Sky Islands Are a Global Tool for Predicting the Ecological and Evolutionary Consequences of Climate Change

Abstract

Sky islands are unique geologic formations, home to populations of organisms that have weathered climate change since the Pleistocene. Long-term isolation and climatic differences between sky islands and adjacent mountain chains result in natural laboratories well suited for examining the direct effects of climate change. Here, we review the global sky island literature to examine how taxa have responded to climate change. Results show lineage formation, reduced genetic variation, and trait evolution across taxa driven by genetic drift and natural selection. These effects continue today due to ongoing habitat reduction and steep selective gradients on sky islands relative to mountain chains. Comparative studies and experimental manipulations are needed to build broad inference into how past climate change has shaped the structure and function of whole ecosystems. The next era of sky island research is poised to create a model for climate change responses and eco-evolutionary dynamics, with profound conservation implications. Expected final online publication date for the Annual Review of Ecology, Evolution, and Systematics, Volume 54 is November 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Genetic variability and population structure of the Montezuma quail (Cyrtonyx montezumae) in the northern limit of its distribution

“…The existence of these isolated populations poses a conservation challenge for managers. These isolated populations have most likely differentiated, as those of numerous vertebrates inhabiting sky islands systems ( Barrowclough et al, 2006 ; Browne & Ferree, 2007 ; Hartley et al, 2023 ; Love et al, 2023 ). The degree to which isolated Montezuma quail populations have differentiated deserves investigation.…”

Identifying ecological and evolutionary research targets and risks in climate change studies to break barriers to broad inference

“…Importantly, from a population perspective, there are many leading and trailing edges. Populations at the leading and trailing edge of species' ranges often have lower within-and higher among-population diversity than populations at the core of the range [51,62] (Fig 2). Because the environmental challenges that organisms face vary depending on where an individual is within the range, population range edges can provide better estimates of the adaptive capacity, the phenotypes, and the function of the species within a given ecosystem [33] that allow it to persist and colonize new habitats.…”