Contraction of the life cycle and the Evolution and Diversification of cave beetles
Final Report Abstract
The project “Contraction of the life cycle and the Evolution and Diversification of cave beetles” aimed to study a group of insects which colonized subterranean ecosystems and developed remarkable morphological and physiological adaptations to these extreme environments. If the description of new taxa and the phylogeny of the group was part of the project, the main question was to document a remarkable and poorly known adaptation of the subterranean species which is the contraction of the life cycle, with drastic reduction of the number of larval instars. This adaptation occurs in the two main groups of cave beetles, suggesting a remarkable convergence allowing their evolutionary success. During the course of the project, we studied cave ground beetles of the tribe Trechini and accumulated DNA data of poorly known or new species. We identified larvae of Trechini by means of molecular barcodes and a comprehensive DNA database compiled during previous projects and completed during the course of the DFG granted project. We tried to breed cave beetles in two natural caves, but could not get larvae for any of the 4 species tried. Therefore, we proceed to dissection of the ovaries of females as the contraction of larval instars is correlated with a reduction of number of ovarioles. We identified a remarkable convergence in the reduction of the number of ovarioles in two different lineages of Trechini ground beetles. The morphological study of the female internal genitalia allowed us inferring the developmental mode of the species. The complete molecular phylogenetical framework now available for Pyrenean Trechini, as well as the data regarding larva and reduction of ovarioles of cave adapted Trechini allow to identify this contraction of lifecycle as a key innovation in the evolution of cave beetles. Diversification analyses are still in progress to formally confirm this result.
Publications
-
2013. A molecular Phylogeny of Alpine subterranean Trechini (Coleoptera: Carabidae). BMC Evolutionary Biology. 13: 248
Faille, A., Casale, A., Balke, M., Ribera, I.
-
2014. Late Miocene origin of a Ibero-Maghrebian clade of ground beetles with multiple colonisations of the subterranean environment. Journal of Biogeography. 41: 1979-1990
Faille, A., Andújar, C., Fadrique, F., Ribera, I.
-
2015. Convergent evolution in the reduction of ovariole number associated with subterranean life in cave beetles. PLOS ONE. 10(7): e0131986
Faille, A., Pluot-Sigwalt, D.
-
2015. Weak impact of tourism activities on biodiversity in a subterranean hotspot of endemism and its implications for the conservation of cave fauna. Insect Conservation and Diversity. 8: 205-215
Faille, A., Bourdeau, C., Deharveng, L.
