Ever since the era of Darwin, adaptive evolution has been a cornerstone of evolutionary biology. One essential related question is do animals adapt similarly to a shared environments? Indeed, scientists have long ago observed that animals usually evolve similar phenotypes in similar environments, and thus formulated classic ecogeographical rules, as e.g., "Bergmann's Law," "Allen's Law," and "Gloger's Law." These discoveries have led to a long-term hypothesis that adaptive evolution of phenotype to similar environments is convergent to a high degree. View the full article