Scutation asymmetries in red-footed tortoise Chelonoidis carbonaria Spix, 1824 (Testudines: Testudinidae)

Abstract

The ability of an individual to withstand random perturbations during its development is considered a good indicator of environmental and genetic stress. A common means of assessing developmental stability is through analysis of fluctuating asymmetry (FA) in bilateral traits. Tortoises, with their large, solid plastron, allow for measurement of body geometry. Their bilateral shell scutes are ideal candidates for asymmetries researches. With this issue in mind we assessed, as a preliminary study, levels of plastron scute asymmetry in a sample of 46 red-footed tortoise Chelonoidis carbonaria from Arauca, N Colombia. We found significative fluctuating asymmetry (FA) but no directional asymmetry, the former not increasing with carapace size and thus indicating that tortoise shells do not become increasingly asymmetrical with age, or in other words, signaling that FA is not being influenced by pholidosis (variability of scale cover mosaic according to the development of the scutes). Asymmetry in plastron shape, although not necessarily apparent at first glance, varied, with gender with males exhibiting higher levels of FA than females. Although we can not identify the potential sources of variation responsible for the observed patterns of developmental instability, we consider this detected form of asymmetry due to unfavorable environmental conditions.

Medicina e bem-estar de animais silvestres e exóticos, vol. 1

“…Quanto à classificação das alterações de carapaças, 16,98% e 83,02% (p<0.0001) foram de origem traumática (queimaduras por incêndio 7,55%; fratura de placas ósseas 5,66% e mordedura por cão 3,77%) e não-traumática (piramidismo 77,36% e má formação de placas córneas 5,66%) (Figura 1), o que acaba reforçando os impactos da criação ilegal e do manejo inadequado na saúde da carapaça desses répteis (MARTINEZ-JIMENEZ et al, 2007;PARÉS-CASANOVA et al, 2020). Além disso, vale lembrar que muitos répteis acabam se tornando vítimas de atropelamento por veículos automobilísticos e queimados em incêndios, em virtude de apresentarem deslocamento lento ao tentarem realizar travessias entre matas e rodovias (RAMOS-ABRANTES et al, 2018;DURIGAN et al, 2020).…”

Symmetry-Breaking Stabilities in Carapace Curvature on Testudo (Reptilia, Testudinidae)

“…Turtles are subjected to a variety of potentially destabilizing forces that can be either self-generated (e.g., propulsor movements) or external [ 28 ]. At this point, a possible speculative biological explanation for the detected asymmetrical pattern in Testudo carapace is that this asymmetry makes turning difficult (“static stability”, understood as the ability to resist passively turning of the body produced by destabilizing forces that damp stability forces), rather than having an effect on the easiness of self-righting potential (“kinematic instability”).…”