The invasive Celastrus orbiculatus has impacts on the native C. scandens through hybridization in the USA
Celastrus orbiculatus (Celastraceae – EPPO A2 List) is a fast-growing woody vine species native to East Asia (China, Central and North Japan, Korean Peninsula and Far East Russia). The species is invasive in North America where is has spread extensively in the Eastern part of the USA and it has been observed to have impacts on native biodiversity and associated ecosystem services. In the EPPO region, C. orbiculatus is reported in a number of countries and it is established in Lithuania and Poland. In the USA, C. orbiculatus can grow in similar areas and habitats to the native C. scandens. In these areas, there has been a decline in C. scandens occurrence while C. orbiculatus has shown an increase, especially in areas with older C. orbiculatus populations. Both species have been shown to be able to hybridize though asymmetrical hybridization with pollen coming primarily from C. orbiculatus. In North-Western Indiana (US), field studies showed that C. orbiculatus had an extreme advantage in both male and female floral production, producing nearly 200 times more flowers per staminate plant and 65 times more flowers per pistillate plant than the native species. Such hybridization between native and invasive species can act to reduce the reproductive effort of the native one. Using nuclear microsatellite DNA markers, it was shown that 39% of the C. scandens seeds were hybrids, compared to only 1.6% of C. orbiculatus seeds. In areas where such species overlaps occur, management of the invasive species should be a priority to reduce the impact on the native species.
Sources
Zaya DN, Leicht-Young SA, Pavlovic NB, Ashley MV (2021) Heterospecific pollination by an invasive congener threatens the native American bittersweet, Celastrus scandens. PLoS ONE 16(3), e0248635.