Sibling rivalry versus mother's curse: can kin competition facilitate a response to selection on male mitochondria?

Area of Science:

• Evolutionary biology
• Genetics
• Mitochondrial genomics

Background:

• Mitochondrial DNA (mtDNA) is maternally inherited, meaning mutations affecting male fitness are not directly selected against in males.
• This can lead to the accumulation of male-harming mtDNA mutations, a phenomenon known as the 'mother's curse'.
• Kin selection offers a potential mechanism for the evolution of male-harming mtDNA mutations if males interact with related females.

Purpose of the Study:

• To investigate whether mitochondrial haplotypes influence fitness in Drosophila melanogaster.
• To determine if social interactions between larvae with different mtDNA affect survival and adult fitness.
• To test the hypothesis that kin selection can act on male-harming mtDNA mutations.

Main Methods:

• Experiments using Drosophila melanogaster with standardized nuclear DNA but distinct mitochondrial DNA.
• Larval interaction experiments to assess effects on survival to adulthood.
• Measurement of adult male and female fitness based on their own and their social partner's larval-stage mtDNA.

Main Results:

• Mitochondrial DNA did not significantly affect larva-to-adult survival.
• Adult male and female fitness were significantly influenced by both their own mtDNA and the mtDNA of their larval social partner.
• Evidence suggests indirect genetic effects mediated by larval interactions.

Conclusions:

• Mitochondrial mutations negatively impacting male fitness can be subject to kin selection.
• Social interactions between larvae, particularly kin, can facilitate the indirect selection of mtDNA alleles.
• Findings have implications for understanding the evolution of mitochondria and other maternally inherited endosymbionts.