Data from: Changing ecological opportunities facilitated the explosive diversification of New Caledonian Oxera (Lamiaceae)

Phylogenies recurrently demonstrate that oceanic island systems have been
home to rapid clade diversification and adaptive radiations. The existence
of adaptive radiations posits a central role of natural selection causing
ecological divergence and speciation, and some plant radiations have been
highlighted as paradigmatic examples of such radiations. However, neutral
processes may also drive speciation during clade radiations, with
ecological divergence occurring following speciation. Here we document an
exceptionally rapid and unique radiation of Lamiaceae within the New
Caledonian biodiversity hotspot. Specifically, we investigated various
biological, ecological and geographical drivers of species diversification
within the genus Oxera. We found that Oxera underwent an initial process
of rapid cladogenesis likely triggered by a dramatic period of aridity
during the early Pliocene. This early diversification of Oxera was
associated with an important phase of ecological diversification triggered
by significant shifts of pollination syndromes, dispersal modes, and life
forms. Finally, recent diversification of Oxera appears to have been
further driven by the interplay of allopatry and habitat shifts likely
related to climatic oscillations. This suggests that Oxera could be
regarded as an adaptive radiation at an early evolutionary stage that has
been obscured by more recent joint habitat diversification and neutral
geographical processes. Diversification within Oxera has perhaps been
triggered by varied ecological and biological drivers acting in a leapfrog
pattern, but geographic processes may have been an equally important
driver. We suspect that strictly adaptive radiations may be rare in plants
and that most events of rapid clade diversification may have involved a
mixture of geographical and ecological divergence.