Regional and local environmental conditions do not shape the response to warming of a marine habitat-forming species

C Crisci,N Bensoussan,M La Rivière,P López-Sendino,C Marschal,M Ribes,J Garrabou,K Mokhtar- Jamaï,E Cebrian,D Aurelle,R Coma,M Bally,N Teixidó,J.-B Ledoux,J.- P Féral,F Zuberer,C Linares

doi:10.1038/s41598-017-05220-4

Abstract

The differential response of marine populations to climate change remains poorly understood. Here, we combine common garden thermotolerance experiments in aquaria and population genetics to disentangle the factors driving the population response to thermal stress in a temperate habitat-forming species: the octocoral Paramuricea clavata. Using eight populations separated from tens of meters to hundreds of kilometers, which were differentially impacted by recent mortality events, we identify 25 °C as a critical thermal threshold. After one week of exposure at this temperature, seven of the eight populations were affected by tissue necrosis and after 30 days of exposure at this temperature, the mean % of affected colonies increased gradually from 3 to 97%. We then demonstrate the weak relation between the observed differential phenotypic responses and the local temperature regimes experienced by each population. A significant correlation was observed between these responses and the extent of genetic drift impacting each population. Local adaptation may thus be hindered by genetic drift, which seems to be the main driver of the differential response. Accordingly, conservation measures should promote connectivity and control density erosion in order to limit the impact of genetic drift on marine populations facing climate change.

Highlights

The current global warming trend is affecting marine ecosystems in several ways, such as by decreasing ocean productivity, altering food web dynamics, shifting species distributions and reducing abundance[1,2,3]
We conducted a comprehensive characterization of the response to thermal stress of Paramuricea clavata populations thriving in distinct temperature regimes, i.e. from localities separated by hundreds of kilometers and from different depths
Through a common garden thermotolerance experiment, we demonstrated the limited influence of local temperature regimes and suggested that genetic drift may hinder the impact of divergent selection and modulate the response of populations to thermal stress

Summary

Introduction

The current global warming trend is affecting marine ecosystems in several ways, such as by decreasing ocean productivity, altering food web dynamics, shifting species distributions and reducing abundance[1,2,3]. These studies suggested that genetic drift and acclimatization might play an important role in the phenotypic divergence between red coral populations by putatively modifying their abilities to adapt to local thermal environments. The aim of this study was twofold: 1) to acquire basic information about the thermotolerance features of P. clavata by monitoring colonies tissue necrosis at different temperatures (25, 26, 27 and 28 °C) in common garden experiments performed in aquaria; and 2) to evaluate the role of environmental conditions ( local thermal regimes) and biological processes (with a focus on local adaptation, genetic drift and acclimatization) in the differential responses of populations to thermal stress by combining colonies tissue necrosis data and population genetic analyses

Objectives

Methods

Results

Conclusion