Data from: Small but not isolated: a population genetic survey of the tropical tree Cariniana estrellensis (Lecythidaceae) in a highly fragmented habitat

Here, we explore the mating pattern and genetic structure of a tropical tree species, Cariniana estrellensis, in a small population in which progeny arrays (n=399), all adults (n=28) and all seedlings (n=39) were genotyped at nine highly informative microsatellite loci. From progeny arrays we were able to identify the source tree for at least 78% of pollination events. The gene immigration rates, mainly attributable to pollen, were high, varying from 23.5% to 53%. Although gene dispersal over long distance was observed, the effective gene dispersal distances within the small population were relatively short, with mean pollination distances varying from 69.9 m to 146.9 m, and seed dispersal distances occurring up to a mean of 119.6 m. Mating system analyses showed that C. estrellensis is an allogamous species (tm=0.999), with both biparental inbreeding (tm-ts=-0.016) and selfing rates (s=0.001) that are not significantly different from zero. Even though the population is
small, the presence of private alleles in both seedlings and progeny arrays and the elevated rates of gene immigration, indicate that the C. estrellensis population is not genetically isolated. However, genetic diversity expressed by allelic richness was significantly lower in post-fragmentation life stages. While there was a loss of genetic diversity, indicating susceptibility of C. estrellensis to habitat fragmentation, no evidence of inbreeding or spatial genetic structure was observed across generations. Overall, C. estrellensis showed some resilience to negative genetic effects of habitat fragmentation, but conservation strategies are needed to preserve the remaining genetic diversity of this population.

本研究针对热带树种*Cariniana estrellensis*的小种群，探究其交配模式与遗传结构。该种群的子代阵列（progeny arrays，n=399）、全部成年个体（n=28）与全部幼苗（n=39）均通过9个高信息量微卫星位点（microsatellite loci）完成基因分型。通过子代阵列，我们得以确定至少78%的授粉事件的花粉供体树。基因迁入率（主要由花粉介导）较高，区间为23.5%至53%。尽管观测到长距离基因扩散现象，但该小种群内的有效基因扩散距离相对较近：平均授粉距离介于69.9米至146.9米之间，种子扩散的平均距离最高可达119.6米。交配系统分析结果显示，*C. estrellensis*为异交物种（tm=0.999），其双亲近交系数（tm-ts=-0.016）与自交率（s=0.001）均与0无显著差异。尽管该种群规模较小，但幼苗与子代阵列中均存在私有等位基因，且基因迁入率较高，这表明该*C. estrellensis*种群并未出现遗传隔离。然而，以等位基因丰富度表征的遗传多样性在生境破碎化后的生活史阶段显著降低。尽管遗传多样性出现流失，表明*C. estrellensis*对生境破碎化具有敏感性，但各世代中均未观测到近交或空间遗传结构的迹象。总体而言，*C. estrellensis*对生境破碎化带来的负面遗传效应具备一定恢复力，但仍需制定保护策略以维持该种群现存的遗传多样性。