QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online June 16, 2004
Journal of Experimental Biology 207, 2663-2669 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.01071

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Seymour, R. S. Articles by Pearson, J. T. Search for Related Content PubMed PubMed Citation Articles by Seymour, R. S. Articles by Pearson, J. T.

Developmental allometry of pulmonary structure and function in the altricial Australian pelican Pelecanus conspicillatus

Roger S. Seymour^1,*, Sue Runciman², Russell V. Baudinette¹ and James T. Pearson³

¹ Environmental Biology, University of Adelaide, Adelaide, SA 5005, Australia
² Anatomy and Histology, Flinders University of South Australia, Adelaide, SA 5001, Australia
³ Cardiac Physiology, National Cardiovascular Center, Suita, Osaka, Japan 565-8565

^* Author for correspondence (e-mail: roger.seymour{at}adelaide.edu.au)

Accepted 4 May 2004

Quantitative methods have been used to correlate maximal oxygen uptake with lung development in Australian pelicans. These birds produce the largest altricial neonates and become some of the largest birds capable of flight. During post-hatching growth to adults, body mass increases by two orders of magnitude (from 88 g to 8.8 kg). Oxygen consumption rates were measured at rest and during exposure to cold and during exercise. Then the lungs were quantitatively assessed using morphometric techniques. Allometric relationships between body mass (M) and gas exchange parameters (Y) were determined and evaluated by examining the exponents of the equation Y=aM^b. This intraspecific study was compared to interspecific studies of adult birds reported in the literature. Total lung volume scales similarly in juvenile pelicans (b=1.05) as in adult birds (b=1.02). However, surface area of the blood–gas barrier greatly increases (b=1.25), and its harmonic mean thickness does not significantly change (b=0.02), in comparison to exponents from adult birds (b=0.86 and 0.07, respectively). As a result, the diffusing capacity of the blood–gas tissue barrier increases much more during development (b=1.23) than it does in adult birds of different sizes (b=0.79). It increases in parallel to maximal oxygen consumption rate (b=1.28), suggesting that the gas exchange system is either limited by lung development or possibly symmorphic. The capacity of the oxygen delivery system is theoretically sufficient for powered flight well in advance of the bird's need to use it.

Key words: bird, lung, juvenile, development, respiration, morphometry, diffusing capacity, symmorphosis