Pere Miquel Parés-Casanova* , Joaquim Soler Massana , and Albert Martínez-Silvestre CRARC, Catalonia Reptiles and Amphibians Rescue Center, Masquefa, Catalonia, Spain * Corresponding author: Pere Miquel Parés-Casanova, CRARC, Catalonia Reptiles, and Amphibians Rescue Center, Masquefa, Catalonia, Spain. Email: pmpares@gencat.cat
Abstract:
Geometric techniques can be easily applied to many zoological problems, from recognizing subpopulations to studying sexual dimorphism. Pseudemys concinna (P. concinna) is a large terrapin species known as the Eastern River Cooter, native to North America. The hypothesis was to test if plastral pattern tends to fade with age. The present study applies geometric techniques to assess size in a sample of 20 fresh corpses of P. concinna (18 females and 2 males). Plastron color (red, blue, and green channels) was used to objectivize this fading pattern. A negative regression between size and color was registered, so the colour plastral intensity of P. concinna LeConte 1830 tends, effectively, to fade with age. Elucidating the cellular and chemical mediators and mechanisms of these slow color changes will likely require laboratory study.
1.Introduction:
Some turtle and tortoise species present a high degree of individual variation and a reported susceptibility to deformation due to environmental effects1,2. Carotenoidbased ornaments provide a good example of ornamental traits3. The genus Pseudemys includes several species of cooters and red-bellied turtle4. Pseudemys concinna (P. concinna) LeConte 1830 is a large riverine turtle species known as Eastern River Cooter, native to North America 4,5. The plastron is yellow and marked anteriorly with a large, darker pattern. The plastral pattern tends to fade with age. The present study aimed to describe the changes in plastron color with age in P. concinna using geometric morphometrics and analysis of color in channels as a potential method. 2. Materials and Methods 2.1. Sample collection A total of 20 fresh corpses (18 females and 2 males) of specimens from P. concinna (range of plastron length: 102.2-241.7 mm, Figure 1) was obtained from CRARC, Catalonia Reptiles and Amphibians Rescue Center….
