Refugial debate: on small sites according to their function and capacity

Abstract

The occurrence and location of long-term refugia determine the current patterns of biodiversity on Earth. The importance of the refugial debate is certain to increase in response to observed and expected species extinctions caused by climate change. Small areas where species survive outside their core range are important, as unique natural phenomena and model systems for observing the response of species to climate change. They can play a crucial role as potential sources for species recovery in the future or can act as progenitors of a new species. While most authors believe that sites connected with only long-term isolation should be included into the refugium concept, this approach can result in the loss of linkage between the ecological and evolutionary processes taking place during different phases of the species range dynamics. Moreover, the papers often interpret the nature of described phenomena in different ways. In response, the conceptual scheme given in our letter summarises the patterns which occur during species range shift. It proposes an equivalent scheme for small refugial sites according to their function and capacity, based on the relict species concept. This approach and proposed terminology is tested on the example of two plant species with different pattern of the long term range dynamics. Our paper highlights the importance of sites harboring 'trailing-edge' young relicts for the future long-term persistence of the species (as old relicts) under unfavorable regional conditions. By considering the age gradients of small refugial sites it is possible to reveal community interactions, species traits or genes that drive the responses of biota to climate changes.

From glacial refugia to hydrological microrefugia: Factors and processes driving the persistence of the climate relict tree Zelkova sicula

“…In fact, Zelkova and Pterocarya figure among the most drought‐tolerant representatives of the Cenozoic relict flora and were the last to disappear from continental Europe (Svenning, 2003). In addition to such inherent factors of the genus and to the peculiar safety role of microrefugia, it can be also speculated that the two modern Mediterranean Zelkova species could have either developed local evolutionary adaptations as a consequence of long isolation in microrefugia (whose environmental conditions are largely different than in macrorefugia) (Mee & Moore, 2013) or even derived from “ecological” speciation under strong adaptive selection in marginal habitats (Kiedrzyński et al., 2017; Nieto Feliner, 2011; Stewart et al., 2010). For instance, investigations on vein density in Z. schneideriana showed that this trait intensifies along with increasing precipitations, highlighting its important role in plant transpiration processes (Wang et al., 2016).…”

Hiding from the climate: Characterizing microrefugia for boreal forest understory species

“…The (micro)refugia concept has been studied and discussed around the globe, across taxa and ecosystems (Andrew & Warrener, 2017;Hannah et al, 2014;Kiedrzyński, Zielińska, Kiedrzyńska, & Rewicz, 2017;Niskanen et al, 2016;Osman et al, 2018;Scheffers, Edwards, Diesmos, Williams, & Evans, 2014;Schut et al, 2014;Terribile et al, 2012) and a considerable amount of speculation and expectation has been expressed on the carrying role of microrefugia to slow down ongoing climate-driven loss of species and genetic biodiversity (Abeli et al, 2018;Hampe & Petit, 2005;Keppel et al, 2012;Provan & Maggs, 2011). Much of the work has been theoretical, and more empirical studies, like ours, are needed to understand the characteristics of microrefugia, to make realistic predictions and to give adequate advice to conservation and management.…”