heterogametic sex


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Related to heterogametic sex: homogametic

heterogametic sex

[¦hed·ə·rō·gə′med·ik ′seks]
(genetics)
That sex of some species which produces two or more different kinds of gametes that differ in their sex chromosome content.
References in periodicals archive ?
- It is common for the heterogametic sex to fail to survive in crosses between well-differentiated species (Haldane 1922; Orr 1993).
Although Haldane's rule applies to asymmetrical sterility or viability between homogametic and heterogametic hybrids in most diploid species, it is not directly relevant to species with other sex determination systems simply because they lack sex chromosomes and a heterogametic sex. However, if Haldane's rule is a consequence of recessivity of hybrid incompatibility genes, then Orr's model (1993) may also apply to haplodiploids, because males are haploid and will express such recessive incompatibility alleles.
This includes the chloroplast chromosome and heterogametic sex chromosomes.
This incompatibility may cause dysfunction in the heterogametic sex only, such as occurs in many birds, mammals, and insects (e.g., Eicher et al.
Hybrid dysfunction in Chorthippus parallelus is restricted to the heterogametic sex and occurs in [F.sub.1] and backcross males (see Virdee and Hewitt 1992).
One then calculates how many of these various ways would give as strong an agreement as we see with the character of heterogametic sex. The ratio of these numbers gives a measurement of the probability of the level of agreement seen using the null hypothesis that the characters are not correlated.
They do not give an explicit statistical test, but merely state that the support given to the rule by the data "might be expected by coincidence alone." It appears that they view only lineages in which the heterogametic sex has changed from male to female as being relevant to the question of Haldane's rule.
Thus, far from "neglect[ing] the evidence for a causal link between the characters supplied by the observation that the sex of hybrid fitness loss does change between taxa that differ in their heterogametic sex" (Brookfield 1993, p.
One of the most striking generalizations in evolutionary biology is "Haldane's rule," the observation that if only one sex is sterile or inviable in the offspring of a cross between two species, it is nearly always the heterogametic sex (Haldane, 1922).