Sex differences in cell-mediated immunity in the Magellanic penguin Spheniscus magellanicus

摘要

Males in domestic and laboratory populations usually display a lower immunocompetence than females due to differential action of steroid hormones, but information for natural populations is scant. Here we show that male Magellanic penguins Spheniscus magellanicus had a significantly lower cell-mediated immunity at hatching of their chicks than females. This was assayed through the phytohemagglutinin injection assay, a standard method of measuring T-cell-dependent immunocompetence in birds. Breeding phenology affected condition at laying and cell-mediated immunity at hatching for males, with higher values for late-breeding males. In females, condition at laying declined with breeding date, with no link with immunocompetence at hatching. Early breeding males may incur date-dependent costs in terms of condition and subsequent immunocompetence. [References: 36]