Forest fragmentation genetics in a formerly widespread island endemic tree: Vateriopsis seychellarum (Dipterocarpaceae)

Habitat fragmentation and changed land use have seriously reduced population size in many tropical forest tree species. Formerly widespread species with limited gene flow may be particularly vulnerable to the negative genetic effects of forest fragmentation and small population size. Vateriopsis seychellarum (Dipterocarpaceae) is a formerly widespread canopy tree of the Seychelles, but is now reduced to 132 adult individuals distributed in eleven sites. Using ten microsatellite loci, a genetic inventory of all adult trees and a sample of 317 progeny, we demonstrate that despite its restricted range, overall genetic diversity was relatively high (HE: 0.56). The juvenile cohort, however, had significantly lower allelic richness (adults RS: 3.91; juveniles RS: 2.83) and observed heterozygosity than adult trees (adults HO: 0.62; juveniles HO: 0.48). Rare alleles were fewer and kinship between individuals was stronger in juveniles. Significant fine-scale spatial genetic structure was observe...

生境破碎化与土地利用变更已严重缩减了诸多热带森林树种的种群规模。曾广泛分布但基因流受限的物种，或许尤其易受森林破碎化与种群小型化带来的负面遗传效应影响。塞舌尔青梅（Vateriopsis seychellarum，龙脑香科Dipterocarpaceae）曾是塞舌尔地区广泛分布的冠层树种，如今仅存132株成年个体，分布于11个样地中。本研究利用10个微卫星位点（microsatellite loci），对该物种所有成年植株及317株子代样本开展遗传普查，结果表明：尽管其分布范围受限，整体遗传多样性仍处于较高水平（HE: 0.56）。然而，幼龄种群的等位基因丰富度（成年个体RS: 3.91；幼龄个体RS: 2.83）与观测杂合度均显著低于成年植株（成年个体HO: 0.62；幼龄个体HO: 0.48）。幼龄个体中的稀有等位基因数量更少，个体间的亲缘关系也更为紧密。研究观测到显著的小尺度空间遗传结构……