Principles of Population Genetics

Cazes, Marie-Hélène; Hartl, Daniel L.; Clark, Andrew

doi:10.2307/1534724

Cited by 12 publications

(14 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The 15-fold range of genetic diversities found within a single species is astonishing, drawing attention to the extremely low genetic diversities in bottlenecked and consanguineous pond populations. The discrepancy between Ne MR and Ne π was the greatest in these tiny populations, and given that their isolation probably greatly exceeds 4Ne generations (Hartl and Clark 2007), their elevated levels of diversity must be retained by factors other than demography. However, it is clear that the excess diversity of the small pond populations originated during the historical large population size, emphasizing that the mechanisms creating genetic diversity and those retaining it under altered circumstances can be different.…”

Section: Discussionmentioning

confidence: 92%

Determinants of genetic diversity in sticklebacks

Kivikoski

Feng

Löytynoja

et al. 2023

Preprint

View full text Add to dashboard Cite

Understanding what determines species and population differences in levels of genetic diversity has important implications for our understanding of evolution, as well as for the conservation and management of wild populations. Previous comparative studies have emphasized the roles of linked selection, life-history trait variation and genomic properties, rather than pure demography, as important determinants of genetic diversity. However, these findings are based on coarse estimates across a range of highly diverged taxa, and it is unclear how well they represent the processes within individual species. We assessed genome-wide genetic diversity (pi) in 45 nine-spined stickleback (Pungitius pungitius) populations and found that pi varied 15-fold among populations (pi min approx. 0.00015, pi max approx 0.0023) whereas estimates of recent effective population sizes varied 122-fold. Analysis of inbreeding coefficients (F ROH) estimated from runs of homozygosity revealed strong negative association between pi and F ROH. Genetic diversity was also negatively correlated with mean body size and longevity, but these associations were not statistically significant after controlling for demographic effects (F ROH). The results give strong support for the view that populations' demographic features, rather than life history differences, are the chief determinants of genetic diversity in the wild.

show abstract

Section: Discussionmentioning

confidence: 92%

Determinants of genetic diversity in sticklebacks

Kivikoski

Feng

Löytynoja

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…Heterozygotes, however, did not result in statistically significant costs in terms of growth and reproduction. These results suggest that rather than being entirely recessive, these mutations are non-additively underdominant [28]. Selection against the heterozygous state leads to a bistable evolutionary dynamic resembling two peaks separated by a low fitness valley.…”

Section: (A) Adaptive Novelty Mediated By Recessive Mutationsmentioning

confidence: 87%

Loss-of-heterozygosity facilitates a fitness valley crossing in experimentally evolved multicellular yeast

2022

View full text Add to dashboard Cite

Determining how adaptive possibilities do or do not become evolutionary realities is central to understanding the tempo and mode of evolutionary change. Some of the simplest evolutionary landscapes arise from underdominance at a single locus where the fitness valley consists of only one less-fit genotype. Despite their potential for rapid evolutionary change, few such examples have been investigated. We capitalized on an experimental system in which a significant evolutionary shift, the transition from uni-to-multicellularity, was observed in asexual diploid populations of Saccharomyces cerevisiae experimentally selected for increased settling rates. The multicellular phenotype results from recessive single-locus mutations that undergo loss-of-heterozygosity (LOH) events. By reconstructing the necessary heterozygous intermediate steps, we found that the evolution of multicellularity involves a decrease in size during the first steps. Heterozygous genotypes are 20% smaller in size than genotypes with functional alleles. Nevertheless, populations of heterozygotes give rise to multicellular genotypes more readily than unicellular genotypes with two functional alleles, by rapid LOH events. LOH drives adaptation that may enable rapid evolution in diploid yeast. Together these results show discordance between the phenotypic and genotypic multicellular transition. The evolutionary path to multicellularity, and the adaptive benefits of increased size, requires initial size reductions.

show abstract

“…Conversely, F IS , the inbreeding coefficient, is only weakly correlated with H O and the other five genetic parameters. This is because, while the other metrics describe the genetic variation present in a population, F IS describes the arrangement of that genetic diversity within and among individuals (i.e., the deficit of heterozygotes relative to Hardy–Weinberg expectations), which is influenced by inbreeding and/or population structure (Hartl & Clark, 2007). While H O captures general patterns of standing genetic variation across these populations, the inbreeding coefficient is most relevant to the question of how ID might affect population dynamics.…”

Section: Methodsmentioning

confidence: 99%

Are genetic variation and demographic performance linked?

Carley

Morris

Walsh

et al. 2022

Evolutionary Applications

View full text Add to dashboard Cite

Quantifying relationships between genetic variation and population viability is important from both basic biological and applied conservation perspectives, yet few populations have been monitored with both long‐term demographic and population genetics approaches. To empirically test whether and how genetic variation and population dynamics are related, we present one such paired approach. First, we use eight years of historical demographic data from five populations of Boechera fecunda (Brassicaceae), a rare, self‐compatible perennial plant endemic to Montana, USA, and use integral projection models to estimate the stochastic population growth rate (λS) and extinction risk of each population. We then combine these demographic estimates with previously published metrics of genetic variation in the same populations to test whether genetic diversity within populations is linked to demographic performance. Our results show that in this predominantly inbred species, standing genetic variation and demography are weakly positively correlated. However, the inbreeding coefficient was not strongly correlated with demographic performance, suggesting that more inbred populations are not necessarily less viable or at higher extinction risk than less inbred populations. A contemporary re‐census of these populations revealed that neither genetic nor demographic parameters were consistently strong predictors of current population density, although populations showing lower probabilities of extinction in demographic models had larger population sizes at present. In the absence of evidence for inbreeding depression decreasing population viability in this species, we recommend conservation of distinct, potentially locally adapted populations of B. fecunda rather than alternatives such as translocations or reintroductions.

show abstract

Principles of Population Genetics

Cited by 12 publications

References 0 publications

Determinants of genetic diversity in sticklebacks

Determinants of genetic diversity in sticklebacks

Loss-of-heterozygosity facilitates a fitness valley crossing in experimentally evolved multicellular yeast

Are genetic variation and demographic performance linked?

Contact Info

Product

Resources

About