关键词: 艾美耳球虫, 繁殖, 高原鼠兔, 青藏高原

Abstract: The effects that parasitism on host reproduction depends on a trade-off between the host’s current reproductive success and its residual reproductive success. Coccidian parasites are microparasites, and the effect of microparasites on current reproductive success is greater than that on residual reproductive success. We tested the hypothesis that coccidian parasites（Apicomplexa:Eimeriiade） would impact on current reproduction of plateau pikas. In field observations, 170 plateau pikas were trapped in early-, middle- and late-breeding seasons. For infection rate, there were significant differences in breeding seasons. In the mid-period of breeding, non-infective females had a higher pregnant rate than infective females, and non-pregnant females had a higher infection intensity than did pregnant females. However, no effects were found in the other two breeding periods. No significant relationships between infection intensity or infection rate and testis and epididymis index were found in males in any breeding period. There also were no significant differences in testis or epididymis indices between infective and non-infective males. In addition, the field observation experiment results show that the infection with coccidia significantly decreased embryo weights. It was consistent with the results in the field infection experiment in this study. Our results demonstrated parasite infection influence on embryo development. Our results suggest that the sex-biased effects on plateau pika reproduction may be related to hosts modifying their reproductive strategy to optimize fitness.