Evidence for interspecific hybridization between exotic ‘Dam manel’ (Nymphaea × erangaeNymphaea nouchali Burm. f.) in Sri Lanka

Biological invasions are considered a serious threat to the biodiversity, and second only to habitat loss, but predicted to soon become the key cause of environmental degradation globally. In addition to competing with natives in natural habitats, another serious threat possessed by Invasive Alien Species (IAS) is their ability to hybridize with natives. The exotic violet flowered Nymphaea × erangae has been introduced to the country for ornamental purposes where it has got naturalized.  Now it is recognized as a silent invader in wetlands of the country. The revealing of Nymphaea populations with intermediate characters, both of the native N. nouchali and Nymphaea × erangae in the wetlands of the island raised the question of the occurrence of natural hybridization. The present study was carried out to investigate the event of natural hybridization between the native and the exotic using morphological data. Data collected from putative hybrids and pure populations of the two parents were subjected to multivariate statistical analyses. The results confirmed the identity of the populations with intermediate characters as hybrids between the native N. nouchali and Nymphaea × erangae, highlighting the importance of conserving the natural populations of the native, as hybridization with the exotic pose a threat to its genetic purity.