Polygamy and low effective population size in a captive Murray cod (Maccullochella peelii peelii) population: genetic implications for wild restocking programs

2009 ◽  
Vol 60 (8) ◽  
pp. 873 ◽  
Author(s):  
Meaghan L. Rourke ◽  
Helen C. McPartlan ◽  
Brett A. Ingram ◽  
Andrea C. Taylor
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Allelic Richness ◽  
Wild Populations ◽  
Effective Population ◽  
Census Size ◽  
Common Response ◽  
In Captivity ◽  
Murray Cod ◽  
Breeding Seasons

Stocking of freshwater fish species with hatchery-bred fish is a common response to depleted wild stocks, but may have numerous genetic implications. Murray cod, Maccullochella peelii peelii (Mitchell), have been produced in captivity for wild stocking programs for more than 30 years. The potential genetic impacts of this stocking program on wild populations was investigated by using eight microsatellite markers to determine the parentage of 1380 offspring from 46 separate spawnings collected over three consecutive breeding seasons, and by estimating the effective population size of the broodfish generation through demographic and genetic methods. Results revealed unexpected incidences of polygamous spawnings (both polygyny and polyandry), multiple spawnings by both sexes within a season and repeated matings between pairs of fish across multiple seasons. Furthermore, approximately half of the broodfish failed to spawn at all over the 3-year study period. This likely contributed to the estimated effective population size of around half of the census size, moderate but significant reductions in allelic richness in all three cohorts investigated and a small but significant reduction in heterozygosity in two cohorts. These results allowed us to make recommendations regarding captive husbandry that will maximise genetic diversity of fish intended for stocking.

scholarly journals Being abundant is not enough: a decrease in effective population size over eight generations in a Norwegian population of the seaweed, Fucus serratus

2008 ◽  
Vol 4 (6) ◽  
pp. 755-757 ◽  
Author(s):  
James A Coyer ◽  
Galice Hoarau ◽  
Kjersti Sjøtun ◽  
Jeanine L Olsen
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Allelic Richness ◽  
Environmental Changes ◽  
Extinction Risk ◽  
Rocky Intertidal ◽  
Effective Population ◽  
Norwegian Population ◽  
Fucus Serratus ◽  
Southern Norway

The brown alga Fucus serratus is a key foundation species on rocky intertidal shores of northern Europe. We sampled the same population off the coast of southern Norway in 2000 and 2008, and using 26 microsatellite loci, we estimated the changes in genetic diversity and effective population size ( N e ). The unexpectedly low N e (73–386) and N e / N ratio (10 −3 –10 −4 ), in combination with a significant decrease (14%) in allelic richness over the 8-year period, suggests an increased local extinction risk. If small N e proves to be a common feature of F. serratus , then being abundant may not be enough for the species to weather future environmental changes.

scholarly journals EFFECTIVE SIZE OF AUTO-TETRAPLOID POPULATION UNDER PARTIAL SELFING

2015 ◽  
Vol 24 (1) ◽  
pp. 31
Author(s):  
Muhamad Sabran
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Numerical Study ◽  
Effective Size ◽  
Double Reduction ◽  
Effective Population ◽  
Census Size ◽  
Sister Chromatids ◽  
Tetraploid Population ◽  
Arbitrary Rate

Effective population size is defined as the number of breeding individual in an idealized population that would show the same amount of dispersion of allele frequencies under random genetic drift or the same amount of inbreeding as the population under consideration. Effective population size depends on the census size of the population and the mating system. In autotetraploid population, effective population size also depends on the probability of double reduction, i.e., a meiotic event when two sister chromatids end in the same gamete. In this research, we will study the effect of the probability of double reduction on the effective size of autotetraploid population reproduced by partial selfing. The formula for the effective population size was derived by equating the variance of the change in gene frequency in idealized population and its value in the autotetraploid population with arbitrary rate of partial selfing and double reduction. The resulted formula, and numerical study based on the formula, indicated that the effective size decreases by the increase of probability of double reduction and the rate of selfing. When there is complete selfing, however, the effective size is not affected by the probability of double reduction.

scholarly journals Historical Analysis of Genetic Variation Reveals Low Effective Population Size in a Northern Pike (Esox lucius) Population

Genetics ◽  
1997 ◽  
Vol 147 (3) ◽  
pp. 1249-1258 ◽  
Author(s):  
Loren M Miller ◽  
Anne R Kapuscinski
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Microsatellite Loci ◽  
Natural Populations ◽  
Historical Analysis ◽  
Fish Population ◽  
Time Interval ◽  
Effective Population ◽  
Entire Interval ◽  
Census Size

Effective population size (Ne) of a natural fish population was estimated from temporal changes in allele frequencies at seven microsatellite loci. Use of a historical collection of fish scales made it possible to increase the precision of estimates by increasing the time interval between samples and to use an equation developed for discrete generations without correcting for demographic parameters. Estimates of Ne for the time intervals 1961–1977 and 1977–1993 were 35 and 72, respectively. For the entire interval, 1961–1993, the estimate of Ne was 48 when based on a weighted mean derived from the above two estimates or 125 when calculated from 1961 and 1993 samples only. Corresponding ratios of effective size to adult census size ranged from 0.03 to 0.14. An Ne of 48 over a 32-year period would imply that this population lost as much as 8% of its heterozygosity in that time. Results suggest the potential for using genetic methods based on microsatellite loci data to compare historical trends in Ne with population dynamic parameters. Such comparisons will help to evaluate the relationship between genetic diversity and long-term persistence of natural populations.

