Flight morphology of Neotropical butterflies: palatability and distribution of mass to the thorax and abdomen

Abstract

We test whether palatability of Neotropical butterflies is associated with distribution of mass to the thorax and abdomen. Thoracic mass is predominantly muscle mass, whereas abdominal mass includes organs of digestion, food storage, and reproduction. To escape from predation, butterflies palatable to the rufous-tailed jacamar (Galbula ruficauda) use fast, erratic flight, whereas unpalatable butterflies have defensive chemicals and slow, regular flight patterns. We adjusted for effects of phylogeny and report partial correlations for two levels of analysis: 1) comparisons among-lineage means, which test for correlations between traits of distantly related lineages, and 2) comparisons among deviations from lineage means (or within lineages), which test for correlations between traits of more closely related species.Among lineages for both males (n=10 lineages) and females (n=9), palatability and thoracic mass were positively correlated, whereas palatability and abdominal mass were negatively correlated. An inverse correlation between thoracic and abdominal mass is a consequence of the two segments composing 75% of the total body mass. Predation, indexed by palatability, may select for increased flight speed and thoracic mass at the expense of the abdomen, but relative flight speed and thoracic mass were not significantly correlated.Within lineages (n=45 species for each sex), thoracic mass was uncorrelated with palatability in both sexes. Relative flight speed correlated positively with thoracic mass and negatively with body mass. Palatability and abdominal mass were negatively correlated for males but not females. Hence differences between the sexes in mass distribution suggest differences in reproductive constraints and predation stress.

Unpredictable environments, nuptial gifts and the evolution of sexual size dimorphism in insects: an experiment

“…Since several studies indicate that relative thorax mass correlates with flight performance (e.g. Srygley & Chai 1990 ;Wickman 1992), flight performance and flight manoeuvrability might actually increase with reduced body size.…”

Integrating across Life‐History Stages: Consequences of Natal Habitat Effects on Dispersal

“…These rearing environments predictably affected the flight morphology of the adult butterflies. Individuals that developed in the low-quality site had higher wing loadings, a trait positively associated with flight speed and perfor mance (Dudley 1990;Srygley and Chai 1990), than in dividuals that developed in the high-quality site. Thorax mass and wing loading strongly affect flight capacity in Lepidoptera (Srygley and Chai 1990).…”

“…Individuals that developed in the low-quality site had higher wing loadings, a trait positively associated with flight speed and perfor mance (Dudley 1990;Srygley and Chai 1990), than in dividuals that developed in the high-quality site. Thorax mass and wing loading strongly affect flight capacity in Lepidoptera (Srygley and Chai 1990). In a study of mul tiple species of Neotropical Lepidoptera, Srygley and Chai (1990) found that populations located in pasture habitats dispersed more and differed in wing and thorax allocation patterns, corrected for body size.…”

“…Thorax mass and wing loading strongly affect flight capacity in Lepidoptera (Srygley and Chai 1990). In a study of mul tiple species of Neotropical Lepidoptera, Srygley and Chai (1990) found that populations located in pasture habitats dispersed more and differed in wing and thorax allocation patterns, corrected for body size. Individuals from pasture habitats had longer and wider forewings and heavier tho raxes than populations in forested landscapes, differences the authors attributed to phenotypic plasticity.…”

“…Individuals from pasture habitats had longer and wider forewings and heavier tho raxes than populations in forested landscapes, differences the authors attributed to phenotypic plasticity. Larger wings relative to body size decrease wing loading, while a heavier thorax is associated with increased flight power in some flying insects (Srygley and Chai 1990;Schilder and Marden 2004). Dispersal is a potentially costly process; body size, body condition, and patterns of morphological allocation are all likely to affect the ability of individuals to undertake and accomplish dispersal.…”