Study finds honey bees inherit altruistic behavior from their mothers

A recent study conducted by Penn State researchers has shed light on the intriguing behavior of honey bees, revealing a form of altruism in these insects. This research, featured in the journal Molecular Ecology, focused on the genetic aspects of “retinue” behavior in female worker honey bees. After exposure to the queen bee’s pheromone, these workers voluntarily deactivate their ovaries, assist in disseminating the pheromone to their fellow workers, and tend to the queen and her eggs.

This altruistic behavior benefits the queen bee’s reproductive success while rendering the worker bees sterile, making it a remarkable example of selflessness in the animal kingdom. Typically, the queen bee is the mother of the entire hive or the vast majority of its inhabitants.

What’s intriguing about this study is that the genes influencing worker bees’ receptiveness to the queen’s pheromone, and subsequently their propensity for retinue behavior, can be inherited from either the mother or the father. However, these genes only lead to altruistic behavior when they come from the mother.

This phenomenon, described by Sean Bresnahan, a doctoral candidate and National Science Foundation Graduate Research Fellow, demonstrates the importance of which parent’s genes an insect inherits, as it can significantly influence their behavior. It goes beyond just the gene sequence; it’s about the source of the gene. Genes passed down from the mother tend to result in different behavior compared to those inherited from the father.

The study also aligns with the Kinship Theory of Intragenomic Conflict, which posits that genes from mothers and fathers may be in conflict over which behaviors to support or not. Previous research suggested that male genes could support selfish behaviors in various species, including mammals, plants, and honey bees. However, this study is the first to show that female genes can pass on altruistic behavior to their offspring.

Honey bees are notable for their altruistic behaviors, where some individuals sacrifice their own reproduction to assist others. This study reveals a nuanced and unexpected form of genetic control over these behaviors. Genes from the queen mother support altruistic behavior in her offspring, reinforcing the propagation of her genes in the population. On the other hand, genes from the fathers support selfish behavior in worker bees, where they prioritize their own reproduction over helping the queen mother.

Since the queen mates with multiple males, worker bees share the same mother but have different fathers. This leads to them sharing more of their mother’s genes with each other, explaining why genes from the mother favor altruistic behavior in honey bees, as per the Kinship Theory of Intragenomic Conflict.

Conducting this study was challenging because, unlike mammals or plants, cross-breeding different lineages of honey bees is complicated. It required expertise in honey bee breeding, which was provided by collaborators at Texas A&M University and Penn State Extension.

The researchers assessed the responsiveness of worker bees to the queen’s pheromone and whether they deactivated their ovaries in response. They also examined genome-wide gene expression in worker bees and the genomes of their parents. This approach allowed them to determine which parent’s genes influenced the behavior of the worker bees.

The study also delved into gene regulatory networks and the intricate conflict happening within the honey bee genome. By analyzing relationships between genes and transcription factors (proteins that control gene expression), the researchers identified biases in gene expression stemming from either the mother or the father. These biases are a hallmark of intragenomic conflict, occurring more frequently than expected and involving genes linked to retinue behavior.

In summary, this research opens a window into the complex interplay of genetics and behavior in honey bees, showcasing the significance of the parent from whom genes are inherited in shaping altruistic or selfish behaviors. Moreover, it highlights how intragenomic conflict plays a crucial role in shaping various traits in bees and potentially other species, providing a foundation for future studies in this field.

Source: Pennsylvania State University

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