scholarly journals THE THEORY OF SPECIATION VIA THE FOUNDER PRINCIPLE

Genetics ◽  
1980 ◽  
Vol 94 (4) ◽  
pp. 1011-1038
Author(s):  
Alan R Templeton
Keyword(s):  
Genetic Variability ◽  
Founder Effect ◽  
Ancestral Population ◽  
Founder Population ◽  
Hawaiian Drosophila ◽  
Severe Reduction ◽  
Selective Forces ◽  
Theoretical Population ◽  
Adaptive Peak ◽  
Founder Event

ABSTRACT The founder principle has been used to explain many instances of rapid speciation. Advances from theoretical population genetics are incorporated into MAYR'S original founder-effect genetic-revolution model to yield a newer model called the genetic transilience. The basic theoretical edifice lies upon the fact that founder event can sometimes lead to an accumulation of inbreeding and an induction of gametic disequilibrium. This, in turn, causes alleles to be selected more for their homozygous fitness effects and for their effects on a more stable genetic background. Selection occurring in multi-locus systems controlling integrated developmental, physiological, behavioral, etc., traits is particularly sensitive to these founder effects. If sufficient genetic variability exists in the founder population, such multilocus genetic systems can respond to drift and the altered selective forces by undergoing a rapid shift to a new adaptive peak known as the genetic transilience. A genetic transilience is, therefore, most likely to occur when the founder event causes a rapid accumulation of inbreeding without a severe reduction in genetic variability. The implications of this model are then examined for three aspects of the founder-effect genetic-transilience model: the attributes of the ancestral population, the nature of the sampling process used t o generate the founders and the attributes of the founder population. The model is used to explain several features of the evolution of the Hawaiian Drosophila, and experimental designs are outlined to test the major predictions of the theory. Hence, this theory of speciation can be tested in the laboratory, using systems and techniques that already exist—a rare attribute of most models of speciation.

scholarly journals Genetic variability in Iranian limb‐girdle muscular dystrophy type 2B patients: An evidence of a founder effect

2019 ◽  
Vol 7 (12) ◽  
Author(s):  
Marzieh Mojbafan ◽  
Shirzadeh Tina ◽  
Fatemeh Zafarghandi Motlagh ◽  
Andrei Surguchov ◽  
Yalda Nilipour ◽  
...  
Keyword(s):  
Muscular Dystrophy ◽  
Genetic Variability ◽  
Founder Effect ◽  
Limb Girdle Muscular Dystrophy

Genetic Variability and Founder Effect in the Pitcher Plant Sarracenia purpurea L.

Evolution ◽  
1979 ◽  
Vol 33 (4) ◽  
pp. 1210 ◽  
Author(s):  
Kent E. Schwaegerle ◽  
Barbara A. Schaal
Keyword(s):  
Genetic Variability ◽  
Founder Effect ◽  
Sarracenia Purpurea ◽  
Pitcher Plant

Range expansion of Brewer's blackbird: phenetics of a new population

1971 ◽  
Vol 49 (2) ◽  
pp. 175-183 ◽  
Author(s):  
Dennis M. Power
Keyword(s):  
United States ◽  
Genetic Variability ◽  
Range Expansion ◽  
Founder Effect ◽  
The United States ◽  
Directional Selection ◽  
Population Variability ◽  
Two Samples ◽  
Stable Part ◽  
Made In

The Brewer's blackbird (Euphagus cyanocephalus) is rapidly expanding its range eastward across Ontario and parts of the United States. This study was to determine if phenetic changes have taken place during or immediately after expansion. A sample was collected in 1968 in the vicinity of McKerrow, Ontario, near the periphery of the zone of expansion and where breeding was first recorded in 1962. For comparison, a second collection was made in the stable part of the range near Winnipeg, Manitoba. Statistical comparisons for 37 skin and skeletal characters were made between the two samples for both sexes. Tests for differences in character means suggest that strong directional selection, different from that in the stable part of the range, is not operating in the newly occupied area. Likewise, differences in population variability seem slight and do not show alterations in genetic variability that would be expected during a Carsonian population flush or that would be expected because of a partial founder effect.

