World Congress of Malacology Antwerp ... - Unitas Malacologica

techniques would have greatly inflated dispersal rates, as these cryptic snails appear to exhibit several
types of site fidelity and homing capability. Meteorological data loggers were also deployed when
tracking began to look for an association between snail movement and weather fluctuations; the
resultant data strongly indicate passive wind dispersal for more distant snail movements. These
tracking and weather data will soon be integrated with a large CMR dataset and genetic assignment
tests to obtain reliable dispersal rate estimates. The results of these studies emphasize the importance
of employing multiple methods to study dispersal.
Origin and early radiation of the Neogastropoda:
Evidence from nuclear and mitochondrial genes
Harasewych, M. G.
Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology,
P.O. Box 37012, MRC 163, Washington DC, 20013-7012,
Email: Harasewych@si.edu
The Neogastropoda are a extremely diverse and successful group of predators that first appeared
abruptly in the fossil record of the Cretaceous. Neogastropods now comprise a significant component
of every benthic marine community (intertidal to hadal, tropical to polar) and several lineages have
invaded freshwater habitats. Because of the rapid proliferation of lineages, each with tendencies to
modify organ systems in parallel fashions, relatively few morphological characters originating during
the initial radiation have been identified, each uniting small subsets of higher taxa, while leaving
relationships among the remaining families unresolved. The absence of congruent patterns of
character distributions in the major organ systems have frustrated initial attempts at phylogenetic
inference using morphological characters. More recently, studies using DNA sequences of several
mitochondrial genes have shown these genes to be powerful and appropriate tools capable of
resolving relationships among families, genera and species of Neogastropoda.
Representatives of fifteen families of neogastropods, as well as of the various hypothesized sister
taxa have been sequenced for mitochondrial and nuclear genes. Phylogenies based on these genes,
individually and in combination are used to provide insight into the origins and early divergences
within the Neogastropoda.
The Cerion land snails of Long Island, Bahamas:
New insights into the relationships and origins of a dynamic fauna
Harasewych, M. G. 1 ; Goodfriend, G.A. 2 ; Gould, S. J. 3
1. Smithsonian Institution, National Museum of Natural History, Department of Invertebrate
Zoology, P.O. Box 37012, MRC 163, Washington DC, 20013-7012,
Email: Harasewych@si.edu
2. Department of Earth and Environmental Sciences, George Washington University, Washington,
DC 20052 (†)
3. Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138 (†)
Land snails of the family Cerionidae are endemic to islands of the tropical western Atlantic, ranging
from the barrier islands and keys of southern Florida, throughout the Bahamas, Greater Antilles,
Cayman Islands, western Virgin Islands, and the Dutch Antilles. These snails live within a few
hundred meters of the shore and form dense but patchy colonies. Variation in shell morphology
among colonies can be enormous, not only throughout the geographic range of Cerion, but even
among neighboring populations separated by less than 100 meters. This lavish yet geographically
circumscribed morphological diversity has led to the description of roughly 600 nominal species,
despite the fact that most will interbreed. There is only a single documented case of two species of
Cerion living in sympatry. The greatest diversity of Cerion occurs on Cuba and in the islands of the
Bahamas. However, most the present range of the genus, including southern Florida and many of the
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