Data from: Early genetic consequences of defaunation in a large-seeded vertebrate-dispersed palm (Syagrus romanzoffiana)

Plant populations are seriously threatened by anthropogenic habitat disturbance. In particular, defaunation may disrupt plant-disperser mutualisms, thus reducing levels of seed-mediated gene flow and genetic variation in animal-dispersed plants. This may ultimately limit their adaptive potential and ability to cope with environmental change. Tropical forest remnants are typically deprived of medium to large vertebrates upon which many large-seeded plants rely for accomplishing effective seed dispersal. Our main goal was to examine the potential early genetic consequences of the loss of large vertebrates for large-seeded vertebrate-dispersed plants. We compared the genetic variation in early-stage individuals of the large-seeded palm Syagrus romanzoffiana between continuous protected forest and nearby partially defaunated fragments in the Atlantic Forest of South America. Using nine microsatellites, we found lower allelic richness and stronger fine-scale spatial genetic structure in the disturbed area. In addition, the percentage of dispersed recruits around conspecific adults was lower, although not significantly, in the disturbed area (median values: 0.0 vs 14.4%). On the other hand, no evidence of increased inbreeding or reduced pollen-mediated gene flow (selfing rate and diversity of pollen donors) was found in the disturbed area. Our findings are strongly suggestive of some early genetic consequences resulting from the limitation in contemporary gene flow via seeds, but not pollen, in defaunated areas. Plant-disperser mutualisms involving medium–large frugivores, which are seriously threatened in tropical systems, should therefore be protected to warrant the maintenance of seed-mediated gene flow and genetic diversity in large-seeded plants.

植物种群正面临人为生境干扰的严重威胁。尤为甚者，动物区系丧失（defaunation）可能破坏植物-传播者互利共生关系，进而降低动物传播植物的种子介导基因流水平与遗传变异程度，最终限制其适应潜力与应对环境变化的能力。热带森林残存斑块通常丧失了众多大型种子植物实现有效种子传播所依赖的中大型脊椎动物类群。本研究的核心目标为探究大型脊椎动物丧失对脊椎动物传播的大型种子植物可能造成的早期遗传效应。我们选取南美洲大西洋森林内的连续保护林与邻近的部分动物区系丧失的林片段作为研究样地，对比分析了大型种子棕榈*Syagrus romanzoffiana*早期个体的遗传变异水平。借助9个微卫星标记（microsatellites），我们发现受干扰样地的等位基因丰富度更低，且精细空间遗传结构更强。此外，受干扰样地内同种成年个体周围的传播定植幼株占比更低（虽未达到显著水平），其中位数分别为0.0%与14.4%。另一方面，受干扰样地未发现近交程度升高或花粉介导基因流降低的迹象（相关指标包括自交速率与花粉供体多样性）。本研究结果强烈表明，动物区系丧失样地中当代种子介导基因流的限制会带来部分早期遗传效应，而花粉介导基因流则未受明显影响。因此，涉及中大型食果动物的植物-传播者互利共生关系（这类关系在热带生态系统中正面临严重威胁）亟需得到保护，以保障大型种子植物的种子介导基因流与遗传多样性得以维持。