scholarly journals Sex change and effective population size: implications for population genetic studies in marine fish

Heredity ◽  
2016 ◽  
Vol 117 (4) ◽  
pp. 251-258 ◽  
Author(s):  
I Coscia ◽  
J Chopelet ◽  
R S Waples ◽  
B Q Mann ◽  
S Mariani
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Marine Fish ◽  
Population Genetic ◽  
Sex Change ◽  
Effective Population ◽  
Genetic Studies

scholarly journals Genetic Diversity, Structure and Effective Population Size of Old-Growth vs. Second-Growth Populations of Keystone and Long-Lived Conifer, Eastern White Pine (Pinus strobus): Conservation Value and Climate Adaptation Potential

2021 ◽  
Vol 12 ◽  
Author(s):  
Om P. Rajora ◽  
John W. R. Zinck
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Effective Population Size ◽  
Population Genetic ◽  
Conservation Value ◽  
Adaptive Potential ◽  
Effective Population ◽  
White Pine ◽  
Old Growth ◽  
Second Growth

Whether old-growth (OG) forests have higher genetic diversity and effective population size, consequently higher conservation value and climate adaptive potential than second-growth (SG) forests, remain an unresolved issue. We have tested the hypothesis that old-growth forest tree populations have higher genetic diversity, effective population size (NE), climate adaptive potential and conservation value and lower genetic differentiation than second-growth forest tree populations, employing a keystone and long-lived conifer, eastern white pine (EWP; Pinus strobus). Genetic diversity and population structure of old-growth and second-growth populations of eastern white pine (EWP) were examined using microsatellites of the nuclear and chloroplast genomes and single nucleotide polymorphisms (SNPs) in candidate nuclear genes putatively involved in adaptive responses to climate and underlying multilocus genetic architecture of local adaptation to climate in EWP. Old-growth and second-growth EWP populations had statistically similar genetic diversity, inbreeding coefficient and inter-population genetic differentiation based on nuclear microsatellites (nSSRs) and SNPs. However, old-growth populations had significantly higher chloroplast microsatellites (cpSSRs) haploid diversity than second-growth populations. Old-growth EWP populations had significantly higher coalescence-based historical long-term NE than second-growth EWP populations, but the linkage disequilibrium (LD)-based contemporary NE estimates were statistically similar between the old-growth and second-growth EWP populations. Analyses of population genetic structure and inter-population genetic relationships revealed some genetic constitution differences between the old-growth and second-growth EWP populations. Overall, our results suggest that old-growth and second-growth EWP populations have similar genetic resource conservation value. Because old-growth and second-growth EWP populations have similar levels of genetic diversity in genes putatively involved in adaptive responses to climate, old-growth, and second-growth populations may have similar adaptive potential under climate change. Our results could potentially be generalized across most of the boreal and temperate conifer forest trees. Our study contributes to address a long-standing issue, advances research field and knowledge about conservation and ecological and climate adaptation of forest trees.

The broad-snouted caiman population recovery in Argentina. A case of genetics conservation

2017 ◽  
Vol 38 (4) ◽  
pp. 411-424 ◽  
Author(s):  
Patricia Susana Amavet ◽  
Eva Carolina Rueda ◽  
Juan César Vilardi ◽  
Pablo Siroski ◽  
Alejandro Larriera ◽  
...  
Keyword(s):  
Genetic Variability ◽  
Population Size ◽  
Effective Population Size ◽  
Population Genetic ◽  
Genetic Parameters ◽  
Population Recovery ◽  
Santa Fe ◽  
Effective Population ◽  
Population Genetic Parameters ◽  
The Impact

Caiman latirostriswild populations have suffered a drastic reduction in the past, and for that reason, a management and monitoring plan was applied since 1990 in Santa Fe, Argentina in order to achieve population recovery. Although ranching system has a noteworthy success in terms of population size recovering, there is no information about the estimation of population genetic parameters. In particular, the consequence of the bottleneck underwent by these populations has not been assessed. We evaluated variability and genetic structure ofC. latirostrispopulations from Santa Fe through time, using microsatellites and mitochondrial DNA. Population genetic parameters were compared among four sites and three different periods to assess the impact of management activities, and effective population size was estimated in order to detect bottleneck events. We observed an increase in microsatellite variability and low genetic variability in mitochondrial lineages through time. Variability estimates are similar among sites in each sampling period; and there is scarce differentiation among them. The genetic background of each sampling site has changed through time; we assume this fact may be due to entry of individuals of different origin, through management and repopulation activities. Moreover, taking into account the expected heterozygosity and effective population size values, it can be assumed that bottleneck events indeed have occurred in the recent past. Our results suggest that, in addition to increasing population size, genetic variability of the species has been maintained. However, the information is still incomplete, and regular monitoring should continue in order to arrive to solid conclusions.

scholarly journals Consequences of sex change for effective population size

2018 ◽  
Vol 285 (1893) ◽  
pp. 20181702 ◽  
Author(s):  
Robin S. Waples ◽  
Stefano Mariani ◽  
Chiara Benvenuto
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Evolutionarily Stable Strategy ◽  
Sex Ratios ◽  
Sex Change ◽  
Standard Theory ◽  
Effective Population ◽  
Potential Conflict ◽  
Individual Level ◽  
The Individual

