Back from the brink: potential for genetic rescue in a critically endangered tree

Rare plant species are vulnerable to genetic erosion and inbreeding associated with small population size and isolation due to increasing fragmentation, though the degree to which these problems undermine population viability remains debated. We explore genetic and reproductive processes in the critically endangered long-lived tropical tree Medusagyne oppositifolia, an endemic to the Seychelles with a naturally patchy distribution. This species is failing to recruit in three of its four populations. We evaluate whether recruitment failure is linked to genetic problems associated with fragmentation, and if genetic rescue can mitigate such problems. Medusagyne oppositifolia comprises 90 extant trees in four populations, with only the largest (78 trees) having successful recruitment. Using 10 microsatellite loci we demonstrated that genetic diversity is high (HE: 0.48 – 0.63; HO: 0.56 – 0.78) in three populations, with only the smallest population having relatively low diversity (HE: 0.26 ...