Data from: Phylogenetic diversity of two geographically overlapping species in the lichen genus Sticta (Ascomycota: Peltigeraceae): Isolation by distance, environment, or fragmentation?

Aim: To test whether the degree of phylogenetic diversity differs in two
congeneric, morphologically similar lichens that are both widespread and
with a similar geographical range (Neotropics and Hawaii), but differ in
altitudinal and habitat preferences, and whether the two species underwent
isolation by distance (IBD), environment (IBE), or fragmentation (IBF).
Location: South and Central America, Caribbean, Hawaii, Azores. Taxon:
Sticta (Peltigeraceae). Methods: Analysis of 395 specimens across the
study area; ITS barcoding marker; maximum likelihood tree reconstruction
within a broad taxonomic framework; TCS haplotype networks; Mantel test of
genetic vs. geographic, environmental, and fragmentation distances;
statistical comparison of BIOclim variables. Results: Sticta andina
exhibited high phenotypic variation and high reticulate phylogenetic
diversity across its range, whereas the phenotypically more uniform S.
scabrosa contained two main haplotypes, one unique to Hawaii (subsp.
hawaiiensis). Sticta andina was restricted to well-preserved andine
forests and paramos, habitats fragmented due to disruptive topology,
whereas S. scabrosa was found in lowland to lower montane forests in
rather exposed microsites, representing a more continuous habitat. These
differences were statistically significant for several BIOclim variables.
Mantel tests on genetic vs. geographic and environmental distances
demonstrated that S. scabrosa followed a pattern of IBD across its full
range but not within continental Central and South America. In contrast,
S. andina did not exhibit IBD but showed weak, yet significant patterns of
IBE at continental level and IBF in the northern Andes. Main Conclusions:
Autecology indirectly drives phylogenetic diversity in the two studied
species. In the low altitude species, S. scabrosa, phylogenetic diversity
is low and shows no correlation with geographic or environmental
distances, except for the differentiation of the Hawaiian subspecies. We
attribute this to rapid expansion and effective gene flow between
populations across a more or less continuously distributed niche
representing partially exposed microsites, including disturbed and
anthropogenic vegetation, such as planted trees. In contrast, in the high
altitude species, S. andina, phylogenetic diversity is high and correlated
with both environmental niche differentiation (IBE) and fragmentation
caused by the final Andean uplift (IBF). Therefore, an autoecological
preference for high altitudes increases the likelihood for higher
phylogenetic diversity.