Bruce effect

Bruce Effect

The Bruce effect is a fascinating phenomenon observed in some mammals, where the presence of a new male can cause a pregnant female to terminate her pregnancy. This effect is named after the British zoologist Hilda Bruce, who first described it in 1959. The Bruce effect is primarily studied in rodents, particularly in laboratory mice, but evidence suggests it may occur in other species as well.

Mechanism

The Bruce effect is thought to be mediated by pheromones, which are chemical signals that influence the behavior and physiology of other members of the same species. When a pregnant female is exposed to the scent of an unfamiliar male, it can trigger hormonal changes that lead to the reabsorption of the embryos or spontaneous abortion. This is believed to be an adaptive strategy that allows the female to avoid investing resources in offspring that may be at risk of infanticide by the new male.

Evolutionary Significance

The evolutionary advantage of the Bruce effect is that it allows females to optimize their reproductive success. By terminating a pregnancy when a new male is present, the female can potentially mate with the new male and produce offspring that are more likely to survive. This is particularly important in species where males may kill offspring that are not their own, a behavior known as infanticide.

Species Observed

While the Bruce effect is most commonly associated with laboratory mice, it has also been observed in other rodent species such as voles and gerbils. There is ongoing research to determine whether similar mechanisms exist in other mammals, including primates and ungulates.

Research and Implications

Understanding the Bruce effect has important implications for the study of reproductive biology and animal behavior. It provides insights into the complex interactions between social environment and reproductive strategies. Additionally, it raises questions about the role of pheromones in mammalian communication and the potential for similar effects in other species.

Also see

• Pheromone
• Infanticide (zoology)
• Reproductive strategy
• Animal behavior