When environmental changes do not cause geographic separation of fauna: differential responses of Baikalian invertebrates

Abstract

BackgroundWhile 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.ResultsSpecies 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.ConclusionsIn 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.

Different rates of molecular evolution of mitochondrial genes in Baikalian and non-Baikalian amphipods

“…The accumulation rate of base substitutions (rate of molecular evolution) depends on various factors, including physiological characteristics, environmental conditions and life history of species (Fazalova et al, 2010;Ellegren and Galtier, 2016). Therefore, significant changes in the rate of molecular evolution in sister groups may provide valuable insight into driving forces of adaptive radiation and speciation.…”

Recent bloom of filamentous algae in Lake Baikal is caused bySpirogyraLink., 1820 of local origin

“…2)There were multiple immigrations and emigrations from the outside, but establishing permanent lineages inside the lake was relatively rare making the Baikal algae noticeably isolated; 3)The Spirogyra species blooming recently in Lake Baikal are most likely local opportunists rather than successful exots exploiting an increase in nutrient influxes. We believe that taking into account long persistence and high variation in numbers over a short period of time, our findings presented here, allow us to propose, that the blooms of filamentous green algae may at least partially explain why relatively long "diatomless" periods in the well-studied diatom record of paleo-climate of Lake Baikal [36,37] did not leave noticeable traces in evolutionary histories of Baikal benthic animals [38,39].…”

中国西南地区的“天空之岛”: Ⅰ系统地理学研究概述

“…如上所述, 复杂的地形地貌、高原抬升和气候变 化对物种系统地理结构的形成有重要作用. 但另一方 面, 不同的物种由于生态幅、 迁徙和适应能力不同, 地 形地貌、气候以及生境变化对它们的影响差异很大 [79] .…”