title: Substrate color-induced melanization in eight turtle species from four chelonian groups.
abstract: Background color convergence of prey occurring through local adaptation or phenotypically plastic responses can reduce predation rates by visual predators. We assessed the capacity for substrate color-induced melanization in eight turtle species within the groups Chelydridae, Emydidae, Kinosternidae, and Trionychidae by rearing individuals on black or white substrates for 160 days. In all aquatic turtle species, integuments of the head and carapace of the individuals that were reared on a black substrate were darker than of those reared on a white substrate. In the terrestrial turtle Terrapene carolina carolina, however, no significant differences in dorsal head skin or carapace color were observed between treatments. Histological examination of tail tips in three aquatic species (Chelydra serpentina serpentina, Graptemys geographica, and Trachemys scripta elegans) indicated that substrate color-induced melanization is morphological, involving the transfer of melanosomes from basal epidermal melanocytes to adjacent keratinocytes. Interestingly, substrate color-induced melanization in a previously studied Pleurodire species apparently involves physiological color change. We could not, however, rule out physiological components to color change in the turtles of our study.
authors.affiliation: Biology Department, Alma College, 614 West Superior Street, Alma, MI 48801, USA. Electronic address: rowe@alma.edu.
authors.forename: John W
authors.initials: JW
authors.lastname: Rowe
authors.affiliation: Biology Department, Alma College, 614 West Superior Street, Alma, MI 48801, USA.
authors.forename: Brittany J
authors.initials: BJ
authors.lastname: Miller
authors.affiliation: Biology Department, Alma College, 614 West Superior Street, Alma, MI 48801, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Stuart
authors.affiliation: Biology Department, Alma College, 614 West Superior Street, Alma, MI 48801, USA.
authors.forename: Cassandra
authors.initials: C
authors.lastname: Snyder
authors.affiliation: Illinois Natural History Survey, 1816 S. Oak Street, Champaign, IL 61820, USA.
authors.forename: John K
authors.initials: JK
authors.lastname: Tucker
authors.affiliation: Biology Department, Alma College, 614 West Superior Street, Alma, MI 48801, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Clark
authors.affiliation: Biology Department, Alma College, 614 West Superior Street, Alma, MI 48801, USA.
authors.forename: Lawrence W
authors.initials: LW
authors.lastname: Wittle
authors.affiliation: Kibbe Field Station, Department of Biological Sciences, Western Illinois University, Macomb, IL 61455, USA.
authors.forename: James T
authors.initials: JT
authors.lastname: Lamer
mesh_terms: D000818:Animals; D004777:Environment; D015603:Keratinocytes / Q000378:metabolism*; D008543:Melanins / Q000378:metabolism*; D020460:Melanosomes / Q000378:metabolism*; D013045:Species Specificity; D014426:Turtles / Q000378:metabolism*
chemical_list: D008543:Melanins
keywords: Background matching; Color change; Integument; Melanin; Turtles