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.
Highlights
Foraging mode is a functional trait affecting species’ impacts on ecological communities (Miller, Ament, & Schmitz, 2014; Post & Palkovacs, 2009; Schmitz, 2008; Schoener, 2011)
This study explores how ecological context is related to population-level variability in foraging mode and associated traits in the Aegean wall lizard (Podarcis erhardii) to test the foraging syndrome hypothesis and infer a potential evolutionary ecological basis for foraging mode changes
The available insect community was very similar, the diet of lizards on walls contained a larger proportion of active prey taxa, whereas lizards from nonwall sites ate a higher proportion of sedentary prey
Summary
Foraging mode is a functional trait affecting species’ impacts on ecological communities (Miller, Ament, & Schmitz, 2014; Post & Palkovacs, 2009; Schmitz, 2008; Schoener, 2011). Predators were grouped according to two foraging modes: active foraging predators that course widely in search of prey, and sit-and-w ait predators that remain relatively sedentary until ambushing their prey (Huey & Pianka, 1981; MacArthur & Pianka, 1966; McLaughlin, 1989; Pianka, 1966; Schoener, 1971). DONIHUE foraging modes fall along a continuum between these two extremes (Butler, 2005; Miles, Losos, & Irschick, 2007; Perry, 1999); species are still classified as either relatively sit and wait or active foraging when testing predictions about foraging mode-associated morphological, performance, and behavioral traits (Miles et al, 2007; Vanhooydonck, Herrel, & Van Damme, 2007) and making predictions about their functional roles in ecological communities (Miller et al, 2014; Schmitz 2010). Sit-and-wait predators almost exclusively encounter and consume highly mobile prey, whereas active foraging predators tend to consume a higher proportion of sedentary, cryptic prey (Huey & Pianka, 1981; Vanhooydonck et al, 2007) and may supplement their diet with plant material (Herrel, 2007)
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