear towards humans. [8] Subsequently, a decrease in awareness of their surroundings may be observed in domesticated animals because of the reduced need to sense natural predators. [9]

Generally a change in mating systems may be observed in its domesticated counterparts. Seasonal mating systems tend to only exist in wild ancestors; however, most domesticated animals have a tendency to breed all year long. The deterioration of monogamous systems may also be seen along with wider mating preferences. These traits may be more commonly seen in domesticated farm animals or pets as they are beneficial to humans. [10]

Intelligence

As living creatures adapt and evolve, the level of intelligence changes to suit their way of living. The level of intelligence of modern humans is considerably higher compared to the hominid ancestors from millions of years ago, among which during this time the volume of the hominid brain began to gradually increase starting from about 600 cm3 in Homo habilis up to 1500 cm3 in Homo neanderthalensis . Although the evolution of humans increases the level of intelligence, the same may not be observed in other animals, especially animals which have great dependence to humans – for example, dogs. While different breeds of modern dogs possess different brain capacity and intelligence, in general, compared to the wolf, the dog's problem-solving capabilities have declined. In a problem-solving experiment, the average success rate for dogs was 5% while the wolves obtained an 80% success rate. [11] On the other hand, in a test on guinea pigs, it was shown that the spatial ability of domestic guinea pigs is higher compared to their ancestor. [12] The level of intelligence in wild ancestors compared to the predecessor differs from species to species as brain volume and behaviour changes.

Genetics

The presence of genetic mutations increases genetic variance across species group. Mutations which are found to be beneficial for the longevity of the species as a whole are likely to be inherited in the next generation; due to this process, genetic difference has become the driving factor of most, if not all of the changes in wild ancestors compared to their predecessors. As wild ancestor species evolve, there are certain genes which would indicate their evolutionary paths. Creatures which would undergo domestication have changes in genes which alter their endocrine systems and hormonal production which can be seen in animals such as domesticated birds, canids, cattle and house pets. This can be seen in the mutation of the thyroid stimulating hormone receptor gene (TSHR) in the domesticated chicken, which affects the reproductive system. In the domestic fox experiment, the gene SorCS1 was found in tame foxes but not in aggressive foxes; this gene is thought to be responsible for the tameness trait in domestic foxes.

Differences in plants

Plants that are bred for crops or food production are selectively bred for increased efficiency, and relatively better taste. Hence, the differences in wild ancestors and cultivated modern crops will reflect that, for example, an increased size of the edible parts of certain fruits.

Domestication syndrome in plants causes differences such as larger sizes, changes in colour and differences in sugar content. The adaptability of modern plants may also be increased compared to their wild ancestors.

Cultivated plants show differences in chemical content compared to their wild counterparts. For example, research has shown that cultivated plants generally produce litter which decomposes faster and is easier to be recycled compared to wild plants. Wild plants which had to generally thrive in nutrient-poor soils promote a higher content of recalcitrant molecules, such as lignin. This stimulates an increase in plant litter toughness, causing it to decompose longer. [13]

Other differences may include:

  • loss of seed dormancy
  • new adaptations to ecological factors such as nutrient composition of the soil, temperature, acidity, light levels, humidity, etc.
  • difference in the method of reproduction (e.g. lack of pollinating organs, depending on human intervention) or even sterility in modern plants.
  • differences in chemical composition (e.g. increase in vitamins, sugar content, etc.)
  • loss of seed dispersal methods
  • a decrease in defensive mechanisms. Since traits such as thorns, spines, protective coverings and poison are less desirable to humans, they are lost to artificial selection. This renders modern plants more susceptible to pests.
  • difference in disease susceptibility

Uses

There are uses of coexisting wild ancestors and their domestic counterparts. The existence of a wild ancestor may be used to increase biodiversity of the variety of species. It mainly helps with conservation but may also be used for genetic improvements, though this practice is mainly done on plants, more specifically food-producing crops. Since wild crops generally have a higher pest resistance, breeding plant hybrids would significantly improve the quality of the cultivated crops. The same technique may be applied to increase bacterial resistance, plant yield, and resistance to biotic stress. [14]

List of wild ancestors and their domesticated counterparts

Species and subspeciesWild ancestor
Dog (Canis familiaris) [15] Extinct Pleistocene population of Gray wolf (Canis lupus) [16]
Cattle (Bos Taurus)Extinct Aurochs (Bos primigenius)
Domestic guinea pig (Cavia porcellus) Montane guinea pig (Cavia tschudii) or cavy (Cavia aperea) [9]
Chicken (Gallus gallus domesticus) Red junglefowl (Gallus gallus)
Domesticated rabbit (Oryctolagus cuniculus) European Rabbit (Oryctolagus cuniculus)
Goat (Capra aegagrus hircus) Bezoar ibex (Capra aegagrus aegagrus)
Ferret (Mustela putorius furo) European polecat (Mustela putorius)
Banana Musa acuminata or plantain (Musa balbisiana)
Squash (Cucurbita pepo subsp. pepo) Okeechobee gourd (Cucurbita okeechobeensis)
Watermelon (C.lanatus) Desert gourd (Citrullus colonchythis)
Eggplant (Solanum melongena) Thorn apple (Solanum incanum)
Apricot (Prunus armeniaca) Briançon apricot (Prunus brigantina)
Cassava (Manihot esculenta subsp. esculenta) Walker's manihot (Manihot walkerae)

Related Research Articles

Neoteny, also called juvenilization, is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny is found in modern humans compared to other primates. In progenesis or paedogenesis, sexual development is accelerated.

