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Testing kin selection with sex allocation data in eusocial hymenoptera
1Department of Biochemistry & Genetics, La Trobe University, Bundoora, Victoria 3083, Australia.
Heredity
|June 26, 1999
Summary
In social insects like ants, bees, and wasps, worker insects adjust sex allocation based on relatedness to offspring. Studies show workers favor females when more related to them, demonstrating kin selection in action.
Area of Science:
- Evolutionary Biology
- Behavioral Ecology
- Social Insects
Background:
- Sex allocation in eusocial Hymenoptera (ants, bees, wasps) is crucial for kin selection studies due to differing relatedness between queens, workers, females, and males.
- Early cross-species comparisons of sex investment ratios in ants suggested worker manipulation of sex allocation, favoring females in single-queen colonies due to higher relatedness to females than males (relatedness asymmetry).
Purpose of the Study:
- To assess the effectiveness of kin selection in eusocial Hymenoptera by examining sex allocation patterns.
- To investigate evidence for worker control over sex allocation within and across species.
- To identify factors confounding cross-species comparisons and explore proximate mechanisms of sex ratio manipulation.
Main Methods:
- Comparative analysis of population sex investment ratios across eusocial Hymenoptera species.
- Intraspecific studies examining sex ratio variation across colonies within species.
- Investigation of proximate mechanisms underlying sex ratio manipulation in ants and wasps.
Main Results:
- Intraspecific studies provide stronger evidence for worker control, with colonies exhibiting high relatedness asymmetry producing predominantly females, while those with low asymmetry produce males.
- Evidence of worker control is also found in proximate mechanisms of sex ratio manipulation in ants and wasps.
- Cross-species comparisons are confounded by factors like breeding system, life history, sexual dimorphism, and phylogenetic relationships.
Conclusions:
- Worker control over sex allocation is evident in several eusocial Hymenoptera species, supporting kin selection theories.
- Worker control is not universally effective, necessitating further manipulative experiments to fully understand evolutionary factors.
- Future research should focus on disentangling the complex evolutionary processes influencing sex allocation in these social insects.