Jablonka E, Lamb M J
Cohn Institute for the History and Philosophy of Science and Ideas, Tel-Aviv University, Israel.
Proc Biol Sci. 1991 Mar 22;243(1308):203-8. doi: 10.1098/rspb.1991.0032.
Studies of reproductive isolation between animal species have shown (i) that if one sex of the hybrids between two species is sterile or inviable, it is usually the heterogametic sex (Haldane's rule), and (ii) the genes on the sex chromosomes play a particularly large role in hybrid sterility and inviability. We propose an explanation for these two observations which is based on the changes in chromosome conformation which take place during gametogenesis. These changes are far greater in sex chromosomes than in autosomes. They are also greater in the heterogametic than in the homogametic sex. We suggest that the sensitivity of hybrids of the heterogametic sex to the genetic divergence that occurs during periods of population isolation is partly the result of the failure of their sex chromosomes to undergo appropriate conformational changes. This hypothesis explains why the sex chromosomes play a disproportionate role in post-zygotic, but not in pre-zygotic, isolation, and why often only the germ line is sensitive to hybridization.
（i）如果两个物种之间的杂种的一方性别不育或无法存活，通常是异配性别（霍尔丹法则）；（ii）性染色体上的基因在杂种不育和无法存活中起着特别重要的作用。我们基于配子发生过程中发生的染色体构象变化，对这两个观察结果提出一种解释。这些变化在性染色体中比在常染色体中要大得多。在异配性别中也比在同配性别中更大。我们认为，异配性别杂种对种群隔离期间发生的遗传分化的敏感性，部分是由于其性染色体未能经历适当的构象变化所致。这一假设解释了为什么性染色体在合子后隔离中起不成比例的作用，而在合子前隔离中则不然，以及为什么通常只有生殖系对杂交敏感。
