Effect of stress on female-specific ornamentation

Abstract

SUMMARYSignal honesty is theorized to be maintained by condition-dependent trait expression. However, the mechanisms mediating the condition dependence of sexually selected traits are often unknown. New work suggests that elevated glucocorticoid levels during physiological stress may play a role in maintaining signal honesty. Here, we experimentally examine the effect of both chronic and acute stress on the expression of the condition-dependent ornamentation of female striped plateau lizards, Sceloporus virgatus. Females were stressed either chronically via corticosterone implants or relatively acutely via autotomy, were sham manipulated or were left unmanipulated. Both stressors resulted in elevations in corticosterone within physiologically relevant levels, though the implants resulted in significantly higher levels than did autotomy. Corticosterone-implanted females were less likely to produce a clutch of eggs, but those individuals that did reproduce had reproductive output similar to that of females from other treatment groups. Compared with females in other groups, the corticosterone-implanted females tended to develop smaller ornaments that had less UV and orange-to-red wavelength reflectance relative to medium wavelength reflectance. The sex steroid hormones testosterone and estradiol were correlated to corticosterone levels, but did not appear to underlie the effect on ornament expression; of the steroids measured, only corticosterone levels were negatively related to ornament size and coloration. Thus, the condition-dependent ornamentation of female lizards is sensitive to chronic elevations in stress hormones, supporting their importance in the maintenance of signal honesty.

Corticosterone: a costly mediator of signal honesty in sand lizards

“…CORT has direct and largely negative effects on color production (Calisi and Hews ; San‐Jose and Fitze ; Weiss et al. ) and, in particular, interferes with the process of melanogenesis through competitive binding of the melanocortin receptor necessary for melanin pigmentation (Ducrest et al. ; Roulin et al.…”

Mutually honest? Physiological ‘qualities’ signalled by colour ornaments in monomorphic king penguins

“…Glucocorticoid hormones (GC) play key roles in mediating physiological trade-offs and energy allocation, and baseline GC levels have been suggested to ensure signal honesty (Husak & Moore, 2008;Weiss et al, 2013). Whereas we found no link between baseline CORT and ornaments in our study, UV hue Because stress responses are energy costly, this is consistent with the idea that the ability to mount stress responses while fasting is reflected in ornamentation, which may be particularly relevant in the context of colonial breeding during exposure to overt social aggressiveness (Côt e, 2000).…”

“…Nephew, Kahn & Romero, 2003). For instance, chronic experimental increases in baseline stress levels (via CORT implants) have been shown to negatively affect UV and orange-red reflectance in female striped plateau lizards (Sceloporus virgatus) (Weiss et al, 2013). These results suggest two alternatives: that birds breeding close to the beach might have habituated to chronic human disturbance (Viblanc et al, 2012b), and that birds up the valley may have been more exposed to parasites (P. Bize, Q. Schull, S. Pardonnet, Y. Handrich, F. Criscuolo, V.A.…”

Biology and Diseases of Reptiles

“…Red-eared sliders (Trachemys scripta elegans), known for anoxia tolerance, have been used to elucidate the mechanisms of neuroglobin (Nayak et al, 2009). Various species of lizards have been the subjects of investigations into stress, behavior, and vertebrate evolutionary studies (Hews and Abell Baniki, 2013;Weiss et al, 2013;Olsson et al, 2013). 19.1).…”