Processes shaping Vietnam's limestone karst biodiversity - the role of barriers and biotic interactions

• Applicant: Dr. Parm Viktor von Oheimb
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: from 2015 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 277543748

Vietnam exhibits an extraordinarily rich biodiversity. However, many details regarding the mechanisms involved in development and maintenance of this biodiversity remain unknown. Two different processes might be of major importance: restriction of dispersal due to barriers and biotic interactions among taxa at small-scale habitat patches. Large dispersal barriers dividing a certain area can allow for coexistence of ecologically similar taxa in one region by leading to separate, non-overlapping distribution ranges of the taxa at both sides of the barrier. The Red River valley is supposed to act as such a dispersal barrier for various organisms in the north of Vietnam. However, ecologically similar taxa might also coexist in the same overall region due to a mosaic distribution pattern among single habitat patches. In this case, biotic interactions (i.e. interspecific competition) between taxa lead to different taxon assemblages at different patches. The countless limestone karst outcrops in Vietnam represent such habitat patches by forming functional islands for organisms that depend on calcium-rich habitats. In this project, I will examine the role of the Red River valley as a barrier for dispersal and the role of biotic interactions among taxa at insular karst outcrops. As a model group I will use the species-rich and limestone bound terrestrial gastropod taxon Clausiliidae (door snails). For examining whether the Red River valley acts as a major dispersal barrier for Clausiliidae, I will do a comprehensive survey in museum collections, literature and databases to compare the species composition north and south of this putative barrier. By calculating the turnover in species composition, I will statistically quantify the strength of this potential barrier. For examining whether biotic interactions cause species assemblages at individual karst outcrops, I will study geometric morphometric data of gastropods' shells (by using landmark and semi-landmark approaches) and genetic data (by sequencing two marker genes and applying phylogenetic analyses). I will test if clausiliid taxa occurring at the same karst outcrop are morphologically less similar and phylogenetically less related than would be expected by chance. This would indicate biotic interactions as main driver for taxon assemblages. The results of this project will give insight into processes that might have substantially contributed to the diversity of one of Vietnam's most species-rich gastropod taxa and of the limestone karst organisms in general.

• DFG Programme: Research Fellowships
• International Connection: United Kingdom
• Host: Professor Fred Naggs