Genetic structure and signature of population decrease in the critically endangered freshwater cyprinid <Emphasis Type="Italic">Chondrostoma lusitanicum</Emphasis> |
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Authors: | Vítor Sousa Filipa Penha Maria J Collares-Pereira Lounès Chikhi Maria M Coelho |
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Institution: | (1) Centro de Biologia Ambiental, Departamento de Biologia Animal, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, Bloco C2-3°Piso, 1749-016 Lisbon, Portugal;(2) Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal;(3) UMR CNRS 5174 Evolution & Diversité Biologique, Université Paul Sabatier, 118 route de Narbonne, Bat. 4R3 b2, 31062 Toulouse cedex 4, France |
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Abstract: | The endemic and critically endangered cyprinid Chondrostoma lusitanicum has a very restricted distribution range. In order to estimate genetic diversity, characterize population structure and infer
the demographic history, we examined six microsatellite loci and cytochrome b (mtDNA) sequences from samples taken throughout C. lusitanicum’s geographical range. Estimates of genetic diversity were low in all samples (average He < 0.35). The microsatellite data
pointed to a major difference between northern (Samarra and Tejo drainages) and southern (Sado and Sines drainages) samples.
This separation was not so clear with mtDNA, since one sample from the Tejo drainage grouped with the southern samples. This
could be related with ancestral polymorphism or with admixture events between northern and southern sites during the late
Pleistocene. Nevertheless, both markers indicate high levels of population differentiation in the north (for microsatellites
F
ST > 0.23; and for mtDNA ΦST > 0.74) and lower levels in the south (F
ST < 0.05; ΦST < 0.40). With microsatellites we detected strong signals of a recent population decrease in effective size, by more than
one order of magnitude, starting in the last centuries. This is consistent with field observations reporting a severe anthropogenic-driven
population decline in the last decades. On the contrary mtDNA suggested a much older expansion. Overall, these results suggest
that the distribution of genetic diversity in C. lusitanicum is the result of both ancient events related with drainage system formation, and recent human activities. The potential effect
of population substructure generating genetic patterns similar to a population decrease is discussed, as well as the implications
of these results for the conservation of C. lusitanicum.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | Endangered endemic Cyprinidae Chondrostoma lusitanicum Demographic history Population structure Microsatellites Mitochondrial DNA |
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