scholarly journals A NEW METHOD FOR ESTIMATING THE EFFECTIVE POPULATION SIZE FROM ALLELE FREQUENCY CHANGES

Genetics ◽  
1983 ◽  
Vol 104 (3) ◽  
pp. 531-548
Author(s):  
Edward Pollak
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Allele Frequency ◽  
New Method ◽  
Standard Errors ◽  
Effective Population ◽  
Census Size ◽  
Population Sizes ◽  
Frequency Changes ◽  
Approximate Expressions

ABSTRACT A new procedure is proposed for estimating the effective population size, given that information is available on changes in frequencies of the alleles at one or more independently segregating loci and the population is observed at two or more separate times. Approximate expressions are obtained for the variances of the new statistic, as well as others, also based on allele frequency changes, that have been discussed in the literature. This analysis indicates that the new statistic will generally have a smaller variance than the others. Estimates of effective population sizes and of the standard errors of the estimates are computed for data on two fly populations that have been discussed in earlier papers. In both cases, there is evidence that the effective population size is very much smaller than the minimum census size of the population.

scholarly journals Simple life-history traits explain key effective population size ratios across diverse taxa

2013 ◽  
Vol 280 (1768) ◽  
pp. 20131339 ◽  
Author(s):  
Robin S. Waples ◽  
Gordon Luikart ◽  
James R. Faulkner ◽  
David A. Tallmon
Keyword(s):  
Life History ◽  
Population Size ◽  
Effective Population Size ◽  
Life History Traits ◽  
Vital Rates ◽  
Effective Population ◽  
Adult Lifespan ◽  
Census Size ◽  
The Rich ◽  
And Migration

Effective population size ( N e ) controls both the rate of random genetic drift and the effectiveness of selection and migration, but it is difficult to estimate in nature. In particular, for species with overlapping generations, it is easier to estimate the effective number of breeders in one reproductive cycle ( N b ) than N e per generation. We empirically evaluated the relationship between life history and ratios of N e , N b and adult census size ( N ) using a recently developed model ( agene ) and published vital rates for 63 iteroparous animals and plants. N b / N e varied a surprising sixfold across species and, contrary to expectations, N b was larger than N e in over half the species. Up to two-thirds of the variance in N b / N e and up to half the variance in N e / N was explained by just two life-history traits (age at maturity and adult lifespan) that have long interested both ecologists and evolutionary biologists. These results provide novel insights into, and demonstrate a close general linkage between, demographic and evolutionary processes across diverse taxa. For the first time, our results also make it possible to interpret rapidly accumulating estimates of N b in the context of the rich body of evolutionary theory based on N e per generation.

scholarly journals GENETIC DRIFT AND ESTIMATION OF EFFECTIVE POPULATION SIZE

Genetics ◽  
1981 ◽  
Vol 98 (3) ◽  
pp. 625-640
Author(s):  
Masatoshi Nei ◽  
Fumio Tajima
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Random Mating ◽  
Effective Size ◽  
Isolated Population ◽  
Effective Population ◽  
Dacus Oleae ◽  
Census Size ◽  
Mating Population ◽  
Frequency Changes

ABSTRACT The statistical properties of the standardized variance of gene frequency changes (a quantity equivalent to Wright's inbreeding coefficient) in a random mating population are studied, and new formulae for estimating the effective population size are developed. The accuracy of the formulae depends on the ratio of sample size to effective size, the number of generations involved (t), and the number of loci or alleles used. It is shown that the standardized variance approximately follows the Χ2 distribution unless t is very large, and the confidence interval of the estimate of effective size can be obtained by using this property. Application of the formulae to data from an isolated population of Dacus oleae has shown that the effective size of this population is about one tenth of the minimum census size, though there was a possibility that the procedure of sampling genes was improper.

scholarly journals How many of them? Genetic diversity, survival and effective population size of the capercaillie population from the Gorce Mountains

2019 ◽  
Vol 62 (2) ◽  
pp. 135-144
Author(s):  
Sebastian SZCZEPAŃSKI ◽  
◽  
Anna SANTOREK ◽  
Beata DULISZ ◽  
Zbigniew ŻUREK ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Effective Population Size ◽  
Allelic Richness ◽  
Isolated Population ◽  
Effective Population ◽  
Field Surveys ◽  
Genetic Profiling ◽  
Factors Affecting ◽  
Non Invasive

Population size and effective population size are important factors affecting probability of extinction of small, isolated population. Hence, from conservation perspective, it is recommended to monitor changes in population size of endangered species. Genetic methods, based on genetic profiling of non-invasive samples of biological material, despite some limitations, were proved to be efficient method in tracking individuals in the field and estimate populations' parameters. We used this strategy to investigate isolated population of the capercaillie (Tetrao urogallus) in the Gorce Mountains. In two study periods (2012–2013 and 2017–2018) almost 400 faeces and feathers were collected. Microsatellite genotyping was performed to identify individuals and estimate genetic diversity. We found that population is stable in terms of size and genetic indices, although allelic richness has significantly increased between 2012–2013 and 2017–2018. In the overall study period (2012–2018) there were 52 individuals identified. However, only 10 birds were found in both study periods. This suggests low survival in the population. Moreover, genetic data indicated low effective population size of the capercaillie in the Gorce Mts. Thus, we suggest that monitoring, either genetic and based on field-surveys, should be implemented in the management and protection of this population.

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