Degree Type

Dissertation

Date of Award

2006

Degree Name

Doctor of Philosophy

Department

Ecology, Evolution, and Organismal Biology

Major

Ecology and Evolutionary Biology

First Advisor

Carol M. Vleck

Abstract

For many bird embryos, periodic cooling occurs when the incubating adult leaves the nest to forage, but the effects of periodic cooling on embryo growth, yolk use and metabolism are poorly known. To address this question I conducted incubation experiments on eggs of zebra finches (Taeniopygia guttata ) that were frequently cooled and then rewarmed or were allowed to develop at a constant temperature. After 12 days of incubation, embryo mass and yolk reserves were less in eggs that experienced periodic cooling, compared to controls incubated constantly at 37.5°C. Embryos that regularly cooled to 20°C had higher mass-specific metabolic rates than embryos incubated constantly at 37.5°C. Periodic cooling delayed development and increased metabolic costs, reducing the efficiency with which egg nutrients were converted into embryo tissue. Avian embryos can tolerate periodic cooling possibly by adjusting their physiology to variable thermal conditions, but at a cost to growth efficiency as well as a decrease in the rate of development. This reduction in embryo growth efficiency adds a new dimension to the fitness consequences of variation in adult nest attentiveness.

DOI

https://doi.org/10.31274/rtd-180813-6665

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Christopher Robin Olson

Language

en

Proquest ID

AAI3243826

File Format

application/pdf

File Size

166 pages

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