RAPID GENETIC DIFFERENTIATION AND FOUNDER EFFECT IN COLONIZING POPULATIONS OF COMMON MYNAS (<i>ACRIDOTHERES TRISTIS</i>)

Baker, Allan J.; Moeed, Abdul

doi:10.1111/j.1558-5646.1987.tb05823.x

Cited by 111 publications

(119 citation statements)

References 41 publications

(26 reference statements)

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“…The size of a founder population is crucial for the long-term survival of island populations; small founder populations can potentially compromise survival due to loss of genetic diversity produced by drift and genetic erosion due to inbreeding (Baker and Moeed, 1987;Hartl and Clark, 1997). The founding populations of San Martiño and Ons islands may have been small because of the limited size of both islands (146 and 428 ha, respectively) and thus, it is likely that the geographic isolation of individuals from the mainland population could function as bottleneck events within each island.…”

Section: Effect Of Founder Population Sizes On Islandsmentioning

confidence: 99%

Genetic drift and rapid evolution of viviparity in insular fire salamanders (Salamandra salamandra)

2011

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Continental islands offer an excellent opportunity to investigate adaptive processes and to time microevolutionary changes that precede macroevolutionary events. We performed a population genetic study of the fire salamander (Salamandra salamandra), a species that displays unique intraspecific diversity of reproductive strategies, to address the microevolutionary processes leading to phenotypic and genetic differentiation of island, coastal and interior populations. We used eight microsatellite markers to estimate genetic diversity, population structure and demographic parameters in viviparous insular populations and ovoviviparous coastal and interior populations. Our results show considerable genetic differentiation (F ST range: 0.06-0.27), and no clear signs of gene flow among populations, except between the large and admixed interior populations. We find no support for island colonization by rafting or intentional/accidental anthropogenic introductions, indicating that rising sea levels were responsible for isolation of the island populations approximately 9000 years ago. Our study provides evidence of rapid genetic differentiation between island and coastal populations, and rapid evolution of viviparity driven by climatic selective pressures on island populations, geographic isolation with genetic drift, or a combination of these factors. Studies of these viviparous island populations in early stages of divergence help us better understand the microevolutionary processes involved in rapid phenotypic shifts.

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Section: Effect Of Founder Population Sizes On Islandsmentioning

confidence: 99%

Genetic drift and rapid evolution of viviparity in insular fire salamanders (Salamandra salamandra)

2011

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“…Berlocher, 1984;Baker & Moeed, 1987;Baker & Dennison, 1991). This is to be expected if the influence of genetic drift has been prominent in creating allele frequency differences among different populations, and if gene flow between different introduced populations has been restricted.…”

Section: Variation Within Introduced Populationsmentioning

confidence: 99%

The successful founder: genetics of introduced Carduelis chloris (greenfinch) populations in New Zealand

1996

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The amount and distribution of genetic variation in seven introduced New Zealand populations of Carduelis chioris were assessed at 40 loci using starch gel electrophoresis and compared with those in native European populations. Fewer alleles (1.45) and fewer polymorphic foci (33 per cent) were detected across the introduced populations than across native populations (1.75, 55 per cent), reflecting the narrow geographical origin of the introduced populations. There was no evidence for severe inbreeding or genetic drift as the levels of average heterozygosity (H = 0.025), percentage polymorphic loci (P = 16.9) and average number of alleles per locus (A = 1.22) were indistinguishable from levels observed within European populations (H = 0.025, P 14.1, A = 1.19). Furthermore, introduced populations were genetically less weakly differentiated (FST = 0.022) than native populations (FST = 0.041), indicating that little genetic drift has been involved in the colonization of the new range.Similar levels of genetic variability in native and introduced greenfinch populations are consistent with theoretical expectations as the founder population size was relatively large (>60 individuals) and a rapid increase in population size directly after colonization was documented.A review of earlier studies on introduced birds also revealed that reductions in levels of genetic variability seem to be inversely proportional to the size of the founder population, and that less variation has been lost if the rate of population growth directly after introduction was fast.