Sequential hermaphroditism, where males change to females (protandry) or the reverse (protogyny), is widespread in animals and plants, and can be an evolutionarily stable strategy (ESS) if fecundity rises faster with age in the second sex. Sequential hermaphrodites also generally have sex ratios skewed towards the initial sex, and standard theory based on fixed sexes indicates that this should reduce effective population size ( N e ) and increase the deleterious effects of genetic drift. We show that despite having skewed sex ratios, populations that change sex at the ESS age do not have reduced N e compared with fixed-sex populations with an even sex ratio. This implies that the ability of individuals to operate as both male and female allows the population to avoid some evolutionary constraints imposed by fixed sexes. Furthermore, N e would be maximized if sex change occurred at a different (generally earlier) age than is selected for at the individual level, which suggests a potential conflict between individual and group selection. We also develop a novel method to quantify the strength of selection for sex reversal.

Analysis of population-genetic processes in different cattle breeds by microsatellite loci of DNA

2017 ◽  
Vol 4 (1) ◽  
pp. 74-78 ◽  
Author(s):  
A. Shelyov ◽  
K. Kopylov ◽  
S. Kramarenko ◽  
O. Kramarenko
Keyword(s):  
Dairy Cattle ◽  
Population Size ◽  
Effective Population Size ◽  
Microsatellite Loci ◽  
Population Genetic ◽  
Effective Population ◽  
Dna Microsatellites ◽  
Black And White ◽  
Cattle Breeds ◽  
Dairy Breed

Aim. The aim of our research was to analyze the population-genetic processes in different dairy breeds using highly polymorphic molecular and genetic markers (DNA microsatellites). Methods. We used 10 loci recommended by the International Society for Animal Genetics (ISAG) to analyze 88 DNA samples of the two most abundant dairy breeds of cattle in Ukraine – Ukrainian red-motley dairy and Ukrainian black-and-white dairy breeds. Using formulae that related the expected linkage disequilibrium (LD) to the effective population size (Ne), Ne was estimated. Results. The work presents the results of the study on genetic processes in the populations of Ukrainian red-and-motley breed using 10 microsatellite loci of DNA. It was shown that, being highly polymorphic multilocus genetic systems, microsatellites of DNA are highly informative markers of populationgenetic processes, occurring in the populations of cattle. Conclusions. The studied populations of Ukrainian dairy cattle breeds are impacted by population-genetic and genetic-automatic processes. In particular, the effect of the latter on Ukrainian red-and-motley dairy breed was noted. These animals had notable signifi cant loss of rare alleles and the manifestation effect of “bottle neck”. The values obtained testify to a low level of inbredness in these populations. The effective population size in the studied Ukrainian dairy cattle breeds was estimated in the approximate range of 397–555 heads which testifi ed to a favorable condition of the population of Ukrainian red-and-motley dairy cattle and a critical condition of the Ukrainian black-and-white dairy breed.

Effective population size and genetic structure of a Piute ground squirrel (Spermophilus mollis) population

2001 ◽  
Vol 79 (1) ◽  
pp. 26-34 ◽  
Author(s):  
Michael F Antolin ◽  
Beatrice Van Horne ◽  
Michael D Berger, Jr. ◽  
Alisha K Holloway ◽  
Jennifer L Roach ◽  
...  
Keyword(s):  
Genetic Analysis ◽  
Population Size ◽  
Effective Population Size ◽  
Ground Squirrel ◽  
Population Genetic ◽  
Ground Squirrels ◽  
Perennial Grasses ◽  
Population Subdivision ◽  
Effective Population ◽  
Population Genetic Analysis

Piute ground squirrels (Spermophilus mollis) are distributed continuously in habitat dominated by native shrubs and perennial grasses in the Snake River Birds of Prey National Conservation Area in Idaho, U.S.A. This habitat is being fragmented and replaced by exotic annual plants, changing it to a wildfire-dominated system that provides poor habitat for ground squirrels. To assess potential effects of this fragmentation on ground squirrel populations, we combined an estimate of effective population size (Ne) based upon a demographic study with a population genetic analysis. The study area included three subpopulations separated from each other by 8–13 km. The ratio of effective population size to census number (Ne/N) was 0.57. Combining Ne/N with dispersal distances from a radio-tracking study, we calculated that neighborhood size was 62.2 ha, which included between 204 and 480 individuals. Our population genetic analysis (based on randomly amplified polymorphic DNA (RAPD) and microsatellite markers) showed relatively low levels of genetic differentiation (Qpopulations [Formula: see text] 0.07–0.10) between subpopulations and no inbreeding within subpopulations (f = 0.0003). These estimates of population subdivision translate into an effective migration rate (Nem) of 2.3–3.3 per year, which represents a high level of gene flow. Invasion by exotics will reduce the overall productivity of the habitat, and will lead to isolation among subpopulations if favorable habitat patches become isolated.

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