Conservation genomics of the endangered Seychelles Magpie‐Robin (Copsychus sechellarum): a unique insight into the history of a precious endemic bird

Abstract

The Seychelles Magpie‐Robin Copsychus sechellarum is an IUCN Red‐List Endangered species endemic to the Seychelles, whose population was reduced to eight individuals on a single island in the 1960s. Translocations from the remaining population to four additional islands have been an integral factor in their recovery, but the potential genetic consequences of their translocation history have not previously been explored. We resequenced the genomes of 141 individuals sampled across the five current island populations and analysed the data to characterize their population structure, as well as to explore suspected inbreeding. Overall, very low levels of heterozygosity were observed, all coupled with long homozygous segments that suggest recent inbreeding, probably the consequence of a population bottleneck in the 1960s. Three of the four translocated populations displayed less genetic diversity than the founder population from which they were taken, a familiar pattern observed as a result of the evolutionary force of genetic drift following founder events. Furthermore, and perhaps surprising given the recent time since the new populations were established, population structure was observed within these same three populations. New awareness of inbreeding in the Seychelles Magpie‐Robin populations, and continued genetic monitoring, will allow for genetically informed management decisions. This is particularly prudent in maximizing the success of the future conservation translocation planned for this species.

Contrasting genomic consequences of anthropogenic reintroduction and natural recolonization in high‐arctic wild reindeer

“…The increased inbreeding in reintroduced populations was also accompanied by lower coalescent N e estimates, with Reintroduction 1 showing a greater reduction (12%) than Reintroduction 2 (4%) compared to the source population. Similar genomic signatures of reintroductions have previously been identified, including in European bison Bison bonasus (Druet et al, 2020), Magpie-robins Copsychus sechellarum (Cavill et al, 2022) and ibex Capra ibex (Grossen et al, 2018). The increased inbreeding in reintroduced populations was attributable to a greater proportion of the genome in RoH >1 Mbp, including in the 1-2 and 2-4 Mbp range.…”

Contrasting genomic consequences of anthropogenic reintroduction and natural recolonisation in high-arctic wild reindeer

“…Similar genomic signatures of reintroductions have previously been identified, including in European bison Bison bonasus (Druet et al . 2020), Magpie-robins Copsychus sechellarum (Cavill et al . 2022), and ibex Capra ibex (Grossen et al .…”

“…Copsychus sechellarum (Cavill et al 2022), and ibex Capra ibex (Grossen et al 2018). The increased inbreeding in reintroduced populations was attributable to a greater proportion of the genome in RoH >1 Mbp, including in the 1-2 and 2-4 Mbp range.…”

Genomic recovery lags behind demographic recovery in bottlenecked populations of the Channel Island fox, Urocyon littoralis

“…For example, an extreme bottleneck in the little spotted kiwi (Apteryx owenii) decreased genetic diversity that still has not recovered despite also being considered a 'conservation success' and being downgraded in conservation status (Taylor et al, 2017). Similar stories of downlisted species that were demographically recovered but still had low genetic diversity are found in the dawn redwood tree (Metasequoia glyptostroboides; Li et al, 2012), the Seychelles Magpie-robin (Copsychus sechellarum; Cavill et al, 2022) and the pink pigeon (Nesoenas mayeri; Jackson et al, 2022). Better incorporation of genetic data, including longterm monitoring, in threatened and endangered species listings will improve management of these populations that are less able to respond to novel challenges.…”