Lizard threat display handicaps endurance

Abstract

Honest-signalling theory asserts that threat displays reliably advertise attributes that influence fighting success. Endurance, as measured by treadmill performance, predicts the outcome of agonistic interactions among lizards. If threat displays in lizards function to advertise endurance capacity then variation in threat displays should correlate with endurance. I tested this prediction for the duration of threat posturing in male side-blotched lizards (Uta stansburiana) and examined whether threat displays act as quality handicaps, reliable signals that expend the attribute that is advertised. Individual variation in the duration of threat posturing correlated with endurance, while an experimental reduction of endurance diminished the duration of threat posturing. As expected of a quality handicap, endurance fell below baseline after display production. A restriction of aerobic metabolism can account for this effect. In threat posturing, lateral compression of the thorax may interfere with respiration or with circulation, limiting aerobic metabolism and causing a compensatory increase in anaerobic metabolism, thereby generating lactate and diminishing locomotor capacity. Concentrations of lactate measured after display production were higher than baseline, consistent with the proposed mechanism. By restricting aerobic metabolism, the threat posture can act as a quality handicap, simultaneously advertising and expending the endurance capacity of displaying lizards.

A performance-based cost to honest signalling in male green anole lizards (Anolis carolinensis)

“…The handful of studies where performance costs have been considered within the context of signalling systems are also not directly comparable with our results; for example, in the case of the conditiondependent abdomen drumming rate in wolf spiders [61], the performance trait and the signal are one and the same. A similar honest signalling system involving performance was also studied by Brandt [6], who showed that endurance performance is limited by the expression of a signal (a laterally compressed threat display that probably inhibits respiration and circulation) in the lizard Uta stansburiana. However, the causality in these two systems is different, in that dewlap size and bite force in A. carolinensis are linked developmentally rather than mechanically.…”

“…Under classical honest signalling and 'handicap' models, the reliability and honesty of animal signals are thought to be maintained by the costs of signal expression and/or maintenance (reviewed in [3]). Male advertisement and threat signals, for example, are typically viewed as handicaps such that only select males are able to bear the costs of intensive signalling ( [4][5][6], but see [7,8] for an opposing view). Indeed, signals may impose a variety of costs on the bearer (reviewed in [9]), which may maintain the overall reliability of a signalling system because they prevent individuals from signalling a higher level of fighting ability than they actually possess.…”

Alert signals enhance animal communication in “noisy” environments

“…The advantage conferred by an alert is therefore tightly linked to both the current conditions in the environment and to receiver distance. The attention-grabbing bob patterns that these lizards use as alerts would presumably be obvious to visually oriented predators as well (e.g., the Puerto Rican lizard-eating cuckoo (Coccyzus vieilloti) and feral mongoose (Herpestes javanicus) both prey on anoles (28,29) and have been observed to attack displaying lizards and exaggerated pushups may also be energetically expensive to produce (30,31). As was noted above, costs of alert production would encourage the use of alerts to situations and distances where they are necessary for conspecific signal detection, as we demonstrate here.…”

Do displays and badges function in establishing the social structure of male toad-headed lizards, Phrynocephalus vlangalii?

“…Displays are important visual signals (Kim 1995;Zug et al 2001;Brandt 2003), and are known to predict a lizard's aggression, endurance and performance capacity (Hover and Jenssen 1976;Brandt 2003;Orrell and Jenssen 2003;Perry et al 2004;Osborne 2005). Such signals allow a rival male or female to identify the quality of a dominant individual without having to engage in physical combat (Osborne 2005).…”

“…In contrast, displays are behaviors that consist of variable body movements, such as the raising and lowering of the head and dewlap in the green anole Anolis carolinensis (Carpenter 1967;Jenssen 1977). Display behaviors are also known to predict an individual lizard's aggressiveness and performance capacity (Hover and Jenssen 1976;Brandt 2003;Orrell and Jenssen 2003;Perry et al 2004;Osborne 2005). Individuals exhibiting different social statuses are expected to develop differences in their display behaviors and badges (Zucker 1989;Andersson et al 2002;Lopez et al 2004;McElroy et al 2007).…”