Temporal increase in mtDNA diversity in a declining population

Abstract

In small and declining populations levels of genetic variability are expected to be reduced due to effects of inbreeding and random genetic drift. As a result, both individual fitness and populations' adaptability can be compromised, and the probability of extinction increased. Therefore, maintenance of genetic variability is a crucial goal in conservation biology. Here we show that although the level of genetic variability in mtDNA of the endangered Fennoscandian lesser white-fronted goose Anser erythropus population is currently lower than in the neigbouring populations, it has increased six-fold during the past 140 years despite the precipitously declining population. The explanation for increased genetic diversity in Fennoscandia appears to be recent spontaneous increase in male immigration rate equalling 0.56 per generation. This inference is supported by data on nuclear microsatellite markers, the latter of which show that the current and the historical Fennoscandian populations are significantly differentiated (F(ST) = 0.046, P = 0) due to changes in allele frequencies. The effect of male-mediated gene flow is potentially dichotomous. On the one hand it may rescue the Fennoscandian lesser white-fronted goose from loss of genetic variability, but on the other hand, it eradicates the original genetic characteristics of this population.

Determining the subspecies composition of bean goose harvests in Finland using genetic methods

“…This amount of sex-biased gene-flow is much larger 472 than what we observed by performing the same calculations for the Canada goose (up to times greater). Evidence of the sex-biased dispersal has been found also in the lesser-white 474 fronted goose (Ruokonen et al 2010) In this study we found that over half of the Finnish bean goose bag consists of the declining taiga 516 bean geese and that the tundra bean goose portion of the bag comes mainly from south-eastern 517…”

Comparative mitochondrial genetics of North American and Eurasian mergansers with an emphasis on the endangered scaly-sided merganser (Mergus squamatus)

“…comm.). A similar finding of sex-biased genetic diversity was documented by Ruokonen et al (2010) for the Fennoscandian lesser white-fronted goose (Anser erythropus) where haplotypic richness increased dramatically over time as a result of increased immigration by males. Because mtDNA is maternally transmitted and female waterfowl species may return to their natal site for subsequent breeding, dispersing males may offer an index of genetic diversity on a larger scale and are thus useful for population genetic surveys in species with sex-biased movement patterns.…”

Metapopulation dynamics of a diadromous galaxiid fish and potential effects of salmonid aquaculture

“…Thus, the observed latitudinal cline in the number of migrants suggests that larval dispersal is predominantly northwards, reflecting the prevailing wind regimes and tidal currents in the area (Cáceres, Valle-Levinson & Atkinson, 2003;Bustos, Landaeta & Balbotin, 2008). High gene flow can help prevent the loss of genetic diversity among diadromous G. maculatus in the short term (Ruokonen et al, 2010). However, given the importance that dispersal has for the evolutionary history of this species (Waters et al, 2000), a disruption of connectivity could have long-term fitness consequences.…”