Incubation Period and Immunocompetence: a comparative study.

PALACIOS, M. G.; MARTIN, T. E.

New Orleans, Lousiana, EEUU

Congreso; 3rd North American Ornithological Conference.; 2002

Ornithological Societies of North America

Understanding the causes underlying variation in life history among organisms is the main goal of life history theory. Developmental rates are an integral component of life history that vary widely across species, can have important fitness consequences, and are tightly linked to other life history traits. In particular, incubation period varies widely among species of similar size and developmental mode, and prolonged incubation has long mystified scientists because of its costs from increased time-dependent mortality. Here we address a hypothesis suggesting that slow embryonic development could allow for development of a better immune system, therefore enhancing the ability of individuals to defend themselves from parasites and disease (Ricklefs 1992, Proc. Natl. Acad. Sci. 89: 4722-4725). We performed a comparative study among passerine species and measured immunocompetence in the field using 2 standard tests: 1) SRBC (sheep red blood cells) test for humoral immunity, and 2) PHA (phytohemaglutinin) test for cell-mediated immunity. Preliminary results suggest that the response to the SRBC test is positively correlated with duration of the incubation period across species, as predicted by the hypothesis. However, a negative relationship was observed for the response to the PHA test. A more complete test including more species from a second year of study will presented.