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Conspicuous male coloration impairs survival against avian predators in Aegean wall lizards, Podarcis erhardii.

Marshall KL, Philpot KE, Stevens M - Ecol Evol (2015)

Bottom Line: Within-species color variation can arise through local adaptation for camouflage, sexual dimorphism and conspicuous sexual signals, which often have conflicting effects on survival.This may have arisen if the models did not resemble lizard coloration with sufficient precision, or if real lizards behaviorally choose backgrounds that improve camouflage.Overall, these results show that sexually dimorphic coloration can affect the risk of predator attacks, indicating that color variation within a species can be caused by interactions between natural and sexual selection.

View Article: PubMed Central - PubMed

Affiliation: Department of Zoology University of Cambridge Cambridge CB2 3EJ UK.

ABSTRACT
Animal coloration is strikingly diverse in nature. Within-species color variation can arise through local adaptation for camouflage, sexual dimorphism and conspicuous sexual signals, which often have conflicting effects on survival. Here, we tested whether color variation between two island populations of Aegean wall lizards (Podarcis erhardii) is due to sexual dimorphism and differential survival of individuals varying in appearance. On both islands, we measured attack rates by wild avian predators on clay models matching the coloration of real male and female P. erhardii from each island population, modeled to avian predator vision. Avian predator attack rates differed among model treatments, although only on one island. Male-colored models, which were more conspicuous against their experimental backgrounds to avian predators, were accordingly detected and attacked more frequently by birds than less conspicuous female-colored models. This suggests that female coloration has evolved primarily under selection for camouflage, whereas sexually competing males exhibit costly conspicuous coloration. Unexpectedly, there was no difference in avian attack frequency between local and non-local model types. This may have arisen if the models did not resemble lizard coloration with sufficient precision, or if real lizards behaviorally choose backgrounds that improve camouflage. Overall, these results show that sexually dimorphic coloration can affect the risk of predator attacks, indicating that color variation within a species can be caused by interactions between natural and sexual selection. However, more work is needed to determine how these findings depend on the island environment that each population inhabits.

No MeSH data available.


Related in: MedlinePlus

Distributions of coloration of Aegean wall lizards (Podarcis erhardii) and replicate clay models in tetrahedral (avian predator) color space. Each color is a point in the tetrahedron determined by the relative stimulation of the four color cone channels (v, sw, mw and lw) of a typical violet‐sensitive avian predator visual system (peafowl; Pavo cristatus). In each focal island population (A: Skopelos and B: Syros), data points depictmale‐ and female‐colored models (blue and red squares), which were designed to resemble avian‐perceived male and female P. erhardii coloration (light blue and orange diamonds), and an unmatched control model (black square).
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ece31650-fig-0002: Distributions of coloration of Aegean wall lizards (Podarcis erhardii) and replicate clay models in tetrahedral (avian predator) color space. Each color is a point in the tetrahedron determined by the relative stimulation of the four color cone channels (v, sw, mw and lw) of a typical violet‐sensitive avian predator visual system (peafowl; Pavo cristatus). In each focal island population (A: Skopelos and B: Syros), data points depictmale‐ and female‐colored models (blue and red squares), which were designed to resemble avian‐perceived male and female P. erhardii coloration (light blue and orange diamonds), and an unmatched control model (black square).

Mentions: Crucially, the JND analysis confirmed that half of the models matched avian‐perceived (average) dorsal coloration of the lizards they were designed to resemble (i.e., ≤3.00 JND) and the other treatments were very close to 3.00 JND (i.e., no higher than 3.69 JND; Table 1). Moreover, all of the model treatments were extremely close luminance matches to the real lizards (i.e., <1.00 JND; Table 1). In addition, to illustrate how closely matching the different model treatments were to that of real lizard coloration from each island population, we plotted avian predator (VS peafowl) photon catches of the models derived from reflectance spectra and of the real lizards obtained from image analysis in tetrahedral color space (see Endler and Mielke 2005; Fig. 2).


