Conquest of the deep, old and cold: an exceptional limpet radiation in Lake Baikal

Abstract

Lake Baikal is the deepest, oldest and most speciose ancient lake in the world. The lake is characterized by high levels of molluscan species richness and endemicity, including the limpet family Acroloxidae with 25 endemic species. Members of this group generally inhabit the littoral zone, but have been recently found in the abyssal zone at hydrothermal vents and oil-seeps. Here, we use mitochondrial and nuclear data to provide a first molecular phylogeny of the Lake Baikal limpet radiation, and to date the beginning of intra-lacustrine diversification. Divergence time estimates suggest a considerably younger age for the species flock compared with lake age estimates, and the beginning of extensive diversification is possibly related to rapid deepening and cooling during rifting. Phylogenetic relationships and divergence time estimates do not clearly indicate when exactly the abyssal was colonized but suggest a timeframe coincident with the formation of the abyssal in the northern basin (Middle to Late Pleistocene).

The endemic Cladophorales (Ulvophyceae) of ancient Lake Baikal represent a monophyletic group of very closely related but morphologically diverse species

“…, Schön and Martens , Stelbrink et al. , Karanovic and Sitnikova ). During the last 5 My, the lake passed through several climate changes, from a subtropical (~5 Mya), a transitional stage (from ~2.6 to 2.4 Mya), to the current cold‐temperate climate (Sherstyankin and Kuimova ).…”

Origin and diversification of Lake Ohrid’s endemic acroloxid limpets: the role of geography and ecology

“…Geography is certainly important, particularly on a horizontal dimension, resulting in independent genetic lineages/clades in both species found along different shorelines and that are potentially geographically separated by unsuitable habitats. On a vertical level, the patterns found suggest that geographic separation has been the main evolutionary process as suggested for other taxonomic groups in Lake Ohrid (see [13, 88]) and for limpets endemic to Lake Baikal [35]. However, genetic differentiation can be weak between and within the two Ohrid species when the geographic distance is low.…”

“…Only recently, phylogenetic relationships have been studied in Lake Baikal’s endemic acroloxid species flock (25 species) based on molecular markers, revealing that intra-lacustrine speciation during the Plio-Pleistocene gave rise to several littoral, sublittoral, and even abyssal species inhabiting oil-seeps and hydrothermal vents below 100 m water depth. However, a reasonable colonization scenario (littoral-abyssal or abyssal-littoral) could not be inferred from the phylogenetic relationships and the vertical distribution pattern of the endemic species [35]. …”

Scientific drilling projects in ancient lakes: Integrating geological and biological histories

“…Biotic drivers might be even more diverse. The underlying mechanisms and causality of some 1725 biotic drivers are well understood (e.g., the pharyngeal jaw of cichlids, Salzburger et al, 2014; depth 1726 preferences, Stelbrink et al, 2015), whereas the influence of species richness and composition on 1727 diversification is controversially discussed (e.g., Day et al, 2008;Harmon and Harrison, 2015;Hubert et 1728Hubert et al, 2015Rabosky and Hurlbert, 2015). Also, the timeframe of evolution has to be considered when 1729 linking geological and biological datasets.…”