Parallel diversification of Australian gall-thrips on Acacia
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| Authors: | McLeish, MJ; Crespi, BJ; Chapman, TW; Schwarz, MP |
| Year: | 2007 |
| Journal: | Molecular Phylogenetics and Evolution 43: 714-725 Article Link (DOI) |
| 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. (c) 2007 Elsevier Inc. All rights reserved. |
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