
	Where results make sense

Topic: Population bottleneck

Related Topics

Genetic drift

Small population size

Population ecology

Population genetics

Statistical population

Toba catastrophe theory

Population dynamics

Evolutionary game theory

Gene flow

North Crows Nest, Indiana

Multiregional hypothesis

Wisent

Modern evolutionary synthesis

Galapagos Archipelago

Population density

In the News (Thu 26 Nov 09)

Northern Trust

Marvin Harrison

Peter Chernin

Gary Locke

Match Play

Penelope Cruz

Mickey Rourke

AR Rahman

Danny Boyle

Hugh Jackman

	Population bottleneck - Wikipedia, the free encyclopedia
		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.
		Population bottlenecks increase genetic drift, as the rate of drift is inversely proportional to the population size.
		A classic example of a population bottleneck is that of the northern elephant seals, whose population fell to about 30 in the 1890's although it now numbers in the tens of thousands.
	en.wikipedia.org /wiki/Population_bottleneck (489 words)

	Population genetics - Wikipedia, the free encyclopedia
		Population genetics is the study of the distribution of and change in allele frequencies under the influence of the five evolutionary forces: natural selection, genetic drift, mutation, migration and nonrandom mating.
		Population genetics was a vital ingredient in the modern evolutionary synthesis, its primary founders were Sewall Wright, J.
		In practice, there are two bodies of evolutionary theory that exist in parallel, traditional population genetics operating in the genotype space and the biometric theory used in plant and animal breeding, operating in phenotype space.
	en.wikipedia.org /wiki/Population_genetics (698 words)

	Population bottleneck
		In evolution theory, a population 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 evolutionary theory, population bottlenecks are thought to accelerate the processes of natural selection and genetic drift.
		Humans today are a legacy of a population bottleneck which occurred 70,000 years ago.
	www.ebroadcast.com.au /lookup/encyclopedia/bo/Bottleneck_effect.html (156 words)

	Population bottleneck (Site not responding. Last check: 2007-10-21)
		In population genetics and evolutionary biology, 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.
		Population bottlenecks increase genetic drift, as the rate of drift is inversely proportional to the population size, which is reduced.
		One theory about this bottlneck is the Toba catastrophe theory, positing that the human population was reduced to a few thousand individuals when the Toba supervolcano in Indonesia erupted and triggered massive environmental change.
	www.sciencedaily.com /encyclopedia/population_bottleneck (483 words)

	untitled (Site not responding. Last check: 2007-10-21)
		Hoelzel, A.R. Impact of population bottlenecks on gentic variation and the importance of life-history; a case study of the northern elephant seal.
		The simulation results showed the size of bottleneck was important (the less individuals the greater the probability of extinction) and that duration of bottleneck was also an important consideration (the probability of extinction was greater for bottlenecks of 10 years than those of 1 year duration).
		Given year of bottleneck (1884) and population size in 1960 (15000 seals), the results showed that the most likely event was a bottleneck of less than 20 seals, consistent with historical beliefs.
	www.life.umd.edu /faculty/wilkinson/ZOOL608V/bottlenecks\Hoelzel99.html (516 words)

	POPULATION BOTTLENECKS: HETEROZYGOSITY vs
		Populations of endangered species also tend to be small, and loss of genetic variation seriously threatens their abilities to persist and recover.
		As N (the population size during the bottleneck) increases the second term (1/[2N]) decreases, and the proportion of the original heterozygosity remaining increases.
		In general, a bottleneck lasting one generation has a fairly small effect on heterozygosity; even if the population is reduced to 2 individuals the expected proportion of heterozygosity is 0.75 (1 - 1/[2*2] = 0.75).
	www.tiem.utk.edu /~gross/bioed/bealsmodules/bottlenecks.html (1014 words)

	Population Bottlenecks and Volcanic Winter
		The bottleneck was caused by a volcanic winter resulting from the super-eruption of Toba in Sumatra.
		DNA studies have identified a significant bottleneck (or bottlenecks) during the last glacial period.
		Ambrose concludes that bottlenecks occurred among genetically isolated human populations because of a six-year long volcanic winter and subsequent hyper-cold millennium after the cataclysmic super-eruption of Toba.
	www.jqjacobs.net /anthro/paleo/bottleneck.html (505 words)

	Population genetics
		E.g., consider a population of 1 million almond trees with a frequency of r at 10%.
		However, suppose the initial population size of almond trees were 10 (with the same frequency of r at 10%).
		Bottleneck effect, combined with inbreeding, is an especially serious problem for may endangered species because great reductions in their numbers has reduced their genetic variability.
	arnica.csustan.edu /Boty1050/Populationgen/population_genetics.htm (1403 words)

	Conservation Ecology: A near-extinction event in lynx: do microsatellite data tell the tale? (Site not responding. Last check: 2007-10-21)
		This population was hunted to the brink of extinction, with fewer than 100 animals (one estimate was as low as 30 individuals) remaining in the late 1920s.
		In a performance test of this method on 11 microsatellite data sets from populations known to have experienced a demographic bottleneck and scored at four to 10 loci, signs of a bottleneck were detected in nine of these under the infinite allele model.
		Hoelzel, A. Impact of population bottlenecks on genetic variation and the importance of life-history; a case study of the northern elephant seal.
	sunsite.wits.ac.za /eco/vol6/iss1/art15/main.html (2730 words)

