Relationships between external morphology and foraging behaviour: bats in the genusMyotis

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Abstract
A morphometric study of 41 species of Myotis revealed significant associations between morphological features and foraging styles, namely aerial feeding, gleaning, feeding over water, and trawling. Aerial feeders have small hind feet, short calcars, short ears, and narrow tragi. Gleaners have small hind feet, long ears, and wide tragi and tend to be larger in body size. Bats that feed over water have large hind feet, short calcars, short ears, and narrow tragi and tend to be smaller in body size. Trawlers have large hind feet and long calcars and tend to be larger in body size. The morphometric analysis also confirmed that some species of Myotis were intermediate in morphological features, coinciding with alternation between foraging styles. The results support the view that the morphological features previously used to assign Myotis species to subgenera are more functional than phylogenetic, a position supported by recent genetic analyses. Examination of foraging styles from a phylogenetic perspective suggests that aerial feeding is ancestral and that subsequent diversification has been associated with partitioning and specialization into either gleaning or foraging over water and trawling. When the predictions from the multivariate analysis of the data for the genus Myotis are used with data from other bats, they suggest that 5 species of Nycteris are gleaners, while 11 species of Eptesicus are either aerial feeders or feed over water.