DREA, C.M.; Duke University: Could female ringtailed lemurs be �masculinized� by maternal androgens?

To examine the broader application of hormonal mechanisms of behavioral and morphological masculinization described for the female spotted hyena (Crocuta crocuta ), the present study explored a similar, but less extreme, phenomenon in the ringtailed lemur (Lemur catta ), a Malagaszy primate in which the female socially dominates males, is size monomorphic with males, and exhibits a pendulous clitoris. Consideration of these masculine traits has focused attention on the role of androgens in female development. To characterize the extent of female morphological masculinization, experiment 1 measured the external genitalia of 18 intact adult lemurs (9 F; 9 M) at the Duke University Primate Center. Females displayed a shorter anogenital distance and larger urethral meatus than did males, but total clitoral width and length were comparable to those of the extruded male glans. Experiment 2 examined seasonal fluctuations in serum testosterone (T), androstenedione (A4), and estradiol (E2) in 22 intact adult lemurs (10 F; 12 M) over the course of 4 annual cycles, and assessed hormonal correlates of prenatal development by charting these same steroids throughout 16 pregnancies. Adults of both sexes showed a significant breeding season peak in steroid production. Whereas male T concentrations exceeded those of females, both sexes showed comparable A4 concentrations. Pregnancies that produced singleton males, twin males, or mixed sex twins showed higher concentrations of all three steroids than did pregnancies that produced singleton or twin females, especially in the third trimester, but steroid levels in female-producing pregnancies consistently exceeded preconception and postpartum values. These data are consistent with the hypothesis that female lemurs may be partially masculinized through exposure to maternal androgens. Funded by NSF grant BCS-0409367.