	Effects of a population bottleneck on whooping crane mitochondrial DNA variation.
		Effects of a population bottleneck on whooping crane mitochondrial DNA variation.
		We assess the genetic effect of this human-caused bottleneck by sequencing 314 base pairs (bp) of the mitochondrial DNA control region from cranes that lived before, during, and after this bottleneck.
		the most common modern haplotype was in low frequency in the prebottleneck population, which demonstrates the powerful effect of genetic drift in changing allele frequencies in very small populations.
	www.uga.edu /srel/Reprint/2394.htm (250 words)

	untitled (Site not responding. Last check: 2007-10-21)
		Bottleneck effect on genetic variance: a theoretical investigation of the role of dominance.
		Impact of population bottlenecks on genetic variation and the importance of life-history; A case study of the northern elephant seal.
		Genetic consequences of a single-founder population bottleneck in Trifolium amoenum (Fabaceae).
	www.life.umd.edu /faculty/wilkinson/ZOOL608V/bottlenecks\bottle.html (501 words)

	New finding accelerates discovery of disease genes and human population history
		Finally, the occurrence of SNPs in large blocks was seen in northern European populations but not seen in the Nigerian populations, suggesting that something happened in the population history of the northern Europeans—a recent bottleneck that shaped the genetic history of this population.
		Scientists speculate that this bottleneck could be related to the founding of Europe or the migration of a small population out of Africa as recently as 50,000 years ago.
		Alternatively, it could be a bottleneck associated with the founding of the first European populations, or even the recolonization of northern Europe after the last ice age.
	www.eurekalert.org /pub_releases/2001-05/WIfB-Nfad-0905101.php (1188 words)

	Genetic Effects of Population Bottleneck on a Restored Deer Herd in a National Military Park
		By 1991 the Chickamauga deer population had increased to an estimated 200-500 individuals.
		We examined the genetic effects of this population bottleneck by determining the following measures of genetic diversity: mean multilocus heterozygosity (H), mean number of alleles per locus (A), and percentage of polymorphic loci (P).
		Genetic effects of a population bottleneck on a restored deer herd in a National Military Park.
	www.uga.edu /srel/Reprint/2346.htm (307 words)

	John Hawks Anthropology Weblog : Two recent bottleneck studies
		Simply put, a longer bottleneck can have a larger population and still fit the data (because of the longer time for an effect), while a more severe bottleneck can be shorter and have the same effect.
		These times divide the entire population history into "epochs." For example, if the population never changed in size, the history would be a "one-epoch" population history, because all of time would be described by a single population size.
		A bottleneck is a three-epoch model, with an ancient large population size crashing at one particular time in the past, then at a later time expanding to another, larger size again.
	johnhawks.net /weblog/reviews/genetics/marth_bottlenecks.html (1839 words)

	Andolfatto.htm (Site not responding. Last check: 2007-10-21)
		The standard population model in evolutionary genetics assumes that a population is random-mating and of constant size.
		This discrepancy in patterns of geographic differentiation for the X chromosome and autosomes could be consistent with a bottleneck if the population size reduction had a larger effect on the X chromosome than on the autosomes, owing to differences in their effective population sizes.
		Although African populations (presumably ancestral) have rarely been sampled, they may be crucial to our understanding of the processes that have shaped variability patterns in derived populations.
	helios.bto.ed.ac.uk /evolgen/andolfatto/research1.htm (1227 words)

	Microevolution
		A new population is formed from a subset of genotypes in the original population.
		Population Bottleneck: A type of genetic drift occurring when many members of a population die, and a few remaining individuals mate, eventually restoring their numbers.
		The new population has lost much of the genetic diversity that was present in the larger ancestral population.
	www.life.uiuc.edu /bio100/lectures/f04lects/23f04microev13drift.html (346 words)

	Biology430.Lectures10
		Many species show some form of population size reduction; the population genetic effect is dependent on the magnitude and duration of the reduction, as well as the dispersal capability and intrinsic rate of natural increase of the species.
		While loss of variation in a population or species is significant, it is also important to understand the population structure of a species.
		Rgeardless of the particular way in which they are calculated, all of these estimates address the same issue, the degree to which replicate populations are genetically isolated from one another (spatially or temporally) and thus are or have been subject to independent evolutionary dynamics.
	bioweb.wku.edu /courses/Biol430/430lects10.htm (643 words)

	Overdominant Alleles in a Population of Variable Size -- Slatkin and Muirhead 152 (2): 775 -- Genetics
		because the proportion of the population that is heterozygous
		The solid curve shows the average number of common alleles in (100) simulated populations undergoing this simple bottleneck, the heavy dashed curve shows the Markov chain prediction for the expected number of alleles over the same time course.
		For small bottlenecks, overdominant alleles behave approximately as if neutral (dotted line), and there is a transition zone in which neither the closed-form approximation nor the neutral expression can adequately predict the probability of allele loss.
	www.genetics.org /cgi/content/full/152/2/775 (3893 words)

