When environmental changes do not cause geographic separation of fauna: differential responses of Baikalian invertebrates.
BACKGROUND
While the impact of climate fluctuations on the demographic histories of species caused by changes in habitat availability is well studied, populations of species from systems without geographic isolation have received comparatively little attention. Using CO1 mitochondrial sequences, we analysed phylogeographic patterns and demographic histories of populations of five species (four gastropod and one amphipod species) co-occurring in the southwestern shore of Lake Baikal, an area where environmental oscillations have not resulted in geographical isolation of habitats.


RESULTS
Species with stronger habitat preferences (gastropods B. turriformis, B. carinata and B. carinatocostata) exhibit rather stable population sizes through their evolutionary history, and their phylogeographic pattern indicates moderate habitat fragmentation. Conversely, species without strong habitat preference (gastropod M. herderiana and amphipod G. fasciatus) exhibit haplotype networks with a very abundant and widespread central haplotype and a big number of singleton haplotypes, while their reconstructed demographic histories show a population expansion starting about 25-50 thousand years ago, a period marked by climate warming and increase in diatom abundance as inferred from bottom-lake sedimentary cores.


CONCLUSIONS
In agreement with previous studies, we found that species reacted differently to the same environmental changes. Our results highlight the important role of dispersal ability and degree of ecological specialization in defining a species' response to environmental changes.
Laboratory of Molecular Systematics, Limnological Institute of the Siberian Branch of the Russian Academy of Sciences, Ulan-Batorskaya 3, 664033 Irkutsk, Russia. fazalova@iiasa.ac.at
Varvara
V
Fazalova
Bruno
B
Nevado
Tatiana
T
Peretolchina
Jeanna
J
Petunina
Dmitry
D
Sherbakov
D033304:Amphipoda / Q000235:genetics*; D000818:Animals; D004272:DNA, Mitochondrial / Q000235:genetics; D017753:Ecosystem; D019143:Evolution, Molecular; D049851:Gastropoda / Q000235:genetics*; D005828:Genetics, Population; D006239:Haplotypes; D058974:Phylogeography; D011156:Population Density; D011157:Population Dynamics; D017422:Sequence Analysis, DNA
D004272:DNA, Mitochondrial