Genomic basis for early-life mortality in sharpsnout seabream

Este artículo contiene 11 páginas, 4 figuras.
Mortality at early life stages of fishes is common in nature and can be shaped by stochastic and selective processes. Selective mortality has rarely been assessed in natural conditions but can now be studied by combining genomic data with information on different life stages that realates to fitness. Here we investigate selective mortality between settlers and six-month survivors of the sharpsnout seabream by genotype-phenotype/environmental association studies in three localities along a geographic gradient. We gathered information on 105 individuals at 85,031 SNPs, obtained from individual based 2b-RAD libraries, as well as 9 phenotypic and environmental variables derived from individual otolith readings. We found common signals across localities for potential selection, such as lower survival rates for individuals hatching earlier, growing faster and experiencing higher temperatures during their planktonic phase. We identified 122 loci with parallel significant association to phenotypic and environmental variables. Importantly, one of these loci mapped to the exonic region of the il20rb, a gene involved in immune response, in the phylogenetically closest reference genome, showing parallel frequency changes in non-synonymous mutations in the three studied populations. Further temporal assessments are needed to understand how polymorphisms that are key to selective mortality are maintained.
This research was funded by projects PopCOmics (CTM2017-88080, funded by MCIN/ AEI/10.13039/501100011033 and by “ERDF A way of making Europe’’ of the European Union) and MarGeCh (PID2020-118550RB, funded by MCIN/AEI/10.13039/501100011033) from the Spanish Government. The authors CC and MP are members of the research group SGR2017-1120 and EM of SGR2017-378 (Catalan Government). HT was supported by a PhD scholarship funded by the Spanish Ministry of Science, Innovation and Universities (FPU15/02390).