Long-term cloud forest response to climate warming revealed by insect speciation history

Montane cloud forests are areas of high endemism, and are one of the more
vulnerable terrestrial ecosystems to climate change. Thus, understanding
how they both contribute to the generation of biodiversity, and will
respond to ongoing climate change, are important and related challenges.
The widely accepted model for montane cloud forest dynamics involves
upslope forcing of their range limits with global climate warming.
However, limited climate data provides some support for an alternative
model, where range limits are forced downslope with climate warming.
Testing between these two models is challenging, due to the inherent
limitations of climate and pollen records. We overcome this with an
alternative source of historical information, testing between competing
model predictions using genomic data and demographic analyses for a
species of beetle tightly associated to an oceanic island cloud forest.
Results unequivocally support the alternative model: populations that were
isolated at higher elevation peaks during the Last Glacial Maximum are now
in contact and hybridising at lower elevations. Our results suggest that
genomic data is a rich source of information to further understand how
montane cloud forest biodiversity originates, and how it is likely to be
impacted by ongoing climate change.