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1 March 2008 Sex-Related Differences in Hematological Stress Indices of Breeding Paedomorphic Mole Salamanders
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Reproduction in amphibians is stressful and perhaps more so in females than males because of the higher energetic costs of producing eggs than sperm. The ratio of two white blood cells, neutrophils and lymphocytes, has been shown in birds, turtles, and amphibians to increase with stress. We captured breeding and nonbreeding, paedomorphic Mole Salamanders (Ambystoma talpoideum), to determine whether the stress of reproduction is reflected by neutrophil:lymphocyte ratios in this species. In blood smears of all individuals, we observed approximately 25.5 leukocytes per 1000 erythrocytes, with 13% of the leukocytes being neutrophils, 41% lymphocytes, and 46% eosinophils. Less than 1% of leukocytes were basophils and monocytes. Neutrophil:lymphocyte ratios of gravid females were significantly higher (and also more variable) than those of reproductive males and of nonreproductive individuals, indicating a higher degree of physiological stress in reproductive females. Reproductive males did not have higher ratios than nonreproductive individuals. We found no effect of body size on neutrophil:lymphocyte ratios. Our hematological stress results are consistent with studies of other amphibians where different methods were used and with other taxa.

Andrew K. Davis and John C. Maerz "Sex-Related Differences in Hematological Stress Indices of Breeding Paedomorphic Mole Salamanders," Journal of Herpetology 42(1), 197-201, (1 March 2008).
Accepted: 1 October 2007; Published: 1 March 2008

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