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

Barrabé Laure, Lavergne Sébastien, Karnadi-Abdelkader Giliane, Drew Bryan T., Birnbaum Philippe, Gâteblé Gildas. 2019. Changing ecological opportunities facilitated the explosive diversification of New Caledonian Oxera (Lamiaceae). Systematic Biology, 68 (3) : 460-481.

https://doi.org/10.1093/sysbio/syy070

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Url - jeu de données - Entrepôt autre : https://doi.org/10.5061/dryad.mm1ft40

Quartile : Outlier, Sujet : EVOLUTIONARY BIOLOGY

Résumé : 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.

Mots-clés Agrovoc : biodiversité, phylogénie

Mots-clés géographiques Agrovoc : Nouvelle-Calédonie, France

Mots-clés libres : Adaptive radiation, Allopatry, Leapfrog radiation, Lamiaceae, New Caledonia, Niche Shifts, Oxera

Classification Agris : F70 - Taxonomie végétale et phytogéographie
F40 - Écologie végétale
F30 - Génétique et amélioration des plantes

Champ stratégique Cirad : CTS 1 (2019-) - Biodiversité

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