ALBERT

Description: A bstract We used 57 morphometric characters to discriminate 17 extant and fossil Cupuladria species and analyzed their phylogenetic relationships in relation to extant Discoporella species. Data were gathered from 496 extant and fossil Cupuladria specimens ranging in age from early Miocene to Recent and distributed from the Caribbean to tropical eastern Pacific. A first series of discriminant analyses distinguished three morphological groups: Cupuladria with vicarious avicularia, Cupuladria without vicarious avicularia, and Discoporella . Further discriminant analyses identified 17 species of Cupuladria . Cladistic analyses of these three groups yielded four equally parsimonious trees. All of the consensus trees exhibited the same topology, dividing the 25 tropical American cupuladriids into four distinct monophyletic clades, including Discoporella , and are consistent with previous molecular phylogenies except that there are no molecular data for the C V2 clade. Diversification of species was higher in the C V1 and C V2 clades than C NV clade, and involved mostly Caribbean species. Cupuladria with vicarious clade 1 (C V1 ) includes: C. monotrema , C. pacificiensis , C. exfragminis , C. cheethami , C. biporosa , and four new species: C. pervagata , C. floridensis , C. colonensis and C. dominicana . Cupuladria with vicarious clade 2 (C V2 ) includes: C. multesima , C. incognita , and three new species C. collyrida , C. veracruxiensis and C. planissima . Cupuladria clade without vicarious (C NV ) includes: C. surinamensis , C. panamensis , and one new species C. gigas . The stratigraphic occurrence of species is consistent with cladogram topology within clades. However hypothesized cladistic relations among clades are the reverse of their stratigraphic occurrence with younger clade C NV appearing as the hypothetical ancestor of the two older clades C V1 and C V2 . More extensive collections of early to middle Miocene specimens of Cupuladria and Discoporella will be required to resolve this apparent paradox.

Description: Changes in the physical environment are major drivers of evolutionary change, either through direct effects on the distribution and abundance of species or more subtle shifts in the outcome of biological interactions. To investigate this phenomenon, we built a fossil data set of drilling gastropod predation on bivalve prey for the last 11 Myr to determine how the regional collapse in Caribbean upwelling and planktonic productivity affected predator–prey interactions. Contrary to theoretical expectations, predation increased nearly twofold after productivity declined, while the ratio of drilling predators to prey remained unchanged. This increase reflects a gradual, several-fold increase in the extent of shallow-water coral reefs and seagrass meadows in response to the drop in productivity that extended over several million years. Drilling predation is uniformly higher in biogenic habitats than in soft sediments. Thus, changes in predation intensity were driven by a shift in dominant habitats rather than a direct effect of decreased productivity. Most previous analyses of predation through time have not accounted for variations in environmental conditions, raising questions about the patterns observed. More fundamentally, however, the consequences of large-scale environmental perturbations may not be instantaneous, especially when changes in habitat and other aspects of local environmental conditions cause cascading series of effects.