Adaptive potential and signatures of natural selection in the globally introduced ringneck parakeet Psittacula krameri

Anthropogenic impact, through animal trade, climate change, habitat fragmentation and globalisation, is a principal cause of global species redistributions and community rearrangements. Species introduced accidently or intentionally to non-native ranges may adapt to survive and proliferate, and native species threatened by environmental change may need to adapt in situ, or track more tolerable conditions through extra-range dispersal. Under both scenarios, we must facilitate greater understanding of the mechanisms that underlie adaptation within a complexity of ecosystem dynamics, which in turn will inform management strategies for both introduced species, and preserving biodiversity. Here, I explore mechanisms that support adaptive potential to rapid environmental change across taxa, and model them to the introduced ringneck parakeet Psittacula krameri. This species has recently successfully traversed extensive climate gradients in establishing introduced global populations. Some of this success may be attributable to morphological, behavioural, physiological or phenological adaptations, and therefore the species represents an opportunity for exploring rapid adaptation. I initially review the navigation of dispersal and invasive pathways, and the importance of specific character traits toward adaptive potential, before identifying genetic and non-genetic adaptive mechanisms (pertinent across taxa) that may help explain observed establishment and population growth of the ringneck parakeet. Mutations as the basis for an evolutionary adaptive response are examined, alongside the significance that the origin and extent of such polymorphisms may have toward a rapid adaptive response. I consider the role of selective sweeps and polygenic models as genetic processes for an adaptive response, alongside non-genetic mechanisms such as phenotypic plasticity and epigenetics that may better support rapid adaptation. Finally, I assess avian literature to interpret genetic and plastic responses as explanations for adaptive potential