Data from: Genetic rescue by distant trees mitigates qualitative pollen limitation imposed by fine-scale spatial genetic structure

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 of 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.