Focus Issue on the Plant Physiology of Global Change: Evolutionary and Ecological Responses to Anthropogenic Climate Change: Update on Anthropogenic Climate Change

Abstract

Strategies that enable species to persist in changing environments have historically been divided into ecological (distributional shifts and phenotypic plasticity) and evolutionary (adaptation and gene flow). However, most species will likely need to rely on a combination of approaches to mitigate extinction risks from ongoing climate change. For example, increased temporal variation in climate could favor genotypes with adaptive plasticity. Furthermore, even species capable of tracking their preferred climate via migration will encounter different abiotic and biotic conditions; plasticity and/or adaptation could facilitate establishment and population growth in new geographic ranges. The relative contributions of adaptation, migration, and plasticity to population persistence in a changing world will likely depend on characteristics such as generation time, mating system, dispersal capacity, the strength and direction of selection, the presence of ecologically relevant genetic variation, the extent of genetic correlations among traits, and the genetic architecture of adaptation. Will adaptation keep pace with rapid climate change? Here, we propose hypotheses based on ecological and evolutionary theory, discuss experimental approaches, and review results from studies that have investigated ecological and evolutionary responses to contemporary climate change. We focus our discussion on plants, but owing to the limited number of publications to date that integrate evolutionary and ecological perspectives, we draw from other taxonomic groups as necessary. For species to survive rapid anthropogenic climate change, they must shift their distributions to track preferred conditions (Angert et al., 2011; Chen et al., 2011), adjust their phenotypes via plasticity (Nicotra et al., 2010), and/or adapt to novel stresses (Aitken et al., 2008; Hoffmann and Sgro, 2011). In most cases, a combination of ecological and evolutionary strategies will be necessary for local and regional persistence in landscapes disturbed by habitat fragmentation, pollution, and invasive species. For example, increased climatic variation (Battisti and Naylor, 2009) could selectively favor phenotypic plasticity (Crozier et al., 2008), which, in turn, could contribute to evolutionary novelty and adaptation (Moczek et al., 2011). Furthermore, many species have already altered their distributions to more poleward and upslope regions because of increasing temperatures (Parmesan and Yohe, 2003; Hickling et al., 2006; Parmesan, 2006; Lenoir et al., 2008; Chen et al., 2011). Migrating populations will undoubtedly encounter novel abiotic and biotic conditions and will need to adjust to different photoperiods, edaphic characteristics, growing season lengths, and altered biotic communities via plasticity and/or adaptation. Gene flow and population admixture could facilitate adaptation by introducing warm- or drought-adapted alleles into populations that are locally adapted to a suite of climatic and nonclimatic variables. Finally, the rate of climate change, combined with the effects of habitat fragmentation, could surpass many species’ abilities to track the climate to which they are currently adapted (Davis and Shaw, 2001). Such species will necessarily have to acclimate or adapt in situ to novel selection pressures or face a heightened probability of extinction (Aitken et al., 2008). Evolution can proceed rapidly (Grant and Grant, 2002; Hairston et al., 2005; Franks et al., 2007), but we know little about the interplay of ecological and evolutionary processes in the context of climate change. Theoretically, adaptation could keep pace with climate change as long as genetic variation, individual fitness, and effective population sizes remain high against a backdrop of strong selection, short generation times, and minimal environmental and demographic stochasticity (Burger and Lynch, 1995; Aitken et al., 2008; Hoffmann and Sgro, 2011). Will adaptive evolution and/or plasticity allow species to alter their phenotypes fast enough to persist despite rapidly changing conditions (Davis and Shaw, 2001; Franks et al., 2007; Crozier et al., 2008; Teplitsky et al., 2008; Nicotra et al., 2010; Hoffmann and Sgro, 2011; Shaw and Etterson, 2012)? Can the inheritance of environmentally induced nongenetic modifications alter the rate and direction of species’ evolutionary response to climate change? And can we make robust predictions about the relative contributions of migration, adaptation, and plasticity as a function of attributes of species or the extent of habitat degradation? This review highlights the interdependence of ecological and evolutionary processes to mitigate extinction risks. We discuss hypotheses and approaches that will illuminate the relative roles of migration, phenotypic plasticity, and adaptation in responses to global change (Table I). We encourage collaborations between ecologists and evolutionary biologists to connect studies of phenology, physiology, mating systems, and dispersal with those of ecological genetics/genomics and quantitative genetics. Table I. Hypotheses and approaches discussed in this paper