Biomechanical, Respiratory and Cardiovascular Adaptations of Bats and the Case of the Small Community of Bats in Chile

Bats are unique among mammals for their ability to fly. The acquisition of powered flight required a series of morphological and physiological changes in the basic mammal body plan. The structure of the limbs is the most obvious specialization, however, adaptations for powered flight encompass most organ systems, in particular the cardiovascular and respiratory apparatus. Flight performance is strongly determined by wing morphology, which in turn is associated with the biomechanics and energetics of flight, as well as ecological aspects such as foraging behavior and habitat selection. In this chapter we focus on respiratory, cardiac and wing morphology characteristics of some bat species present in Chile, correlating the results with ecological and behavioral information. The small community of Chilean bat species shows a pattern similar to that found in other bat communities. With respect to wing morphology we found that Tadarida brasiliensis, Desmodus rotundus and Mormopterus kalinowskii have small wing areas, while molossids have high aspect ratios and that of D. rotundus is only moderate. D. rotundus has a smaller mass specific wing span, and the highest wing loading. Myotis chiloensis has a second moment of area of humerus (Ih), lower than expected from allometric predictions, suggesting poorer resistance. Based on these results four functional groups may be recognized: i) species with high wing loading and low wing span such as D. rotundus, capable of rapid flight with moderate power consumption, ii) species with high wing loading and high aspect ratio, such as the molossids T. brasiliensis and M. kalinowski, which are capable of fast flight and low power consumption, characteristic of foragers in open areas; iii) species with low wing loading and low wing span such as most vespertilionids, capable of slow and maneuverable flights in a bat that inhabits wooded areas; and iv) L. cinereus, forming an isolated group characterized by high speed and agility. Also the respiratory and cardiovascular systems of bats are modifications or refinements that allow them to survive this extreme way of life. Bats have lung volumes about 72% greater than non-flying mammals of the same size. Pulmonary ventilation can rapidly increase 10 to 17 times as flight begins. These respiratory adaptations, along with