Recent evolutionary radiations such as Darwin’s finches, East African cichlids or Heliconius butterflies have served as model systems to understand how novel variation and new species arise. These systems, clearly in the early stages of divergence, have stimulated research into the behavioral, ecological, and genetic bases of reproductive isolation that have arguably transformed our understanding of the origins of biodiversity. However, no analogous classic radiation comes to mind in the largest ecosystem on earth, the ocean. The overarching goal of our research is to develop the hamlets (Hypoplectrus spp, Serranidae, photographs below), simultaneously hermaphroditic reef fishes from the wider Caribbean, into a model system for the study of marine speciation.
The hamlets are diverse, with a variety of color patterns and geographic distributions that provide the opportunity to repeat comparisons both taxonomically and geographically. They encapsulate the entire spectrum of divergence, from genomic similarity to well-diverged species. Mate choice and spawning can be directly observed in the field throughout the year, providing a handle on reproductive isolation which surpasses nearly any other marine group for the sheer number and quality of behavioral observations that can be made in natural populations. Color pattern has been identified as an important ecological trait that is also used for mate choice, and specific hypotheses regarding the role played by natural and sexual selection in speciation have been developed. Finally, a number of genomic resources are available for the group.