Oral Presentation Australian Society for Fish Biology Conference 2017

Genomic signatures of local adaptation reveal source-sink dynamics in a high gene flow fish species (#124)

Katherine Cure 1 2 , Luke Thomas 3 , Jean-Paul A. Hobbs 4 , David V. Fairclough 5 , Jason W. Kennington 6
  1. Australian Institute of Marine Science, Crawley, WA, Australia
  2. UWA Oceans Institue & School of Plant Biology, The University of Western Australia, Crawley, WA, Australia
  3. Hopkins Marine Station, Stanford University, Pacific Grove, California, USA
  4. Department of Environment and Agriculture, Curtin University, Bentley, WA, Australia
  5. Western Australian Fisheries and Marine Research Laboratories, Department of Fisheries, Hillarys, WA, Australia
  6. Centre for Evolutionary Biology, School of Animal Biology, The University of Western Australia, Perth, Crawley, Australia

Understanding source-sink dynamics is important for conservation management, particularly when climatic events alter species’ distributions. Following a 2011 ‘marine heatwave’ in Western Australia, we observed high recruitment of the endemic fisheries target species Choerodon rubescens, towards the cooler (southern) end of its distribution. Here, we use a genome wide set of 14 559 single-nucleotide polymorphisms (SNPs) to identify the likely source population for this recruitment event. Most loci (76%) showed low genetic divergence across the species’ range, indicating high levels of gene flow and confirming previous findings using neutral microsatellite markers. However, a small proportion of loci showed strong patterns of differentiation and exhibited patterns of population structure consistent with local adaptation. Clustering analyses based on these outlier loci indicated that recruits at the southern end of C. rubescens range originated 400 km to the north, at the centre of the species’ range, where average temperatures are up to 3°C warmer. Survival of these recruits may be low because they carry alleles adapted to an environment different to the one they now reside in, but their survival is key to establishing locally adapted populations at and beyond the range edge as water temperatures increase with climate change.