Context Dependent Territory Defense: The Importance of Habitat Structure in Anolis sagrei

Abstract

Territoriality is a potentially costly endeavor, and several mechanisms for mitigating the costs of territoriality have been investigated in the wild. For example, territory owners can reduce the costs of defending territory boundaries by prioritizing defense of the most valuable areas within territories, investing less energy in low quality areas. We staged pairwise encounters between adult male lizards on natural territories in the wild, to test whether male brown anoles, Anolis sagrei, would differentially defend certain regions of their territories over others. Based on our observations that male A. sagrei spend most of their time on elevated perches on tree trunks or branches compared with sites on the ground, we predicted that territory residents would respond more aggressively to territory invasions that took place on elevated perches than to invasions on the ground. We measured significant differences in the behavior of residents following invasion on the ground vs. on the elevated perches, and results partially supported our hypothesis. Males performed more displays and approached intruders more often when territory invasion took place on the ground, but were quicker to attack intruders that entered territories on elevated perches. Our hypothesis was only partially supported, potentially indicating that elevated perches are preferred as outposts to monitor valuable sites on the ground. Our study provides evidence that territory defense varies not just among individuals, but also within individuals at different locations in a territory.

Manipulating Testosterone to Assess Links between Behavior, Morphology, and Performance in the Brown Anole Anolis sagrei

“…In anoles and other lizards, bite force determines dominance in male-male contests to establish territories and acquire access to females (Lailvaux et al 2004;Lappin and Husak 2005;Husak et al 2006). Because contests that escalate to biting can often result in serious injury or death of the participants (Calsbeek and Marnocha 2006), honest signaling can provide a mutually beneficial means of pacific resolution when contestants are unevenly matched in performance. We found that absolute measures of bite force were positively correlated with dewlap area and that relative measures of size-specific bite force were positively correlated with relative dewlap area for pretreatment (but not posttreatment) measurements (Fig.…”

Sex‐specific adult dispersal and its selective consequences in the brown anole,Anolis sagrei

“…However, both scenarios could be consistent with the hypothesis that male–male competition limits dispersal if small males filled vacancies left by dead residents, whereas large males usurped territories from smaller neighbours. Experimental studies with A. sagrei have shown that the stability of territory boundaries may be mediated through the dear enemy effect (Paterson 2002; Calsbeek & Marnocha 2006) whereby neighbour recognition reduces the costs of territory defence. Moreover, removing territory residents increases rates of territory takeover by males on nearby territories (Paterson 2002).…”

Testosterone, growth and the evolution of sexual size dimorphism

“…To identify individuals, we permanently marked each lizard with a unique combination of coloured elastomer tags (Nauwelaerts et al. , 2000) that were injected subcutaneously into the ventral surfaces of the limbs (Calsbeek & Marnocha, 2006). We used size measurements to calculate an index of SSD (Lovich & Gibbons, 1992) for SVL and body mass: SSD = (male size/female size) − 1.…”