The diversification of butterfly wing patterns: progress and prospects

Butterfly wings display rich phenotypic diversity and are associated with complex biological functions, thus serving as an important evolutionary system to address the genetic basis and evolution of phenotypic diversification. We review recent butterfly studies that revealed complex functions underlying diversified wing patterns and describe the genetic and environmental factors involved in wing pattern determinations. These factors lead to inter-specific divergence, genetic polymorphism, and phenotypic plasticity, which in many cases are decided by several key genes. We also summarize the research advances on gene co-option as an important origin of functional complexity and evolutionary novelty. These findings reveal a pattern of evolutionary innovation within a constrained developmental framework during butterfly wing morphogenesis, but further research is required to gain a systematic and comprehensive understanding.