The endemic gastropod fauna of Lake Titicaca: correlation between molecular evolution and hydrographic history

Ecology and Evolution

Oliver Kroll¹  Robert Hershler⁴  Christian Albrecht¹  Edmundo M. Terrazas⁵  Roberto Apaza²  Carmen Fuentealba³  Christian Wolff¹ 

[1] Department of Animal Ecology and Systematics, Justus Liebig University Giessen, Germany;Instituto de Ecología, Universidad Mayor de San Andres, La Paz, Bolivia;Departamento de Zoologia, Universidad de Concepcion, Chile;National Museum of Natural History, Smithsonian Institution, Washington, D.C.;Facultad de Ciencias Biologicas, Universidad Nacional del Altiplano, Puno, Peru

关键词: Altiplano;    Heleobia;    molecular clock;    phylogeography;    species flock;   

DOI  :  10.1002/ece3.280

来源: Wiley

【 摘 要 】

Abstract

Lake Titicaca, situated in the Altiplano high plateau, is the only ancient lake in South America. This 2- to 3-My-old (where My is million years) water body has had a complex history that included at least five major hydrological phases during the Pleistocene. It is generally assumed that these physical events helped shape the evolutionary history of the lake's biota. Herein, we study an endemic species assemblage in Lake Titicaca, composed of members of the microgastropod genus Heleobia, to determine whether the lake has functioned as a reservoir of relic species or the site of local diversification, to evaluate congruence of the regional paleohydrology and the evolutionary history of this assemblage, and to assess whether the geographic distributions of endemic lineages are hierarchical. Our phylogenetic analyses indicate that the Titicaca/Altiplano Heleobia fauna (together with few extralimital taxa) forms a species flock. A molecular clock analysis suggests that the most recent common ancestor (MRCAs) of the Altiplano taxa evolved 0.53 (0.28–0.80) My ago and the MRCAs of the Altiplano taxa and their extralimital sister group 0.92 (0.46–1.52) My ago. The endemic species of Lake Titicaca are younger than the lake itself, implying primarily intralacustrine speciation. Moreover, the timing of evolutionary branching events and the ages of two precursors of Lake Titicaca, lakes Cabana and Ballivián, is congruent. Although Lake Titicaca appears to have been the principal site of speciation for the regional Heleobia fauna, the contemporary spatial patterns of endemism have been masked by immigration and/or emigration events of local riverine taxa, which we attribute to the unstable hydrographic history of the Altiplano. Thus, a hierarchical distribution of endemism is not evident, but instead there is a single genetic break between two regional clades. We also discuss our findings in relation to studies of other regional biota and suggest that salinity tolerance was the most likely limiting factor in the evolution of Altiplano species flocks.

【 授权许可】

CC BY-NC   
© 2011 The Authors. MicrobiologyOpen published by Blackwell Publishing Ltd.

Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.