Effects of Neonatal Testicular Suppression with a GnRH Antagonist on Social Behavior in Group-Living Juvenile Rhesus Monkeys

Social animals must communicate to define group membership and coordinate social organization. For social insects, communication is predominantly mediated through chemical signals, and as social complexity increases, so does the requirement for a greater diversity of signals. This relationship is particularly true for advanced eusocial insects, including ants, bees, and wasps, whose chemical communication systems have been well-characterized. However, we know surprisingly little about how these communication systems evolve during the transition between solitary and group living. Here, we demonstrate that the sensory systems associated with signal perception are evolutionarily labile. In particular, we show that differences in signal production and perception are tightly associated with changes in social behavior in halictid bees. Our results suggest that social species require a greater investment in communication than their solitary counterparts and that species that have reverted from eusociality to solitary living have repeatedly reduced investment in these potentially costly sensory perception systems.

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Peak occurrence of female sexual initiation predicts day of conception in rhesus monkeys (Macaca mulatta)

Reproduction Fertility and Development ◽

10.1071/rd00080 ◽

2000 ◽

Vol 12 (8) ◽

pp. 397 ◽

Cited By ~ 24

Author(s):

Julia L. Zehr ◽

Pamela L. Tannenbaum ◽

Benjamin Jones ◽

Kim Wallen

Keyword(s):

Rhesus Monkeys ◽

Social Groups ◽

Group Living ◽

Sexual Initiation ◽

Adult Males ◽

Non Invasive ◽

Sexual Solicitation ◽

Delivery Date ◽

Conception Date ◽

Highly Correlated

The present study investigated whether peaks in female sexual initiation could accurately predict conception in group-living female rhesus monkeys. Behavioral observations, 4 or 5 days per week in large, stable, social groups of monkeys, provided frequencies of female initiation of proximity, sexual solicitation, mounts, and ejaculations. Since a preovulatory peak in female sexual initiation is likely linked to the preovulatory oestradiol surge, we used the third day after a peak in behavior as the behavioral estimate of conception date. For each pregnancy, an independent estimate of conception date was derived from ultrasound determination of fetal length. Estimates of conception based on female initiation of proximity with adult males were accurate for more than 90% of pregnancies, whereas observation of ejaculations by males predicted conception in fewer than 60% of pregnancies. Behavioral and ultrasound estimates of conception date were highly correlated and differed by less than 1 day on average. Accordingly, predictions of delivery date based on behavioral estimates of conception date were as accurate as those based on ultrasound-derived estimates. These data suggest that female-initiated sexual behavior can be used in rhesus monkeys as a practical, non-invasive tool for producing timed matings in social groups of monkeys, providing accurate estimates of conception date, gestational age, and predicted date of birth.

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