Pérez-Méndez Néstor, Jordano Pedro, García Cristina, Valido Alfredo
Department of Integrative Ecology, Estación Biológica de Doñana (EBD-CSIC), C/Americo Vespucio s/n, La Cartuja, 41092 Sevilla, Spain.
Plant Biology, Centro de Investigação em Biodiversidade e Recursos Geneticos (CIBIO/InBio), Campus Agrário de Vairão, Rua Padre Armando Quintas, Vairão. 4485-661, Porto, Portugal.
Sci Rep. 2016 Apr 19;6:24820. doi: 10.1038/srep24820.
Anthropogenic activity is driving population declines and extinctions of large-bodied, fruit-eating animals worldwide. Loss of these frugivores is expected to trigger negative cascading effects on plant populations if remnant species fail to replace the seed dispersal services provided by the extinct frugivores. A collapse of seed dispersal may not only affect plant demography (i.e., lack of recruitment), but should also supress gene flow via seed dispersal. Yet little empirical data still exist demonstrating the genetic consequences of defaunation for animal-dispersed plant species. Here, we first document a significant reduction of seed dispersal distances along a gradient of human-driven defaunation, with increasing loss of large- and medium-bodied frugivores. We then show that local plant neighbourhoods have higher genetic similarity, and smaller effective population sizes when large seed dispersers become extinct (i.e., only small frugivores remain) or are even partially downgraded (i.e., medium-sized frugivores providing less efficient seed dispersal). Our results demonstrate that preservation of large frugivores is crucial to maintain functional seed dispersal services and their associated genetic imprints, a central conservation target. Early signals of reduced dispersal distances that accompany the Anthropogenic defaunation forecast multiple, cascading effects on plant populations.
人为活动正在导致全球大型食果动物的种群数量下降和灭绝。如果残存物种无法替代已灭绝的食果动物所提供的种子传播服务，这些食果动物的消失预计将对植物种群引发负面的连锁反应。种子传播的崩溃不仅可能影响植物种群统计学特征（即缺乏补充更新），还应会抑制通过种子传播的基因流动。然而，仍然几乎没有实证数据表明动物传播植物物种的去动物化所带来的遗传后果。在此，我们首先记录了随着人类导致的去动物化梯度变化，大型和中型食果动物的数量损失增加，种子传播距离显著缩短。然后我们表明，当大型种子传播者灭绝（即仅剩下小型食果动物）或甚至部分退化（即中型食果动物提供的种子传播效率较低）时，当地植物群落具有更高的遗传相似性和更小的有效种群规模。我们的结果表明，保护大型食果动物对于维持功能性种子传播服务及其相关的遗传印记至关重要，这是一个核心的保护目标。伴随着人为去动物化出现的种子传播距离缩短的早期信号预示着对植物种群的多重连锁效应。
