ALAN KOHN
University of Washington, Department of Biology

Killer Snails—Killer Diversity: Comparative Biology of the Most Diverse Marine Genus

Abstract

Comparative biological study of species-rich taxa can generate insights into the evolutionary origin and maintenance of biodiversity. I will recount highlights of a half century in the company of beautiful but venomous and deadly denizens of the south seas, the hyperdiverse, mainly tropical gastropod genus Conus. I will raise (but not answer all of) the following questions:

1. The very large number of species (>500) and geologic youth (~55my) of Conus indicate very rapid rates of speciation. When, where, and how did all these speciation events take place?
2. What anatomical, molecular, ecological, and developmental attributes might foster rapid
   diversification?
3. In addition to high general species richness (? diversity), many species co-occur at finer spatial scales (? diversity: up to 36 species on a single coral reef). Do these species avoid competition by partitioning resources, and if so, how?
4. In contrast, few species co-occur in other habitats. Why do some environments support many species, and others few or only one?
5. How are species-level phylogenetic hypotheses, available only recently from gene sequence data, affecting our understanding of comparative biology?

Background

The general aim of my research is to increase understanding of the evolutionary processes that have led to high biotic diversity in tropical marine environments. Its more specific goal is to elucidate important evolutionary trends in diversity, morphology, distribution, and ecology of one of the largest families of marine molluscs, the Conidae, from its early Cenozoic origin through the Tertiary and Quaternary periods. The focal genus Conus is particularly important because of its immense size (about 500 extant and at least as many extinct species), its extensive range of variation in diversity, geographic distribution, ecology, and development, and its highly neurotoxic venoms. Current research efforts emphasize the evolution of taxonomic diversity, Tertiary marine paleoecology, and relationships between larval developmental mode and biogeographic patterns.

Prior to my retirement, some of my graduate students addressed similar questions in their research, but most developed independent studies in diverse areas of functional morphology, ecology and distribution of a variety of local as well as tropical marine invertebrates. Currently, a postdoctoral researcher is using molecular genetic methods to generate hypotheses of the phylogenetic relationships of Conus species. Undergraduates in the lab are studying shell and radular tooth morphometrics. These data will be used to better understand the feeding process in Conus and to test phylogenetic hypotheses resulting from the gene sequences.

Select Publications

Kohn, A.J. Comparative biology of Conus in the light of phylogeny: a preliminary report. Boll. Malacol. Suppl. 4: 37-42, 2002.

Kohn, A.J. Maximal species richness in Conus: diversity, diet and habitat on reefs of northeast Papua New Guinea. Coral Reefs, 20: 25-38, 2001.

Duda, T.F. Jr., A.J. Kohn, and S.R. Palumbi. Origins of diverse feeding ecologies within Conus, a genus of venomous marine gastropods. Biol. Jour. Linn. Soc. London, 73: 391-409, 2001.

Kohn, A.J. and I. Arua (1999) An early Pleistocene molluscan assemblage from Fiji: gastropod faunal composition, paleoecology and biogeography. Palaeogeogr., Palaeoclimatol., Palaeoecol., 46: 99-145.

Kohn, A.J. (1999) Anti-predator defences of shelled gastropods. In: Functional morphology of the invertebrate skeleton, E. Savazzi, ed. John Wiley and Sons, Chichester, pp. 169-181.

Kohn, A.J., M. Nishi and B. Pernet (1999) Snail spears and scimitars: A character analysis of Conus radular teeth. Jour. Moll. Studies 68: 461-481.

Catalogue of Recent and Fossil Conus, 1937-2000. www.biology.washington.edu/akohn/