Fragmented habitat compensates for the adverse effects of genetic bottleneck

• Published in: Current Biology
• Main Authors: Loytynoja, Ari, Rastas, Pasi, Valtonen, Mia, Kammonen, Juhana, Holm, Liisa, Olsen, Morten Tange, Paulin, Lars, Jernvall, Jukka, Auvinen, Petri
• Other Authors: Institute of Biotechnology, Bioinformatics, Ari Pekka Löytynoja / Principal Investigator, Centre for Information Technology, Organismal and Evolutionary Biology Research Programme, Genetics, Computational genomics, Faculty of Science, Department of Geosciences and Geography, Jukka Jernvall / Principal Investigator, DNA Sequencing and Genomics
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cell Press 2023
• Subjects: Effective population-size; Salmon salmo-salar; Postglacial colonization; Phoca-hispida; Evolution; Marine; Europe; 1181 Ecology; evolutionary biology; Phoca hispida; ringed seal; Salmo salar
• Online Access: http://hdl.handle.net/10138/357775

In the face of the human-caused biodiversity crisis, understanding the theoretical basis of conservation ef-forts of endangered species and populations has become increasingly important. According to population genetics theory, population subdivision helps organisms retain genetic diversity, crucial for adaptation in a changing environment. Habitat topography is thought to be important for generating and maintaining popu-lation subdivision, but empirical cases are needed to test this assumption. We studied Saimaa ringed seals, landlocked in a labyrinthine lake and recovering from a drastic bottleneck, with additional samples from three other ringed seal subspecies. Using whole-genome sequences of 145 seals, we analyzed the distribution of variation and genetic relatedness among the individuals in relation to the habitat shape. Despite a severe his-tory of genetic bottlenecks with prevalent homozygosity in Saimaa ringed seals, we found evidence for the population structure mirroring the subregions of the lake. Our genome-wide analyses showed that the sub -populations had retained unique variation and largely complementary patterns of homozygosity, highlighting the significance of habitat connectivity in conservation biology and the power of genomic tools in under-standing its impact. The central role of the population substructure in preserving genetic diversity at the metapopulation level was confirmed by simulations. Integration of genetic analyses in conservation deci-sions gives hope to Saimaa ringed seals and other endangered species in fragmented habitats. Peer reviewed