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Encyclopedia > Founder effect
Simple illustration of founder effect. The original population is on the left with three possible founder populations on the right.
Simple illustration of founder effect. The original population is on the left with three possible founder populations on the right.

The founder effect was defined by Ernst Mayr in 1963 to be the effect of establishing a new population by a small number of individuals, carrying only a small fraction of the original population's genetic variation. As a result, the new population may be distinctively different, both genetically and phenotypically, from the parent population from which it is derived. In extreme cases, the founder effect is thought to lead to the speciation and subsequent evolution of new species. The founder effect is a feature that can also occur in memetic evolution. Image File history File links Founder_effect. ... Image File history File links Founder_effect. ... This article has been identified as possibly containing errors. ... This article does not cite any references or sources. ... Individuals in the mollusk species Donax variabilis show diverse coloration and patterning in their phenotypes. ... Charles Darwins first sketch of an evolutionary tree from his First Notebook on Transmutation of Species (1837) Speciation is the evolutionary process by which new biological species arise. ... This article is about evolution in biology. ... It has been suggested that Memetics be merged into this article or section. ...


In the figure shown, the original population has nearly equal numbers of blue and red individuals. The three smaller founder populations show that one or the other color may predominate (founder effect), due to random sampling of the original population. A population bottleneck may also cause a founder effect even though it is not strictly a new population. A population bottleneck (or genetic bottleneck) is an evolutionary event in which a significant percentage of a population or species is killed or otherwise prevented from reproducing, and the population is reduced by 50% or more, often by several orders of magnitude. ...


In addition to founder effects, the new population is often a very small population and so shows increased sensitivity to genetic drift, an increase in inbreeding, and relatively low genetic variation. This can be observed in the limited gene pool of Easter Islanders and those native to Pitcairn Island. Species with a small population size are subject to a higher chance of extinction because their small population size makes them more vulnerable to genetic drift, resulting in stochastic variation in their gene pool, their demography and their environment. ... In population genetics, genetic drift is the statistical effect that results from the influence that chance has on the success of alleles (variants of a gene). ... It has been suggested that inbreeding depression be merged into this article or section. ... Genetic variation is the variation in the genetic material of a population, and includes the nuclear, mitochodrial, ribosomal genomes as well as the genomes of other organelles. ... The gene pool of a species or a population is the complete set of unique alleles that would be found by inspecting the genetic material of every living member of that species or population. ... motto: ( Rapa Nui ) Also called Te Pito O Te Henua (Ombligo del mundo) (Navel of the world) Capital Hanga Roa Area  - City Proper  163. ...

Contents

Founder effects in island ecology

Founder populations are essential to the study of island biogeography and island ecology. A natural tabula rasa is not easily found, but a classic series of studies on founder population effects were done following the catastrophic 1883 eruption of Krakatau (Krakatoa), which erased all life on the island remnant. Another continuing study has been following the biocolonization of Surtsey, Iceland, a new volcanic island that erupted offshore between 1963 and 1967. An earlier event, the Toba eruption in Sumatra of about 73,000 YBP, covered some parts of India with 3–6 m of ash, and must have coated the Nicobar Islands and Andaman Islands, much nearer in the ash fallout cone, with life-smothering layers, restarting their biodiversity from effectively zero. The study of island biogeography is a field within biogeography that attempts to establish and explain the factors that affect the species diversity of a particular community. ... The PETER AHCHING THEORY on POLYNESIAN ORIGINS. Copyright 2003-05. ... Tabula rasa (Latin: scraped tablet or clean slate) refers to the epistemological thesis that individual human beings are born with no innate or built-in mental content, in a word, blank, and that their entire resource of knowledge is built up gradually from their experiences and sensory perceptions of the... Krakatoa or Krakatau or Krakatao is a volcanic island in the Sunda Strait between Java and Sumatra in Indonesia. ... Surtsey, sixteen days after the onset of the eruption Surtsey (Icelandic: Surturs island) is a volcanic island off the southern coast of Iceland. ... The Toba eruption (the Toba event) was the largest volcanic eruption on Earth in the last 28 million years. ... Before Present (BP) years are the units of time (counted backwards to the past) used to report raw radiocarbon ages and dates referenced to the BP scale origin in the year AD 1950 (identical to 1950 CE). ... The metre (American English:meter) is a measure of length. ... Map of Nicobar Islands The Nicobar Islands are an island chain in the eastern Indian Ocean, and are part of the Union Territory of Andaman and Nicobar Islands, India. ... This article or section may be confusing for some readers, and should be edited to be clearer or more simplified. ...


Founder effects in human populations

Due to various migrations throughout human history, founder effects are somewhat common among humans in different times and places. The effective founder population of Quebec was only 2,600. After twelve to sixteen generations, with an eighty-fold growth but minimal gene dilution from intermarriage, Quebec has what geneticists call optimal linkage disequilibrium (genetic sharing).[1] The result: far fewer genetic variations, including those that have been well studied because they are connected with inheritable diseases. , Motto: Je me souviens (French: I remember) Capital Quebec City Largest city Montreal Official languages French Government - Lieutenant-Governor Pierre Duchesne - Premier Jean Charest (PLQ) Federal representation in Canadian Parliament - House seats 75 - Senate seats 24 Confederation July 1, 1867 (1st) Area  Ranked 2nd - Total 1,542,056 km² (595... Linkage disequilibrium (LD) is the non-random association of alleles at two or more loci on a chromosome. ...


