Genetic structure of a recent climate change-driven range extension

Abstract

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 'naïve' ecosystems. The barrens-forming 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 F(ST), 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.

Rapid range expansion increases genetic differentiation while causing limited reduction in genetic diversity in a damselfly

“…This way, the effects of climate-induced range expansion on the genetic diversity of the edge populations can be minor. Although a decrease in allelic richness has been detected in edge populations in two studies (Watts et al, 2010;Garroway et al, 2011), all previous studies that have investigated genetic patterns of recent climate-induced range expansion also conclude that expansion occurred in a continuous wave of expansion with extensive gene flow (Watts et al, 2010;Dawson et al, 2010;Banks et al, 2010;Garroway et al, 2011;Buckley et al, 2012). In addition, the bottleneck analysis did not reveal a clear pattern of edge populations undergoing bottlenecks; instead we found evidence for a bottleneck in the recent past in two edge populations and one core population.…”

“…Despite its relevance, only very recently the genetic consequences of natural, contemporary range expansions have started to receive attention (Watts et al, 2010;Banks et al, 2010;Garroway et al, 2011;Buckley et al, 2012). Results so far are equivocal.…”

Genetic structure of dioecious and trioecious Salix myrsinifolia populations at the border of geographic range

“…Recently, more attention has been paid to the consequences of natural, contemporary range expansions (Banks et al 2010;Garroway et al 2011;Swaegers et al 2013). These studies showed that the current range expansion may not only generate more independently replicated edge populations but also likely results in different population genetic patterns throughout the expansion front.…”

The application of genetics to marine management and conservation: examples from the Indo-Pacific

“…Histories.-Invasive species have played a large role in changing global marine systems, in some cases drastically altering the biological communities of invaded areas (Blum et al 2007, Robinson et al 2007, Banks et al 2010, and are recognized as a pressing global concern (Sutherland et al 2010). The Indo-Pacific is no exception, with a number of non-indigenous species (NIS) recorded throughout the region.…”