Stepping stones to isolation: Impacts of a changing climate on the connectivity of fragmented fish populations

• Published in: Evolutionary Applications
• Main Authors: Young, Emma F., Tysklind, Niklas, Meredith, Michael P., de Bruyn, Mark, Belchier, Mark, Murphy, Eugene J., Carvalho, Gary R.
• Other Authors: British Antarctic Survey (BAS), Natural Environment Research Council (NERC), Ecologie des forêts de Guyane (UMR ECOFOG), Université des Antilles (UA)-Université de Guyane (UG)-Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA), Bangor University, School of Life and Environm ental Sciences, University of Sydney, Natural Environment Research Council AFI06/16, NE/H023038/1, NE/H023704/1, Investissement d'Avenir of the ANR ANR-10-LABX-25-01
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: connectivity; individual-based modelling; Notothenia rossii; ocean warming; Scotia Sea; Champsocephalus gunnari; population genetics; [SDV]Life Sciences [q-bio]; Antarctic; Antarctic Peninsula; Stepping Stones; The Antarctic; Antarc*
• Online Access: https://hal.inrae.fr/hal-02627947; https://hal.inrae.fr/hal-02627947/document; https://hal.inrae.fr/hal-02627947/file/2018_Young_Evolutionary%20Applications_1.pdf; https://doi.org/10.1111/eva.12613

International audience In the marine environment, understanding the biophysical mechanisms that drive variability in larval dispersal and population connectivity is essential for estimating the potential impacts of climate change on the resilience and genetic structure of populations. Species whose populations are small, isolated and discontinuous in distribution will differ fundamentally in their response and resilience to environmental stress, compared with species that are broadly distributed, abundant and frequently exchange conspecifics. Here, we use an individual-based modelling approach, combined with a population genetics projection model, to consider the impacts of a warming climate on the population connectivity of two contrasting Antarctic fish species, Notothenia rossii and Champsocephalus gunnari. Focussing on the Scotia Sea region, sea surface temperatures are predicted to increase significantly by the end of the 21st century, resulting in reduced planktonic duration and increased egg and larval mortality. With shorter planktonic durations, the results of our study predict reduced dispersal of both species across the Scotia Sea, from Antarctic Peninsula sites to islands in the north and east, and increased dispersal among neighbouring sites, such as around the Antarctic Peninsula. Increased mortality modified the magnitude of population connectivity but had little effect on the overall patterns. Whilst the predicted changes in connectivity had little impact on the projected regional population genetic structure of N.rossii, which remained broadly genetically homogeneous within distances of -1,500km, the genetic isolation of C.gunnari populations in the northern Scotia Sea was predicted to increase with rising sea temperatures. Our study highlights the potential for increased isolation of island populations in a warming world, with implications for the resilience of populations and their ability to adapt to ongoing environmental change, a matter of high relevance to fisheries and ecosystem-level ...