BRUCE EFFECT Meaning and
Definition
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The Bruce effect refers to a phenomenon observed in certain animal species, specifically rodents and primates, wherein the female undergoes spontaneous abortion or resorption of her embryos upon encountering a new dominant male. This effect is believed to serve as an adaptive reproductive strategy for the female, ensuring the survival and success of her offspring.
Named after the Scottish biologist Hilda Bruce, who first documented this process in mice, the Bruce effect is thought to occur because the new dominant male perceives the existing embryos as belonging to their predecessor. By causing the female to terminate the pregnancy, the new male not only eliminates potential competitors but also increases the probability of his own offspring being produced.
The Bruce effect operates via an interesting physiological mechanism. The presence of the dominant male activates the female's neuroendocrine system, resulting in the secretion of stress hormones. These stress hormones interfere with the hormonal maintenance of pregnancy, leading to the loss of embryos. This effect is typically temporary, as the female will soon enter into estrus, becoming receptive to the new male's mating advances.
While the Bruce effect is primarily observed in species that live in social groups and undergo frequent male turnover, its significance extends beyond reproductive strategies. It has been used as a model to study the influence of social interactions and stress on reproductive outcomes, shedding light on the intricate dynamics between males, females, and offspring in various animal species.
Etymology of BRUCE EFFECT
The term "Bruce effect" is named after the British zoologist and ethologist, Hilda Bruce. Hilda Bruce initially conducted research in the 1950s on the reproductive behavior of rodents, specifically mice. She discovered that when a female mouse was exposed to a new male during pregnancy, it often resulted in an early termination of the pregnancy or resorption of the embryos. This phenomenon was later termed the "Bruce effect" in recognition of her contributions to the field.
