Evolution of Traditional Aerodynamic Variables in Bats (Mammalia: Chiroptera) within a Comprehensive Phylogenetic Framework

AMADOR, L.I.; ALMEIDA, FRANCISCA C.; GIANNINI, NP

JOURNAL OF MAMMALIAN EVOLUTION

SPRINGER

Lugar: Berlin; Año: 2019

1064-7554

Chiropterais the only group of mammals capable of powered flight. The mechanical basis ofbat flight is well established, but evolution of its constituent aerodynamicvariables remains poorly understood. Here we determine the macroevolutionarypatterns of traditional aerodynamic variables (wing loading, aspect ratio, tip shapeindex) in a comprehensive phylogeny of Chiroptera using an extensive datasetincluding key Eocene fossils. We optimized variables as continuous charactersand fitted models of character evolution to identify shifts in characteroptima. The reconstructed ancestral chiropteran morphotype presented low wingloading and low-to- intermediate aspect ratio, and remained unaltered for muchof the first half of bat evolution (Paleogene). This evolutionary pattern maybe explained by stabilizing selection responding to the strong constraintsimposed by echolocation and flight on body size, and the physical constraintsregarding aerodynamic efficiency acting on wing shape. Posterior specializationin some groups permitted divergence toward novel aerodynamic morphotypes in thesecond half of the chiropteran evolutionary history (Neogene). We linked themost notable aerodynamic changes to ecological release from echolocationconstraints (Pteropodidae), dietary-foraging shifts (Phyllostomidae,Noctilionidae), or advantage in face of environmental changes (Molossidae,Taphozoinae). The independently-evolved specialization of fast, enduring flightthat allowed Molossidae and Taphozoinae (Emballonuridae) to perform aerialhawking of swarming insects in open spaces was linked to significant shifts inthe optima of both wing loading and aspect ratio. These shifts were probablyassociated with the gradual spread of open-mosaic landscapes at a global scalesince the Oligocene.