Recent advances in New Caledonian biogeography.

Area of Science:

• Biogeography and evolutionary biology.
• Geology and plate tectonics.
• Biodiversity and conservation.

Background:

• New Caledonia's biota is exceptionally diverse and endemic, with unique evolutionary affinities.
• The discovery of Amborella's phylogenetic position has spurred research into New Caledonia's biogeography.
• Ongoing debates question whether the biota survived marine transgressions or arrived via dispersal.

Purpose of the Study:

• To review recent molecular studies on New Caledonian biogeography published since 2013.
• To evaluate hypotheses explaining the region's unique biodiversity patterns, including endemism and absences.
• To explore the role of geological history and plate tectonics in shaping the biota.

Main Methods:

• Literature review of molecular studies and geological evidence.
• Analysis of biogeographic patterns in relation to geological events.
• Comparative analysis of biota across different terranes and islands.

Main Results:

• Geological evidence for complete marine submersion is limited.
• Vicariance due to tectonic activity, including accretion and rifting, better explains endemism and absences.
• The region's complex geological history, involving Gondwanan basement and accreted terranes, is key to its biogeography.

Conclusions:

• New Caledonia's biota is shaped by its complex geological history and vicariant events, not solely by long-distance dispersal after submersion.
• Tectonic processes at plate boundaries have created unique habitats and isolation, driving high endemism.
• Understanding these geological underpinnings is crucial for explaining the distribution and evolutionary trajectories of New Caledonia's unique flora and fauna.