Meeting Abstract

9.5  Monday, Jan. 4  Community ecology, evolution, and molecules of keystone significance FERRER, RP*; ZIMMER, RK; Seattle Pacific University; University of California, Los Angeles ferrer1@spu.edu

The keystone species concept is seminal in ecological theory. It involves species whose impacts on communities are far greater than would be predicted from their relative abundances or biomasses. Similarly, select neuroactive compounds function in keystone roles. They are rare within natural habitats but connect such seemingly disparate processes as microbial loop dynamics and apex predation. Outstanding examples draw on four distinct sets of compounds: dimethylsulfoniopropionate (DMSP and metabolites), tetrodotoxin (TTX and its precursor, arginine), saxitoxin (STX), and pyrrolizidine alkaloids (PAs). Introduced into a respective community by one, or only a few, autotrophic or microbial species, these molecules originally function in chemical defense. When borrowed by resistant consumer species, however, they are used either in chemical defense against higher-order predators, or as chemosensory cues that elicit courtship and mating, alarm, and predatory search. Requisite to these multifunctional properties, biosynthetic capacity first evolves with mechanisms for autoimmunity and/or toxin storage in primary producers. Subsequently, consumers evolve resistances or tolerances, and the toxins are transferred through food webs via trophic interactions. In consumers, mechanisms develop for recognizing toxins as feeding cues, and eventually as signals or pheromones in chemical communication within, or between, species. Through convergent evolution, one, or a few, neuroactive compounds thus inform phylogenetically diverse species in a given community. These select molecules initiate major direct and indirect effects, causing potent reverberations and structuring respective communities within terrestrial, freshwater, coastal-ocean and open-ocean habitats.