Haldane's rule

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Haldane's rule is an observation published by JBS Haldane in 1922 that if one sex does not occur in type hybrids , is less common or is more often sterile, then it is the heterogametic sex (the one with two different sex chromosomes ). This observation can be demonstrated in different animal groups such as mammals , birds , butterflies and Drosophila . As in mammals and Drosophila-If the heterogametic sex is male (XY chromosomes), but in birds and butterflies the female (WZ chromosomes) and Haldane's rule match, the cause must lie with the gonosomes.

causes

The reason for this observation is not yet fully understood, and there may be several. There are several theories that are used to explain this.

  • Hermann Joseph Muller's dominance theory states that the heterogametic sex is always affected by negative mutations on the X chromosome , while the homogametic sex is only affected if the mutated allele is dominant. If the mutated allele is recessive, the other X chromosome can take over the function in the homogametic sex, but not in the heterogametic sex.
  • The faster male theory by C.-I. Wu believes that alleles that lead to sterility of hybrid males evolve faster than alleles for hybrid female sterility. In insects , in fact, features of male genitalia evolve more rapidly through sexual selection . This increases the likelihood that there will be incompatibilities with foreign characteristics, since the X-linked / female characteristics evolve more slowly and completely separately. In butterflies, the characteristics of the male genitalia also evolve more quickly, but hybrid females in particular are affected according to Haldane's rule, so that the faster male theory does not apply in this case.
  • Brian Charlesworth and colleagues' Faster-X theory suggests that the X chromosome evolves rapidly through selection, and because it is often very large, it is more likely to accumulate negative alleles that are effective in heterozygous hybrids. However, that would mean that female sexual characteristics would evolve faster than asexual ( autosomal ) characteristics, which could not be shown.

literature

HA Orr: Haldane's rule In: Annu. Rev. Ecol. Syst. 28 (1997) pp. 195-218

swell

  1. ↑ JBS Haldane: Sex ratio and unisexual sterility in hybrid animals In: J. Genet. 12 (1922) pp. 101-109
  2. ↑ HJ Muller: Isolating mechanisms, evolution, and temperature In: Biol. Symp. 6 (1942) pp. 71-125
  3. ^ HJ Muller & G. Pontecorvo: Recessive genes causing interspecific sterility and other disharmonies between Drosophila melanogaster and simulans in: Genetics 27 (1942) p. 157
  4. ↑ C.-I. Wu & AW Davis: Evolution of postmating reproductive isolation: the composite nature of Haldane's rule and its genetic bases In: Am. Nat. 142 (1993) pp. 187-212
  5. ↑ C.-I. Wu, NA Johnson & MF Palopoli: Haldane's rule and its legacy: Why are there so many sterile males? In: Trends Ecol. Evol. 11 (1996) pp. 411-413
  6. ^ B. Charlesworth, JA Coyne & N. Barton: The relative rates of evolution of sex chromosomes and autosomes In: Am. Nat. 130 (1987) pp. 113-146