Sexual dimorphism in conspicuousness and ornamentation in the enigmatic leaf-nosed lizard Ceratophora tennentii from Sri Lanka

Martin J. Whiting, Daniel W A Noble, Ruchira Somaweera*

*Corresponding author for this work

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Measures of physiological performance capacity, such as bite force, form the functional basis of sexual selection. Information about fighting ability may be conveyed through a structural feature such as a rostrum (i.e. horn) or a colour signal and thereby help reduce costly conflict. We quantified sexual dimorphism in key traits likely to be the targets of sexual selection in Tennent's leaf-nosed lizard (Ceratophora tennentii) from Sri Lanka, and examined their relationship to bite force and body condition. We found body length and bite force to be similar for males and females. However, head length was significantly greater in males and they had significantly more conspicuous throats and labials (chromatic contrast and luminance) than females. Males also had a proportionally larger rostrum, which we predicted could be an important source of information about male quality for both sexes. Rostrum length was correlated with throat chromatic contrast in males but not females. Nonetheless, the rostrum and aspects of coloration did not correlate with bite force or body condition as we predicted. We have no information on contest escalation in this species but if they rarely bite, as suggested by a lack of difference in bite force between males and females, then bite force and any associated signals would not be a target of selection. Finally, males and females had similar spectral reflectance of the mouth and tongue and both had a peak in the ultra-violet, and were conspicuous to birds. Lizards only gaped their mouths during capture and not when threatened by a potential predator (hand waving). We hypothesize that conspicuous mouth colour may act as a deimatic signal, startling a potential predator, although this will need careful experimental testing in the future.

Original languageEnglish
Pages (from-to)614-625
Number of pages12
JournalBiological Journal of the Linnean Society
Volume116
Issue number3
DOIs
Publication statusPublished - 1 Nov 2015

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