Apparently James Bond possessing
heterogametic genes is of paramount importance for a large proportion of the audience studios do not wish to alienate.
Males typically have two different kinds of sex chromosomes (XY) and are called the
heterogametic sex.
The Alpine swift we describe was a male and, considering that in avian species the females are
heterogametic (WZ) whereas males are homogametic (ZZ), Polydactyly in this bird may have been a recessive, sex-linked genetic anomaly.
Haldane (1922) observed that where one sex is absent, rare, or infertile in [F.sub.1] hybrids, it is usually the
heterogametic sex.
The first step is establishment of the chromosomal sex at the time of fertilization of the ovum--the
heterogametic (XY) sex is male and the homogametic sex (XX) is female.
Evidence of female
heterogametic genetic sex determination in white sturgeon," Journal of Heredity, vol.
In all birds, the female is the
heterogametic sex (ZW), while the male is homogametic (ZZ).
(2005) suggested that females were the
heterogametic sex (WZ) after finding one sex-linked marker that mapped only to the maternal linkage map (presumably on the W chromosome).
In avians, male homogametic sex (ZZ), the gonads develop symmetrically, whereas female
heterogametic sex (ZW), the gonads develop asymmetrically- only the left side develops into a functional ovary (Romanoff, 1960).
Abbreviations: AFLP, amplified fragment-length polymorphisms; dph, days post-hatching; ESD, environmental sex determination; GSD, genetic sex determination; GXE, genotype-by-temperature interaction; PCR, polymerase chain reaction; SD, sex determination; TE, temperature effect; TSD, temperature sex determination: ZW/ZZ, female
heterogametic sex-determination system.
The rule predicts that if one or the other sex is rare or inferior in hybrids, then that sex is likely to be
heterogametic. In Cyprinodon, hybrids between distantly related species often show evidence of female-biased sex ratios or male inferiority (Turner and Liu, 1977; Cokendolpher, 1980; Tech, 2006).