Research ArticleEVOLUTIONARY BIOLOGY

The evolution of anti-bat sensory illusions in moths

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Science Advances  04 Jul 2018:
Vol. 4, no. 7, eaar7428
DOI: 10.1126/sciadv.aar7428
  • Fig. 1 Maximum likelihood tree of Saturniidae shows that elongated hindwing lobes and hindwing tails convergently evolved multiple times.

    Colored branches indicate the four identified convergent regimes and adaptive peaks, denoted by a white numerical circle. Regimes 1 and 2 (red and green, respectively), extra long tail; regime 3 (yellow), short tail; regime 4 (blue), elongated lobes. Gray branches labeled NC indicate nonconvergent adaptive peaks. Phylogeny based on 797 anchored hybrid enrichment (AHE) loci; all nodes are supported by 100% bootstrap values unless otherwise noted.

  • Fig. 2 Geometric morphometric analysis of hindwing shape reveals changes in morphospace across four saturniid subfamilies.

    Principal components analyses (PCA) visualize hindwing morphospace by (A) subfamily, showing that Saturniinae and Arsenurinae have independently evolved into the same morphospace. PC, principal component. (B) Experimental treatment, showing that moths with hindwing alterations exist in similar morphospace to extant species that have not been subjected to wing alteration. Dots represent individual specimens in the analysis. Color refers to (A) subfamily or (B) experimental manipulations. Confidence ellipses facilitate understanding of shape space and the amount of variation residing within subfamilies. Hypothetical shape approximations are plotted in the background to aid in visualizing shape change. In addition, the four identified convergent regimes and adaptive peaks, seen in Fig. 1, are denoted by a white numerical circle. Regimes 1 and 2, extra long tails; regime 3, short tails; and regime 4, elongated hindwing lobes.

  • Fig. 3 Moths with longer hindwings escape an increasing proportion of bat attacks.

    The inner white line represents the predicted mean posterior probability distribution from a Bayesian mixed logistic regression model. The gray area is the SD of posterior probability distributions of the prediction. Points represent proportions for each treatment calculated using a Bayesian mixed logistic model controlling for bat identity and hunting night (time). Vertical bars represent the SD of posterior probability distributions, whereas horizontal error bars represent observed SD of hindwing length for each treatment. Images of moth treatments are positioned on their respective vertical error bars. Only one picture is shown for an intact or sham treatment, as they have the same morphology. Sample sizes for bat-moth interactions are as follows: Argema mimosae (intact = 30, ablated = 17, sham = 13, and short = 22), Actias luna (intact = 64, ablated = 38, sham = 37, elongated = 83, short = 93, and blunt = 48), Antheraea polyphemus (intact = 40, sham = 35, elongated = 29, and shortened = 44).

  • Fig. 4 Hindwing tails redirect bat attack against moths.

    Behavioral analyses reveal that (A) bats aim an increasing proportion of their attacks at the posterior half of the moth (indicated by yellow cylinder with asterisk) and that (B) bats attacked the first and third sections of tailed moths 75% of the time [A. luna: intact, sham, elongated; A. mimosae: intact, sham, shortened (sections highlighted in purple)], providing support for the multiple-target illusion. An enlarged echo illusion would likely lead bats to target the hindwing just behind the abdomen of the moth, at the perceived echo center (second section, highlighted in green); however, bats targeted this region only 25% of the time. Bat success in capturing moths varied as they targeted different sections of the moth: first = 76%, second = 15%, and third = 6%. The model in (A) was built the same as in Fig. 3.

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/7/eaar7428/DC1

    Fig. S1. Twisted and cupped hindwing tail ends in Saturniidae.

    Fig. S2. Hindwing morphology of the three silk moth species was altered by cutting and gluing hindwing material.

    Fig. S3. IPI does not change on the basis of moth treatment.

    Fig. S4. IPI does not change on the basis of moth genus or hindwing length.

    Fig. S5. ASR demonstrates multiple origins of the hindwing tail trait within the Saturniinae subfamily.

    Fig. S6. ASR demonstrates multiple origins of adaptive peaks within the Saturniinae subfamily.

    Table S1. Kinematic output results from 100 ms of tethered moth flight leading up to bat-moth interaction.

    Table S2. Bat identity and experience (that is, learning) do not affect the outcome of the trial.

    Table S3. Bats do not change call parameters during attack on silk moths of differing morphologies.

    Movie S1. Phylomorphospace by tail regime.

    Movie S2. Phylomorphospace by tail regime (no labels).

    Movie S3. Phylomorphospace by adaptive peak.

    Movie S4. Phylomorphospace by adaptive peak (no labels).

    Movie S5. Bat attack on elongated hindwing lobes.

    Movie S6. Bat attack on intact hindwing tails.

    Movie S7. Bat attack on intact tail ends.

  • Supplementary Materials

  • The PDF file includes:
    • Fig. S1. Twisted and cupped hindwing tail ends in Saturniidae.
    • Fig. S2. Hindwing morphology of the three silk moth species was altered by cutting and gluing hindwing material.
    • Fig. S3. IPI does not change on the basis of moth treatment.
    • Fig. S4. IPI does not change on the basis of moth genus or hindwing length.
    • Fig. S5. ASR demonstrates multiple origins of the hindwing tail trait within the Saturniinae subfamily.
    • Fig. S6. ASR demonstrates multiple origins of adaptive peaks within the Saturniinae subfamily.
    • Table S1. Kinematic output results from 100 ms of tethered moth flight leading up to bat-moth interaction.
    • Table S2. Bat identity and experience (that is, learning) do not affect the outcome of the trial.
    • Table S3. Bats do not change call parameters during attack on silk moths of differing morphologies.
    • Legends for movies S1 to S7

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  • Other Supplementary Material for this manuscript includes the following:
    • Movie S1 (.mov format). Phylomorphospace by tail regime.
    • Movie S2 (.mov format). Phylomorphospace by tail regime (no labels).
    • Movie S3 (.mov format). Phylomorphospace by adaptive peak.
    • Movie S4 (.mov format). Phylomorphospace by adaptive peak (no labels).
    • Movie S5 (.mov format). Bat attack on elongated hindwing lobes.
    • Movie S6 (.mp4 format). Bat attack on intact hindwing tails.
    • Movie S7 (.mp4 format). Bat attack on intact tail ends.

    Files in this Data Supplement:

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