A1 Refereed original research article in a scientific journal
Parental allocation of additional food to own health and offspring growth in a variable environment
Authors: Karell P, Pietiäinen H, Siitari H, Pihlaja T, Kontiainen P, Brommer JE
Publisher: NATL RESEARCH COUNCIL CANADA-N R C RESEARCH PRESS
Publication year: 2009
Journal: Canadian Journal of Zoology
Journal name in source: CANADIAN JOURNAL OF ZOOLOGY-REVUE CANADIENNE DE ZOOLOGIE
Journal acronym: CAN J ZOOL
Volume: 87
Issue: 1
First page : 8
Last page: 19
Number of pages: 12
ISSN: 0008-4301
DOI: https://doi.org/10.1139/Z08-133
Web address : https://doi.org/10.1139/Z08-133
Abstract
Life-history theory predicts increased investment in current reproduction when future reproduction is uncertain and a more balanced investment in current and future reproduction when prospects for both are good. The outcome of the balance in parental allocation depends on which life-history component maximizes the fitness benefits. In our study system, a 3-year vole cycle generates good prospects of current and future reproduction for Ural owls (Strix uralensis Pallas, 1771) in increase vole phases and uncertain prospects in decrease vole phases. We supplementary-fed Ural owls during the nestling period in 2002 ( an increase phase) and 2003 ( a decrease phase), and measured offspring growth, parental effort, and physiological health by monitoring haematocrit, leucocyte profiles, intra- and inter-celluar blood parasites, and ( in 2003) humoral antibody responsiveness. Food supplementation reduced parental feeding rate in both years, but improved a female parent's health only in 2002 ( an increase phase) and had no effects on males in either year. Nevertheless, supplementary-fed offspring reached higher asymptotic mass and fledged earlier in both years. Furthermore, early fledging reduced offspring exposure to blood-sucking black flies ( Diptera, Simuliidae) in the nest. We discuss how parental allocation of resources to current and future reproduction may vary under variable food conditions.
Life-history theory predicts increased investment in current reproduction when future reproduction is uncertain and a more balanced investment in current and future reproduction when prospects for both are good. The outcome of the balance in parental allocation depends on which life-history component maximizes the fitness benefits. In our study system, a 3-year vole cycle generates good prospects of current and future reproduction for Ural owls (Strix uralensis Pallas, 1771) in increase vole phases and uncertain prospects in decrease vole phases. We supplementary-fed Ural owls during the nestling period in 2002 ( an increase phase) and 2003 ( a decrease phase), and measured offspring growth, parental effort, and physiological health by monitoring haematocrit, leucocyte profiles, intra- and inter-celluar blood parasites, and ( in 2003) humoral antibody responsiveness. Food supplementation reduced parental feeding rate in both years, but improved a female parent's health only in 2002 ( an increase phase) and had no effects on males in either year. Nevertheless, supplementary-fed offspring reached higher asymptotic mass and fledged earlier in both years. Furthermore, early fledging reduced offspring exposure to blood-sucking black flies ( Diptera, Simuliidae) in the nest. We discuss how parental allocation of resources to current and future reproduction may vary under variable food conditions.
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