Founder effects can also occur naturally as competing genetic lines die out. This means that an effective founder population consists only of those whose genetic print is identifiable in subsequent populations. Because in sexual reproduction, genetic recombination ensures that with each generation only half the genetic material of a parent is represented in the offspring, some genetic lines may die out entirely, even though there are numerous progeny. A recent study[2] concluded that of the people migrating across the Bering land bridge at the close of the ice age, only 70 left their genetic print in modern descendants, a minute effective founder population— which is easily misread as though implying that only 70 people crossed to North America. The misinterpretations of "Mitochondrial Eve" are a case in point: it may be hard to explain that a "mitochondrial Eve" was not the only woman of her time. Genetic recombination is the process by which a strand of DNA is broken and then joined to the end of a different DNA molecule. ... Nautical chart of Bering Strait, site of former land bridge between Asia and North America The Bering land bridge, also known as Beringia, was a land bridge roughly 1600 km (1000 miles) north to south at its greatest extent, which joined present-day Alaska and eastern Siberia at various times... Variations in CO2, temperature and dust from the Vostok ice core over the last 400 000 years For the animated movie, see Ice Age (movie). ... Mitochondrial Eve (mt-mrca) is the name given by researchers to the woman who is the matrilineal most recent common ancestor (MRCA) for all living humans. ...


In humans, founder effects can arise from cultural isolation, and inevitably, endogamy. For example, the Amish populations in the United States, which have grown from a very few founders, have not recruited newcomers, and tend to marry within the community, exhibit founder effects. Though still rare absolutely, phenomena such as polydactyly (extra fingers and toes, a symptom of Ellis-van Creveld syndrome) are more common in Amish communities than in the US population at large.[3] Similar religious and cultural founder effects have been demonstrated through the prevalence of otherwise rare diseases among South African Muslims, among whom cleidocranial dysostosis is more common (due to one founder who was a Chinese immigrant who converted to Islam)[citation needed]. There is also the presence of high cases of fumarase deficiency among the 10,000 members of the Fundamentalist Church of Jesus Christ of Latter Day Saints community, a breakaway sect which practices both endogamy and polygamy, where it is estimated 75 to 80 percent of the community are blood relatives of just two men - founders John Y. Barlow and Joseph Smith Jessop.[4] Endogamy is the practice of marrying within a social group. ... The Amish (Amisch or Amische) (IPA: ) are an Anabaptist Christian denomination in the United States and Canada (Ontario and Manitoba) known for their plain dress and avoidance of modern conveniences such as cars and electricity. ... Polydactyly or polydactylism (from the Greek poly = many + daktylos = finger), also known as hyperdactyly, is a congenital physical anomaly consisting of supernumerary fingers or toes. ... Ellis-van Creveld Syndrome (also called chondroectodermal dysplasia or mesoectodermal dysplasia) is a rare genetic disorder of the skeletal dysplasia type, with numerous anomalies including post-axial polydactyly, congenital heart defects (most commonly an atrial septal defect producing a common atrium, occurring in 60% of affected individuals), pre-natal tooth... Cleidocranial dysostosis or Cleidocranial dysplasia is a hereditary congenital abnormality of humans. ... For people named Islam, see Islam (name). ... Fumarase deficiency is an enzyme irregularity that causes severe mental retardation, unusual facial features, brain malformation, and epileptic seizures due to an abnormally low amount of fumarase in cells. ... The FLDS Temple near Eldorado, Texas The Fundamentalist Church of Jesus Christ of Latter Day Saints (FLDS) is a group of Mormon fundamentalists. ... The term polygamy (many marriages in late Greek) is used in related ways in social anthropology, sociobiology, and sociology. ...


See also

Species with a small population size are subject to a higher chance of extinction because their small population size makes them more vulnerable to genetic drift, resulting in stochastic variation in their gene pool, their demography and their environment. ... Dad does not seem too surprised; perhaps this has happened to him before! Last Common Ancestor (LCA) is the most recent common ancestor of two populations that came to be separated by a species barrier. ...

References

  1. ^ genizon.com
  2. ^ Hey, Jody, 2005. "On the Number of New World Founders: A Population Genetic Portrait of the Peopling of the Americas" in PLoS Biol 2005 May 24;3(6):e193 webpage
  3. ^ McKusick, V. A.; Egeland, J. A.; Eldridge, R.; Krusen, D. E.: Dwarfism in the Amish. I. The Ellis-van Creveld syndrome. Bull. Johns Hopkins Hosp. 115: 306-336, 1964. PMID 14217223
  4. ^ boston.com
  • Mayr, E. 1963. Animal Species and Evolution. Harvard University Press, Cambridge, Massachusetts.

This article has been identified as possibly containing errors. ...

External links

  • Founder effect
  • Quebec Founder Population Project

  Results from FactBites:
 
BIOdotEDU (360 words)
If a small number of individuals are separated from the original population, and the conditions are right, the smaller group can go on to form a new breeding population of their own, and thus start (or "found") a whole new species.
New populations that arise from the founder effect clearly have different evolutionary potentials from the original populations.
Founder populations are usually very small; therefore, change can be quite rapid and these populations can accumulate new adaptations much faster than large populations.
Welcome to Founders Academy (178 words)
Founders Academy believes that education is both an entitlement and an obligation of all citizens.
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