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Contrasting views over a hybrid complex: Between speciation and evolutionary "dead-end"

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Author

  • Irene Pala
  • Maria Manuela Coelho

Summary, in English

The Squalius alburnoides complex, of hybrid origin, comprises diploid, triploid and tetraploid forms and has a widespread distribution in the Iberian waters. The southern populations of this complex, sympatric with S. pyrenaicus, show high genetic variability, diversity of forms and reproductive modes which create pathways that may allow for the establishment of a new species in the future. Here we report a contrasting view over the S. alburnoides complex: in the Mondego River basin (northern Portugal), nuclear "non-hybrid" and tetraploid forms are absent and a clearly impoverished genetic diversity is observed, contributing to a general scarcity of possibilities of generating novel genetic material. Moreover, the bisexual species involved in the maintenance of the complex in this basin (S. carolitertii) exhibits a considerably lower genetic variability, when compared with S. pyrenaicus. The observed differences suggest that, despite being originated by similar hybridization events and maintained by analogous reproductive mechanisms, different populations of the complex were exposed to distinct evolutionary constrains, which in some cases resulted in diversification and speciation while in others led to a compromising situation in terms of evolutionary potential. Additionally, and for the first time all forms were used in the calculation of genetic distances and diversity indices, widening the possibilities of analysis of the complex by allowing the inclusion of a large part of the available data, irrespective of ploidy level.

Publishing year

2005

Language

English

Pages

283-294

Publication/Series

Gene

Volume

347

Issue

2

Document type

Journal article

Publisher

Elsevier

Topic

  • Biological Sciences

Keywords

  • Genetic diversity
  • Triploids
  • Cyprinids
  • Microsatellites
  • Evolutionary potential

Status

Published

ISBN/ISSN/Other

  • ISSN: 1879-0038