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Biomedical subjects

Rupert C Marshall

Publications and source records attributed to Rupert C Marshall.

5 recordsLinked to original sources
PubMed2005

Male song quality affects circulating but not yolk steroid concentrations in female canaries (Serinus canaria).

Male song complexity is a sexually selected trait found in many songbirds, including strains of the domestic canary. Studies on several species have shown that male song can affect the hormonal state of females and may also influence concentrations of maternal hormones in the yolk of their eggs. In this study, we show that the level of circulating androgens and oestrogens of female canaries, as measured in faeces, varies with the quality of male song to which they are exposed. The female-perceived quality of male canary song depends on the production of special 'sexy syllables' to which females respond with more sexual displays. Using playback of synthetic song we show that females hearing songs with sexy syllables have higher levels of faecal testosterone than control females hearing songs without them. However, unlike previous studies on the canary, we found no evidence that such females laid eggs with more testosterone (or other steroids) in their egg yolks. We discuss these results in relation to the evolution of male signalling and maternal investment strategies.

Animals↗
PubMed2003

Sexual selection and individual genetic diversity in a songbird.

Here, we report for the first time, to our knowledge, a strong correlation between a measure of individual genetic diversity and song complexity, a sexually selected male trait in sedge warblers, Acrocephalus schoenobaenus. We also find that females prefer to mate with males who will maximize this diversity in individual progeny. The genetic diversity of each offspring is further increased by means of nonrandom fertilization, as we also show that the fertilizing sperm contains a haplotype more genetically distant to that of the egg than expected by chance. These findings suggest that species' mating preferences may be subject to fine tuning aimed at increasing offspring viability through increased genetic diversity. This includes external and internal mechanisms of selection, even within the ejaculate of a single male.

Animals↗