The importance of marginal population hotspots of cold‐adapted species for research on climate change and conservation

Abstract

Areas hosting hotspots of low‐latitude marginal populations of cold‐adapted plant species could be key areas for understanding geographical attributes that result in refugia during climatic shifts as well as the conservation of genetic diversity in the face of climate change. Low‐latitude populations of cold‐adapted plants are important because they may harbour the combination of alleles that foster persistence in a warmer climate. Consequently, identification of areas where arctic‐alpine, circumpolar and circumboreal species reach the low‐latitude ends of their distribution will present a unique opportunity to uncover processes that shaped current biogeographical patterns, as well as prepare for future scenarios. Here, we identify 35 main marginal population hotspots (19 and 16 areas in North America and Europe, respectively) of 183 plant taxa. These hotspots represent areas where southern marginal populations of cold‐adapted species co‐occur. The identification of hotspots was based on geographic overlap of southernmost locations of the target species, in a 50 × 50 km grid. With a threshold of two species in a single grid cell or in two contiguous cells, the analysis revealed that hotspots are in most cases located in the southern portion of major mountain chains. However, hotspots also occur in lowland areas at high latitudes (Fennoscandia, Alaska, Hudson Bay) which do not necessarily correspond to known cold‐ or warm‐stage refugia (e.g. Alps). Rockies and Sierra Nevada both in California and Spain, Apennines, and the southern Scandes, maintain their hotspot status even with more stringent cut‐off thresholds (>3 and >5 species per cell group). From a conservation point of view, our analysis reveals that only a small portion of the hotspots are currently included within protected areas. We discuss the importance of marginal population hotspots to future research on climate change and, finally, outline how conservation strategies can capitalize on the knowledge gained from studying climate change effects on cold‐adapted plants.

The future of cold‐adapted plants in changing climates: Micranthes (Saxifragaceae) as a case study

“…Subsequently, further in-depth studies on the genetic diversity and biology of these species, and those with similar distributions, are warranted. Further, these southern populations may harbor unique adaptations, phylogenetic history, and evolutionary potential, and therefore, should be given special conservation status (Abeli et al, 2018). Additionally, our analyses with Arctic plants recovered range shifts into cooler, northern habitats, which is in support of previous research (Jump & Penuelas, 2005;Sturm et al, 2001).…”

“…Climate change is expected to have a negative impact on cold environments in the future, and this will put strong selection pressures on cold-adapted plant species (Abeli et al, 2018;Gottfried et al, 2012;Stocker et al, 2013). Our results suggest, in agreement with previous work (Abeli et al, 2018;Ernakovich et al, 2014;Thuiller et al, 2005), that although Arctic and alpine ecosystems have similar climate conditions with short and cold growing seasons, climate change will lead to varied responses even among closely related species. Nine of 12 species of Micranthes that occur in the Arctic lose habitat (83%), while six out of 17 species that occur in mountains (65%) lose habitat as a result of predicted climate change.…”

“…Our models predict that the five species spanning from Arctic biomes to temperate mountains will lose the most southern parts of their ranges (Supporting Information Figure S1F,K,O,AA,BB). Many cold-adapted species have been shown to reach their southernmost occurrences in temperate mountain chains, and these populations are thought to be hotspots of unique ecological conditions and/or contain unique alleles as a result of acting as refugia during glacial expansions (Abeli et al, 2018). Subsequently, further in-depth studies on the genetic diversity and biology of these species, and those with similar distributions, are warranted.…”

“…Additionally, due to the limited range of many of the high-elevation and high-latitude plants, species indicative of these ecosystems have the potential to act as indicators of climate change for these regions (Gignac, 2001). Therefore, by comparing and contrasting Arctic and alpine ecosystems at a global scale, factors critical for the survival and adaptation of the flora in these areas may be revealed (Abeli, Vamosi, & Orsenigo, 2018).…”

“…Mountains contain around 25% of terrestrial biological diversity, and these regions make up half of the world's biodiversity hotspots (Stöcklin, 2011). Additionally, mountains play a unique ecological role because many cold-adapted species reach their southernmost occurrences in midlatitude mountain chains; it has been argued that these montane areas likely harbor important biological diversity (Abeli et al, 2018). Mountain ecosystems have received much attention in global warming research because there is a marked decrease in surface area as elevation increases (Randin et al, 2009), and empirical evidence for upward elevational shifts has been demonstrated in temperate mountain systems for a range of species (Elsen & Tingley, 2015).…”