PRICE, R. M.; Univ. of Chicago: Ornamentation in neogastropods is surprisingly constant in the northern hemisphere of the Eastern Pacific

Shell ornamentation is thought to be more common and more elaborate in tropical neogastropod species than in cold water species. To test this hypothesis, I quantified ornamentation in neogastropods across latitudes. I coded the presence of thirty-four characters that describe ornamentation (23 external and 11 internal, that is, in the aperture) from 659 species in the Roy, Jablonski, and Valentine database that records the latitudinal ranges of neogastropods in the northern hemisphere of the Eastern Pacific. For each species, I scored external and internal ornamentation according to the number and strength of characters present in each category. Interestingly, neither the proportion of species with high external ornamentation scores nor the median external ornamentation score changes across latitudes, so I reject the hypothesis with respect to external ornamentation. This surprising result is due in part to the fact that species with elaborate ornamentation are exceedingly rare in the Eastern Pacific; only four species, for example, have long spines. The median internal ornamentation score does decrease in temperate latitudes. The internal score for species restricted to temperate latitudes is significantly lower than in those found only in the tropics (Mann-Whitney U, P < 0.00). However, species restricted to the tropics do not differ from those with ranges that extend over both tropical and temperate latitudes nor from species occurring in tropical, temperate, and boreal latitudes. Thus, internal ornamentation is more common and more elaborate in species whose ranges extend into the tropics. These results differ from previous inferences about ornamentation that were derived from Indo-West Pacific faunas, implying a longitudinal, as well as a latitudinal, trend across the Pacific.