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Abstract

Next article FreeAbout the CoverFull TextPDF Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinked InRedditEmailQR Code SectionsMoreCoverThe 30th plate from Ernst Haeckel's Kunstformen der Natur (Artforms of nature) (1904), pictured on the cover, depicts echinoids at various stages of development—planktonic larva, metamorphosed juvenile, and benthic adult. Echinoids, which include sand dollars and sea urchins, spend their earliest days as free-swimming larvae before metamorphosing and settling to the sea floor as juveniles. Larval mortality is estimated to be high in marine planktonic environments. Although the causes of mortality are poorly understood, predation is considered a significant source of mortality for the eggs, embryos, and larvae of marine organisms. With little protection and provisioning in an environment that cannot be accurately predicted from the mother's position on the sea floor, other mechanisms may have evolved to increase a larva's chance of surviving its time in the plankton. One mechanism that can counter the effects of “growing up” all alone in a risky and unpredictable environment is developmental plasticity, the ability to change in response to experience or environment. A particularly well-documented category of developmental plasticity is the defensive responses that exposure to predators can induce in prey organisms. Recent research documents an unusual predator-induced response in the pluteus larvae of the sand dollar Dendraster excentricus: cloning (asexual reproduction) and reduced larval size as consequence of cloning. The smaller than usual plutei are subsequently less vulnerable to some planktivorous predators. In this issue (pp. 103–114), Dawn Vaughn presents evidence that predator-induced cloning in D. excentricus plutei is influenced by maternity. Half-sibling plutei (three mothers, same father) were exposed to stimuli from predators (i.e., fish mucus) for 9 days during early development. Vaughn found that plutei of different mothers varied in the rate and frequency of cloning. Unexpectedly, all plutei exposed to fish mucus were smaller and developmentally delayed when compared to all plutei reared in the absence of mucus. The results from this study support the hypothesis that mothers have an influence on cloning of larval offspring; however, reduced larval size was a uniform response to fish mucus and did not indicate a maternal effect. The potential advantages conferred by successful larval cloning (i.e., the production of two larvae from one larva) may then differ among unrelated conspecifics, while the developmental effect of reduced size as a potential adaptation to predators is a consistent response shared by all larval conspecifics. Future research on cloning in echinoid larvae will benefit from further consideration of the influence of benthic mothers on their planktonic offspring and may provide additional insight into how developmental plasticity mediates the effects of developing in an unpredictable environment. Cover design: Beth Liles, Marine Biological Laboratory. Next article DetailsFiguresReferencesCited by The Biological Bulletin Volume 217, Number 2October 2009 Published in association with the Marine Biological Laboratory Article DOIhttps://doi.org/10.1086/BBLv217n2cover Views: 71 © 2009 by Marine Biological Laboratory. All rights reserved. Crossref reports no articles citing this article.