Conservation Implications
Anthropogenic GCC is one of the most significant threats to Earth’s
biodiversity (Elsen & Tingley, 2015; Bellard et al., 2014). Tropical
montane species are predicted to suffer the greatest effects because
they are likely to be endemic with restricted geographic ranges and
narrow climatic tolerance (Williams, Jackson, & Kutzbach, 2007; La
Sorte & Jetz, 2010). Several studies have documented upslope range
shifts in response to GCC-associated temperature and precipitation
changes (e.g. Freeman, Scholer, Ruiz-Gutierrez, & Fitzparick, 2018;
Raxworthy et al., 2008b; Chen et al., 2009). These shifts can result in
reduced or fragmented habitat, decreasing genetic diversity and making
species vulnerable to extinction (Moritz et al., 2008; Williams et al.,
2007). In addition, in the case of locally adapted, highly structured
populations, increased dispersal and gene flow upslope could introduce
maladaptive genes (Weiss-Lehman & Shaw, 2019). It is therefore
imperative to understand how tropical montane populations are structured
in order to predict, monitor, and mitigate the effects of GCC.
Here, we provide a foundational estimate of population structure,
genetic diversity, and historical gene flow for mountain treeshrews in
KNP. These data can be used to monitor GCC-induced population genetic
changes over time. Montane communities in KNP could experience an
upslope shift of ca. 490 m by 2100 CE (Still, 1999; Camacho et al.,
2018), assuming mild Intergovernmental Panel on Climate Change scenarios
(IPCC 2013, www.ipcc.ch/report/ar5/wg1/). Although the factors that
limit the mountain treeshrew at its lower elevational boundary are
unknown, assuming that the species tracks the predicted 490 m upslope
shift - whether because of climatic limitations or ecological
interactions with lowland species expanding upslope - we predict that it
will experience range contraction. The species already occupies the
upper elevational limits within KNP, so an upslope shift in the lower
bound of its distribution could not be countered with expansion at its
upper limit. The lack of strong population structure across elevations
means that upslope dispersal of lower elevation mountain treeshrews on
MK will likely not increase extinction risk by introducing maladaptive
genetic diversity. However, reduction in available habitat could make
the species vulnerable.
We also predict that mountain treeshrews would maintain connectivity
between MK and MT. However, the Crocker Range has few peaks above 1400
masl, and connectivity between KNP and the rest of the Crocker Range
could be severed (Figure 7). This highlights the importance of KNP as a
future refugium for montane species, as it contains the highest peak in
the region and the greatest high-elevation forested area. Conservation
efforts should focus on protecting forest habitat at 900 masl to
facilitate gene flow and preserve genetic diversity.