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Section: Methodsmentioning

confidence: 99%

“…FST values were calculated using the BIOSYS computer package (Swofford & Selander, 1989) and averaged over all polymorphic loci to produce FST (Baker & Moeed, 1987;Baker et a!., 1990 (1) is the average frequency of all private alleles and N is the average number of individuals sampled per locus per population (Slatkin,198 Sb). FST statistics and the private allele method do not always produce congruent estimates (e.g.…”

Section: Methodsmentioning

confidence: 99%

“…alleles that are found in only one population (Slatkin, 1985b). The estimate from FST was calculated as:FST values were calculated using the BIOSYS computer package (Swofford & Selander, 1989) and averaged over all polymorphic loci to produce FST (Baker & Moeed, 1987;Baker et a!., 1990 Caccone & Sbordoni, 1987;Waples, 1987;Johnson et a!., 1988; Crouau-Roy, 1989).Because each population was characterized by at least one locus that differed diagnostically from all other populations, our genetic data could also provide an estimate of the rate of migration. We reasoned that homozygotes of rare alleles at a diagnostic locus were likely to be recent arrivals from another, genetically distinct, population.…”

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Migration, gene flow and reproductive isolation between and within morphotypes of the isopod Excirolana in two oceans

Lessios

Weinberg

1993

Heredity

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The rate of gene flow between populations depends both on the dispersal ability of the organism and on the probability that migrants can successfully mate with residents. The degree to which this reproductive isolation can impede genetic exchange can be assessed by studying both migration and gene flow. We carried out such a study in Panamanian populations of Excirolana, an intertidal isopod with no planktonic larvae that inhabits both coasts of Central and South America. In Panama Excirolana is represented by three morphs of E. braziliensis (two closely related and found on opposite sides of Central America, a third only in the eastern Pacific) and by E. chamensis. Because populations of Excirolana from each beach in Panama, regardless of species or morphotype affiliation, are characterized by a unique combination of alleles, this isopod provides the opportunity to use genetic data to determine the number of immigrants that land on a given beach as well as the number of individuals that transfer alleles between populations. We studied isozyme patterns of 10 populations of E. braziliensis and one population of E. chamensis. Rates of gene flow were estimated both from FST statistics and from private alleles. In contrast to the private allele method, FST statistics gave results that were internally consistent in that they produced lower estimates of apparent gene flow between oceans and recognized species than they did between populations of the same morph. Rate of gene flow between populations belonging to the two morphs of E. braziliensis in the eastern Pacific was as low as apparent gene flow across the Central American isthmus and no larger than the rate of genetic exchange between E. braziliensis and E. chamensis. One locality that contained both morphs in sufficiently large numbers showed heterozygote deficits relative to Hardy-Weinberg expectations. Reproductive isolation is, therefore, of sufficient strength to justify the conclusion that the two Pacific morphs of E. braziliensis should be assigned to different species. Gene flow rate between populations of the same morph was an order of magnitude larger than rate of gene exchange between morphs but still less than one propagule per generation. Rate of immigration into every beach, calculated from the number of homozygotes of rare alleles (in excess of what would be expected from random matings among the residents), was surprisingly high for an organism with apparently limited means of dispersal and with fixed genetic differences between adjacent populations. Individuals of E. braziliensis evidently move between beaches much more freely than alleles move between populations. Therefore, some degree of reproductive isolation exists even between genotypes that belong to the same morph.Keywords: diagnostic loci, dispersal, FST statistics, geographic variation, isozymes, private alleles. tion genetics the terms 'migration' and 'gene flow' are Introduction often used interchangeably (thus implying that migrantsThe rate of gene flow between populations depends ca...

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RAPID GENETIC DIFFERENTIATION AND FOUNDER EFFECT IN COLONIZING POPULATIONS OF COMMON MYNAS (ACRIDOTHERES TRISTIS)

Cited by 111 publications

References 41 publications

Genetic drift and rapid evolution of viviparity in insular fire salamanders (Salamandra salamandra)

Genetic drift and rapid evolution of viviparity in insular fire salamanders (Salamandra salamandra)

The successful founder: genetics of introduced Carduelis chloris (greenfinch) populations in New Zealand

Migration, gene flow and reproductive isolation between and within morphotypes of the isopod Excirolana in two oceans

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