Forgotten treasures – using historic collections to assess the diversity and systematics of wide-ranging taxa: A case study using African Hinge-back Tortoises (Kinixys spp.)

• Applicant: Dr. Flora Ihlow
• Subject Area: Systematics and Morphology (Zoology)
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 427271746

The implementation of molecular genetic approaches into taxonomy accelerated exponentially the discovery of unrecognized taxa and many putatively widely distributed species were identified as species complexes. This implies that putatively widespread and common species may harbor multiple narrowly distributed and endangered taxa. Consequently, putatively widespread taxa need considerably more attention. However, obtaining range-wide sampling for taxa with ranges dissecting several political borders is expensive, time consuming, and hampered by legislative restrictions. Therefore, genetic samples obtained from scientific collections represent an appealing alternative. Unfortunately, DNA of museum specimens is often heavily degraded, fragmented, and contaminated with exogenous DNA. Thus, processing requires extensive precautions, special facilities, and approaches. The advent of Next Generation Sequencing (NGS) and hybridization-based target enrichment have revolutionized genetic research and improved the possibilities for using historic material significantly. The proposed project will apply NGS and aDNA approaches to elucidate exemplarily the diversity of three wide-ranging tortoise species using historic collection material, a set of mitochondrial and nuclear markers, and a stepwise analyses protocol. For the selected species only a few fresh samples are available from restricted range portions but large numbers of historic specimens are housed in scientific collections. All three species occupy wide distribution ranges spanning across up to 13 countries in sub-Saharan Africa. My preliminary genetic analyses revealed high misidentification rates for these morphologically challenging species and thus render the current taxonomic identification of name-bearing type specimens questionable. In addition, the currently accepted distribution ranges are evidently highly speculative as demonstrated by genetic analyses as well as species distribution models. In the frame of this project range-wide genetic variation and the taxonomic identity of the name-bearing type specimens and all respective synonyms of the African Hinge-back Tortoises Kinixys belliana, K. spekii and K. zombensis will genetically be re-examined. Taxonomy will be revised where necessary. By assigning dubious specimens to the correct species, distribution ranges will be corrected and updated. The project aims to develop a simple, fast, and cost-efficient workflow that facilitates quantitative assessments of genetic diversity for wide-ranging taxa using a limited number of historic samples. Taxonomically relevant levels of genetic divergence between congeners will be used to calibrate a ‘multi-locus yardstick’ to place observed divergences within the target group into a meaningful context. This will facilitate the reliable identification of cryptic or overlooked taxa. The resulting protocol can be applied to any wide-ranging vertebrate taxon.

• DFG Programme: Research Grants