Research seminar: MALE PREGNANCY AND PARASITE DEFENCE

Abstract

Females produce large eggs, males small sperm. This is the basis for the diverging life-history strategies among males and females, and implies that females invest more into the offspring. They are the choosy sex, live longer and hence, need a more efficient immune response. However, provisioning of eggs and higher parental investment are correlated within the female and can usually not be disentangled. Sex-role reversed species are thus needed to investigate whether the typical female traits depend only on life-history or on sex per se. In the broad-nosed pipefish Syngnathus typhle, males brood the eggs in a paternal brood pouch, where they are directly connected to the male over a placenta-like structure. Here, males have higher investment into reproduction than females.

We experimentally addressed the strength of typical female traits, and investigated sexual immune dimorphism and transfer of immunity from parents to offspring. Whereas males usually contribute little to immune transfer due to both evolutionary but also mechanistic constraints, we here demonstrate that in pipefish males are the sex with the more efficient immune response. Secondly, they also influence offspring immune defence via direct up-regulation of the immunocompetence and via a changed immune gene expression pattern. This indicates that sex-role reversal in connection with male pregnancy opens the door for bi-parental influences on offspring immunity, and may represent one additional advantage for the evolution of male pregnancy.

Seminario organizado por el Departamento de Biodiversidad y Biología Evolutiva del Museo Nacional de Ciencias Naturales (MNCN), CSIC, y retransmitido a través de Cienciatk.