Data from: A mistletoe tale: postglacial invasion of Psittacanthus schiedeanus (Loranthaceae) to Mesoamerican cloud forests revealed by molecular data and species distribution modeling

Background: Ecological adaptation to host taxa is thought to result in
mistletoe speciation via race formation. However, historical and
ecological factors could also contribute to explain genetic structuring
particularly when mistletoe host races are distributed allopatrically.
Using sequence data from nuclear (ITS) and chloroplast (trnL-F) DNA, we
investigate the genetic differentiation of 31 Psittacanthus schiedeanus
(Loranthaceae) populations across the Mesoamerican species range. We
conducted phylogenetic, population and spatial genetic analyses on 274
individuals of P. schiedeanus to gain insight of the evolutionary history
of these populations. Species distribution modeling, isolation with
migration and Bayesian inference methods were used to infer the
evolutionary transition of mistletoe invasion, in which evolutionary
scenarios were compared through posterior probabilities. Results: Our
analyses revealed shallow levels of population structure with three
genetic groups present across the sample area. Nine haplotypes were
identified after sequencing the trnL-F intergenic spacer. These haplotypes
showed phylogeographic structure, with three groups with restricted gene
flow corresponding to the distribution of individuals/populations
separated by habitat (cloud forest localities from San Luis Potosí to
northwestern Oaxaca and Chiapas, localities with xeric vegetation in
central Oaxaca, and localities with tropical deciduous forests in
Chiapas), with post-glacial population expansions and potentially
corresponding to post-glacial invasion types. Similarly, 44 ITS ribotypes
suggest phylogeographic structure, despite the fact that most frequent
ribotypes are widespread indicating effective nuclear gene flow via
pollen. Gene flow estimates, a significant genetic signal of demographic
expansion, and range shifts under past climatic conditions predicted by
species distribution modeling suggest post-glacial invasion of P.
schiedeanus mistletoes to cloud forests. However, Approximate Bayesian
Computation (ABC) analyses strongly supported a scenario of simultaneous
divergence among the three groups isolated recently. Conclusions: Our
results provide support for the predominant role of isolation and
environmental factors in driving genetic differentiation of Mesoamerican
parrot-flower mistletoes. The ABC results are consistent with a scenario
of post-glacial mistletoe invasion, independent of host identity, and that
habitat types recently isolated P. schiedeanus populations, accumulating
slight phenotypic differences among genetic groups due to recent migration
across habitats. Under this scenario, climatic fluctuations throughout the
Pleistocene would have altered the distribution of suitable habitat for
mistletoes throughout Mesoamerica leading to variation in population
continuity and isolation. Our findings add to an understanding of the role
of recent isolation and colonization in shaping cloud forest communities
in the region.