Stepping stones to isolation: Impacts of a changing climate on the connectivity of fragmented fish populations
Authored by Emma F Young, Mark Belchier, Michael P Meredith, Eugene J Murphy, Niklas Tysklind, Gary R Carvalho, Bruyn Mark de
Date Published: 2018
DOI: 10.1111/eva.12613
Sponsors:
French National Research Agency (ANR)
United Kingdom Natural Environment Research Council (NERC)
British Antarctic Survey
Platforms:
No platforms listed
Model Documentation:
Other Narrative
Mathematical description
Model Code URLs:
Model code not found
Abstract
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 management.
Tags
connectivity
Population genetics
Individual-based modelling
Gene flow
Larval dispersal
Local adaptation
Global ocean
Seascape genetics
Icefish champsocephalus-gunnari
Mackerel icefish
Scotia sea
Ocean warming
Champsocephalus gunnari
Notothenia rossii
Antarctic circumpolar current
South
shetland islands
Notothenioid fish