WHEN ENVIRONMENTAL CHANGES DO NOT CAUSE
GEOGRAPHIC SEPARATION OF FAUNA: DIFFERENT
DEMOGRAPHIC RESPONSES OF BAIKALIAN INVERTEBRATES
V. Fazalova* 1,2, B. Nevado3,4, T. Peretolchina1, Z. Kuzmenkova1, D. Sherbakov1,5
1Laboratory
of Molecular Systematics, Limnological Institute SB RAS, Ulan-
Batorskaya 3, 664033 Irkutsk, Russia; 2Evolution and Ecology Program, International
Institute for Applied Systems Analysis, Schlossplatz 1, A-2361 Laxenburg, Austria;
3Vertebrate
Department, Royal Belgian Institute of Natural Sciences, Vautierstraat 29,
1000 Brussels, Belgium; 4Evolutionary Ecology Group, University of Antwerp,
Groenenborgerlaan 171, B-2020 Antwerpen, Belgium, 5Faculty of Biology and Soil
Science, Irkutsk State University, Sukhe-Batora 5, 664003 Irkutsk, Russia
e-mail: fazalova@iiasa.ac.at *Corresponding author
Keywords: Lake Baikal; Baicalia carinata; B. carinatocostata; B. turriformis; Maackia
herderiana; Gmelinoides fasciatus; mtDNA CO1; phylogeography; demographic
reconstructions; global climate change; sedimentary cores;
While the impact of climatic 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
COI mitochondrial sequences, we analyse phylogeographic patterns and demographic
histories of populations of five species co-occuring in the southwestern shore of Lake
Baikal, an area where environmental oscillations have not resulted in geographical
isolation of habitats. The five species analysed include four gastropod species (rockdwellers Maackia herderiana and Baicalia turriformis and sand-dwellers B. carinata
and B. carinatocostata) and one amphipod species (ecologically flexible Gmelinoides
fasciatus). We found that population sizes of species with strong habitat preference (B.
turriformis, B. carinata and B. carinatocostata) remained rather stable through their
evolutionary history. Conversely, ecologically flexible M. herderiana and G. fasciatus
were found to have expanded their population sizes starting about 30-50 thousand years
ago, a period marked by an increase in diatom abundance as inferred from bottom-lake
sedimentary cores. In agreement with previous studies, we find that ecological and life
history traits do not predict specific demographic histories. Instead, our results suggest
that dispersal abilities and degree of ecological specialization play a significant role in
the response of species to environmental changes.