Data from: Fire-induced population reduction and landscape opening increases gene flow via pollen dispersal in Pinus halepensis

Population reduction and disturbances may alter dispersal, mating patterns
and gene flow. Rather than taking the common approach of comparing
different populations or sites, here we studied gene flow via
wind-mediated effective pollen dispersal on the same plant individuals
before and after a fire-induced population drop, in a natural stand of
Pinus halepensis. The fire killed 96% of the pine trees in the stand and
cleared the vegetation in the area. Thirteen trees survived in two groups
separated by ~80 m, and seven of these trees had serotinous (closed)
pre-fire cones that did not open despite the fire. We analyzed pollen from
closed pre- and post-fire cones using microsatellites. The two groups of
surviving trees were highly genetically differentiated, and the pollen
they produced also showed strong among-group differentiation and very high
kinship both before and after the fire, indicating limited and very local
pollen dispersal. The pollen not produced by the survivors also showed
significant pre-fire spatial genetic structure and high kinship,
indicating mainly within-population origin and limited gene flow from
outside, but became spatially homogeneous with random kinship after the
fire. We suggest that post-fire gene flow via wind-mediated pollen
dispersal increased by two putative mechanisms: 1) a drastic reduction in
local pollen production due to population thinning, effectively increasing
pollen immigration; 2) an increase in wind speeds in the vegetation-free
post-fire landscape. This research shows that dispersal can alleviate
negative genetic effects of population size reduction, and that
disturbances might enhance gene flow, rather than reduce it.