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Cryptic speciation in the field vole: a multilocus approach confirms three highly divergent lineages in Eurasia

Authors

  • J. Paupério,

    Corresponding author
    1. Department of Biology, University of York, York, UK
    2. Departamento de Biologia, Faculdade de Ciências da Universidade do Porto, Porto, Portugal
    • CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Vairão, Portugal
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  • J. S. Herman,

    1. Department of Biology, University of York, York, UK
    2. Department of Natural Sciences, National Museums Scotland, Edinburgh, UK
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  • J. Melo-Ferreira,

    1. CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Vairão, Portugal
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  • M. Jaarola,

    1. Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
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  • P. C. Alves,

    1. CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Vairão, Portugal
    2. Departamento de Biologia, Faculdade de Ciências da Universidade do Porto, Porto, Portugal
    3. Wildlife Biology Program, College of Forestry and Conservation, University of Montana, 32 Campus Drive, Missoula, MT 59801, USA
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  • J.B. Searle

    1. Department of Biology, University of York, York, UK
    2. Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
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Correspondence: Joana Paupério, Fax: (00351) 252661780; E-mail: joanapcastro@cibio.up.pt

Abstract

Species are generally described from morphological features, but there is growing recognition of sister forms that show substantial genetic differentiation without obvious morphological variation and may therefore be considered ‘cryptic species’. Here, we investigate the field vole (Microtus agrestis), a Eurasian mammal with little apparent morphological differentiation but which, on the basis of previous sex-linked nuclear and mitochondrial DNA (mtDNA) analyses, is subdivided into a Northern and a Southern lineage, sufficiently divergent that they may represent two cryptic species. These earlier studies also provided limited evidence for two major mtDNA lineages within Iberia. In our present study, we extend these findings through a multilocus approach. We sampled 163 individuals from 46 localities, mainly in Iberia, and sequenced seven loci, maternally, paternally and biparentally inherited. Our results show that the mtDNA lineage identified in Portugal is indeed a distinct third lineage on the basis of other markers as well. In fact, multilocus coalescent-based methods clearly support three separate evolutionary units that may represent cryptic species: Northern, Southern and Portuguese. Divergence among these units was inferred to have occurred during the last glacial period; the Portuguese lineage split occurred first (estimated at c. 70 000 bp), and the Northern and Southern lineages separated at around the last glacial maximum (estimated at c. 18 500 bp). Such recent formation of evolutionary units that might be considered species has repercussions in terms of understanding evolutionary processes and the diversity of small mammals in a European context.

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