Molecular phylogeny of the Cicindela maritima (Coleoptera: Cicindelidae) group indicates fast radiation in western North America

Abstract

As a basis for the study of ecological diversification in the genus Cicindela, we conducted a phylogenetic analysis of all 10 Nearctic and a single Palearctic species in the Cicindela maritima group. The phylogeny was derived from a total of 1,896 base pairs of mitochondrial DNA coverings regions of the mt genome. We also sequenced a variable expansion segment of the nuclear 18S rRNA which was found invariant in all species of the C. maritima group but different from all other Cicindela analyzed to date. This result, and the phylogenetic analysis of mtDNA, suggests that the C. maritima group is monophyletic. The mtDNA places the Palearctic C. maritima basal to the North American taxa. The widespread C. repanda and C. hirticollis are the basal taxa in the North American clade; 6 species from the western part of the continent form a clade of very closely related species with little divergence between mtDNA haplotypes. We also compiled data on habitat associations and phenology. Traced on the phylogeny both parameters have undergone frequent character changes during the evolution of the lineage, suggesting that ecological diversification, in combination with geographical subdivision, may have promoted taxonomic diversification in this group. The rapid radiation in the mountains of western North America is consistent with hypotheses that implicate topographic complexity in the increased rate of species diversification.