The spotted turtle is declining throughout eastern Northern America due to habitat loss and poaching. From this study, most specifically on the Southeastern population, females had greater shell heights, heavier body masses, and longer plastrons than males.
^Parham, James Ford; Simison, W. Brian; Kozak, Kenneth H.; Feldman, Chris R. & Shi, Haitao (2001): New Chinese turtles: endangered or invalid? A reassessment of two species using mitochondrial DNA, allozyme electrophoresis and known-locality specimens. Animal Conservation4(4): 357–367. HTML abstract Erratum: Animal Conservation5(1): 86 HTML abstract
^Feldman, C.R. and J.F. Parham. (2002). Molecular phylogenetics of Emydine turtles: taxonomic revision and the evolution of shell kinesis. Molecular Phylogenetics and Evolution 22:388-398.
^Spinks, P.Q. and H.B. Shaffer. (2009). Conflicting Mitochondrial and Nuclear Phylogenies for the Widely Disjunct Emys (Testudines: Emydidae) Species Complex, and What They Tell Us about Biogeography and Hybridization. Systematic Biology 58(1):1-20.
^Litzgus, Jacqueline; Mousseau, Timothy (2004). Demography of A Southern Population of the Spotted Turtle (Clemmys guttata). Southeastern Naturalist3(3):391-400.