Implications for alpine species conservation
Our finding of a drastic population decline since the last glaciation retreat, coupled with field observations of extremely limited habitat and small population sizes, suggests that this species complex may be vulnerable to localized extinction. For many Nebria species in North America, lower elevational distributions have shifted upward in the past 40 years (Kavanaugh 2015). If population range shifts are associated with warmer temperatures in the Holocene, it is very likely that populations will continue to shrink with ongoing global warming. This could be exacerbated by the loss of Sierra Nevada glaciers and a reduction in winter snowpack (Basagic & Fountain, 2011; Belmecheri, Babst, Wahl, Stahle, & Trouet, 2016). Although N. ingens complex is not an economically significant animal, it is difficult to predict the consequence of a general predator disappearing from a comparatively depauperate alpine ecosystem.