Wild ancestors are the original
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
from which
domesticated
Domestication is a sustained multi-generational relationship in which humans assume a significant degree of control over the reproduction and care of another group of organisms to secure a more predictable supply of resources from that group. A ...
plants and animals are derived. Examples include
dog
The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. Do ...
s which are derived from
wolves
The wolf (''Canis lupus''; plural, : wolves), also known as the gray wolf or grey wolf, is a large Canis, canine native to Eurasia and North America. More than thirty subspecies of Canis lupus, subspecies of ''Canis lupus'' have been reco ...
and
flax
Flax, also known as common flax or linseed, is a flowering plant, ''Linum usitatissimum'', in the family Linaceae. It is cultivated as a food and fiber crop in regions of the world with temperate climates. Textiles made from flax are known in ...
which is derived from ''
Linum bienne
''Linum bienne'', the pale or narrowleaf flax, is a flowering plant in the genus ''Linum'', native to the Mediterranean region and western Europe, north to England and Ireland.
Pale flax grows as a biennial plant, biennial or perennial plant i ...
''. In most cases the wild ancestor species still exists, but some domesticated species, such as
camel
A camel (from: la, camelus and grc-gre, κάμηλος (''kamēlos'') from Hebrew or Phoenician: גָמָל ''gāmāl''.) is an even-toed ungulate in the genus ''Camelus'' that bears distinctive fatty deposits known as "humps" on its back. C ...
s, 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
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charle ...
,
artificial selection
Selective breeding (also called artificial selection) 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 m ...
, and
hybridization
Hybridization (or hybridisation) may refer to:
*Hybridization (biology), the process of combining different varieties of organisms to create a hybrid
*Orbital hybridization, in chemistry, the mixing of atomic orbitals into new hybrid orbitals
*Nu ...
.
Wild ancestors have gone through genetic changes to achieve
biological mutualism
Mutualism describes the ecological interaction between two or more species where each species has a net benefit. Mutualism is a common type of ecological interaction. Prominent examples include most vascular plants engaged in mutualistic intera ...
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
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charle ...
and
artificial selection
Selective breeding (also called artificial selection) 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 m ...
. 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.
Ancestors of two different species may overlap. A term for this is ''
concestor—''coined by Nicky Warren—from the book ''
The Ancestor's Tale
''The Ancestor's Tale: A Pilgrimage to the Dawn of Life'' is a science book by Richard Dawkins and Yan Wong on the subject of evolution, which follows the path of humans backwards through evolutionary history, describing some of humanity's co ...
'' by
Richard Dawkins
Richard Dawkins (born 26 March 1941) is a British evolutionary biologist and author. He is an emeritus fellow of New College, Oxford and was Professor for Public Understanding of Science in the University of Oxford from 1995 to 2008. An ath ...
.
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
![Red Junglefowl hen India](https://upload.wikimedia.org/wikipedia/commons/1/15/Red_Junglefowl_hen_India.jpg)
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. 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.
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
The red junglefowl (''Gallus gallus'') 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 ...
, is believed to have an origin in parts of South and Southeast Asia. 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.
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
![Inside a wild-type banana](https://upload.wikimedia.org/wikipedia/commons/e/eb/Inside_a_wild-type_banana.jpg)
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 relative
A crop wild relative (CWR) is a wild plant closely related to a domesticated plant. It may be a wild ancestor of the domesticated (cultivated) plant or another closely related taxon.
Overview
The wild relatives of crop plants constitute an i ...
s. A lot of crop plants were also moved into human-managed conditions which caused the
selection pressures
Any cause that reduces or increases reproductive success in a portion of a population potentially exerts evolutionary pressure, selective pressure or selection pressure, driving natural selection. It is a quantitative description of the amount of ...
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
Watermelon (''Citrullus lanatus'') is a flowering plant species of the Cucurbitaceae family and the name of its edible fruit. A scrambling and trailing vine-like plant, it is a highly cultivated fruit worldwide, with more than 1,000 varieti ...
''), which are believed to have derived from ''
Citrullus colocynthis
''Citrullus colocynthis'', with many common names including Abu Jahl's melon, (native name in Turkey) colocynth, bitter apple, bitter cucumber, egusi, vine of Sodom, or wild gourd, is a desert viny plant native to the Mediterranean Basin and ...
'' after being domesticated as a water and food source in northeastern Africa over 4000 years ago. ''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
The domesticated silver fox (''Vulpes vulpes'' forma ''amicus'') 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 fox ...
in Russia by
Dmitry Belyayev. Changes in physical appearance which are caused by selective breeding can be seen in pets such as
koi fish
or more specifically , are colored varieties of the Amur carp ('' Cyprinus rubrofuscus'') that are kept for decorative purposes in outdoor koi ponds or water gardens.
Koi is an informal name for the colored variants of ''C. rubrofuscus'' kep ...
and
betta fish
''Betta'' is a large genus of small, active, often colorful, freshwater ray-finned fishes, in the gourami family (Osphronemidae). The best known ''Betta'' species is ''B. splendens,'' commonly known as the Siamese fighting fish and often kept ...
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
The amygdala (; plural: amygdalae or amygdalas; also '; Latin from Greek, , ', 'almond', 'tonsil') is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex verteb ...
and larger
medial prefrontal cortex
In mammalian brain anatomy, the prefrontal cortex (PFC) covers the front part of the frontal lobe of the cerebral cortex. The PFC contains the Brodmann areas BA8, BA9, BA10, BA11, BA12, BA13, BA14, BA24, BA25, BA32, BA44, BA45, BA46, ...
and also reduced
white matter
White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelinated axons, also called tracts. Long thought to be passive tissue, white matter affects learning and brain functions, modulating the distribution ...
. This causes domestic rabbits to have a decreased fight-or-flight response and thus domesticated rabbits show less indication of fear towards humans. Subsequently, a decrease in awareness of their surroundings may be observed in domesticated animals because of the reduced need to sense natural predators.
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.
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 cm
3 in ''
Homo habilis
''Homo habilis'' ("handy man") is an extinct species of archaic human from the Early Pleistocene of East and South Africa about 2.31 million years ago to 1.65 million years ago (mya). Upon species description in 1964, ''H. habilis'' was highly ...
'' up to 1500 cm
3 in ''
Homo neanderthalensis
Neanderthals (, also ''Homo neanderthalensis'' and erroneously ''Homo sapiens neanderthalensis''), also written as Neandertals, are an Extinction, extinct species or subspecies of archaic humans who lived in Eurasia until about 40,000 years ag ...
''. 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. 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. 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
The thyrotropin receptor (or TSH receptor) is a receptor (and associated protein) that responds to thyroid-stimulating hormone (also known as "thyrotropin") and stimulates the production of thyroxine (T4) and triiodothyronine (T3). The TSH recep ...
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
Litter consists of waste products that have been discarded incorrectly, without consent, at an unsuitable location. Litter can also be used as a verb; to litter means to drop and leave objects, often man-made, such as aluminum cans, paper cups, ...
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
Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity ...
. This stimulates an increase in plant litter toughness, causing it to decompose longer.
Other differences may include:
* loss of
seed dormancy
Seed dormancy is an evolutionary adaptation that prevents seeds from germinating during unsuitable ecological conditions that would typically lead to a low probability of seedling survival. Dormant seeds do not germinate in a specified period of ...
* 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
In Spermatophyte plants, seed dispersal is the movement, spread or transport of seeds away from the parent plant.
Plants have limited mobility and rely upon a variety of dispersal vectors to transport their seeds, including both abiotic vectors, ...
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.
List of wild ancestors and their domesticated counterparts
References
{{reflist
Domestication