Species-richness of the Anopheles annulipes complex (Diptera: Culicidae) revealed by tree and model-based allozyme clustering analyses

Abstract

The Australasian Anopheles annulipes complex contains at least ten sibling species, some of which are important vectors of myxomatosis in rabbits. We aimed to establish how many species occurred among specimens from 61 sites throughout Australia, scored for 32 putative allozyme loci. We compared the number of species predicted from tree-based clustering of operational taxonomic units (OTUs) with that from a novel model-based Bayesian clustering approach for individual genotypes. We rejected the hypothesis of conspecificity of OTUs if they differed by at least 20% fixed differences and 0.300 Nei's standard genetic distance D. According to these criteria, 18-25 species occur, making this the most species-rich anopheline complex known to date. A conservative estimate from the Bayesian analysis was 15-20 species. There was large overlap in the assignment of individuals to clusters inferred from the Bayesian and tree-based analyses. The genetic clustering of northern and southern distributed species and an apparent cline in alleles of the enzyme glucose phosphate isomerase suggest that a latitude-dependent factor, such as temperature, may have played a role in speciation and the subsequent distribution of species. Ecological niche modelling of clusters predicted that none occur in New Guinea, emphasizing that additional, as yet unsampled, species may occur. (c) 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 523-539.