Climate change refugia and habitat connectivity promote species persistence

Abstract

Background: Climate change refugia, areas buffered from climate change relative to their surroundings, are of increasing interest as natural resource managers seek to prioritize climate adaptation actions. However, evidence that refugia buffer the effects of anthropogenic climate change is largely missing. Methods: Focusing on the climate-sensitive Belding's ground squirrel (Urocitellus beldingi), we predicted that highly connected Sierra Nevada meadows that had warmed less or shown less precipitation change over the last century would have greater population persistence, as measured by short-term occupancy, fewer extirpations over the twentieth century, and long-term persistence measured through genetic diversity. Results: Across California, U. beldingi were more likely to persist over the last century in meadows with high connectivity that were defined as refugial based on a suite of temperature and precipitation factors. In Yosemite National Park, highly connected refugial meadows were more likely to be occupied by U. beldingi. More broadly, populations inhabiting Sierra Nevada meadows with colder mean winter temperatures had higher values of allelic richness at microsatellite loci, consistent with higher population persistence in temperature-buffered sites. Furthermore, both allelic richness and gene flow were higher in meadows that had higher landscape connectivity, indicating the importance of metapopulation processes. Conversely, anthropogenic refugia, sites where populations appeared to persist due to food or water supplementation, had lower connectivity, genetic diversity, and gene flow, and thus might act as ecological traps. This study provides evidence that validates the climate change refugia concept in a contemporary context and illustrates how to integrate field observations and genetic analyses to test the effectiveness of climate change refugia and connectivity. Conclusions: Climate change refugia will be important for conserving populations as well as genetic diversity and evolutionary potential. Our study shows that in-depth modeling paired with rigorous fieldwork can identify functioning climate change refugia for conservation.

Eco‐evolution on the edge during climate change

“…However, too much variation in fitness among patches can also lead to the evolution of decreased dispersal (Poethke et al 2011). Networks of connected patches such as described here are currently providing refugia for Belding's ground squirrels Urocitellus beldingi and desert bighorn sheep Ovis canadensis nelsoni near their warm range margins (Epps et al 2006, Morelli et al 2017. Prioritizing an environmentally heterogeneous suite of patches could also help preserve genetic and species diversity (Sgrò et al 2010, Hoffmann andSgro 2011).…”

“…In some cases, assisted recolonization of extirpated patches from locations with similar climates might slow invasion by other species and prolong persistence of the metapopulation. Networks of connected patches such as described here are currently providing refugia for Belding's ground squirrels Urocitellus beldingi and desert bighorn sheep Ovis canadensis nelsoni near their warm range margins (Epps et al 2006, Morelli et al 2017. Whether this strategy will be fruitful for other species depends on the rate of climate change, genetic variation of the warm-margin metapopulation, and the probability of detrimental invasions by other species.…”

Climate‐change refugia: biodiversity in the slow lane

“…), validate projected change (Morelli et al . ), and identify threshold conditions beyond which refugia could lose their functionality and become ecological traps, which reduce fitness instead of increasing persistence (Morelli et al . ).…”

Mapping physiology: biophysical mechanisms define scales of climate change impacts

“…Ongoing climate change is having clear impacts on the abundance, health and distribution of organisms and subsequently on patterns of biodiversity and ecosystem function (Doney et al, 2012; Bonebrake et al, 2018). In an effort to forecast and potentially mitigate some of the worst impacts of these changes, conservation biologists are increasingly turning to forecasting approaches to predict which populations and species are most vulnerable to accelerating climate change (Dong et al, 2017; Sará et al, 2018; Rilov et al , 2019), where environmental change is occurring most rapidly (Sunday et al, 2015; Brito-Morales et al, 2018) and what measures might be enacted to protect threatened species and ecosystems by either reducing the effects of non-climatic stressors such as development and overharvesting (Przeslawski et al, 2005; Sará et al, 2018) or by prioritizing the protection of refugia (Morelli et al, 2017). Laboratory- and field-based physiological methods are playing an increasingly important role in our understanding of how climate change is affecting natural and managed systems and of the range of possible conservation interventions that can be enacted (Seebacher and Franklin, 2012; Chown and Gaston, 2016; Marn et al, 2017; Teal et al, 2018; Rilov et al, 2019).…”