Pattern of phylogenetic diversification of the Cychrini ground beetles in the world as deduced mainly from sequence comparisons of the mitochondrial genes.

The phylogenetic position of the tribe Cychrini within the subfamily Carabinae (the family Carabidae) was estimated by comparing the nucleotide sequences of the mitochondrial NADH dehydrogenase subunit 5 (ND5) gene and the nuclear 28S ribosomal DNA (rDNA). The phylogenetic trees suggest that the Cychrini would most probably be the oldest line within the Carabinae. Phylogenetic trees were constructed by comparing the mitochondrial cytochrome C oxidase subunit I (COI) gene sequences from 33 species of the Cychrini from various localities that include the whole distribution ranges of the representative species within all the known genera in the world. The trees suggest that the Cychrini members radiated into a number of phylogenetic lineages within a short period, starting about 44 million years ago (MYA). Most of the phylogenetic lineages or sublineages are geographically linked, each consisting of a single or only a few species without scarce morphological differentiation in spite of their long evolutionary histories (silent or near-silent evolution [see Adv. Biophys. 36 (1999) 65; J. Mol. Evol. 53 (2001) 517]). The fact suggests that the geographic isolation per se did not bring about conspicuous morphological differentiation. The phylogenetic lineages of the Cychrini well correspond to the taxonomically defined genera and the subgenera.