Niche syndromes reveal climate-driven extinction threat to island endemic conifers

Abstract

Anthropogenic climate change is predicted to cause many extinctions worldwide1. Although species endemic to islands or archipelagos have high conservation value and are vulnerable to human impacts2,3, there has been no global analysis of climate-driven extinction risk focused on island endemics. Here, we use conifers as a model system to assess extinction risk among island endemics under climate projections for 2070. We employ the emerging technique of combining native and non-native occurrence data to model climatic conditions under which each species can sustain a population4–7 and also incorporate horticultural data to model the broader range of conditions that allow short-term survival. Our projections indicate that some species will retain suitable climatic conditions, some will experience conditions completely precluding survival and others will experience intermediate-risk conditions that lead to population decline and eventual extinction. Based on different climate change models, we report island size thresholds of 400 to 20,000 km2, below which extinction risks increase. These patterns are driven by correlations among island area and the breadth of species’ realized, fundamental and tolerance niches. Notably, realized and fundamental niche breadth are positively correlated. Our results highlight management interventions needed to protect species from climate-driven extinction across islands of different sizes. Island species are at risk as the climate changes. Island conifers are used as a model species and a combination of native and non-native occurrence data allows identification of realized, tolerable and fundamental niches; linking to island size provides an estimate of extinction risk.