The Role of Diet in Shaping the Chemical Signal Design of Lacertid Lizards

Abstract

Lizards communicate with others via chemical signals, the composition of which may vary among species. Although the selective pressures and constraints affecting chemical signal diversity at the species level remain poorly understood, the possible role of diet has been largely neglected. The chemical signals of many lizards originate from the femoral glands that exude a mixture of semiochemicals, and may be used in a variety of contexts. We analyzed the lipophilic fraction of the glandular secretions of 45 species of lacertid lizard species by gas chromatography/mass spectrometry. The proportions of nine major chemical classes (alcohols, aldehydes, fatty acids, furanones, ketones, steroids, terpenoids, tocopherols and waxy esters), the relative contributions of these different classes ('chemical diversity'), and the total number of different lipophilic compounds ('chemical richness') varied greatly among species. We examined whether interspecific differences in these chemical variables could be coupled to interspecific variation in diet using data from the literature. In addition, we compared chemical signal composition among species that almost never, occasionally, or often eat plant material. We found little support for the hypothesis that the chemical profile of a given species' secretion depends on the type of food consumed. Diet breadth did not correlate with chemical diversity or richness. The amount of plants or ants consumed did not affect the relative contribution of any of the nine major chemical classes to the secretion. Chemical diversity did not differ among lizards with different levels of plant consumption; however, chemical richness was low in species with an exclusive arthropod diet, suggesting that incorporating plants in the diet enables lizards to increase the number of compounds allocated to secretions, likely because a (partly) herbivorous diet allows them to include compounds of plant origin that are unavailable in animal prey. Still, overall, diet appears a relatively poor predictor of interspecific differences in the broad chemical profiles of secretions of lacertid lizards.

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

“…In addition, while climate (Baeckens, Martín, García‐Roa, Pafilis, et al, 2018; Martín, Ortega, & López, 2015) and diet (Baeckens, García‐Roa, et al, 2017; García‐Roa et al, 2017; Kopena et al, 2011) can affect lizard chemical signal design, our preliminary data suggest these factors are unlikely drivers of the observed divergence between the source and islet populations. As the source population was peninsular and at sea level, and due to the close physical proximity of the source and experimental populations (maximum linear distance of 28 km), all of the populations experience comparable temperature, precipitation and wind (Belasen et al, 2017; Table S6).…”

“…Prior to any statistical analyses, proportion data was arcsin transformed (Baeckens, García‐Roa, Martín, & Van Damme, 2017; Baeckens, Martín, García‐Roa, Pafilis, et al, 2018; Baeckens, Martín, García‐Roa, & Van Damme, 2018; Sokal & Rohlf, 1995). Alternative transformations, such as the compositional analysis for proportions (Aebischer, Robertson, & Kenward, 1993), provided similar results.…”

Female northern grass lizards judge mates by body shape to reinforce local adaptation

“…Future work could usefully investigate other visual signals and chemical signals to determine whether factors other than body shape may also contribute the decision process of T. septentrionalis . It has been found that Takydromus lizards among species having the visual [ 51 ] and chemical [ 52 – 55 ] communication systems and abilities to signal with conspecifics and alter their behaviour.…”

Female northern grass lizards judge mates by body shape to reinforce local adaptation

“…Future work could usefully investigate other visual signals and chemical signals to determine whether factors other than body shape may also contribute the decision process of T. septentrionalis. It has been found that Takydromus lizards among species having the visual [51] and chemical [52][53][54][55] The body posture of heterospeci c (a, between male T. septentrionalis and female T. sexlineatus) and conspeci c homosexual (b, between males of T. septentrionalis) mating partners.…”