Central and rear-edge populations can be equally vulnerable to warming.

Scott Bennett,Bijo Arackal Joy,Alexandra H Campbell,Thibaut De Bettignies,Thomas Wernberg

doi:10.1038/ncomms10280

Abstract

Rear (warm) edge populations are often considered more susceptible to warming than central (cool) populations because of the warmer ambient temperatures they experience, but this overlooks the potential for local variation in thermal tolerances. Here we provide conceptual models illustrating how sensitivity to warming is affected throughout a species' geographical range for locally adapted and non-adapted populations. We test these models for a range-contracting seaweed using observations from a marine heatwave and a 12-month experiment, translocating seaweeds among central, present and historic range edge locations. Growth, reproductive development and survivorship display different temperature thresholds among central and rear-edge populations, but share a 2.5 °C anomaly threshold. Range contraction, therefore, reflects variation in local anomalies rather than differences in absolute temperatures. This demonstrates that warming sensitivity can be similar throughout a species geographical range and highlights the importance of incorporating local adaptation and acclimatization into climate change vulnerability assessments.

Highlights

Rear edge populations are often considered more susceptible to warming than central populations because of the warmer ambient temperatures they experience, but this overlooks the potential for local variation in thermal tolerances
This paradigm has a long history in ecology and biogeography[6,7], and in the context of temperature thresholds implies that rear-edge populations have smaller thermal-safety margins than central populations, making them more vulnerable to perturbation and species range contractions[6] (Fig. 1a)
Our results demonstrate that thermal-safety margins are remarkably similar for a habitatforming seaweed from central and rear-edge populations, highlighting that conspecific populations can be sensitive to warming throughout a species geographical range

Summary

Introduction

Rear (warm) edge populations are often considered more susceptible to warming than central (cool) populations because of the warmer ambient temperatures they experience, but this overlooks the potential for local variation in thermal tolerances. Reflects variation in local anomalies rather than differences in absolute temperatures This demonstrates that warming sensitivity can be similar throughout a species geographical range and highlights the importance of incorporating local adaptation and acclimatization into climate change vulnerability assessments. If populations do not have locally adapted thermal limits (that is, Fig. 1a), thermal-safety margins would differ throughout a species range and we would expect responses to high temperatures among populations to be best explained by variation in absolute maximum temperature. Our results demonstrate that thermal-safety margins are remarkably similar for a habitatforming seaweed from central and rear-edge populations, highlighting that conspecific populations can be sensitive to warming throughout a species geographical range

Methods

Results

Conclusion