Question

In arctic ground squirrels, adult females are more likely to give alarm calls than adult males. If alarm calls are favored by kin selection, why might this difference occur? Could alarm calls be explained by group selection? Why or why not?

Short answer

Alarm calls align with kin selection because females protect relatives, whereas group selection is less probable due to self-interest.

Step-by-step solution

Understanding Kin Selection

Kin selection is a form of natural selection that favors behaviors which increase the reproductive success of an organism's relatives, even at a cost to their own survival or reproduction. This occurs because relatives share genes, so helping relatives can ensure the survival of shared genes.

Applying Kin Selection to Alarm Calls

Adult female arctic ground squirrels might give alarm calls more often than males because females tend to have closer and more kin contacts, such as offspring and other female relatives. By giving alarm calls, they warn their relatives of danger, thereby increasing the survival chances of shared genes.

Considering Group Selection Theory

Group selection suggests that traits can evolve based on the benefits they provide to a group, rather than just individuals or their relatives. However, this theory is less favored due to the risk of self-interest within the group.

Explaining Alarm Calls as Group Selection

While alarm calls could theoretically benefit the group by warning everyone of danger, this behavior is more consistently explained by kin selection. This is because alarm calls often involve personal risk, which individuals are less likely to take unless there is a genetic benefit to their relatives more than to unrelated group members.

Conclusion

Alarm calls in arctic ground squirrels are more likely explained by kin selection as females potentially have more relatives in the group to protect, while group selection is a less probable explanation due to the weaker force and risk of individuals acting selfishly.

Key concepts

Alarm Calls

Alarm calls are fascinating vocal signals made by various animal species to warn others of nearby predators or danger. These sounds are especially important in the animal kingdom because they help enhance the survival chances of the alerted individuals. Often, the animal making the call faces greater risk itself, since it might draw the predator's attention. However, the trade-off is worthwhile if the call protects its kin, who share common genes with the caller.

• Alarm calls play a crucial role in communication within animal groups.
• They often involve a selfless act that benefits others, mainly kin.
• Although the caller risks its safety, the benefits come in enhanced survival of relatives.

Understanding the logic behind why an animal would put itself in danger by issuing an alarm call is critical for grasping the impact of behaviors like kin selection and how these behaviors evolve through natural selection.

Arctic Ground Squirrels

Arctic ground squirrels are small mammals found in the cold tundra regions. Female arctic ground squirrels tend to give alarm calls more frequently than males. This difference can be attributed to their social structures and responsibilities.

• Females typically have stronger social bonds with their kin, such as their young or sisters.
• They spend considerable time in communal settings, making their alarm calls more impactful in safeguarding the community.
• Males might roam more and have fewer direct connections during dangerous encounters.

By calling out during threats, female arctic ground squirrels help protect their relatives, who share a substantial portion of genes, promoting the continuation of common genetic traits.

Natural Selection

Natural selection is a fundamental principle of evolutionary biology. It explains how certain traits become more common in a population over generations if they contribute to an organism's reproductive success. This idea is centered on survival and reproduction advantages.

• Traits favored by natural selection increase survival and reproduction chances.
• Natural selection operates based on differential survival and reproduction.
• Alarm calls can be favored if they increase the survival of the caller's kin, indirectly aiding the trait's persistence in a population.

For the arctic ground squirrels, those exhibiting behaviors like alarm calling, especially if connected with kin protection, can benefit from natural selection by ensuring the survival of their genetic lines.

Group Selection

Group selection describes the evolution of traits based on benefits to the group rather than just individual organisms or their relatives. This hypothesis has been debated because it suggests that behaviors advantageous to the group might spread, despite individual risks.

• While intriguing, group selection is often less convincing than kin selection.
• In group settings, self-serving behavior can undermine the group's adaptive potential.
• Traits like alarm calls might benefit the group, but without genetic ties, the individual benefits can outweigh the costs.

In the case of arctic ground squirrels, kin selection is a more robust explanation for alarm calls than group selection since individual incentives to protect relatives can surpass the broader group benefits or risks.

Reproductive Success

Reproductive success reflects an organism's ability to produce offspring that survive and reproduce. This concept is essential for understanding natural selection, as those who successfully pass on their genes influence the future of the population.

• Higher reproductive success means contributing traits to future generations.
• Behaviors like alarm calling can improve relatives' survival, indirectly enhancing reproductive success.
• For female arctic ground squirrels, alarm calls can ensure their offspring's survival, thus improving their reproductive success.

Behaviors driven by kin selection lead to increased reproductive success through the survival and subsequent reproduction of relatives that share genes, perpetuating these advantageous traits.