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Reproductive Isolation & Sex-Linked Evolution

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Abstractions about how reproduction and sex differences shape evolution, spanning hybrid-incompatibility and isolation mechanisms (Drosophila hybrid sterility, Haldane's rule, Wallace effect), sex-specific trait expression (sex-limited genes, Rensch's rule), and asexual reproduction (parthenogenesis).

7 abstractions in this family — domain-specific abstractions that sit near one another in structural-signature space (k-means over structural-signature embeddings). Each is shown with its short description.

  • Drosophila Hybrid Sterility — Block gene flow between diverged Drosophila lineages when otherwise viable hybrids cannot produce functional gametes because lineage-compatible genetic and developmental systems become incompatible in the hybrid background.
  • Haldane's Rule — Predict which sex of a species hybrid breaks down first: when one F1 sex is absent, sterile, or inviable, it is almost always the heterogametic one (XY or ZW), because its single sex chromosome cannot mask accumulated incompatibilities.
  • Parasexual Cycle — A fungal genetic cycle that combines chromosome complements by fusion and returns viable descendants through nonmeiotic chromosome reduction, sometimes reshuffling inherited variants.
  • Parthenogenesis — Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly without need for fertilization.
  • Rensch's Rule — The macroevolutionary regularity that sexual size dimorphism scales allometrically with body size across related species — the larger-on-smaller-sex slope exceeding 1.0 in male-larger clades and falling below 1.0 in female-larger ones.
  • Sex-Limited Genes — Describe autosomal genetic effects whose phenotype is expressed in only one sex because sex-specific anatomy, hormones, regulation, or developmental context gates expression despite shared carriage.
  • Wallace Effect — The evolutionary process (reinforcement) by which natural selection actively strengthens prezygotic reproductive isolation at secondary contact, favouring any heritable trait that reduces cross-population mating whenever the hybrids between the diverging populations are less fit.