Ecological and Biomechanical Insights into the Evolution of Gliding in Mammals

Abstract

Gliding has evolved independently at least six times in mammals. Multiple hypotheses have been proposed to explain the evolution of gliding. These include the evasion of predators, economical locomotion or foraging, control of landing forces, and habitat structure. Here we use a combination of comparative methods and ecological and biomechanical data collected from free-ranging animals to evaluate these hypotheses. Our comparative data suggest that the origins of gliding are often associated with shifts to low-quality diets including leaves and plant exudates. Further, data from free-ranging colugos suggest that although gliding is not more energetically economical than moving through the canopy, it is much faster, allowing shorter times of transit between foraging patches and therefore more time available to forage in a given patch. In addition to moving quickly, gliding mammals spend only a small fraction of their overall time engaged in locomotion, likely offsetting its high cost. Kinetic data for both take-off and landing suggest that selection on these behaviors could also have shaped the evolution of gliding. Glides are initiated by high-velocity leaps that are potentially effective in evading arboreal predators. Further, upon landing, the ability to control aerodynamic forces and reduce velocity prior to impact is likely key to extending distances of leaps or glides while reducing the likelihood of injury. It is unlikely that any one of these hypotheses exclusively explains the evolution of gliding, but by examining gliding in multiple groups of extant animals in ecological and biomechanical contexts, new insights into the evolution of gliding can be gained.

Touchdown to take-off: at the interface of flight and surface locomotion

“…Exploiting the principles of claws, van der Waals forces and wet adhesion, animals have evolved to generate the required attachment forces (figure 2) [60][61][62][63][64][65][66][67][68]. This enables animals to negotiate and exploit complex surfaces with a combination of effective aerial approaches, contact strategies, surface locomotion techniques and take-off manoeuvres of which the dynamics are not well understood [1,[69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84][85]. By contrast, aerial robots are just starting to implement some of these successful perching and locomotion strategies.…”

“…) using pitch-up manoeuvres [71,78]. Birds, flying squirrels and gliding lizards of the genus Draco have also been found to pitch up for rapid deceleration prior to landing [1,74,[79][80][81].…”

Ecology and mode-of-life explain lifespan variation in birds and mammals

“…species which feed in trees, water or aerially) will live longer than terrestrial foragers, because they will be more capable of escaping from predators than species that feed on the ground [13,17,20]; and (iv) fossorial (i.e. species that live in permanent burrows) and semi-fossorial species will live longer than purely terrestrial species, because they possess means to escape predation and unfavourable conditions through refuge [21].…”

How animals glide: from trajectory to morphology

“…Vogel (2006) considers the problems associated with coping with gravity in air more generally for all organisms from plants to birds. A recent symposium in 2011 focused on the biomechanics and behavior of most of the major types of animal gliders (including extinct taxa), providing the most comprehensive summary of gliding to date (Boistel et al 2011, Byrnes and Spence 2011, Jusufi et al 2011, Koehl et al 2011, McGuire and Dudley 2011 have been observed to simply drop from their arboreal perch into the water below, demonstrating that they might not use gliding for escape, as might be expected.…”