Reconstructing eight decades of genetic variation in an isolated Danish population of the large blue butterfly Maculinea arion.

Line V Ugelvig,David R Nash,Per S Nielsen,Jacobus J Boomsma

doi:10.1186/1471-2148-11-201

Line V Ugelvig, David R Nash + Show 2 more

Open Access

https://doi.org/10.1186/1471-2148-11-201

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Abstract

BackgroundFragmentation of terrestrial ecosystems has had detrimental effects on metapopulations of habitat specialists. Maculinea butterflies have been particularly affected because of their specialized lifecycles, requiring both specific food-plants and host-ants. However, the interaction between dispersal, effective population size, and long-term genetic erosion of these endangered butterflies remains unknown. Using non-destructive sampling, we investigated the genetic diversity of the last extant population of M. arion in Denmark, which experienced critically low numbers in the 1980s.ResultsUsing nine microsatellite markers, we show that the population is genetically impoverished compared to nearby populations in Sweden, but less so than monitoring programs suggested. Ten additional short repeat microsatellites were used to reconstruct changes in genetic diversity and population structure over the last 77 years from museum specimens. We also tested amplification efficiency in such historical samples as a function of repeat length and sample age. Low population numbers in the 1980s did not affect genetic diversity, but considerable turnover of alleles has characterized this population throughout the time-span of our analysis.ConclusionsOur results suggest that M. arion is less sensitive to genetic erosion via population bottlenecks than previously thought, and that managing clusters of high quality habitat may be key for long-term conservation.

Highlights

Fragmentation of terrestrial ecosystems has had detrimental effects on metapopulations of habitat specialists
Theory indicates [9] and comparative studies across 170 species have shown [10] that a significant proportion of endangered populations/species have reduced levels of genetic variation compared to related non-endangered species, suggesting that genetic factors often play a role in population extinctions [11]
The Møn population had a medium level of genetic diversity in comparison with the Swedish populations, i.e. lower than the functional metapopulations in Skåne, Öland and Gotland, but higher than three isolated single site populations [20]

Summary

Introduction

Fragmentation of terrestrial ecosystems has had detrimental effects on metapopulations of habitat specialists. Endangered species often occur in small isolated populations where demographic and environmental stochasticity impose additional risks of local extinction. This has made some researchers question the role that genetic factors play in driving population extinction [5], because genetic factors are likely to be negligible when population decline occurs rapidly. When effective population sizes remain moderate, inbreeding over many generations may have marked fitness effects due to increasing disease susceptibility and inbreeding depression [2,6,7,8] This is because purging tends to remove primarily the few deleterious recessive alleles with large negative effects, and hardly affects the more numerous slightly deleterious alleles [6]. Theory indicates [9] and comparative studies across 170 species have shown [10] that a significant proportion of endangered populations/species have reduced levels of genetic variation compared to related non-endangered species, suggesting that genetic factors often play a role in population extinctions [11]

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Conclusion