Meeting Abstract

49.2  Jan. 6  Impacts of food concentration and larval stage on incidence of cloning in Dendraster excentricus plutei MCDONALD, K.A.*; VAUGHN, D.; University of Washington, Friday Harbor Labs; University of Washington, Friday Harbor Labs kamcdon@u.washington.edu

Asexual reproduction confers efficient use of limiting resources. Some freshwater plankters undergo a shift in reproductive mode in response to environmental cues, capitalizing on ephemeral increases in food density. Studies have indicated that asexuality may be widespread in echinoderm planktonic larvae, but the ecology of larval cloning is largely unexplored. In this study we examine the impact of feeding on occurance and timing of cloning in larvae of the sand dollar Dendraster excentricus by varying (1) algal density, (2) duration of food availability, and (3) timing of availability relative to developmental stage. Initial results show effects of algal density and timing of food delivery on incidence of cloning in cultures of D. excentricus plutei. Cultures reared on high-food diets or exposed transiently to a high-food environment begin generating clones as primary larvae develop the third (posterodorsal) pair of larval arms. High-food pulses, in particular, rapidly result in uniform cultures of earlier-staged plutei. Rather than constituting a developmental rarity, cloning may occur early and often in D. excentricus cohorts when environmental conditions favor rapid growth.