title: Parallel diversification of Australian gall-thrips on Acacia.
abstract: The diversification of gall-inducing Australian Kladothrips (Insecta: Thysanoptera) on Acacia has produced a pair of sister-clades, each of which includes a suite of lineages that utilize virtually the same set of 15 closely related host plant species. This pattern of parallel insect-host plant radiation may be driven by cospeciation, host-shifting to the same set of host plants, or some combination of these processes. We used molecular-phylogenetic data on the two gall-thrips clades to analyze the degree of concordance between their phylogenies, which is indicative of parallel divergence. Analyses of phylogenetic concordance indicate statistically-significant similarity between the two clades. Their topologies also fit with a hypothesis of some degree of host-plant tracking. Based on phylogenetic and taxonomic information regarding the phylogeny of the Acacia host plants in each clade, one or more species has apparently shifted to more-divergent Acacia host-plant species, and in each case these shifts have resulted in notable divergence in aspects of the phenotype including morphology, life history and behaviour. Our analyses indicate that gall-thrips on Australian Acacia have undergone parallel diversification as a result of some combination of cospeciation, highly restricted host-plant shifting, or both processes, but that the evolution of novel phenotypic diversity in this group is a function of relatively few shifts to divergent host plants. This combination of ecologically restricted and divergent radiation may represent a microcosm for the macroevolution of host plant relationships and phenotypic diversity among other phytophagous insects.
authors.affiliation: South African National Biodiversity Institute, Kirstenbosch Research Centre, Private Bag X7, Claremont, Cape Town, South Africa. mcleish@sanbi.org
authors.forename: M J
authors.initials: MJ
authors.lastname: McLeish
authors.forename: B J
authors.initials: BJ
authors.lastname: Crespi
authors.forename: T W
authors.initials: TW
authors.lastname: Chapman
authors.forename: M P
authors.initials: MP
authors.lastname: Schwarz
mesh_terms: D000045:Acacia / Q000145:classification / Q000235:genetics* / Q000469:parasitology; D000818:Animals; D004272:DNA, Mitochondrial / Q000235:genetics; D019143:Evolution, Molecular; D007313:Insecta / Q000145:classification / Q000235:genetics* / Q000254:growth & development; D008957:Models, Genetic; D008969:Molecular Sequence Data; D020648:Peptide Elongation Factor 1 / Q000235:genetics; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial; D020648:Peptide Elongation Factor 1; D012336:RNA, Ribosomal, 16S