Perhaps the most remarkable pattern of living things on the planet is the increase in biological diversity towards the equator. Such latitudinal diversity patterns occur in both the terrestrial and marine environments. Since I was a child, I always wanted to know why things are the way they are. When I found out there are no conclusive explanations for this question, I set out to tackle one small group of this puzzle.
      I chose cowries, a well-known and heavily collected group of marine snails. The beauty of their shells and the animal itself comes as a bonus. I picked cowries because a lot was already known about them. Pretty much all species are described, meaning that when you go to the next island or biogeographic region you are not going to all of a sudden discover ten or fifty new species you have to account for. Also, their diversity profile (as seen below) is similar to other diversity contours for more diverse groups that are too large to comprehensively sample. People had studied their fossil record, their morphology and anatomy. I decided I could contribute a molecular phylogeny for the group. With this framework of relationships, I can determine the historical branching patterns and the relative timing of divergences. Hopefully, cowries can be used as a model group to investigate the roles of various speciation mechanisms in generating the remarkable tropical marine diversity.