Discordant phylogenetic endemism patterns in a recently diversified Brassicaceae lineage from the Atacama Desert: when choices in phylogenetic and species distribution information matter

Aim: Phylogenetic endemism (PE) has become a useful estimator of
evolutionary history in conservation, given its capacity to estimate
diversity hotspots as the combination of phylogenetic diversity (PD) and
range size distributions of co-occurring taxa. However, potential
limitations could preclude a general assessment of PE, especially in the
presence of incongruent phylogenetic signals and the use of different
estimates of species distribution at fine spatial scales. Here, we assess
the utility of using PE in a recently diversified plant tribe. Location:
Atacama Desert, Argentina, Chile, and Peru. Taxon: Schizopetalae tribe
(Brassicaceae). Methods: We assessed PD and PE to determine whether
incongruent phylogenetic trees derived from nuclear and chloroplast DNA
and different estimates of species distribution (based on species
distribution modelling-SDM- and minimum convex polygons-MCP) impact the
location of PE hotspots. Results: Results show no influence from
discordant phylogenetic signal between gene trees on PE estimates.
Instead, the choice of the summary of species’ range (i.e., SDM or MCP)
has greater influence on the location of PE hotspots. Main conclusions:
Despite the observed discrepancies, results in PE accumulation are
congruent enough to support the use of this index in conservation-related
analyses for the Atacama Desert flora. Nonetheless, further analyses are
recommended to determine and contextualize the impacts of phylogenetic
incongruence and species distributional estimates on PE, especially when
other scenarios involving larger spatial and taxonomic sampling scales
remain unexplored.