Research ArticleENTOMOLOGY

Color polymorphism in an aphid is maintained by attending ants

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Science Advances  07 Sep 2016:
Vol. 2, no. 9, e1600606
DOI: 10.1126/sciadv.1600606

Figures

  • Fig. 1 Color polymorphism in M. yomogicola and attending ant, L. japonicus.

    Large black aphids and small green ones are green morphs, whereas large and small orange and brown ones are red morphs.

  • Fig. 2 Results of experiment 1 (A) and experiment 2 (B).

    (A) Effect of ant attendance on the survival of aphid colonies. The ratio of survived aphid colonies. Aphid colonies were attended by ants (Attending), not attended by ants (Not attending), or attended by ants but experienced the effects of Tanglefoot (Control). n.s., not significant. (B) Effect of the proportion of the green morph in an aphid colony on the degree of ant attendance. The plots represent the residuals from the two-dimensional regression plane, with ant colony size and aphid colony size as independent variables. The superimposed function (solid line) is a three-dimensional function that was selected as the best fit model from the four candidate functions based on Akaike’s information criteria (AIC) comparisons.

Tables

  • Table 1 The results of the multiple regressions of the two factors (aphid number is the number of aphids in a colony and ant head width is an index of ant colony size) on attending ants per aphid.

    Aphid number is negatively correlated with attending ants per aphid (P = 0.00659). Statistical significance is marginal for ant head width (P = 0.06171). F = 5.449; df = (2,82); P = 0.006; R2 = 0.1173.

    FactorEstimateSEtP
    Intercept−0.02090.119257−0.1750.8613
    Aphid number−0.000310.000112−2.7880.00659
    Ant head width (∝ant colony size)0.214100.1130241.8940.06171
  • Table 2 Regression coefficients and AIC values for the four regressed functions.

    Significance levels of the coefficients are indicated by asterisks (***P < 0.001).

    Function typeEquationabcPAIC
    LinearaX−0.02550.854−50.931
    Second dimensionaX2 + bX0.3304−0.3312−49.963
    Third dimensionaX3 + bX2 + cX−4.2858***5.2189***−1.4946***−64.835
    Smoothing spline0.0015−61.681

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