Identifying glacial refugia in a geographic parthenogen using palaeoclimate modelling and phylogeography: the New Zealand stick insect Argosarchus horridus (White)

Abstract

We have used phylogeographic analysis of mitochondrial DNA (COI and COII genes) and ecological niche modelling (ENM) to reconstruct the population history of Argosarchus horridus (White), a widespread species of New Zealand stick insect. These data were used to address outstanding questions on the role of glacial refugia in determining the distribution and genetic structure of New Zealand species. Phylogeographic analysis shows a general pattern of high diversity in upper North Island and reduced diversity in lower North Island and South Island. The ENM indicates that during the last glacial maximum, A. horridus was largely restricted to refugia around coastal areas of North Island. The ENM also suggests refugia on the northeast coast of South Island and southeast coast of North Island and this prediction is verified by phylogeographic analysis, which shows a clade restricted to this region. Argosarchus horridus is also most likely a geographic parthenogen where males are much rarer at higher latitudes. The higher levels of genetic variation in northern, bisexual populations suggest southern and largely unisexual populations originated from southwardly expanding parthenogenetic lineages. Bayesian skyline analysis also provides support for a recent population size increase consistent with a large increase in geographic distribution in the late Pleistocene. These results exemplify the utility of integrating ENM and phylogeographic analysis in testing hypotheses on the origin of geographic parthenogenesis and effects of Pleistocene environmental change on biodiversity.

Persistence of New Zealand Quaternary beetles

“…Marske et al 2009Marske et al , 2011, and the mainly unglaciated North Island has been a source area for insects that were previously extirpated in the South Island and recolonised later (e.g. Marshall et al 2009;Buckley et al 2009Buckley et al , 2010. Our finding that there has been morphological stasis in the Auckland area is consistent with the presence of long-term refugia in the North Island and we would predict other sites in northern New Zealand to contain stable, long-term communities of beetles.…”

Climate Change and Evolutionary Adaptations at Species' Range Margins

“…Nonetheless, a commonly observed consequence of rapid postglacial expansions is the genetic impoverishment of populations inhabiting newly colonized areas compared to those residing in areas of persistently suitable habitat (55). This has been demonstrated in a wide variety of insect taxa, including Lepidoptera, phasmids, weevils, pitcher-plant mosquitoes, grasshoppers, caddis flies, bees, Megaloptera, and cicadas (3,4,11,17,30,45,54,55,79,83,94,117). The patterns are indicative of rapid postglacial range expansion in many regions of the globe including Europe (11), North America (36), New Zealand (16,79), and Asia (3).…”

What does the geography of parthenogenesis teach us about sex?

“…Modern introductions to the phenomenon of geographic parthenogenesis often focus on a co-occurrence of three patterns [3,4]: first, parthenogens tend to have a wider distribution than their sexual counterparts [3]; second, they tend to occupy higher latitudes (mostly studied in the Northern Hemisphere [5]; but see [6,7]) and third, they tend to occur in higher altitudes [8]. In addition to the above-mentioned broad patterns, a disproportionate occurrence of parthenogens in arid habitats compared with their sexual counterparts (e.g.…”