Physiological trade-offs in reproduction and condition dependence of a secondary sexual trait

• This thesis examines parental condition, how it is traded off against reproduction and how it is displayed in a secondary sexual trait. The studies were performed on nest-box breeding collared flycatchers Ficedula albicollis on the island of Gotland, in the Baltic Sea. Early breeding and high fitness were found to be associated with high levels of glycosylated haemoglobin possibly governed by migratory exertion and infectious disease. In order to test if immune function is expressed in secondary sexual traits and how it is traded off against reproductive effort a series of experiments were performed, in which birds were challenged with an antigen, via a vaccine containing neutralised paramyxovirus. The forehead patch of the male collared flycatcher serves as a badge of status and is under sexual selection. Good condition, as reflected in strong immune response and low levels of blood parasites was found to be associated with bigger patch size. Patch size was also found to vary in size within the same breeding season in a pattern predictable from immune response data. Immune response, in itself, was found to be costly in terms of reduced survival, confirming that trade-offs involving suppression of immune response may increase fitness. Mating effort was found to be traded off against immune function and moult. Experimental brood size manipulations revealed a trade-off females between number of offspring and immune function. Thus I suggest a set of parameters useful for condition estimation. I also show that immune response is costly and, second, that pathogen resistance probably plays an important role in the shaping of secondary sexual traits and life-history decisions.

Subject headings

NATURVETENSKAP  -- Biologi -- Utvecklingsbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Developmental Biology (hsv//eng)

Keyword

Developmental biology

Trade-offs

life history

immune ecology

cost of reproduction

costs of immune response

sexual selection

migration

moult

Newcastle disease

HbA1C

Ficedula albicollis

Utvecklingsbiologi

Developmental biology

Utvecklingsbiologi

Animal Ecology

zooekologi

Publication and Content Type

vet (subject category)

dok (subject category)