Divergent evolutionary histories of two sympatric spruce bark beetle species.

BARK beetles; POPULATION differentiation; NORWAY spruce; PLEISTOCENE Epoch; HOLOCENE Epoch

Ips typographus and Pityogenes chalcographus are two sympatric Palearctic bark beetle species with wide distribution ranges. As both species are comparable in biology, life history, and habitat, including sharing the same host, Picea abies, they provide excellent models for applying a comparative approach in which to identify common historical patterns of population differentiation and the influence of species-specific ecological characteristics. We analysed patterns of genetic diversity, genetic structure and demographic history of ten I. typographus and P. chalcographus populations co-distributed across Europe using both COI and ITS2 markers. Rather than similarities, our results revealed striking differences. Ips typographus was characterised by low genetic diversity, shallow population structure and strong evidence that all extant haplogroups arose via a single Holocene population expansion event. In contrast, genetic variation and structuring were high in P. chalcographus indicating a longer and more complex evolutionary history. This was estimated to be five times older than I. typographus, beginning during the last Pleistocene glacial maximum over 100 000 years ago. Although the expansions of P. chalcographus haplogroups also date to the Holocene or just prior to its onset, we show that these occurred from at least three geographically separated glacial refugia. Overall, these results suggest that the much longer evolutionary history of P. chalcographus greatly influenced the levels of phylogeographic subdivision among lineages and may have led to the evolution of different life-history traits which in turn have affected genetic structure and resulted in an advantage over the more aggressive I. typographus. [ABSTRACT FROM AUTHOR]

Copyright of Molecular Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)