When Nature Decides who Stays and who Goes:Priority effects Extirpating the Non-Native Brown Trout Salmo Trutta fario L. Population from a Himalayan River

Climate-induced stochastic events bring forth idiosyncratic changes in habitat and community assemblage patterns of an area. Nature governs its priorities in such incidents, where native taxa are preferred over the invasive ‘late-comers’, thus leading to extirpation of the latter, according to the concept of ‘priority effects’¹. This stronghold of nature strictly comes into play when an ecosystem is least altered from its natural state. River Asiganga in Uttarakhand, India was chosen as a case study to understand this theory, where cloudburst-induced flash floods are considered to be a reason for the complete wipe-out of non-native brown trout (Salmo trutta fario), leaving behind the native snow trout (Schizothorax species).