Genetic Diversity Predicts Pathogen Resistance and Cell-mediated Immunocompetence in House Finches by Ms DM Hawley, Dr. KV Sydenstricker, Dr GV Kollias and Professor AA Dhondt
Scientists have long suspected that genetic diversity influences individual health, but this idea had not been tested in an experimental setting where the playing field is leveled. We investigated whether house finches with less genetic variation become more severely diseased in response to a pathogen challenge. Finches with lower genetic variation showed more severe eye symptoms that are characteristic of infections from this naturally-occurring pathogen. The stronger symptoms may reflect compromised immunity: when we challenged birds with a T-cell stimulant, less genetically variable birds mounted weaker responses. Our study provides direct support that genetic variation impacts individual disease resistance and immunity.
Contact: Ms DM Hawley, Ecology and Evolutionary Biology, Cornell University, Corson Hall, ITHACA, NEW YORK, 14853, United States

No sex difference in yolk steroid concentrations of avian eggs at laying by Dr KM Pilz, Professor E Adkins-Regan and Dr H Schwabl
Bird eggs contain steroids of maternal origin. These maternal steroids affect offspring development, and have been hypothesised to influence offspring sex. However, previous studies of the sex-determination hypothesis have examined steroid levels in incubated eggs, which may not accurately reflect maternal steroid levels. We conducted the first study relating steroid concentrations in unincubated eggs with the embryonic sex of offspring, as determined by genetic sexing. Steroid concentrations of male and female eggs were not different in unincubated eggs, but were different in incubated eggs. Thus, maternal steroids do not appear to play a critical role in avian sex determination.
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Contact: Tim Watson
tim.watson@royalsoc.ac.uk
44-207-451-2508
Royal Society
28-Jun-2005