Monster Seminar Jam - Chemical Cues and the Keystone Species Concept
Dr. Dick Zimmer, Department of Ecology and Evolutionary Biology, University of California, Los Angeles
The rocky intertidal has provided many textbook examples of predators regulating prey populations, such as the seminal works of Murdoch (1969), Paine (1966, 1974, 1976), Connell (1961, 1970), and others. Extraordinary at the time, and now, these inquiries demonstrated how interactions among relatively few species can disproportionately affect community structure. Completely unexplored, however, were the sensory mechanisms mediating predation and/or competition. How did whelks choose prey? How did seastars detect and find mussels? Building on these cornerstone studies, we conducted field and laboratory investigations on the chemosensory basis for keystone interactions in rocky-intertidal communities. Contact proteins, produced by barnacles for biomineralization, acted as pervasive chemical cues. Using fractions arising from size-exclusion, ion-exchange, and LCA-affinity chromatographies, the peak (~ 260 kDa glycoprotein complex) that triggered whelk (Acanthinucella spirata, Nucella emarginata, N. lapillus) predation also evoked settlement by barnacle larvae. Forces exerted by seastar (Pisaster ochraceous) tube feet on rocky substrata were enhanced significantly by protein additions from mussel (Mytilus californianus), but less so from additions from alternative prey (control) species. Combined, these findings lead to new insights about search tactics and their demographic consequences in rocky-intertidal habitats. They also suggest future research towards characterizing prey gene expression and cue production mediating predation risk. Ultimately, they show how contact chemosensory information can determine trait-mediated interactions, control trophic cascades, and therefore, structure natural communities.
Date and Time:
June 5, 2008,
10:30 am - 1:00 pm
206-860-3380 send email