Abstract
Animal seed dispersers may influence plant genetic diversity, though
there are few examples linking disperser behavior to population genomic
diversity. We hypothesized that breeding colonies of the frugivorous
White-Crowned Pigeon (Patagioenas leucocephala) would increase
population diversity and decrease population differentiation in fruit
trees at nesting sites due to increased seed dispersal from foraging
trips. We measured the density and extent of colonies at Parque Nacional
Jaragua (Dominican Republic) and used nuclear and plastid SNPs from
ddRADseq to examine the spatial genetic structure of two common species:
poisonwood (Metopium toxiferum), a key fruit resource during the
breeding season, and gumbo limbo (Bursera simaruba). We found that
pigeon nesting aggregations in and around Parque Nacional Jaragua occupy
areas between 3 and 5 Km2, with an estimated number of active nests for
2016 extrapolated to 3 km2 of 159,144 21,484 s.e., making this one of
the largest breeding aggregations for the species across its range.
However, colony locations did not determine tree genetic diversity and
differentiation. Gumbo limbo (consumed by a diverse community) showed
less isolation by distance than poisonwood. Saplings and plastid
markers, expected to be more strongly influenced by seed dispersal, did
not display geographic structure associated with colony sites,
suggesting that patterns were not primarily due to pigeon foraging. Our
results highlight the diversity of population genomic patterns among
co-occurring species with similar ecological niches and demonstrate the
limitations for frugivores to influence genetic differences among plant
species.