On the reliability of a simple method for scoring phenotypes to estimate heritability: A case study with pupal color in Heliconius erato phyllis, Fabricius 1775 (Lepidoptera, Nymphalidae).

In this paper, two methods for assessing the degree of melanization of pupal exuviae from the butterfly Heliconius erato phyllis, Fabricius 1775 (Lepidoptera, Nymphalidae, Heliconiini) are compared. In the first method, which was qualitative, the exuviae were classified by scoring the degree of melanization, whereas in the second method, which was quantitative, the exuviae were classified by optical density followed by analysis with appropriate software. The heritability (h(2)) of the degree of melanization was estimated by regression and analysis of variance. The estimates of h (2) were similar with both methods, indicating that the qualitative method could be particularly suitable for field work. The low estimates obtained for heritability may have resulted from the small sample size (n = 7-18 broods, including the parents) or from the allocation-priority hypothesis in which pupal color would be a lower priority trait compared to morphological traits and adequate larval development.

On the reliability of a simple method for scoring phenotypes to estimate heritability: a case study with pupal color in Heliconius erato phyllis, Fabricius 1775 (Lepidoptera, Nymphalidae)

In this paper, two methods for assessing the degree of melanization of pupal exuviae from the butterfly Heliconius erato phyllis, Fabricius 1775 (Lepidoptera, Nymphalidae, Heliconiini) are compared. In the first method, which was qualitative, the exuviae were classified by scoring the degree of melanization, whereas in the second method, which was quantitative, the exuviae were classified by optical density followed by analysis with appropriate software. The heritability (h2 ) of the degree of melanization was estimated by regression and analysis of variance. The estimates of h 2 were similar with both methods, indicating that the qualitative method could be particularly suitable for field work. The low estimates obtained for heritability may have resulted from the small sample size (n = 7-18 broods, including the parents) or from the allocation-priority hypothesis in which pupal color would be a lower priority trait compared to morphological traits and adequate larval development.

Pupal melanization in Heliconius erato phyllis (Lepidoptera; Nymphalidae): genetic and environmental effects.

This paper deals with estimates of heritability and the effect of two different kinds of environment on the melanization of pupae in the butterfly Heliconius erato phyllis. The results for heritability showed greater differences when the offspring were regressed on male or female values for pupal colour. Pupal colour followed a system of discrete scores, from 2 for the light pupae to 5 for the darkest one. Estimate of the heritability (h2) was 0.44 when the average score of the siblings were regressed on the mid-parental value. When regressed on the male parent, h2 was larger (0.54), being very low when regressed on the female parent (0.09). Estimate by the analysis of variance was also 0.44 when both male and female sibs were included in the analysis (for male sibs, h2=0.43 and for female sibs, 0.47). To test for the effect of the environment, each brood was divided in three, one being the control, the second subjected to a black environment when reaching the fifth instar and the third to a white environment. Those in the black environment originated dark pupae that scored 5 or 4; for those in the white environment, there was no difference with the controls. Caterpillars when entering the prepupal stage were also subjected to the black treatment (early and late prepupal stage, respectively, for treatments called black A and black B). A significant effect was observed only when early prepupal stage was subjected to the black environment.