The effect of differential reproductive rates on the survival of a gene represented in a founder population

1982 ◽  
Vol 19 (A) ◽  
pp. 19-25
Author(s):  
C. C. Heyde
Keyword(s):  
Genetic Variability ◽  
Density Dependence ◽  
Founder Population ◽  
Isolated Populations ◽  
Moran Model ◽  
Mild Conditions ◽  
Reproductive Rates

Gene survival in a population which increases without density dependence is considered using a generalization of the Moran model for haploid individuals in which we have differential reproductive rates. It is shown under very mild conditions that ultimate fixation is certain. This provides some mathematical support for the phenomenon of reduced genetic variability in isolated populations established from founder groups.

Genetic stability of Australian Phalaris (Phalaris tuberosa L.) under domestication

1971 ◽  
Vol 22 (6) ◽  
pp. 895 ◽  
Author(s):  
JR McWilliam ◽  
HE Schroeder ◽  
DR Marshall ◽  
RN Oram
Keyword(s):  
Natural Selection ◽  
Genetic Variability ◽  
Natural Regeneration ◽  
Ancestral Population ◽  
Agronomic Characters ◽  
Apparent Lack ◽  
Ecotypic Differentiation ◽  
Eastern Australia ◽  
Controlled Environments ◽  
Italian Origin

Thirty isolates of the Australian cultivar of phalaris (Phalaris tubevosa), sampled over the range of its distribution in south-eastern Australia, were evaluated as seeds and seedlings in controlled environments and as spaced plants and swards in the field. The variation found within and between the populations for a number of morphological, developmental, chemical, and agronomic characters indicates that the species has undergone little, if any, ecotypic differentiation during almost 90 years of cultivation in Australia. The results also indicate that the cultivar was derived from a single ancestral population of P. tuberosa and are consistent with the earlier claims that this population was of Italian origin. The evolutionary conservatism and the apparent lack of ecological adaptation in the cultivar are not due to a lack of genetic variability, but rather to the longevity and adaptability of individual plants, and the absence of natural regeneration in established stands, all of which have reduced the scope of natural selection.

scholarly journals Founder Effects in Hereditary Hemorrhagic Telangiectasia

2021 ◽  
Vol 10 (8) ◽  
pp. 1682
Author(s):  
Tamás Major ◽  
Réka Gindele ◽  
Gábor Balogh ◽  
Péter Bárdossy ◽  
Zsuzsanna Bereczky
Keyword(s):  
Genetic Algorithms ◽  
Common Core ◽  
Founder Effect ◽  
Hereditary Hemorrhagic Telangiectasia ◽  
Founder Mutation ◽  
Founder Effects ◽  
Core Haplotype ◽  
Founder Event ◽  
Mutation Databases ◽  
Smad4 Mutation

A founder effect can result from the establishment of a new population by individuals from a larger population or bottleneck events. Certain alleles may be found at much higher frequencies because of genetic drift immediately after the founder event. We provide a systematic literature review of the sporadically reported founder effects in hereditary hemorrhagic telangiectasia (HHT). All publications from the ACVRL1, ENG and SMAD4 Mutation Databases and publications searched for terms “hereditary hemorrhagic telangiectasia” and “founder” in PubMed and Scopus, respectively, were extracted. Following duplicate removal, 141 publications were searched for the terms “founder” and “founding” and the etymon “ancest”. Finally, 67 publications between 1992 and 2020 were reviewed. Founder effects were graded upon shared area of ancestry/residence, shared core haplotypes, genealogy and prevalence. Twenty-six ACVRL1 and 12 ENG variants with a potential founder effect were identified. The bigger the cluster of families with a founder mutation, the more remarkable is its influence to the populational ACVRL1/ENG ratio, affecting HHT phenotype. Being aware of founder effects might simplify the diagnosis of HHT by establishing local genetic algorithms. Families sharing a common core haplotype might serve as a basis to study potential second-hits in the etiology of HHT.

