Ants that seem to defy biology – They lay eggs that hatch into another species

Mechanism: haplodiploidy and “male cloning”

• Commenters unpack haplodiploidy:
  • Females are diploid (two chromosome sets, from egg + sperm).
  • Males are haploid (one set), normally from unfertilized eggs.
• In M. ibericus:
  • Queens can produce:
    • Pure ibericus males from unfertilized eggs.
    • Pure ibericus queens when fertilized by ibericus males.
    • Hybrid sterile female workers when fertilized by structor males.
    • Pure structor males in a “cloning” mode where the queen’s nuclear DNA is removed and only the male’s genome remains (mitochondria still from queen).
• This is framed as an instance of “sperm parasitism”: male sperm replaces/destroys the maternal genome in some eggs.

Evolutionary logic and benefits

• Several comments outline an evolutionary sequence:
  1. Normal hybridization between related populations.
  2. Mutation causing hybrid females to become sterile workers while pure ibericus females become queens → boosts ibericus gene share.
  3. Ibericus evolves a way to perpetuate structor males locally (clones) so it can keep making hybrid workers even where wild structor is absent.
• Hypotheses for hybrid workers:
  • Hybrid vigor (heterosis) might make them better workers.
  • Regardless, they’re necessary once ibericus loses the ability to make its own workers.
• Debate on “who” removes maternal DNA: the queen vs a selfish mechanism encoded by structor sperm; consensus is that whatever evolved likely benefits both lineages.
• Some note apparent tension with Hamilton’s rule; others respond that both genomes benefit directly, so no altruism is required.

Species concept and “defying biology”

• Multiple comments stress that this doesn’t overturn biology but exposes how fuzzy “species” is:
  • Classic “fertile offspring” definition has many exceptions (hybrids, ring species, asexual lineages).
  • Here, hybrids are sterile workers, so ibericus and structor are already beyond the usual “same species” boundary.
• The article’s call to “rethink species” is seen as more about refining human categories than overturning fundamentals.

Eusociality, individuality, and superorganisms

• Some suggest viewing the colony as a single organism: queens and males are the reproductive “germ line,” workers analogous to somatic cells.
• Others push back: ants and colonies do not have “goals”; what looks like collective purpose is just selection on genes and lineages.
• Discussion emphasizes that eusocial systems stretch our normal notion of “individual.”

Broader context and open questions

• Thread connects this case to:
  • Parthenogenesis in many animals, diverse sex-determination systems, and other reproductive oddities (kleptogenesis in salamanders, etc.).
  • Analogies to organelles: structor males as a kind of “domesticated organelle” of the superorganism.
• Unclear points flagged:
  • Why males are so rarely produced in lab colonies.
  • The exact cellular machinery by which maternal DNA is eliminated or silenced.
  • Long-term evolutionary stability of a partially clonal male line.