Causes and consequences of fine-scale population structure in a critically endangered freshwater seal

Annals of Occupational and Environmental Medicine

Mia Valtonen³  Jukka U Palo⁴  Jouni Aspi²  Minna Ruokonen²  Mervi Kunnasranta³  Tommi Nyman¹ 

[1] Institute for Systematic Botany, University of Zurich, Zurich, Switzerland

[2] Department of Biology, University of Oulu, Oulu, Finland

[3] Department of Biology, University of Eastern Finland, Joensuu, Finland

[4] Laboratory of Forensic Biology, Hjelt Institute, University of Helsinki, Helsinki, Finland

关键词: Small population;    Landscape genetics;    Genetic erosion;    Gene flow;    Effective population size;    Cryptic population structure;   

Others  :  863069
DOI  :  10.1186/1472-6785-14-22

 received in 2014-01-28, accepted in 2014-07-03,  发布年份 2014

【 摘 要 】

Background

Small, genetically uniform populations may face an elevated risk of extinction due to reduced environmental adaptability and individual fitness. Fragmentation can intensify these genetic adversities and, therefore, dispersal and gene flow among subpopulations within an isolated population is often essential for maintaining its viability. Using microsatellite and mtDNA data, we examined genetic diversity, spatial differentiation, interregional gene flow, and effective population sizes in the critically endangered Saimaa ringed seal (Phoca hispida saimensis), which is endemic to the large but highly fragmented Lake Saimaa in southeastern Finland.

Results

Microsatellite diversity within the subspecies (H_E = 0.36) ranks among the lowest thus far recorded within the order Pinnipedia, with signs of ongoing loss of individual heterozygosity, reflecting very low effective subpopulation sizes. Bayesian assignment analyses of the microsatellite data revealed clear genetic differentiation among the main breeding areas, but interregional structuring was substantially weaker in biparentally inherited microsatellites (F_ST = 0.107) than in maternally inherited mtDNA (F_ST = 0.444), indicating a sevenfold difference in the gene flow mediated by males versus females.

Conclusions

Genetic structuring in the population appears to arise from the joint effects of multiple factors, including small effective subpopulation sizes, a fragmented lacustrine habitat, and behavioural dispersal limitation. The fine-scale differentiation found in the landlocked Saimaa ringed seal is especially surprising when contrasted with marine ringed seals, which often exhibit near-panmixia among subpopulations separated by hundreds or even thousands of kilometres. Our results demonstrate that population structures of endangered animals cannot be predicted based on data on even closely related species or subspecies.

【 授权许可】

   
2014 Valtonen et al.; licensee BioMed Central Ltd.

【 图 表 】

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