Conspicuous male coloration impairs survival against avian predators in Aegean wall lizards, Podarcis erhardii.

Marshall KL, Philpot KE, Stevens M - Ecol Evol (2015)

Distributions of coloration of Aegean wall lizards (Podarcis erhardii) and replicate clay models in tetrahedral (avian predator) color space. Each color is a point in the tetrahedron determined by the relative stimulation of the four color cone channels (v, sw, mw and lw) of a typical violet‐sensitive avian predator visual system (peafowl; Pavo cristatus). In each focal island population (A: Skopelos and B: Syros), data points depictmale‐ and female‐colored models (blue and red squares), which were designed to resemble avian‐perceived male and female P. erhardii coloration (light blue and orange diamonds), and an unmatched control model (black square).
© Copyright Policy - creativeCommonsBy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4588654&req=5

ece31650-fig-0002: Distributions of coloration of Aegean wall lizards (Podarcis erhardii) and replicate clay models in tetrahedral (avian predator) color space. Each color is a point in the tetrahedron determined by the relative stimulation of the four color cone channels (v, sw, mw and lw) of a typical violet‐sensitive avian predator visual system (peafowl; Pavo cristatus). In each focal island population (A: Skopelos and B: Syros), data points depictmale‐ and female‐colored models (blue and red squares), which were designed to resemble avian‐perceived male and female P. erhardii coloration (light blue and orange diamonds), and an unmatched control model (black square).
Mentions: Crucially, the JND analysis confirmed that half of the models matched avian‐perceived (average) dorsal coloration of the lizards they were designed to resemble (i.e., ≤3.00 JND) and the other treatments were very close to 3.00 JND (i.e., no higher than 3.69 JND; Table 1). Moreover, all of the model treatments were extremely close luminance matches to the real lizards (i.e., <1.00 JND; Table 1). In addition, to illustrate how closely matching the different model treatments were to that of real lizard coloration from each island population, we plotted avian predator (VS peafowl) photon catches of the models derived from reflectance spectra and of the real lizards obtained from image analysis in tetrahedral color space (see Endler and Mielke 2005; Fig. 2).

Bottom Line: Within-species color variation can arise through local adaptation for camouflage, sexual dimorphism and conspicuous sexual signals, which often have conflicting effects on survival.This may have arisen if the models did not resemble lizard coloration with sufficient precision, or if real lizards behaviorally choose backgrounds that improve camouflage.Overall, these results show that sexually dimorphic coloration can affect the risk of predator attacks, indicating that color variation within a species can be caused by interactions between natural and sexual selection.

View Article: PubMed Central - PubMed

Affiliation: Department of Zoology University of Cambridge Cambridge CB2 3EJ UK.

ABSTRACT
Animal coloration is strikingly diverse in nature. Within-species color variation can arise through local adaptation for camouflage, sexual dimorphism and conspicuous sexual signals, which often have conflicting effects on survival. Here, we tested whether color variation between two island populations of Aegean wall lizards (Podarcis erhardii) is due to sexual dimorphism and differential survival of individuals varying in appearance. On both islands, we measured attack rates by wild avian predators on clay models matching the coloration of real male and female P. erhardii from each island population, modeled to avian predator vision. Avian predator attack rates differed among model treatments, although only on one island. Male-colored models, which were more conspicuous against their experimental backgrounds to avian predators, were accordingly detected and attacked more frequently by birds than less conspicuous female-colored models. This suggests that female coloration has evolved primarily under selection for camouflage, whereas sexually competing males exhibit costly conspicuous coloration. Unexpectedly, there was no difference in avian attack frequency between local and non-local model types. This may have arisen if the models did not resemble lizard coloration with sufficient precision, or if real lizards behaviorally choose backgrounds that improve camouflage. Overall, these results show that sexually dimorphic coloration can affect the risk of predator attacks, indicating that color variation within a species can be caused by interactions between natural and sexual selection. However, more work is needed to determine how these findings depend on the island environment that each population inhabits.

No MeSH data available.


Related in: MedlinePlus