The article by Warren, Glor, and Turelli explores the evolution of environmental niches and the concept of niche conservatism in species. They develop new methods to quantify niche overlap using traditional ecological measures and mathematical statistics, addressing conflicting conclusions in previous studies on niche conservation. The authors reanalyze a classic study of Mexican animals and introduce a framework to address different definitions of "niche conservatism." They find that environmental niches of sister species are more similar than expected under various null hypotheses but rarely identical. The study also examines the influence of niche conservatism on community structure, suggesting that it is not strongly constrained by phylogenetic distances. The results highlight the importance of treating niche conservation as a continuum and provide robust methods for comparing niche models, which can be applied to other areas of ecology and evolutionary biology.The article by Warren, Glor, and Turelli explores the evolution of environmental niches and the concept of niche conservatism in species. They develop new methods to quantify niche overlap using traditional ecological measures and mathematical statistics, addressing conflicting conclusions in previous studies on niche conservation. The authors reanalyze a classic study of Mexican animals and introduce a framework to address different definitions of "niche conservatism." They find that environmental niches of sister species are more similar than expected under various null hypotheses but rarely identical. The study also examines the influence of niche conservatism on community structure, suggesting that it is not strongly constrained by phylogenetic distances. The results highlight the importance of treating niche conservation as a continuum and provide robust methods for comparing niche models, which can be applied to other areas of ecology and evolutionary biology.