Discrimination of chemical stimuli in conspecific fecal pellets by a visually adept iguanid lizard, Crotaphytus collaris

Abstract

Iguanid lizards are known for visual acuity and a diminished vomeronasal organ, which has led to mixed conclusions on whether iguanids use chemical cues. The collared lizard, Crotaphytus collaris, is a territorial iguanid that lives in open rocky habitats. Fecal pellets placed prominently on open rocky perches may provide an ideal mechanism for intraspecific chemical signaling. In order to determine whether collared lizards can discriminate between chemical stimuli found in conspecific fecal pellets, we collected 24 males and 25 females to analyze sexspecific behavioral responses via tongue-flicks and a newly observed behavior for the species, gular pumps, to cotton swabs containing water, cologne, chemical stimuli from conspecific male and female fecal pellets, and the lizard's own fecal pellet. Both sexes were able to discriminate chemical stimuli from water via at least one behavior. Male collared lizards exhibited greater rates of response (tongueflick and gular pumps) toward male fecal pellets when compared to the negative water control. Our results also suggest individuals may be able to discriminate between fecal pellets, as indicated by generally greater (but nonsignificant) counts of male tongue-flick responses to male fecal pellets when compared to their own. Collared lizard chemical discrimination appears to utilize tongue-flick and gular pump behaviors, possibly associated with distinct chemosensory modes (vomerolfaction and olfaction). Based on this study, we suggest that chemical signals may play a greater role in intraspecific communication than previously thought in this highly visual lizard.

Responses to Femoral Gland Secretions by Visually Adept Male and Female Collared Lizards

“…; López & Martín ). Chemoreception may be less well developed in iguanian lizards that employ their highly developed vision to detect approaching prey while scanning from elevated perches that are then captured using short chases (Evans ; Wilgers & Horne ). In many iguanians, selection has favored social signals involving conspicuous coloration and stereotypical displays that are transmitted visually (Shine ; Baird et al.…”

“…For example, experimental studies have shown that chemical secretions function in species recognition, advertisement of resource holding power to same-sex rivals, courtship signals to potential female mates, recognition of familiar vs. unfamiliar rivals, and even recognition of individuals (Mart ın & L opez 2007;Carazo et al 2008;Font et al 2012;L opez & Mart ın 2012). Chemoreception may be less well developed in iguanian lizards that employ their highly developed vision to detect approaching prey while scanning from elevated perches that are then captured using short chases (Evans 2003;Wilgers & Horne 2009). In many iguanians, selection has favored social signals involving conspicuous coloration and stereotypical displays that are transmitted visually (Shine 1990;Baird et al 2012), perhaps as a consequence of selection for the acute vision required for sit-and-wait foraging tactics.…”

Susceptibility of lizards to predation under two levels of vegetative cover

“…Chemical communication in other iguanids is mediated by lizard's depositions (Labra, 2007;Wilgers and Horne, 2008). Neither depositions nor typical recognition behaviors (tongue flicking and gular pump) were identified during the trials which suggest chemical communication may not be relevant to our study.…”

“…There is good evidence that many species of lizards use chemical cues for some form of communication (Quinn and Hews, 2005;Labra, 2007;Wilgers and Horne, 2008), potentially affecting the behavior of individuals during the trials. Chemical communication in other iguanids is mediated by lizard's depositions (Labra, 2007;Wilgers and Horne, 2008).…”

Caracterização quí­mica de secreções de glândulas pré-anais e femorais de espécies brasileiras de lagartos da famí­lia Teiidae (Squamata)

“…No trabalho de BULL e colaboradores (1999b) há indícios de que os semioquímicos presentes nas fezes compreendem compostos lipofílicos, uma vez que machos responderam às fezes quando dissolvidas em diclorometano, mas não o fizeram quando as fezes foram apresentadas dissolvidas em água. Há evidências de que machos de Crotaphytus collaris (Crotaphytidae), uma espécie de lagarto conhecida por sua acuidade visual, é capaz de detectar e discriminar coespecíficos apenas com base em informações químicas presentes nas fezes (WILGERS & HORNE, 2009).…”