Cruising the rain forest floor: butterfly wing shape evolution and gliding in ground effect

Abstract

Summary1. Flight is a key innovation in the evolutionary success of insects and essential to dispersal, territoriality, courtship and oviposition. Wing shape influences flight performance and selection likely acts to maximize performance for conducting essential behaviours that in turn results in the evolution of wing shape. As wing shape also contributes to fitness, optimal shapes for particular flight behaviours can be assessed with aerodynamic predictions and placed in an ecomorphological context. 2. Butterflies in the tribe Haeterini (Nymphalidae) are conspicuous members of understorey faunas in lowland Neotropical forests. Field observations indicate that the five genera in this clade differ in flight height and behaviour: four use gliding flight at the forest floor level, and one utilizes flapping flight above the forest floor. Nonetheless, the association of ground level gliding flight behaviour and wing shape has never been investigated in this or any other butterfly group. 3. We used landmark-based geometric morphometrics to test whether wing shapes in Haeterini and their close relatives reflected observed flight behaviours. Four genera of Haeterini and some distantly related Satyrinae showed significant correspondence between wing shape and theoretical expectations in performance trade-offs that we attribute to selection for gliding in ground effect. Forewing shape differed between sexes for all taxa, and male wing shapes were aerodynamically more efficient for gliding flight than corresponding females. This suggests selection acts differentially on male and female wing shapes, reinforcing the idea that sex-specific flight behaviours contribute to the evolution of sexual dimorphism. 4. Our study indicates that wing shapes in Haeterini butterflies evolved in response to habitat-specific flight behaviours, namely gliding in ground effect along the forest floor, resulting in ecomorphological partitions of taxa in morphospace. The convergent flight behaviour and wing morphology between tribes of Satyrinae suggest that the flight environment may offset phylogenetic constraints. Overall, this study provides a basis for exploring similar patterns of wing shape evolution in other taxa that glide in ground effect.

Variation in Forewing Size Linked to Migratory Status in Monarch Butterflies

“…Butterflies in general utilize a combination of efficient gliding and active flapping [39]. Theoretically, species with elongated forewings and a larger aspect ratio employ extensive gliding which lowers their energy consumption whereas species using active flapping flight display more compacted forewing shape which allows for increased maneuverability [40].…”

Exploring Color Pattern Diversification in Early Lineages of Satyrinae (Nymphalidae)

“…2.3e-f), and this possibly evolved ca. 29 million years ago (Cespedes et al 2015). Transparency makes these butterflies nearly invisible in the forest understory and can be considered a defense against predation.…”

Did Adult Diurnal Activity Influence the Evolution of Wing Morphology in Opoptera Butterflies?

“…Male and female reproductive activities typically require different flight behaviors like territorial displays in males (Rutowski 1991, Wickman 1992 and searching for oviposition sites in females. Such differences in flight behavior and mass allocation (females have heavier abdomens) can lead to the evolution of wing shape dimorphism (Srygley 2001, DeVries et al 2010, Cespedes et al 2015.…”

“…In some species of Morpho (Satyrinae, Morphini), males spend a considerable amount of time performing patrolling flight at the canopy level, and they have longer wings that are aerodynamically efficient for gliding (DeVries et al 2010). Furthermore, genera in the tribe Haeterini (Satyrinae) like Cithaerias butterflies that glide in ground-effect have significantly longer wings than their midstory Dulcedo relatives that utilize flapping flight (Cespedes et al 2015). Elongate wings that have high aspect ratios and low wing centroids produce the best gliding performance by maximizing lift and reducing drag (Dudley 2000).…”