Marie, A. D. | Search bioRxiv

bioRxiv2022

Where does the rainbow end? A case study of self-sustaining rainbow trout Oncorhynchus mykiss populations in tropical rivers

The great physiological, behavioral and morphological plasticity of salmonids contributed to the success of their introduction into a wide range of habitats. However, rainbow trout (Oncorhynchus mykiss) is the only salmonid species to live in the tropics. Like for any cold-water species, water temperature is assumed to be a major constraint to the presence and expansion of rainbow trout. In this study, we collected detailed records of the introduction history of rainbow trout at 35 sites across the island over 80 years, and we document the presence of self-sustainable trout at each site. We explored the linear relationship between water temperature and elevation.

ecology↗

bioRxiv2022

The invasive land flatworm Obama nungara in La Reunion, a French island in the Indian Ocean, the first report of the species for Africa

The land flatworm Obama nungara, a species originating from South America and already invasive in many European countries, is recorded from La Reunion, a French island in the Indian Ocean. This is the first record of O. nungara from this locality and also the first record of the species for Africa. Two specimens were collected, one from Petite France (commune of Saint Paul) and one from La Plaine des Gregues (commune of Saint Joseph); the two localities are widely separated, one in the Western part and one in the South-eastern part of the island. This suggests that the species is already present in several locations in La Reunion. The sightings were communicated to us in 2021, but it is likely that the species is already present since 2020. A molecular analysis of the specimen from Petite France showed that it had the same cox1 haplotype as specimens previously recorded from several countries of Europe; it is hypothesized that the species was imported from Europe, probably from France. We mapped climatic suitability of the species in La Reunion and found that O. nungara could potentially invade a large part of the island. One record was apparently associated with the transport of plates of travertine, a construction material which has numerous cavities, suitable for the transport and survival of adult or cocoons of land flatworms.

zoology↗