Hierarchical structure of mitochondrial lineages of Tomicus destruens (Coleoptera, Scolytidae) related to environmental variables.

We investigated here the relation of environmental variables with the distribution of mitochondrial lineages using a bark beetle species of Mediterranean distribution as a model. We analysed a total number of 460 DNA sequences of Tomicus destruens provided by intensive and extensive collection and GenBank entries. We combined phylogeography and regression models to study the role of five environmental predictors at fine scale in the distribution of a local genealogy. The analysis revealed a high genetic diversity, with 52 haplotypes present in Sierra Espuña forest (SE Spain) and 21 haplotypes in the other 14 Spanish populations, all included in the western clade of the Mediterranean phylogeography of the species. We found a micro-distribution of the species related to altitude and putative niche segregation between lineages associated with the micro-environmental conditions of their host pine trees. We compared the phylogeographic hypothesis obtained here with the phylogeography obtained integrating our data with all data published elsewhere. Here, we demonstrate a relation between the environmental heterogeneity and the haplotypic diversity at Mediterranean Basin scale. This analysis allows us to support the evolutionary scenario where the phylogeography and current molecular diversity of T. destruens is a consequence of the recolonization from two principal refugia at both extremes of the Mediterranean Basin and, according to our data, we propose that the heterogeneity of habitats allows fixation of the mitochondrial lineages. [ABSTRACT FROM AUTHOR]