Instituto Superior of Agronomy, Centre for Applied Ecology "Prof. Baeta Neves"/INBIO, University of Lisbon, Lisbon, Portugal.
Departamento de Ecología Integrativa, Estación Biológica de Doñana (EBD), Consejo Superior de Investigaciones Científicas (CSIC), Sevilla, Spain.
Mol Ecol. 2019 Oct;28(19):4363-4374. doi: 10.1111/mec.15233. Epub 2019 Sep 27.
Restricted seed dispersal frequently leads to fine-scale spatial genetic structure (i.e., FSGS) within plant populations. Depending on its spatial extent and the mobility of pollinators, this inflated kinship at the immediate neighbourhood can critically impoverish pollen quality. Despite the common occurrence of positive FSGS within plant populations, our knowledge regarding the role of long-distance pollination preventing reproductive failure is still limited. Using microsatellite markers, we examined the existence of positive FSGS in two low-density populations of the tree Pyrus bourgaeana. We also designed controlled crosses among trees differing in their kinship to investigate the effects of increased local kinship on plant reproduction. We used six pollination treatments and fully monitored fruit production, fruit and seed weight, proportion of mature seeds per fruit, and seed germination. Our results revealed positive FSGS in both study populations and lower fruit initiation in flowers pollinated with pollen from highly-genetically related individuals within the neighbourhood, with this trend intensifying as the fruit development progressed. Besides, open-pollinated flowers exhibited lower performance compared to those pollinated by distant pollen donors, suggesting intense qualitative pollen limitation in natural populations. We found positive fine-scale spatial genetic structure is translated into impoverished pollen quality from nearby pollen donors which negatively impacts the reproductive success of trees in low-density populations. Under this scenario of intrapopulation genetic rescue by distant pollen donors, the relevance of highly-mobile pollinators for connecting spatially and genetically distant patches of trees may be crucial to safeguarding population recruitment.
限制种子传播通常会导致植物种群内出现小尺度空间遗传结构（即 FSGS）。根据其空间范围和传粉媒介的流动性，这种临近亲缘关系的膨胀会严重降低花粉质量。尽管植物种群内普遍存在正 FSGS，但我们对长距离传粉防止繁殖失败的作用的了解仍然有限。本研究使用微卫星标记，检验了树木 Pyrus bourgaeana 的两个低密度种群中是否存在正 FSGS。我们还设计了亲缘关系不同的树木之间的控制杂交，以研究增加局部亲缘关系对植物繁殖的影响。我们使用了六种授粉处理，并对果实产生、果实和种子重量、每果成熟种子比例以及种子发芽情况进行了全面监测。结果表明，两个研究种群中均存在正 FSGS，并且来自邻近亲缘关系个体的花粉授粉的花朵中，果实起始较少，随着果实发育的进行，这种趋势加剧。此外，与来自远距离花粉源授粉的花朵相比，自花授粉的花朵表现出较低的性能，这表明在自然种群中存在强烈的定性花粉限制。我们发现，来自附近花粉源的正小尺度空间遗传结构会导致花粉质量下降，从而对低密度种群中树木的繁殖成功产生负面影响。在这种由远距离花粉源进行种群内遗传拯救的情况下，高流动性传粉媒介对于连接空间和遗传上遥远的树木斑块可能至关重要，以保障种群的补充。
