Limited potential for adaptation to climate change in a broadly distributed marine crustacean

Abstract

The extent to which acclimation and genetic adaptation might buffer natural populations against climate change is largely unknown. Most models predicting biological responses to environmental change assume that species' climatic envelopes are homogeneous both in space and time. Although recent discussions have questioned this assumption, few empirical studies have characterized intraspecific patterns of genetic variation in traits directly related to environmental tolerance limits. We test the extent of such variation in the broadly distributed tidepool copepod Tigriopus californicus using laboratory rearing and selection experiments to quantify thermal tolerance and scope for adaptation in eight populations spanning more than 178 of latitude. Tigriopus californicus exhibit striking local adaptation to temperature, with less than 1 per cent of the total quantitative variance for thermal tolerance partitioned within populations. Moreover, heat-tolerant phenotypes observed in low-latitude populations cannot be achieved in highlatitude populations, either through acclimation or 10 generations of strong selection. Finally, in four populations there was no increase in thermal tolerance between generations 5 and 10 of selection, suggesting that standing variation had already been depleted. Thus, plasticity and adaptation appear to have limited capacity to buffer these isolated populations against further increases in temperature. Our results suggest that models assuming a uniform climatic envelope may greatly underestimate extinction risk in species with strong local adaptation.

Evolutionary and Ecological Responses to Anthropogenic Climate Change

“…1; Wang et al, 2010). Locally adapted ecotypes may experience greater risk of extinction as climate change accelerates if they have narrow climatic tolerances and limited dispersal capacity (Kelly et al, 2012). In contrast, broad niche breadth and phenotypic plasticity could buffer genotypes from the immediate effects of global change (Banta et al, 2012).…”

“…Indeed, long-term studies of pedigreed animal populations have revealed extensive plasticity and little adaptive evolution in the context of climate change, suggesting that species can alter their phenotypes much faster via plasticity than adaptation Ozgul et al, 2009). Nevertheless, current levels of phenotypic plasticity that are sufficient for short-term response to global change could be inadequate once temperatures and water stress exceed historical levels (Kelly et al, 2012). In some regions, climatic conditions are expected to become increasingly variable temporally (IPCC, 2007), which could selectively favor plasticity, promoting evolutionary change in reaction norms (hypothesis 5: climate change favors plasticity; Nussey et al, 2005;Etterson, 2008;Anderson et al, 2012).…”

“…Manipulative experiments that include replicated genotypes of known origin, collected from multiple populations across the range of a species, can test all of the hypotheses in Table I (Leakey and Lau, 2012), especially when combined with provenance trials or longitudinal studies. Comparisons of ancestral (pretreatment) and descendant (posttreatment) genotypes in artificial selection experiments can also be used to evaluate whether adaptation to climate change is likely, and if so, how many generations will be needed (Kelly et al, 2012).…”

Plasticity in thermal tolerance has limited potential to buffer ectotherms from global warming

“…The ability to thermoregulate changes geographically [2,15,56,64,65], and by habitat type (see discussion of aquatic versus terrestrial taxa above), and thus many taxa may not have behavioural mechanisms at their disposal. There is also much debate about the degree to which populations can evolve to combat changing conditions [66][67][68][69][70][71]. Plasticity is of course a trait that can evolve, and the evolution of plasticity (or canalization of plastic responses [72]) has been suggested as a means by which organisms can evade negative effects of climate change [73].…”

Micro-scale environmental variation amplifies physiological variation among individual mussels

“…Rocky intertidal zone populations offer one tractable system for addressing these issues [22]. Inhabitants of this zone are routinely subjected to episodic environmental stress at low tide, including thermal stress, hypoxia and desiccation.…”