Genomic trajectories of a near-extinction event in the Chatham Island black robin

作者：Johanna von Seth, Tom van der Valk, Edana Lord, Hanna Sigeman, Remi‐André Olsen, Michael R. Knapp, Olga Kardailsky, Fiona E. Robertson, Marie L. Hale, Dave Houston, Euan S. Kennedy, Love Dalén, Karin Norén, Melanie Massaro, Bruce C. Robertson, Nicolás Dussex · 发表于：BMC Genomics · 年份：2022 · DOI：10.1186/s12864-022-08963-1 · 被引用次数：38 · 研究领域：Genetic diversity and population structure、Evolution and Genetic Dynamics、Genomics and Phylogenetic Studies

BACKGROUND: Understanding the micro--evolutionary response of populations to demographic declines is a major goal in evolutionary and conservation biology. In small populations, genetic drift can lead to an accumulation of deleterious mutations, which will increase the risk of extinction. However, demographic recovery can still occur after extreme declines, suggesting that natural selection may purge deleterious mutations, even in extremely small populations. The Chatham Island black robin (Petroica traversi) is arguably the most inbred bird species in the world. It avoided imminent extinction in the early 1980s and after a remarkable recovery from a single pair, a second population was established and the two extant populations have evolved in complete isolation since then. Here, we analysed 52 modern and historical genomes to examine the genomic consequences of this extreme bottleneck and the subsequent translocation. RESULTS: We found evidence for two-fold decline in heterozygosity and three- to four-fold increase in inbreeding in modern genomes. Moreover, there was partial support for temporal reduction in total load for detrimental variation. In contrast, compared to historical genomes, modern genomes showed a significantly higher realised load, reflecting the temporal increase in inbreeding. Furthermore, the translocation induced only small changes in the frequency of deleterious alleles, with the majority of detrimental variation being shared between the two population...