Using genomic data to revisit an early example of reproductive character displacement inHaitianAnolislizards

AbstractThe pattern of reproductive character displacement (RCD)—in which traits associated with reproductive isolation are more different where two species occur together than where they occur in isolation—is frequently attributed to reinforcement, a process during which natural selection acting against maladaptive mating events leads to enhanced prezygotic isolation between species or incipient species. One of the first studies ofRCDto include molecular genetic data was described 40 years ago in a complex of Haitian trunk anole lizards using a small number of allozyme loci. In this example,Anolis caudalisappears to experience divergence in the color and pattern of an extensible throat fan, or dewlap, in areas of contact with closely related species at the northern and southern limits of its range. However, this case study has been largely overlooked for decades; meanwhile, explanations for geographic variation in dewlap color and pattern have focused primarily on adaptation to local signalling environments. We reinvestigate this example using amplified fragment length polymorphism (AFLP) genome scans, mtDNAsequence data, information on dewlap phenotypes andGISdata on environmental variation to test the hypothesis ofRCDgenerated by reinforcement in Haitian trunk anoles. Together, our phenotypic and genetic results are consistent withRCDat the southern and northern limits of the range ofA. caudalis. We evaluate the evidence for reinforcement as the explanation forRCDin Haitian trunk anoles, consider alternative explanations and provide suggestions for future work on the relationship between dewlap variation and speciation inHaitian trunk anoles.