Scaritinae are a subfamily of ground beetles (Carabidae), containing about 1900 species and 125 genera. They share a distinctive body shape linked to a burrowing lifestyle. The diversity of Scaritinae is concentrated in the tropics and warmer regions of the southern hemisphere, particularly Southern Africa, Madagascar and Australia. The evolutionary history (phylogeny) of scaritines is unknown, leading to conflicting classification schemes and uncertainty over the definition of genera, especially in one subgroup of scaritines, the tribe Scaritini. In particular, it is unclear whether Scaritinae are descended from a common ancestor (monophyletic) or whether they are an artificial group defined by convergent adaptations to burrowing. Phylogenetic relationships of the Scaritinae were investigated in detail for the first time using morphological and molecular data. Analysis of morphological characters resulted in multiple equally parsimonious trees. Bayesian analysis supported a monophyletic Scaritinae and within Scaritini, a basal position of subtribes Carenina and Pasimachina. Relationships of subtribe Scaritina were impossible to reconstruct due to a complex pattern of convergent evolution and character reversals. 18S rRNA gene sequences were aligned using ClustalX and by incorporating secondary structure information using MAFFT. Consistent results were obtained by Bayesian analysis of the MAFFT alignments, supporting the clades Scaritinae and Scaritini, Carenina and Scaritina. The Australian scaritines (Carenina) were found to be sister to all remaining Scaritini. An historical biogeographic reconstruction of the Scaritini was undertaken by incorporating evidence from extant distributions, fossils and the phylogenetic data. It is likely that evolution of the basal lineages of Scaritini occurred before the fragmentation of Gondwana and that the present-day distributions of the later radiation of Scaritina are due to dispersal. As with most groups of Carabidae, the lack of fossil evidence and molecular clock dating precludes any firm biogeographical conclusions.
Hogan, J
Faculty of Health and Life SciencesDepartment of Biological and Medical Sciences
Year: 2012
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