Hyper-cryptic radiation of a tropical montane plant lineage

Species are seen as the fundamental unit of biotic diversity, and thus
their delimitation is crucial for defining measures for diversity
assessments and studying evolution. Differences between species have
traditionally been associated with variation in morphology. And yet, the
discovery of cryptic diversity suggests that the evolution of distinct
lineages does not necessarily involve trait differences. Here, we analyze
1,684,987 variant sites and over 4000 genes for more than 400 samples to
show how a tropical montane plant lineage (Geonoma undata species complex)
is composed of numerous unrecognized genetic groups that are not
morphologically distinct. We find that 11 to 14 clades do not correspond
to the three currently recognized species. Most clades are genetically
independent and geographic distance and topography are the most important
factors determining this genetic divergence. This lineage does not match
the model of an adaptive radiation, but instead, constitutes the first
example of a hyper-cryptic plant radiation in tropical mountains.