Global hotspots of butterfly diversity are threatened in a warming world
Abstract
Insects and their many ecosystem functions are in decline and threatened by climate change1,2, yet lack of globally comprehensive information limits the understanding and management of this crisis3. Here we use butterflies as a global model insect system4–7 and uncover a remarkable concentration of their diversity in rare and rapidly shrinking high-elevation climates. Integrating comprehensive phylogenetic and geographic range data for 12,119 species, we find that global centers of butterfly richness, rarity, and phylogenetic diversity are unusually concentrated in tropical and sub-tropical mountain systems. Mountains8 hold 3.5 times more butterfly hotspots (top 5%) than lowlands and two thirds of the assessed species are primarily mountain-dwelling. Only a fraction (14%-36%) of these diversity centers overlap with those of ants, terrestrial vertebrates and vascular plants, and this spatial coincidence rapidly decreases above 2,000 m elevation where butterflies are uniquely concentrated. The geographically restricted temperature conditions of these mountain habitats put butterflies at extreme risk from global warming. We project that 64% of butterflies' temperature niche space in tropical realms will erode by 2070. Our study identifies critical conservation needs for butterflies and illustrates how the consideration of global insect systems is key for assessing and managing biodiversity loss in a rapidly warming world.
