Limited options for native goodeid fish simultaneously confronted to climate change and biological invasion

" The process by which climate warming promotes the invasive expansion of tropical and sub-tropical species is commonly studied within the niche conservatism framework, which ignores the possibility of rapid evolution of thermal niche. We demonstrate that competition with the tropical invasive Pseudoxiphophorus bimaculatus has led to thermal niche displacement in the temperate fish Girardinichthys multiradiatus. Data mining of field records indicates that temperature is the main factor determining which species is dominant, behavioural performance profiles confirmed thermal segregation of these species and laboratory trials demonstrate that G. multiradiatus co-occurring with P. bimaculatus has shifted their thermal optimum to a lower temperature. An exploration of the consequences of these processes under climate change using a thermodynamic model predicts increased frequency of P. bimaculatus with global warming. This reveals a dilemma facing temperate species confronting tropical competitors; the need to adjust their thermal niche to escape competition behind a shrinking cold barrier, a lose–lose situation given current climatic trends "