Data from: Genetic inference of epiphytic orchid colonization; it may only take one

Colonization of vacant habitat is a fundamental ecological process that
affects the ability of species to persist and undergo range modifications
in continually shifting landscapes. Thus, understanding factors that
affect and limit colonization has important ecological and conservation
implications. Epiphytic orchids are increasingly threatened by various
factors, including anthropogenic habitat disturbance. As cleared areas
(e.g. pastures) are recolonized by suitable host trees, the establishment
and genetic composition of epiphytic orchid populations are likely a
function of their colonization patterns. We used genetic analyses to infer
the prevailing colonization pattern of the epiphytic orchid, Brassavola
nodosa. Samples from three populations (i.e. individuals within a tree)
from each of five pastures in the dry forest of Costa Rica were genotyped
with neutral nuclear and chloroplast markers. Spatial autocorrelation and
hierarchical genetic structure analyses were used to assess the
relatedness of individuals within populations, among populations within
pastures and among populations in different pastures. The results showed
significant relatedness within populations (mean r = 0.166) and
significant but lower relatedness among populations within a pasture (mean
r = 0.058). Our data suggest that colonization of available habitats is by
few individuals with subsequent population expansion resulting from in
situ reproduction, and that individuals within a tree are not a random
sample of the regional seed pool. Furthermore, populations within a
pasture were likely colonized by seeds produced by founders of a
neighbouring population within that pasture. These results have important
ramifications for understanding conservation measures needed for this
species and other epiphytic orchids.