Molecular Ecology and Evolution
Sun , Mei .
Molecular identification of hybridization and introgression in Bruguiera (Rhizophoraceae).
Biodiversity of mangrove ecosystems is difficult to assess, at least partially due to the lack of genetic verification of morphology-based documentation of species. In addition to convergent evolution in morphology, the frequent appearance of new taxonomic entities through natural hybridization may also have contributed to the difficulty in identifying mangrove species. For example, morphological intermediates between sympatric Bruguiera gymnorrhiza and Bruguiera sexangula have been reported as a variety of B. sexangula or a new hybrid species, B. × rhynchopetala. Molecular markers can assist in biodiversity assessment by helping identify hybridization and define species boundaries. This study investigated natural hybridization and introgression in Bruguiera over a wide geographical distribution in the Indo-West Pacific region, including population samples from four mangrove forests located in the coastal regions of Hainan Island of China, north Sulawesi of Indonesia, and north Australia. A large number of species-specific inter-simple sequence repeat (ISSR) markers were found in B. gymnorrhiza and B. sexangula, and the ISSR profiling of B. × rhynchopetala revealed genomic additivity of a hybrid. Principle coordinate analysis (PCO) could separate the hybrids from parental species in all geographical locations, but the hybrid individuals varied in their positioning in the PCO scatter plots both within and between populations, suggesting that B. × rhynchopetala encompassed different generations of introgressants in addition to F1s. High genetic identity between B. × rhynchopetala and B. gymnorrhiza within each geographical location suggested a unidirectional introgression or preferential hybrid backcrosses to B. gymnorrhiza. Based on molecular data, it can be concluded that B. × rhynchopetala has not evolved into a new hybrid species, and its persistence in mangrove forests can be explained by recurrent hybridization and introgression.
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1 - University of Hong Kong, School of Biological Sciences, Pokfulam Road, Hong Kong, Hong Kong SAR, China
Presentation Type: Poster:Posters for Topics
Location: Event Tent/Cliff Lodge
Date: Tuesday, July 28th, 2009
Time: 5:30 PM