1.2 Alliance formation in bottlenose dolphins (tursiops sp.)  (Page 7/7)

Conclusion

The bottlenose dolphin is an excellent example of how social alliances can benefit the fitness of individuals. Both direct and indirect fitness benefits are derived from social alliances which males use to acquire mates, dolphins use to gather food, and females or others use for defense. The direct fitness is derived from the improved opportunity for mates, food, or protection, but because certain members of the group get a disproportionate amount of these resources, related individuals are often allied to allow for indirect fitness benefits in which a relative is benefitted by additional resources. The specific dynamics of the dolphin alliances shed light on how and why they are evolutionarily advantageous while also providing interesting insight into the daily lives of these complex organisms.

Discussion questions

1. What are some factors that may have allowed the specific types of alliances in dolphins to be selected for?
2. How does kin selection by dolphins satisfy Hamilton’s Rule?

Glossary

• Affiliative interaction - interactions that occur to increase a sense of bonding among members of a group, such as contact swimming, petting, or rubbing in dolphins
• Consort - (n) a spouse or companion; (v) to habitually associate with
• Conspecificity - organisms that belong to the same species
• Equivalence rule - a theory that animals group things into classes of equivalent value and treat all members of a certain class as interchangeable
• Estrus - a period of time when females are sexually receptive and fecund
• First-order alliance - an alliance consisting of two or three males working together to consort a single female
• Fission-fusion grouping pattern - a form of social organization in which a large social group partitions into subgroups that change size and composition often
• Haplotype - alleles at multiple loci transmitted together on the same chromosome
• Kin selection (Hamilton’s rule) - Genes should increase in frequency when rB>C, where r is the genetic relatedness of the recipient to the actor, B is the benefit gained by the recipient, and C is the cost to the actor
• Inclusive fitness - the sum of direct fitness (the individual’s fitness) and indirect fitness (impact on fitness of social partners) weighted by the relatedness between the actor and the recipient
• Labile - tending to alter quickly and spontaneously
• Male-biased - the overrepresentation of males in a given population
• Nested alliance - an alliance within an alliance
• Reciprocal altruism - a form of altruism in which one organism provides a benefit to another and expects the benefit to be returned in the future
• Second-order alliance - an alliance consisting of males in first-order alliances working together to steal females from other alliances or to defend their own females
• Triadic interaction - interactions that occur in a group of three (A, B and C) where individuals attempt to band against an individual in the alliance (e. g. A and B versus C)

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About the author

I am a sophomore Biochemistry and Cell Biology major from Dallas, TX. I enjoy drawing, painting, baking, and spending time with friends. In studying animal behavior, I am fascinated by learning about the motivation of organisms to behave in certain ways and how seemingly different behavior can be driven by similar principles. Most of the time, studying animal behavior proved easy mostly because it is interesting and applicable. I found myself often trying to relate what we learned in class to humans and trying to observe certain behaviors in my friends and myself.