Adaptive significance of Pavlovian conditioning on reproductive behavior and fertility in Japanese quail (Coturnix japonica)

Abstract

The adaptive significance of Pavlovian conditioning has been an established idea within the learning literature. Pavlov himself indicated the potential for associative learning's role as an adaptive mechanism. As investigations into Pavlovian conditioning moved into the laboratory, the idea of adaptive significance was lost. The current body of work seeks to re-establish the adaptive importance of Pavlovian conditioning by investigating changes in the reproductive behavior of Japanese quail. Experiment 1 was a preliminary exploration of the relationship between the reproductive behaviors of the male and female Japanese quail, and fertility rates. Fertility rates were highly correlated with female immobility and male copulatory efficiency--a measure of copulatory behavior quality for males. Also, female immobility was highly correlated with male copulatory efficiency. In Experiment 2, changes in reproductive behavior and fertility due to Pavlovian conditioning were examined. The results indicated that Pavlovian conditioning altered the fertility rates for subjects if both partners of the copulatory pair were signaled. The Pavlovian conditioning procedure was refined for Experiment 3, which also showed changes in fertility rates as well as male copulatory efficiency. These experiments served to establish that Pavlovian conditioning can increase copulatory behavior and fertility when both partners of the copulatory pair are signaled. Experiments 4 - 6 investigated how factors related to the Conditioned Stimulus impact reproductive behavior and fertility rates. Experiment 4 showed that altering the CS-US interval for females did not produce significant differences in behavior or fertility. Experiment 5 demonstrated that context could be a viable CS in the Pavlovian conditioning of behavior and fertility. Experiment 6 showed that a naturalistic cue did not significantly alter either behavior or fertility over an arbitrary cue. In Experiment 7, visual access as an Unconditioned Stimulus in the Pavlovian conditioning of reproductive behavior was examined. Visual access to a female increased behavior and fertility over a control procedure, but not as much as full copulatory access. The present experiments provide definitive evidence of the adaptive significance of Pavlovian conditioning through changes in reproductive behavior and fertility. The relevance of the findings to Pavlovian conditioning in other behavior systems is discussed.