Correlates of snail shell variation along a unidirectional freshwater gradient in Lithasia geniculata (Haldeman, 1840) (Caenogastropoda: Pleuroceridae) from the Duck River, Tennessee, USA

Russell Minton, e-mail:

Department of Biological and Environmental Sciences, University of Houston Clear Lake, 2700 Bay Area Boulevard MC 39, 77058 Houston, USA

K. C. Hart, e-mail:

Department of Biological and Environmental Sciences, University of Houston Clear Lake, 2700 Bay Area Boulevard MC 39, 77058 Houston, USA

Riccardo Fiorillo, e-mail:

School of Science and Technology, Georgia Gwinnett, 1000 University Center Lane, 30043 Lawrenceville, USA

Christopher Brown, e-mail:

School of Science and Technology, Georgia Gwinnett, 1000 University Center Lane, 30043 Lawrenceville, USA

Phenotypic plasticity in snail shells is a well-documented phenomenon, specifically in freshwater species. In riverine taxa, shells respond to the unidirectional gradient of flow and depth as well as to predation by crushing predators. Using populations of Lithasia geniculata from the Duck River, Tennessee, USA, we examined environmental correlates of shell shape change and resistance to crushing along a riverine gradient. Shells were more globose, more robust, and more resistant to crushing forces downstream relative to upstream; these characteristics were correlated with river discharge and presence of molluscivorous fish. Size, however, did not have effects on shape nor crushing strength. These data are consistent with those observed in other snail species, and expand on our knowledge of potential fitness benefits and causes of plasticity in freshwater snail shells

Key words
river discharge; geometric morphometrics; phenotypic plasticity; crushing resistance; morphology

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Folia Malacologica (2018) 26: 95-102
First published on-line: 2018-06-05 00:00:00
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