Ecological Load and Balancing Selection in Circumboreal Barnacles

• Published in: Molecular Biology and Evolution
• Main Authors: Nunez, Joaquin C B, Rong, Stephen, Damian-Serrano, Alejandro, Burley, John T, Elyanow, Rebecca G, Ferranti, David A, Neil, Kimberly B, Glenner, Henrik, Rosenblad, Magnus Alm, Blomberg, Anders, Johannesson, Kerstin, Rand, David M
• Other Authors: Michael, Rosenberg, Centre for Marine Evolutionary Biology, NSF, Fulbright Spain Graduate Studies Scholarship, National Institutes of Health, Carl Trygger Foundation, Swedish Research Council, Bushnell Graduate Research and Education Fund
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press (OUP) 2020
• Subjects: Arctic; Pacific
• Online Access: http://dx.doi.org/10.1093/molbev/msaa227; http://academic.oup.com/mbe/advance-article-pdf/doi/10.1093/molbev/msaa227/34590047/msaa227.pdf; http://academic.oup.com/mbe/article-pdf/38/2/676/36084604/msaa227.pdf

Abstract Acorn barnacle adults experience environmental heterogeneity at various spatial scales of their circumboreal habitat, raising the question of how adaptation to high environmental variability is maintained in the face of strong juvenile dispersal and mortality. Here, we show that 4% of genes in the barnacle genome experience balancing selection across the entire range of the species. Many of these genes harbor mutations maintained across 2 My of evolution between the Pacific and Atlantic oceans. These genes are involved in ion regulation, pain reception, and heat tolerance, functions which are essential in highly variable ecosystems. The data also reveal complex population structure within and between basins, driven by the trans-Arctic interchange and the last glaciation. Divergence between Atlantic and Pacific populations is high, foreshadowing the onset of allopatric speciation, and suggesting that balancing selection is strong enough to maintain functional variation for millions of years in the face of complex demography.