When biogeographical provinces collide: hybridization of reef fishes at the crossroads of marine biogeographical provinces in the Arabian Sea

Researchers have uncovered a significant hybrid hotspot at the Socotra Archipelago, where reef fishes from distinct marine biogeographical provinces—including the Red Sea, Gulf of Aden, Arabian Sea, western Indian Ocean, and Indo-Polynesian Province—interbreed. This study identifies 14 species from four reef fish families exhibiting hybridization, often involving a rare local species and a broadly distributed Indo-Pacific counterpart. Genetic analysis using mitochondrial and nuclear markers confirmed hybrid status in morphologically intermediate individuals, revealing unidirectional gene flow and fertile hybrids capable of forming breeding groups with parental species. The findings suggest that Socotra's unique biogeographical location, reef habitat, environmental conditions, and abundance disparities facilitate hybridization at an unprecedented rate compared to other marine regions.

DiBattista, J. D., Rocha, L. A., Hobbs, J.-P. A., He, S., Priest, M. A., Sinclair‐Taylor, T. H., Bowen, B. W., & Berumen, M. L. (2015). When biogeographical provinces collide: hybridization of reef fishes at the crossroads of marine biogeographical provinces in the Arabian Sea. Journal of Biogeography, 42(9), 1601–1614. Portico. https://doi.org/10.1111/jbi.12526