Colonization and diversification dynamics in ancient lake species flocks inferred from meta-analyses on freshwater gastropods
Evolution, Anthropology
Final Report Abstract
The aim of this project was to shed light on the evolutionary processes in ancient lake gastropods and to unveil potential drivers that possibly triggered diversification in these groups. To do so, several genetic datasets comprising both lacustrine endemics as well as on-lacustrine relatives were compiled. These datasets were subjected to molecular phylogenetic and molecular-clock analyses in order to test for the monophyly of these lacustrine species, to reveal interspecific relationships within these groups and to date the origin of species flocks and diversification dynamics over time. In general, most of the ancient lake taxa were recovered reciprocally monophyletic, indicating that these colonized their respective ancient lake only once. Divergence time estimates suggest that the majority of these lake endemics evolved intralacustrine, highlighting the important role of such ancient lakes to serve as reservoirs during adverse conditions. More importantly, however, given their comparatively stable conditions over time, these ecosystems triggered diversification in freshwater gastropods and other groups and thus acted as cradles for the regional biodiversity. In contrast, the dated phylogeny of the famous group of Lake Tanganyikan paludomid gastropods suggest that these lake endemics probably originated well before the lake came into existence. Moreover, the comprehensive sampling of non-lacustrine African relatives indicates that the Tanganyikan paludomids do not form a monophyletic group but may rather consists of different reciprocally monophyletic clades, of which some are more closely related to the African genera Cleopatra and Pseudocleopatra. This, in turn, suggests that the dynamic tectonic and limnological changes in the East African Rift caused both the colonization of Lake Tanganyika but also the emigration and re-colonization during adverse conditions inside and outside the lake. Large-scale environmental changes such as changes in riverine interconnections, the deepening of a lake and the associated emergence of novel habitats thus very likely triggered diversification in both ancient lake gastropods and other floras and faunas. However, other abiotic factors such as climate-mediated lake-level fluctuations or megadroughts may have altered past communities or even wiped out complete species and genera. Although more and more highresolution limnological data become available in the course of deep-drilling projects, it will remain difficult to link these fast-changing environmental changes to particular speciation events, because the latter took place much more slowly in most of the macroorganisms (compared to microorganisms such as diatoms or the fast-evolving East African cichlids). On the other hand, the results of the study on viviparid gastropods suggest that speciesor even genus-specific diagnostic features such as the shell sculpture is probably very plastic and changed quickly during habitat transitions in both fossils and the extant fauna. Whereas this finding has important implications on the use of shell characters in freshwater gastropod taxonomy and systematics, it further shows that the past and present gastropod fauna responded comparatively quickly to environmental changes that may not necessarily led to speciation. Using genomic approaches on both the species and population level will certainly provide novel insights into micro-evolutionary patterns of these ancient lake gastropods (and other groups) and the impact of abiotic factors in near future.
Publications
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2019, Historical faunal exchange between the Pontocaspian Basin and North America. Ecol. Evol. 9, 10816–10827
Vandendorpe, J., van Baak, C.G.C., Stelbrink, B., Delicado, D., Albrecht, C., Wilke, T.
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2019, The near-complete mitogenome of the critically endangered Pseudocleopatra dartevellei (Caenogastropoda: Paludomidae) from the Congo River assembled from historical museum material. Mitochondrial DNA Part B 4, 3229–3231
Stelbrink, B., Kehlmaier, C., Wilke, T., Albrecht, C.
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2019. Forgotten for decades: Lake Lanao and the genetic assessment of its mollusc diversity. Hydrobiologia 843, 31–49
Stelbrink, B., von Rintelen, T., Albrecht, C., Clewing, C., Naga, P.O.
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2020, Global diversification dynamics since the Jurassic: low dispersal and habitat-dependent evolution explain hotspots of diversity and shell disparity in River Snails (Viviparidae). Syst. Biol.
Stelbrink, B., Richter, R., Köhler, F., Riedel, F., Strong, E.E., Van Bocxlaer, B., Albrecht, C., Hauffe, T., Page, T.J., Aldridge, D.C., Bogan, A.E., Du, L.-N., Manuel-Santos, M.R., Marwoto, R.M., Shirokaya, A.A., von Rintelen, T.
