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 Hawa...