Genetic structure of a recent climate change-driven range extension
Banks, SC and Ling, SD and Johnson, CR and Piggott, MP and Williamson, JE and Beheregaray, LB, Genetic structure of a recent climate change-driven range extension, Molecular Ecology, 19, (10) pp. 2011-2024. ISSN 0962-1083 (2010) [Refereed Article]
The life-history strategies of some species make them strong candidates for rapid
exploitation of novel habitat under new climate regimes. Some early-responding species
may be considered invasive, and negatively impact on �na�ve� ecosystems. The barrensforming
sea urchin Centrostephanus rodgersii is one such species, having a high dispersal
capability and a high-latitude range margin limited only by a developmental temperature
threshold. Within this species� range in eastern Australian waters, sea temperatures have
increased at greater than double the global average rate. The coinciding poleward range
extension of C. rodgersii has caused major ecological changes, threatening reef
biodiversity and fisheries productivity. We investigated microsatellite diversity and
population structure associated with range expansion by this species. Generalized linear
model analyses revealed no reduction in genetic diversity in the newly colonized region.
A �seascape genetics� analysis of genetic distances found no spatial genetic structure
associated with the range extension. The distinctive genetic characteristic of the
extension zone populations was reduced population-specific FST, consistent with very
rapid population expansion. Demographic and genetic simulations support our inference
of high connectivity between pre- and post-extension zones. Thus, the range shift
appears to be a poleward extension of the highly-connected rangewide population of C.
rodgersii. This is consistent with advection of larvae by the intensified warm water East
Australian current, which has also increased Tasmanian Sea temperatures above the
species� lower developmental threshold. Thus, ocean circulation changes have improved
the climatic suitability of novel habitat for C. rodgersii and provided the supply of
recruits necessary for colonization.