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.

Likelihood-Based Estimation of the Effective Population Size Using Temporal Changes in Allele Frequencies: A Genealogical Approach

Genetics ◽  
2002 ◽  
Vol 160 (2) ◽  
pp. 741-751 ◽  
Author(s):  
Pierre Berthier ◽  
Mark A Beaumont ◽  
Jean-Marie Cornuet ◽  
Gordon Luikart
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Genetic Drift ◽  
Classical Method ◽  
Extinction Risk ◽  
Effective Population ◽  
Upper Limit ◽  
Credible Intervals ◽  
Using Data ◽  
Statistic Approach

AbstractA new genetic estimator of the effective population size (Ne) is introduced. This likelihood-based (LB) estimator uses two temporally spaced genetic samples of individuals from a population. We compared its performance to that of the classical F-statistic-based Ne estimator () by using data from simulated populations with known Ne and real populations. The new likelihood-based estimator () showed narrower credible intervals and greater accuracy than () when genetic drift was strong, but performed only slightly better when genetic drift was relatively weak. When drift was strong (e.g., Ne = 20 for five generations), as few as ~10 loci (heterozygosity of 0.6; samples of 30 individuals) are sufficient to consistently achieve credible intervals with an upper limit <50 using the LB method. In contrast, ~20 loci are required for the same precision when using the classical F-statistic approach. The estimator is much improved over the classical method when there are many rare alleles. It will be especially useful in conservation biology because it less often overestimates Ne than does and thus is less likely to erroneously suggest that a population is large and has a low extinction risk.

Evolutionary potential but not extinction risk of Lahontan cutthroat trout (Oncorhynchus clarkii henshawi) is associated with stream characteristics

2012 ◽  
Vol 69 (4) ◽  
pp. 615-626 ◽  
Author(s):  
Mary M. Peacock ◽  
Ned A. Dochtermann
Keyword(s):  
Population Size ◽  
Effective Population Size ◽  
Extinction Risk ◽  
Spatial Scales ◽  
Cutthroat Trout ◽  
Effective Population ◽  
Evolutionary Potential ◽  
Oncorhynchus Clarkii ◽  
Lahontan Cutthroat Trout ◽  
Habitat Variables

Habitat fragmentation represents a major extinction threat for species of all taxa. Isolated populations have a higher risk of local extinction because of environmental variability and demographic processes associated with small populations. Here we examine the relationships among isolation, habitat size, habitat characteristics and variability, and genetic effective population size with extinction risk for 10 isolated and three interconnected populations of Lahontan cutthroat trout ( Oncorhynchus clarkii henshawi ) sampled from throughout their range. Contrary to expectations, we did not find a relationship between most habitat variables and extinction risk. However, we did find strong relationships between habitat variables and genetic effective population size, including a significant negative correlation between pool density and effective population size. Small effective population sizes can result in reduced genetic variation and losses of evolutionary potential and adaptability to changing environments. The absence of strong habitat correlates with extinction risk — despite an observed relationship with effective population size — highlights the need to consider habitat diversity at multiple spatial scales when considering management scenarios to both promote population persistence and maintain evolutionary relevance.

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.

scholarly journals Initial approach to the Conservation Genetics of the Guatemalan Beaded Lizard (Heloderma charlesbogerti): A route to genetic rescue

2021 ◽  
Author(s):  
Sergio A Gonzalez-Mollinedo ◽  
Thomas Schrei ◽  
Brad Locke
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Effective Population Size ◽  
Extinction Risk ◽  
Genetic Erosion ◽  
Unknown Origin ◽  
Single Individual ◽  
Effective Population ◽  
Genetic Management ◽  
Low Genetic Diversity

In this study, samples from 33 Guatemalan Beaded Lizard (Heloderma charlesbogerti) were analyzed for genetic diversity. Twenty-three samples were obtained from wild individuals from two separate population areas, and 10 samples were obtained from captive individuals. Because the seasonally dry tropical forest habitat sampled for this study, is degraded and fragmented, it was hypothesized that beaded lizard populations were small and isolated and would be subject to genetic erosion and an elevated extinction risk. To test this hypothesis, eight microsatellite markers were employed to analyze 22 individual samples from the population of Cabanas, Zacapa, a single individual from the eastern-most population and 10 captive individuals of unknown origin. An average of three alleles per maker was reported for the Cabanas population, evidencing a low genetic diversity. In addition, a recent bottleneck event was detected and an effective population size of 19.6 was estimated. Demographic reconstruction using a Bayesian approach was inconclusive possibly due to a small dataset and shallow coalescence trees obtained with the generated data. No clear structuring pattern was detected for the Cabanas population and most samples from individuals in captivity were found to have similar alleles to the ones from Cabanas. Population designation is challenging without the genotyping of every wild population, but unique alleles were found in captive individuals of unknown origin that could suggest that different genotypes might exist within other, less studied, wild populations. Low genetic diversity, and a small effective population size represent a risk for the Cabanas population facing the threats of isolation, habitat loss and climate change. These findings suggest that genetic management of the Cabanas population might be utilized to avoid high rates of inbreeding and subsequent inbreeding depression.

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.

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