Niche Occupation and Rapid Adaptation Mechanisms of Invasive Guppies in Polluted Water Bodies

Freshwater ecosystems are facing a global biodiversity crisis and biological invasion crisis at the same time. The guppy (Poecilia reticulata) is one of the most invasive fish species worldwide. It can successfully live in polluted water, providing a good model for studying eco-evolutionary processes of rapid adaptation and ecological niche occupation. This paper reviews the progress of ecological niche occupation and rapid adaptation mechanisms of invasive guppies in polluted waters. Existing research shows that the guppy can have its native range from South America to almost 70 countries in the world, and it often affects native species, such as resource competition, reproductive interference and changes in ecological functions. A polluted environment is conducive to rapid adaptation of guppy with multi-level, including life-history characteristics (transformation to an r-selection strategy), sexually selected characteristics (change and microevolution of sexually selected characteristics such as ornamental colors), the molecular-level variation or response (for example, CYP1A gene selection, transcriptome changes).On the other hand, the rapid adaptation of guppies, in turn, favours their niche occupation, giving rise to a positive feedback loop of "pollution→adaptation→invasion persistence". Currently, this field still has deficiencies in the balance of geographic coverage and the degree of contributions from phenotypic plasticity and genetic adaptation. This paper suggests that future studies should strengthen the cross-regional comparison and utilize genomic methods to integrate with field ecological observations to provide a scientific basis for the governance of invasion of polluted waters.