Polymorphism in Marine Mollusks and Biome Development

Clarke, Arthur H. Polymorphism in Marine Mollusks and Biome Development. Smithsonian Contributions to Zoology, number 274, 14 pages, 5 figures, 1978.—Many arctic marine mollusks exhibit much greater intraspecific variation in shell shape and sculpturing and greater interspecific morphological overlap than temperate or tropical species of the same families. Tropical marine mollusks ordinarily exhibit more pronounced interspecific morphological distinctness in mixed-species communities and more remarkable intraspecific polychromatism in single-species dominated communities than their temperate or arctic relatives. A number of groups do not exhibit any variability shifts with latitude but shifts opposite to those here described have not been observed. Changes in the nature and intensity of natural selection, which are deemed to occur with increased biome maturation, appear to account for these morphological trends . OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. SERIES COVER DESIGNThe coral Montastrea cavernosa (Linnaeus). Library of Congress Cataloging in Publication Data Clarke, Arthur Haddleton, 1926Polymorphism in marine mollusks and biome development. (Smithsonian contributions to zoology ; no. 274) Bibliography; p. 1. Mollusks—Arctic regions. 2. Mollusks—Tropics. 3. Polymorphism (Zoology) 4. Animal societies. 5. Marine ecology. I. Title. II. Series: Smithsonian Institution. Smithsonian contributions to zoology ; no. 274. Q1.S54 no. 274 [QJL429] 591'.08s [594'.09'28] 77-16821