<span class="mw-page-title-main">Hybrid (biology)</span> Offspring of cross-species reproduction

In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different varieties, species or genera through sexual reproduction. Generally, it means that each cell has genetic material from two different organisms, whereas an individual where some cells are derived from a different organism is called a chimera. Hybrids are not always intermediates between their parents, but can show hybrid vigor, sometimes growing larger or taller than either parent. The concept of a hybrid is interpreted differently in animal and plant breeding, where there is interest in the individual parentage. In genetics, attention is focused on the numbers of chromosomes. In taxonomy, a key question is how closely related the parent species are.

<span class="mw-page-title-main">Domestication</span> Selective breeding of plants and animals to serve humans

Domestication is a multi-generational mutualistic relationship between humans and other organisms, in which humans took over control and care to obtain a steady supply of resources including food. The process was gradual and geographically diffuse, based on trial and error.

<span class="mw-page-title-main">Selective breeding</span> Breeding for desired characteristics

Selective breeding is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant males and females will sexually reproduce and have offspring together. Domesticated animals are known as breeds, normally bred by a professional breeder, while domesticated plants are known as varieties, cultigens, cultivars, or breeds. Two purebred animals of different breeds produce a crossbreed, and crossbred plants are called hybrids. Flowers, vegetables and fruit-trees may be bred by amateurs and commercial or non-commercial professionals: major crops are usually the provenance of the professionals.

<span class="mw-page-title-main">Feral</span> Wild-living but normally domestic animal or plant

A feral animal or plant is one that lives in the wild but is descended from domesticated individuals. As with an introduced species, the introduction of feral animals or plants to non-native regions may disrupt ecosystems and has, in some cases, contributed to extinction of indigenous species. The removal of feral species is a major focus of island restoration.

<span class="mw-page-title-main">Breeding back</span> Artificial selection

Breeding back is a form of artificial selection by the deliberate selective breeding of domestic animals, in an attempt to achieve an animal breed with a phenotype that resembles a wild type ancestor, usually one that has gone extinct. Breeding back is not to be confused with dedomestication.

<span class="mw-page-title-main">Red junglefowl</span> Species of bird; wild origin of the domesticated chicken

The red junglefowl is a tropical bird in the family Phasianidae. It ranges across much of Southeast Asia and parts of South Asia. It was formerly known as the bankiva or bankiva fowl. It is the species that gave rise to the chicken ; the grey junglefowl, Sri Lankan junglefowl and green junglefowl have also contributed genetic material to the gene pool of the chicken.

<span class="mw-page-title-main">Dog breeding</span> Mating selected dogs for specific qualities

Dog breeding is the practice of mating selected dogs with the intention of maintaining or producing specific qualities and characteristics. When dogs reproduce without such human intervention, their offspring's characteristics are determined by natural selection, while "dog breeding" refers specifically to the artificial selection of dogs, in which dogs are intentionally bred by their owners. Breeding relies on the science of genetics, hence a breeder who is knowledgeable on canine genetics, health, and the intended purpose of the dogs attempts to breed suitable dogs.

<span class="mw-page-title-main">Wolfdog</span> Dog breed

A wolfdog is a canine produced by the mating of a domestic dog with a gray wolf, eastern wolf, red wolf, or Ethiopian wolf to produce a hybrid.

Purebreds are "cultivated varieties" of an animal species achieved through the process of selective breeding. When the lineage of a purebred animal is recorded, that animal is said to be "pedigreed". Purebreds breed true-to-type which means the progeny of like-to-like purebred parents will carry the same phenotype, or observable characteristics of the parents. A group of purebreds is called a pure-breeding line or strain.

<span class="mw-page-title-main">Divergent evolution</span> Accumulation of differences between closely related species populations, leading to speciation

Divergent evolution or divergent selection is the accumulation of differences between closely related populations within a species, sometimes leading to speciation. Divergent evolution is typically exhibited when two populations become separated by a geographic barrier and experience different selective pressures that drive adaptations to their new environment. After many generations and continual evolution, the populations become less able to interbreed with one another. The American naturalist J. T. Gulick (1832–1923) was the first to use the term "divergent evolution", with its use becoming widespread in modern evolutionary literature. Classic examples of divergence in nature are the adaptive radiation of the finches of the Galapagos or the coloration differences in populations of a species that live in different habitats such as with pocket mice and fence lizards.

