Relevant genetic changes in nature  have not yet been shown to alter the boundaries of existing genetic variation for any species. Further, a recent global analysis of 91 species found, on average, a 5.4-6.5% decline in genetic diversity within populations since the start of the Industrial Revolution, with much larger declines for island species  . In Leigh et al. , genetic declines were documented in both common and already endangered species of fish, mammals, birds, insects, amphibians and reptiles. These declines in genetic diversity, though not caused by climate change, decrease the abilities of wild species to adapt to climate change via evolutionary responses. Evolutionary rescue of entire species has not yet been observed in nature, nor is it expected, based on experimental and theoretical studies .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report