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J Exp Biol. 2018 Jan 9;221(Pt 1). pii: jeb162693. doi: 10.1242/jeb.162693.

Aerobic power and flight capacity in birds: a phylogenetic test of the heart-size hypothesis.

Author information

1
Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile robertonespolorossi@gmail.com jordi.altimiras@liu.se.
2
Center of Applied Ecology and Sustainability (CAPES), Facultad de Ciencias Biológicas, Universidad Católica de Chile, Santiago 6513677, Chile.
3
Centro de Investigación en Recursos Naturales y Sustentabilidad (CIRENYS), Universidad Bernardo O'Higgins, Santiago, Chile.
4
Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile.
5
AVIAN Behavioural Genomics and Physiology Group, Division of Biology, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
6
Instituto de Ecología, Carrera de Biología, Universidad Mayor de San Andrés, La Paz, Bolivia.
7
Departament de Biologia Evolutiva, Ecologia i Ciéncies Ambientals, Institut de Recerca de la Biodiversitat (IRBio), Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
8
Departamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales (CSIC), Madrid, Spain.
9
AVIAN Behavioural Genomics and Physiology Group, Division of Biology, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden robertonespolorossi@gmail.com jordi.altimiras@liu.se.

Abstract

Flight capacity is one of the most important innovations in animal evolution; it only evolved in insects, birds, mammals and the extinct pterodactyls. Given that powered flight represents a demanding aerobic activity, an efficient cardiovascular system is essential for the continuous delivery of oxygen to the pectoral muscles during flight. It is well known that the limiting step in the circulation is stroke volume (the volume of blood pumped from the ventricle to the body during each beat), which is determined by the size of the ventricle. Thus, the fresh mass of the heart represents a simple and repeatable anatomical measure of the aerobic power of an animal. Although several authors have compared heart masses across bird species, a phylogenetic comparative analysis is still lacking. By compiling heart sizes for 915 species and applying several statistical procedures controlling for body size and/or testing for adaptive trends in the dataset (e.g. model selection approaches, phylogenetic generalized linear models), we found that (residuals of) heart size is consistently associated with four categories of flight capacity. In general, our results indicate that species exhibiting continuous hovering flight (i.e. hummingbirds) have substantially larger hearts than other groups, species that use flapping flight and gliding show intermediate values, and that species categorized as poor flyers show the smallest values. Our study reveals that on a broad scale, routine flight modes seem to have shaped the energetic requirements of birds sufficiently to be anatomically detected at the comparative level.

KEYWORDS:

Aves; Cardiovascular system; Comparative phylogenetics; Ornstein–Uhlenbeck models; Stroke volume

PMID:
29150450
DOI:
10.1242/jeb.162693
[Indexed for MEDLINE]
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