Journal
JOURNAL OF BIOGEOGRAPHY
Volume 40, Issue 11, Pages 2167-2179Publisher
WILEY
DOI: 10.1111/jbi.12155
Keywords
Barcoding; connectivity; conservation biogeography; coral reef biodiversity; demographic expansion; evospots; Ophiuroidea; palaeoclimates; refugia; speciation
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Funding
- French Agence Nationale de Recherche (programme BIOTAS) [ANR-06-BDIV-002]
- National Science Foundation [NSF DEB-0529724]
- African Coelacanth Ecosystem Programme II
- University of Pretoria
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AimThe global biodiversity crisis requires the identification of regions with high evolutionary potential, i.e. evolutionary hotspots (evospots). We created an analytical framework based on comparative phylogeography and coalescent methods to assess the dynamics of diversification and population persistence in the reef ecosystem of a little-studied region: the Southwestern Indian Ocean (SWIO). LocationCoral reefs of the SWIO, with comparative data from the Pacific Ocean. MethodsWe generated sequences of mitochondrial DNA (COI and 16S) for 10 widespread brittle-stars (345 specimens) from 21 localities (8 in the SWIO). We analysed them by combining comparative phylogeography approaches, coalescent-based methods, molecular clocks and the concept of evolutionarily significant units (ESUs) to draw conclusions about the drivers of biodiversity in the region. ResultsCryptic diversity was prevalent, increasing lineage diversity within the 10 nominal species by 70% within the SWIO and by 200% across the Indo-West Pacific. All seven new SWIO lineages meet the criteria for ESUs and at least six are biological species. We detected likely intraregional diversifications dating to the Plio-Pleistocene, supporting the SWIO as a generator of biodiversity. Geographical restriction of ESUs, long coalescent times (>80ka) and old in situ diversification (>1Ma) point to the persistence of populations over multiple glacio-eustatic cycles. We provide data suggesting demographic expansion during sea-level high stands. Regional connectivity was lower, and cryptic differentiation higher in lecithotrophs than in planktotrophs. Main conclusionsThe analytical framework based on a biodiversity survey makes it possible to identify evospots by assessing the potential of a region to maintain and generate biodiversity and by evaluating the evolutionary processes and potential drivers at play.
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