Predator-driven natural selection on risk-taking behavior in anole lizards

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Science  01 Jun 2018:
Vol. 360, Issue 6392, pp. 1017-1020
DOI: 10.1126/science.aap9289
  • Fig. 1 Assessment of risk-taking behavior and morphological characterization of A. sagrei individuals.

    (A) Anolis sagrei (left) and Leiocephalus carinatus (right) photographed on the experimental islands. (B) Experimental assessment of behavioral traits (26). Following (25), an A. sagrei individual was gently placed into a wooden refuge inside a butterfly cage. During a 3-min habituation period, we placed a clear plastic cage that contained a live adult L. carinatus between the refuge and a natural perch. Then, we remotely opened the door of the refuge and the A. sagrei individual was able to see the predator for 5 min (1). At the end of this period, we closed the door of the refuge and removed the plastic container with the L. carinatus from the experimental cage. After another 5-min habituation period, we again opened the refuge cover and measured the “time to initiation of exploration in a new environment” (2), defined as the time interval between the time we opened the refuge cover and the time when the lizard started exploring the experimental cage by poking its head out of the refuge. We defined “time exposed on the ground” as the interval between the “exposed time start” (3)—defined as the time when the experimental lizard went out of the refuge (i.e., all its body, excluding the tail)—and the “exposed time end” (4), the time when the lizard either climbed the perch or hid underneath the rocks. See (26) for details. (C) Example of an x-ray image from which we measured the morphological traits in this study (i.e., SVL and hindlimb length).

  • Fig. 2 Association between individual variation in behavior and survival of A. sagrei females after the 4-month experimental period.

    (A and B) Time to initiation of exploration in a new environment (A) and time exposed on the ground (B) are represented separately for predator-free versus predator islands. Solid lines represent the fitted model logistic regression; dashed lines denote 95% confidence intervals. Dots represent individual values for both survivors (dots at top of each panel) and darker dots are indicative of several individuals having similar values. See table S4 for a representation of results pooling both sexes together.

  • Fig. 3 Comparison of survival frequencies and habitat use between sexes and experimental treatments.

    (A) The proportion of females surviving was higher on predator-free islands than on predator islands, but this difference was marginally nonsignificant for males. Error bars indicate SEM. (B) Both sexes used the ground less on predator islands, but this difference was greater for females than for males.

  • Table 1 Best mixed-effects models describing female survival on the experimental islands.
    EstimateSEzP value
    Predator-free islands (n = 63)
    (Intercept)2.82 1.052.7 0.007
    Random effectsIsland0.180.4230.430.669
    Fixed effectsTime to initiation of exploration–1.030.4–2.550.011
    Relative hindlimb length48.715.783.080.002
    Predator islands (n = 68)
    Random effectsIsland0001
    Fixed effectsExposed time on ground–1.270.61–2.10.035
    Body size (SVL)–0.340.14–2.480.013
  • Predator-driven natural selection on risk-taking behavior in anole lizards

    Oriol Lapiedra, Thomas W. Schoener, Manuel Leal, Jonathan B. Losos, Jason J. Kolbe

    Materials/Methods, Supplementary Text, Tables, Figures, and/or References

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    • Materials and Methods 
    • Figs. S1 to S9
    • Tables S1 to S5
    • References 

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