Aegean wall lizards switch foraging modes, diet, and morphology in a human‐built environment

Abstract

Foraging mode is a functional trait with cascading impacts on ecological communities. The foraging syndrome hypothesis posits a suite of concurrent traits that vary with foraging mode; however, comparative studies testing this hypothesis are typically interspecific. While foraging modes are often considered typological for a species when predicting foraging‐related traits or mode‐specific cascading impacts, intraspecific mode switching has been documented in some lizards. Mode‐switching lizards provide an opportunity to test foraging syndromes and explore how intraspecific variability in foraging mode might affect local ecological communities.Because lizard natural history is intimately tied to habitat use and structure, I tested for mode switching between populations of the Aegean wall lizard, Podarcis erhardii, inhabiting undisturbed habitat and human‐built rock walls on the Greek island of Naxos. I observed foraging behavior among 10 populations and tested lizard morphological and performance predictions at each site. Furthermore, I investigated the diet of lizards at each site relative to the available invertebrate community.I found that lizards living on rock walls were significantly more sedentary—sit and wait—than lizards at nonwall sites. I also found that head width increased in females and the ratio of hindlimbs to forelimbs in both sexes increased as predicted. Diet also changed, with nonwall lizards consuming a higher proportion of sedentary prey. Lizard bite force also varied significantly between sites; however, the pattern observed was opposite to that predicted, suggesting that bite force in these lizards may more closely relate to intraspecific competition than to diet.This study demonstrates microgeographic variability in lizard foraging mode as a result of human land use. In addition, these results demonstrate that foraging mode syndromes can shift intraspecifically with potential cascading effects on local ecological communities.

Predator and prey functional traits: understanding the adaptive machinery driving predator–prey interactions

“…Indeed, individual Aegean wall lizards live and hunt both in their ancestral sandy habitats and in agrarian habitats containing rock walls. Recent work has shown that individuals on rock walls are ambush hunters, jumping from rock to rock, but that individuals in sandy habitats engage in active running pursuit 42 . To facilitate jumping, individuals on rock walls have longer hindlimb-to-forelimb ratios than do their sandy habitat counterparts 42 .…”

“…Recent work has shown that individuals on rock walls are ambush hunters, jumping from rock to rock, but that individuals in sandy habitats engage in active running pursuit 42 . To facilitate jumping, individuals on rock walls have longer hindlimb-to-forelimb ratios than do their sandy habitat counterparts 42 . These hunting mode differences lead to dietary differences, where sandy habitat hunters consume more sedentary prey and rock wall hunters consume more mobile prey 42 .…”

“…To facilitate jumping, individuals on rock walls have longer hindlimb-to-forelimb ratios than do their sandy habitat counterparts 42 . These hunting mode differences lead to dietary differences, where sandy habitat hunters consume more sedentary prey and rock wall hunters consume more mobile prey 42 . Eurasian perch compete for resources within pelagic habitats and this leads to within-population divergence in habitat usage such that some population members use littoral zones 43 .…”

Rapid and repeated divergence of animal chemical signals in an island introduction experiment

“…Podarcis erhardii , the Aegean Wall Lizard, is a common small‐bodied lizard that can be found throughout the Cyclades island group (Aegean Sea, Greece). Adults range in body size between 40 and 75 mm (Valakos et al, 2008) and are largely insectivorous (Adamopoulou, Valakos, & Pafilis, 1999; Donihue, 2016), occasionally bolstering their diet with fruits and conspecific eggs (Brock, Bednekoff, et al, 2014; Brock, Donihue, et al, 2014).…”

The context dependence of non-consumptive predator effects

“…At one extreme of a continuum, actively roaming/coursing predators typically have large habitat domains; at the other, sit-and-wait/ambush predators usually exhibit smaller domains. Notably, predators may switch hunting modes (Helfman 1990;Olson & Eklov 2005;Donihue 2016), which can change space use, habitat domain size, and contingency in the nature of interactions. Smaller prey may forage locally, whereas larger prey may roam widely depending on their forage requirements in relation to the distribution of plant (or other resource) quality and productivity (Haskell et al .…”