Diversity and evolution of Antarctic gastropods explored by a genomic approach


Professor Dr. Michael Schrödl
Staatliche Naturwissenschaftliche Sammlungen Bayerns (SNSB)
Zoologische Staatssammlung München

project description

The Antarctic irwertebrate fauna appears highiy diverse, but is only localiy and sporadically explored - and already threatened by global climate change. Gastropods are abundant, species rieh, ecologically and economically irnportant, count with a rieh fossil record and are wellestablished äs model organisms for many scientific disciplines. Most of the roughly 600 Antarctic gastropod species are regarded valid at the mornent based on shell features of often just a few or single specimens. Intraspecific morphological variability, soft pari anatomy, biology» and ecology are usually unknown, and many synonyms have been proposed. Wolecular data are limited to CÖI barcode sequences of few individuals of the more common species: Phylogenetic analyses of single genes suggest complexes of cryptic species or deep lineages, which may show distinct geographic distributions and special ecological niches. Rarity of species or samples prohibits general population genetics approaches. The prirnary goal of our herein proposed project is revealing the species diversity of Antarctic gastropods comprehensively and reliably. In addition to mltochondrial CÖI, we will use next generation sequencing (NGS) and newly established methods (double digest Restriction Associated DMA sequencing, ddRADseq) to efficiently generate a multitude of independent nuclear genomic sequence markers. We will include all species and subsamples from rnore than 2000 Southern Öcean gastropod samples available at the ZSM Mollusca collection suitable for genetic studies, plus further material to be collected at expeditions or from other museums. We will perform phylogenetic analyses (ML, Bayes, in subgroups BEST) and combined, up~to-date molecular species delimitation approaches {ABGD, GMYCS BP&P), An integrative taxonomic approach reiying on congruence will be applied to revea! conservative and reliable evolutionary species units, which will be used for diversity analyses, We will also explore genomic evolutionary archives of seiected gastropod lineages performing fossil-calibrated BEAST chronograms. The dynamics of diversification will be analyzed via recent Birth-Death-Shift models, and historical biogeography will be reconstructed using recent Software (e.g, RASP). With our massif genomic data from many subtaxa we will test current paradigms on biogeography and evolution, such äs glacial cycles causing an "Antarctic speciation pump", and evaluate competing hypotheses on glacial refuges and migration scenarios. The herein proposed combination of ddRADseqs with up~to~date multi-iocus analyses is novel, extremely cost and time effective, and can include thousands instead of few specimens» without any a priori selectron. It is expected to be very powerful to delimitate newty collected, unrecognized, or cryptic species, even jf badly sampled or just represented by singletons. We trust this approach is a quantum leap forward referring to the exploration of remote and highiy diverse faunas, Our pioneer project thus will generate massif novel and comprehensive data and results on Antarctic gastropods which might change previous ideas on e.g. biogeography or ecology, that aimost entirely relted on ill-defined „morphospecies" concepts, Eventually, evolutionary species units will be characterized morphologically, geographicaliy and ecologically. This will be the basis for future studies on past evolutionary adaptations, ecological niche rnodelling, and predicting response to global change and ocean acidification.

DFG-Verfahren: Infrastruktur-Schwerpunktprogramme

Internationaler Bezug: Australien, Großbritannien, Italien

Beteiligte Person: Dr. Nerida G. Wilson

term from 2013 to 2019