Island populations have significantly less genetic variation than mainland populations, according to a study analyzing data on allozymes, nuclear DNA markers, mitochondrial DNA, inversions, and quantitative traits. The study found that 165 out of 202 comparisons showed lower genetic variation in island populations, with an average reduction of 29%. This trend was consistent across various measures, including genetic variation in endemic species, which showed lower variation than nonendemic island species in mammals and birds but not in insects. The reduced genetic variation in island populations is attributed to factors such as small population size, limited dispersal, and founder effects. Genetic variation is crucial for evolutionary adaptation to environmental changes, and its loss in island populations increases their vulnerability to extinction. The study concludes that genetic factors contribute to the higher extinction rates of island populations compared to mainland ones.Island populations have significantly less genetic variation than mainland populations, according to a study analyzing data on allozymes, nuclear DNA markers, mitochondrial DNA, inversions, and quantitative traits. The study found that 165 out of 202 comparisons showed lower genetic variation in island populations, with an average reduction of 29%. This trend was consistent across various measures, including genetic variation in endemic species, which showed lower variation than nonendemic island species in mammals and birds but not in insects. The reduced genetic variation in island populations is attributed to factors such as small population size, limited dispersal, and founder effects. Genetic variation is crucial for evolutionary adaptation to environmental changes, and its loss in island populations increases their vulnerability to extinction. The study concludes that genetic factors contribute to the higher extinction rates of island populations compared to mainland ones.