Data from: Male rock lizards may compensate reproductive costs of an immune challenge affecting sexual signals

Sexual signals can be evolutionarily stable if they are condition
dependent or costly to the signaler. One of these costs may be the
trade-off between maintaining the immune system and the elaboration of
ornaments. Experimental immune challenges in captivity show a reduction in
the expression of sexual signals, but it is not clear whether these
detrimental effects are important in nature and, more importantly, whether
they have reproductive consequences. We designed a field experiment to
challenge the immune system of wild male Carpetan rock lizards,
Iberolacerta cyreni, with a bacterial antigen (LPS). The immune challenge
decreased relative reflectance of UV structural and melanin-dependent
sexual coloration in the throat and the lateral ocelli, whereas the
carotenoid-dependent dorsal green coloration was not affected. Immune
activation also decreased proportions of ergosterol and
cholesta-5,7-dien-3-ol in femoral secretions. These results support a
trade-off between the immune system and both visual and chemical sexual
ornaments. Moreover, reproductive success of males, estimated with DNA
microsatellites, depended on the expression of some color and chemical
traits. However, the immune challenge did not cause overall differences in
reproductive success, although it increased with body size/age in control
but not in challenged males. This suggests the use of alternative
reproductive strategies (e.g. forced matings) in challenged males,
particularly in smaller ones. These males might consider that their
survival probabilities are low and increase reproductive effort as a form
of terminal investment in spite of their "low-quality" sexual
signals and potential survival costs.