Respiration and energetics of embryonic development in a large altricial bird, the Australian pelican (Pelecanus conspicillatus)

Author:

Pearson James T.1,Seymour Roger S.1,Baudinette Russell V.1,Runciman Susan2

Affiliation:

1. Department of Environmental Biology, University of Adelaide, Adelaide 5005, South Australia

2. Department of Anatomy and Histology, Flinders University, GPO Box 2100,Adelaide 5001, South Australia

Abstract

SUMMARY We examined whether the previously reported low cost of embryonic development in pelicans could be attributed to a more efficient conversion of egg energy to hatchling tissues as a result of high initial egg water content,low embryonic metabolic rate and growth later in incubation than in more precocious species. We therefore determined egg and hatchling composition and the development of embryonic respiration in the Australian pelican Pelecanus conspicillatus, which lays one of the largest eggs (140-210 g) with an altricial developmental mode. The small yolk fraction (21%) is typical of all pelecaniforms; however, we found that intraspecific variability in fresh egg mass was related to water content (principally in the albumen),but independent of yolk mass (mean 13 g dry mass). P. conspicillatuseggs have, on average, 635 kJ of energy, irrespective of egg mass across the whole range of egg mass. The embryonic developmental pattern of O2 consumption and CO2 production showed clear plateaus lasting 2-3 days immediately prior to internal pipping, resembling the typical precocial pattern. However,the rate of pre-internal pipping O2 consumption was low in comparison with that of precocial species of similar egg mass. There is no evidence to support the hypothesis that the observed plateau in rates of O2 uptake is due to a diffusion limitation of the eggshell gas conductance in this species. Embryonic metabolic rate nearly doubled during the pipping period, but the mass-independent metabolic rate of the hatchling was low in comparison with that of the resting adult. The total O2consumed (11 063 ml) is equivalent to 217.3 kJ (or 34% of egg energy) based on indirect calorimetry and the observed respiratory exchange ratio of 0.71. Thus, the cost of development (direct calorimetry) was 0.29 kJ J-1in the egg (mean egg mass 168 g), which is one of lowest reported values. As a result, the production efficiency of pelican embryonic development was 61.6%,higher than the average for birds in general (56.9%) and, in particular, of seabirds that have prolonged incubation periods on the basis of egg mass. High efficiency in embryonic development in this species was attained as a result of rapid embryonic growth later in incubation, low hatchling energy density(23.6 kJ g-1 dry matter) and dry matter content, low embryonic metabolic rate throughout incubation and a shorter than expected incubation period of 33 days (predicted 36 days).

Publisher

The Company of Biologists

Subject

Insect Science,Molecular Biology,Animal Science and Zoology,Aquatic Science,Physiology,Ecology, Evolution, Behavior and Systematics

Cited by 5 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

1. Development of the Avian Respiratory System;Current Perspectives on the Functional Design of the Avian Respiratory System;2023

2. Effects of egg size on Double-crested Cormorant (Phalacrocorax auritus) egg composition and hatchling phenotype;Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology;2009-02

3. Comparison of the respiratory transition at birth or hatching in viviparous and oviparous amniote vertebrates;Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology;2007-12

4. An allometric study of lung morphology during development in the Australian pelican, Pelicanus conspicillatus, from embryo to adult;Journal of Anatomy;2005-10

5. Developmental allometry of pulmonary structure and function in the altricial Australian pelican Pelecanus conspicillatus;Journal of Experimental Biology;2004-07-01

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