Females typically have two of the same kind of sex chromosome (XX) and are called the homogametic
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.
There appears to be a contrast between complete failure by female [F.sub.1] hybrids to produce eggs and partial fertility of some male hybrids, suggesting this system provides another exception to Haldane's rule that in interspecific hybrids the heterogametic sex (in this case males; XO) will have lower fertility than the homogametic
sex (female Hemideina XX).
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.
A viable alternative on a commercial scale is the YY technology derived from males that possess a novel homogametic
YY genotype, which allows for the production of genetically male tilapia based on crosses between YY males and XX females (Vera-Cruz et al., 1996; Mair et al., 1997; Muller & Horstgen, 2007; Alcantar-Vazquez et al., 2014).
Fopp-Bayat, "Meiotic gynogenesis revealed not homogametic
female sex determination system in Siberian sturgeon (Acipenser baeri Brandt)," Aquaculture, vol.
In all birds, the female is the heterogametic sex (ZW), while the male is homogametic
In dioecious dwarf surfclam Mulinia lateralis (Say, 1822), it has been also found that its gynogenetic progeny are all females indicating that they must be the homogametic
sex (carrying 2X-chromosomes), and triploids showed both genders, males and females, such that it was proposed that they were XXX and XXY, with the Y-chromosome being dominant over the X-chromosome.
To date, all the mapping studies have confirmed that the female willows are the heterogametic gender, while the males are the homogametic
sex, suggesting a ZW sex determination system in willows, and the gender locus is consistently mapped to the centromeric region on willow's chromosome XV [38-40].
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).
Females are heterogametic (Z0 or WZ) and males are homogametic
(ZZ), although sporadic rearrangements created multiple sex chromosome systems in some species (Traut et al.