	[No title] (Site not responding. Last check: 2007-10-21)
		Feb 23,1998 More on genetic drift: When populations undergo severe reductions in size, resulting in a reduction of Ne, these are known as population bottlenecks.
		A severe population bottleneck that occurs as a result of a small group of emigrants establishing a new population is refered to as a founder event.
		Under neutrality in a stable population there is a theoretical mutation-drift equilibrium between the number of alleles and their frequencies in a population: most alleles are rare and are what Kimura refered to as transient polymorphism.
	www.colorado.edu /epob/epob3200ramey/Lecture11.html (429 words)

	[No title]
		Overview of Lecture What happens to genetic diversity during: - a population decline - a pop bottleneck - a pop recovery Inbreeding - estimate of inbreeding coefficients - estimate of effective pop size - the phenotypic effects of inbreeding What are the long-term effects in the genetic frame of population decline and bottlenecks?
		Number of alleles after a bottleneck depends on distribution of alleles before the bottleneck: EMBED Equation.3 where m = number of alleles prior to bottleneck pi = frequency of the ith allele Ne = effective number of individuals at the bottleneck What determines the level of genetic variation within an isolated population?
		Population 1: few offspring per mature individual and little variation in reproductive success among individuals, e.g., humans 500 male and females mate randomly generating 1,000 offspring.
	www.cnr.berkeley.edu /~alyons/class_notes/f01/espm103_conbio/11_espm103_oct04.doc (536 words)

	Germline Bottlenecks and the Evolutionary Maintenance of Mitochondrial Genomes -- Bergstrom and Pritchard 149 (4): 2135 ...
		Germline Bottlenecks and the Evolutionary Maintenance of Mitochondrial Genomes -- Bergstrom and Pritchard 149 (4): 2135 -- Genetics
		By analogy with the population genetics of diploid organisms,
		bottleneck size may be separated from the associated mitochondria.
	www.genetics.org /cgi/content/full/149/4/2135 (5846 words)

	Loss of genetic variation in greater prairie chickens (Site not responding. Last check: 2007-10-21)
		We examined historic (1951) and contemporary (19961999) populations of prairie chickens in Wisconsin to determine whether there was a loss of genetic variation following the population bottleneck.
		Population mean heterozygosity and number of alleles per locus were significantly lower in the late 1990s than in 1951.
		This loss of genetic variation following a population bottleneck is consistent with the results of a similar study in Illinois, but we found no evidence of a reduction in hatching success.
	www.uwm.edu /People/pdunn/PC%20folder/ConBio.html (213 words)

	Population genetics: Destruction of Eve (Site not responding. Last check: 2007-10-21)
		A controversial hypothesis suggesting a recent population bottleneck for the malaria parasite, Plasmodium falciparum, has received much attention, and provoked the publication of evidence for and against.
		This divergence time coincides roughly with the start of human population expansion, as might be expected of a genetically complex organism able to evade host immunity.
		Recent selective sweeps for drug-resistant genotypes may have restricted the genetic diversity of the parasite, resembling effects attributed to a historic population bottleneck.
	www.nature.com /nature/links/020718/020718-5.html (230 words)

	Finite population size
		Suppose you are studying a population of moths at Bodega Marine Reserve.
		After the El Niño rains of 1998, the moth population exploded and defoliated all the lupines on the Reserve.
		Imagine that you are observing evolution by drift in 10 replicate small populations.
	ib.berkeley.edu /courses/ib162/5NovFinP.htm (322 words)

	Endangered Species Bulletin: Restoring Mauna Kea's Crown Jewel
		To overcome the legacy of the population bottleneck, we are implementing a genetic management strategy for the Mauna Kea silversword in close cooperation with Steven Bergfeld and Lyman Perry of the Division of Forestry and Wildlife and Patrice Moriyasu of the University of Hawaii's Volcano Rare Plant Facility.
		One management option is to transfer pollen by hand among flowering plants in the natural population or between flowering plants in the natural and outplanted populations, then use the seeds from the crosses to produce container-grown seedlings for outplanting.
		One factor of overriding importance is the size of the ungulate populations on Mauna Kea.
	www.findarticles.com /p/articles/mi_m0ASV/is_1998_March/ai_54023083 (1267 words)

	Genetic consequences of a single-founder population bottleneck in Trifolium amoenum (Fabaceae) -- Knapp and Connors 86 ...
		Genetic consequences of a single-founder population bottleneck in Trifolium amoenum (Fabaceae) -- Knapp and Connors 86 (1): 124 -- American Journal of Botany
		was evaluated in the bottlenecked population and in a larger
		amoenum population from Occidental (15% of loci polymorphic;
	www.amjbot.org /cgi/content/abstract/86/1/124 (276 words)

Try your search on: Qwika (all wikis)