Deleterious mutation and the evolution of eusociality

Area of Science:

• Evolutionary Biology
• Behavioral Ecology

Background:

• Kin selection theory, focusing on relatedness, is commonly applied to explain the evolution of eusociality.
• Haplodiploid systems highlight differing relatedness (e.g., sisters vs. daughters), a key factor in kin selection arguments.
• Existing kin selection models are insufficient to explain the persistence of sexual reproduction over asexual reproduction.

Purpose of the Study:

• To investigate the role of deleterious mutations in the evolution of eusociality.
• To challenge the assumption that relatedness is the sole determinant in the evolution of social behavior.
• To reconcile the evolution of sexual reproduction and eusociality.

Main Methods:

• Theoretical modeling of evolutionary processes.
• Analysis of genetic relatedness in social insect systems.
• Incorporation of deleterious mutation rates (U) and selection coefficients (s) into evolutionary models.

Main Results:

• Deleterious mutations can favor the evolution of eusociality, as helping siblings reduces the transmission of harmful alleles.
• The strength of this effect is proportional to the product of the genomewide deleterious mutation rate and the selection coefficient (Us).
• Relatedness alone is not sufficient to explain the evolution of eusociality or sexual reproduction.

Conclusions:

• Deleterious mutation pressure provides an alternative and complementary explanation for the evolution of eusociality.
• The evolution of both sex and eusociality can be influenced by factors beyond simple genetic relatedness.
• A nuanced understanding of evolutionary pressures, including mutation load, is crucial for explaining complex social systems.