Riding an escalator: upward range shift and patterns of genetic response to climate change in Acer caudatifolium

Aim Rapid global warming is threatening global biodiversity, and it will
likely lead to varying degrees of local adaptation, particularly among
plant species. Besides, rising temperatures frequently result in upslope
distribution shifts towards climatic optima (i.e., the escalator effect)
within a limited dispersal space, such as in insular environments. Here,
we integrated ecological and genetic approaches to investigate how climate
change will impact the genetic compositions and spatial distributions of
Taiwan endemic maple Acer caudatifolium. Location Taiwan Methods We
estimate the distribution range shifts of A. caudatifolium under climate
change through species distribution modeling (SDM). We also use 368
genotyped samples to infer dispersal and genetic hotspots and quantify the
contributions of geography/environments to genetic variations. We further
assess the potential risk to A. caudatifolium under different climate
warming scenarios. Results We detected three genetic diversity hotspots
near mountainous glacial refugia and two dispersal hotspots in northern
Taiwan and the central-to-southern Central Mountain Range. Overall range
reductions and an altitudinal upslope-shift were observed in SDM. Using
both linear and nonlinear regression approaches, we found that genetic
variation was significantly associated with geographic distance and
elevation-related climatic variables. The potential risk analysis revealed
that the northernmost summit-dwelling populations were the most
vulnerable. Furthermore, the major risk factor differed among populations:
for central populations, temperature and precipitation jointly determined
the potential risk, whereas precipitation was the only risk factor for
northern and southern populations. Main conclusions This case study
demonstrates how various climate factors, mountain height, and the
availability of corridors jointly determine the demographic fates and
sustainability of island maples in the face of climate change. This study
also provided estimates of the implications of global warming, which can
be conducive to developing appropriate conservation strategies.