<span class="mw-page-title-main">Domesticated silver fox</span> Type of fox

The domesticated silver fox is a form of the silver fox that has been to some extent domesticated under laboratory conditions. The silver fox is a melanistic form of the wild red fox. Domesticated silver foxes are the result of an experiment designed to demonstrate the power of selective breeding to transform species, as described by Charles Darwin in On the Origin of Species. The experiment at the Institute of Cytology and Genetics in Novosibirsk, Russia explored whether selection for behaviour rather than morphology may have been the process that had produced dogs from wolves, by recording the changes in foxes when in each generation only the most tame foxes were allowed to breed. Many of the descendant foxes became both tamer and more dog-like in morphology, including displaying mottled- or spotted-coloured fur.

<span class="mw-page-title-main">Domestication of vertebrates</span> Overview of animal domestication

The domestication of vertebrates is the mutual relationship between vertebrate animals including birds and mammals, and the humans who have influence on their care and reproduction.

<span class="mw-page-title-main">Domestication of the dog</span> Process which created the domestic dog

The domestication of the dog was the process which created the domestic dog. This included the dog's genetic divergence from the wolf, its domestication, and the emergence of the first dogs. Genetic studies suggest that all ancient and modern dogs share a common ancestry and descended from an ancient, now-extinct wolf population – or closely related wolf populations – which was distinct from the modern wolf lineage. The dog's similarity to the grey wolf is the result of substantial dog-into-wolf gene flow, with the modern grey wolf being the dog's nearest living relative. An extinct Late Pleistocene wolf may have been the ancestor of the dog.

<span class="mw-page-title-main">Dog behavior</span> Internally coordinated responses of dogs to internal and external stimuli

Dog behavior is the internally coordinated responses of individuals or groups of domestic dogs to internal and external stimuli. It has been shaped by millennia of contact with humans and their lifestyles. As a result of this physical and social evolution, dogs have acquired the ability to understand and communicate with humans. Behavioral scientists have uncovered a wide range of social-cognitive abilities in domestic dogs.

<span class="mw-page-title-main">Genetic pollution</span> Problematic gene flow ⇨ wild populations

Genetic pollution is a term for uncontrolled gene flow into wild populations. It is defined as "the dispersal of contaminated altered genes from genetically engineered organisms to natural organisms, esp. by cross-pollination", but has come to be used in some broader ways. It is related to the population genetics concept of gene flow, and genetic rescue, which is genetic material intentionally introduced to increase the fitness of a population. It is called genetic pollution when it negatively impacts the fitness of a population, such as through outbreeding depression and the introduction of unwanted phenotypes which can lead to extinction.

<span class="mw-page-title-main">Free-ranging dog</span> Dog not confined to a yard or house

A free-ranging dog is a dog that is not confined to a yard or house. Free-ranging dogs include street dogs, village dogs, stray dogs, feral dogs, etc., and may be owned or unowned. The global dog population is estimated to be 900 million, of which around 20% are regarded as owned pets and therefore restrained.

<span class="mw-page-title-main">Domestication syndrome</span> Proposed biological phenomenon

Domestication syndrome refers to two sets of phenotypic traits that are common to either domesticated animals, or domesticated plants. These traits were identified by Charles Darwin in The Variation of Animals and Plants Under Domestication.

<span class="mw-page-title-main">Domestication of the cat</span> Evolutionary origins of domesticated cats

The domestic cat originated from Near-Eastern and Egyptian populations of the African wildcat, Felis sylvestris lybica. The family Felidae, to which all living feline species belong, arose about ten to eleven million years ago and is divided into eight major phylogenetic lineages. The Felis lineage in particular is the lineage that the domestic cat is a member of. A number of investigations have shown that all domestic varieties of cats come from a single species of the Felis lineage, Felis catus. Variations of this lineage are found all over the world, and until recently scientists have had a hard time pinning down exactly which region gave rise to modern domestic cat breeds. Scientists believed that it was not just one incident that led to the domesticated cat but multiple, independent incidents at different places that led to these breeds. More complications arose from the fact that the wildcat population as a whole is very widespread and very similar to one another. These variations of wildcat can and will interbreed freely with one another when in close contact, further blurring the lines between taxa. Recent DNA studies, advancement in genetic technologies, and a better understanding of DNA and genetics as a whole has helped make discoveries in the evolutionary history of the domestic cat. Archaeological evidence has documented earlier dates of domestication than formerly believed.

Domesticated animals in the Philippines include pigs, chickens, water buffalo, goats, cats, and dogs. Domestication is when a species is selectively bred to produce certain traits that are seen as desirable. Some desirable traits include quicker growth and maturity, increased fertility, adaptability to various conditions, and living in herds. Domesticated animals play an important socioeconomic role in the Philippines, as seen through their widespread use in rituals.

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