Unraveling the Pontocaspian biodiversity crisis

• Applicant: Professor Dr. Thomas Wilke
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions ; Systematics and Morphology (Zoology)
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 445025902

We are currently facing the “6th mass extinction event”. This is particularly evident in the Pontocaspian region – the brackish-water bodies of the Caspian Sea, Black Sea and Aral Sea basins. Many Pontocaspian species are in severe decline or face extinction (the “Pontocaspian biodiversity crisis”). Mollusks (Gastropoda, Bivalvia) are particularly affected due to their benthic lifestyles and a high degree of endemism. However, it has been difficult to evaluate the extent of the crisis because of potential sampling and taxonomic biases. There is evidence that the number of endemic mollusks species in the Pontocaspian area is inflated. Moreover, after the breakdown of the former Soviet Union, field work in the Pontocaspian area entered in a state of crisis. Thus, it is not clear whether there is, indeed, a loss of up to 80% of endemic mollusks species in the Pontocaspian region over the past 30 years, as suggested, or whether there have never been ca. 100 modern endemic mollusks species. The problem is circular. Due to the ongoing biodiversity crisis, a critical assessment of species boundaries is difficult and due to our inability to clarify species boundaries, the extent of the current biodiversity crisis cannot be determined without bias.The main objective of this proposal is to use mollusks as model taxon to disentangle the effects of the taxonomic crisis, the sampling crisis and the biodiversity crisis using state-of-the art “museomics”, targeted field work as well as modelling and species delimitation approaches to explain the sharp decline of reported endemic species in the Pontocaspian area.Specifically, we aim 1) to assess species-level relationships of Pontocaspian mollusks using artificial intelligence approaches that involve (ancient) DNA, proteomics, 3D-morphometrical and ecological information, 2) to identify potential refugia in the Pontocaspian region (deeper and subterranean waters, limans, foreshore zones) based on predictive modelling and targeted field work, 3) to assess the adequacy of biodiversity records by examining sampling effects on the number of endemic species reported over time using sampling-success analyses and radiocarbon dating, and 4) to quantify the differential contributions of the taxonomic crisis and the sampling crisis on the loss of endemic Pontocaspian mollusk species to understand the extent of the current biodiversity crisis using multivariate analyses. Our null hypothesis to be tested is that there is no actual loss of endemic Pontocaspian species and that the lack of recent records is due to taxonomic consolidations and decreasing sampling efforts.Building upon the synergies offered by this Russian-German collaboration, we will provide novel, integrated pathways to clarify species identities and boundaries that will allow us to map the extent and nature of biodiversity crises with important implications for conservation as well as global change adaption and mitigation strategies.

• DFG Programme: Research Grants
• International Connection: Russia, Ukraine
• Partner Organisation: Russian Science Foundation, until 3/2022
• Cooperation Partners: Professor Dr. Vitaliy V. Anistratenko; Professor Dr. Maxim Vinarski, until 3/2022