The Relationship between Lipid and Reproductive Cycles of a Subtropical Population of Peromyscus leucopus

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Abstract
Lipid indices, basic weights, and reproductive parameters of monthly collections of P. leucopus from the lower Rio Grande Valley of Texas were measured from January through December 1975. a total of 100 adult males and 114 adult females were used in the analyses. Basic weight and percent water varied little among months. There was no significant difference at the .05 probability level in lipid index between the sexes in any month, but mean lipid indices varied significantly among months in both sexes. a peak of reproductive activity occurred in May, June, and July and lipid indices were significantly lower at this time. Starved mice exhibited a mean lipid index of .198, whereas the mean for summer animals was .225, suggesting that mice in summer have largely depleted their metabolizable lipid reserves. Comparisons suggest that the lipid cycle differs in geographically distant populations of P. leucopus. We postulate that changes in food supply, as influenced by rainfall, may regulate the pattern of lipid deposition.