scholarly journals Background selection and patterns of genetic diversity in Drosophila melanogaster

1996 ◽  
Vol 68 (2) ◽  
pp. 131-149 ◽  
Author(s):  
Brian Charlesworth
Keyword(s):  
Genetic Diversity ◽  
Drosophila Melanogaster ◽  
Genetic Variability ◽  
Chromosomal Location ◽  
Theoretical Models ◽  
Distal Portion ◽  
Background Selection ◽  
Deleterious Mutations ◽  
Chromosome 4 ◽  
Selective Forces

SummaryTheoretical models of the effects of selection against deleterious mutations on variation at linked neutral sites (background selection) are used to predict the relations between chromosomal location and genetic variability at the DNA level, in Drosophila melanogaster. The sensitivity of the predictions to variation in the mutation, selection and recombination parameters on which they are based is examined. It is shown that many features of the observed relations between chromosomal location and level of genetic diversity in D. melanogaster can be explained by background selection, especially if the weak selective forces acting on transposable elements are taken into account. In particular, the gradient in diversity in the distal portion of the X chromosome, and the lack of diversity on chromosome 4 and at the bases of the major chromosomes, can be fully accounted for. There are, however, discrepancies between predicted and observed values for some loci in D. melanogaster, which may reflect the effects of forces other than background selection.

scholarly journals Retrotransposon-based genetic variation ofPoa annuapopulations from contrasting climate conditions

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6888 ◽  
Author(s):  
Piotr Androsiuk ◽  
Justyna Koc ◽  
Katarzyna Joanna Chwedorzewska ◽  
Ryszard Górecki ◽  
Irena Giełwanowska
Keyword(s):  
Genetic Variation ◽  
Genetic Variability ◽  
Kola Peninsula ◽  
Founder Effect ◽  
Environmental Changes ◽  
High Plasticity ◽  
Demographic Expansion ◽  
The Balkans ◽  
Wide Range ◽  
The Antarctic

BackgroundPoa annuaL. is an example of a plant characterized by abundant, worldwide distribution from polar to equatorial regions. Due to its high plasticity and extraordinary expansiveness,P. annuais considered an invasive species capable of occupying and surviving in a wide range of habitats including pioneer zones, areas intensively transformed by human activities, remote subarctic meadows and even the Antarctic Peninsula region.MethodsIn the present study, we evaluated the utility of inter-primer binding site (iPBS) markers for assessing the genetic variation ofP. annuapopulations representing contrasting environments from the worldwide range of this species. The electrophoretic patterns of polymerase chain reaction products obtained for each individual were used to estimate the genetic diversity and differentiation between populations.ResultsiPBS genotyping revealed a pattern of genetic variation differentiating the six studiedP. annuapopulations characterized by their different climatic conditions. According to the analysis of molecular variance, the greatest genetic variation was recorded among populations, whereas 41.75% was observed between individuals within populations. The results of principal coordinates analysis (PCoA) and model-based clustering analysis showed a clear subdivision of analyzed populations. According to PCoA, populations from Siberia and the Kola Peninsula were the most different from each other and showed the lowest genetic variability. The application of STRUCTURE software confirmed the unique character of the population from the Kola Peninsula.DiscussionThe lowest variability of the Siberia population suggested that it was subjected to genetic drift. However, although demographic expansion was indicated by negative values of Fu’sFSstatistic and analysis of mismatch distribution, it was not followed by significant traces of a bottleneck or a founder effect. For the Antarctic population, the observed level of genetic variation was surprisingly high, despite the observed significant traces of bottleneck/founder effect following demographic expansion, and was similar to that observed in populations from Poland and the Balkans. For the Antarctic population, the multiple introduction events from different sources are considered to be responsible for such an observation. Moreover, the results of STRUCTURE and PCoA showed that theP. annuafrom Antarctica has the highest genetic similarity to populations from Europe.ConclusionsThe observed polymorphism should be considered as a consequence of the joint influence of external abiotic stress and the selection process. Environmental changes, due to their ability to induce transposon activation, lead to the acceleration of evolutionary processes through the production of genetic variability.

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