Skip to content
Login Register

#avian biology

2 public questions tagged with this topic.

Sex determination-l

Which chromosome combination determines a female bird?

Female birds carry contrasting sex chromosomes Z and W, analogous to XY in male mammals but heterogamety reversed. Males carry ZZ, females ZW. During oogenesis female produces ova bearing either Z or W determining offspring sex. ZW complement triggers ovarian differentiation driven by reduced DMRT1 dosage and expression of W-linked ovary-promoting genes producing asymmetric gonads with functional left ovary. This constitution contrasts with ZZ males developing testes, male song and plumage. Hence female bird chromosome formula definitively ZW, distinguishing avian from mammalian nomenclature a

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 6: ZW determines female bird.

View Details
Fertilization in mammals-lll

Sex determination in birds involves:

Avian sex determination contrasts with mammalian XX-XY system. Birds utilize ZZ-ZW mechanism where males are homogametic ZZ and females heterogametic ZW. Dosage of DMRT1 gene on Z chromosome drives testis development; higher dose in ZZ promotes SOX9 expression, while single dose in ZW allows ovarian fate. W chromosome carries female determining factors like HINTW. Unlike temperature or X0 systems, ZZ-ZW is genetic. This system affects gonadal differentiation, secondary sexual traits and avian breeding strategies. Understanding is crucial for poultry sexing and evolutionary comparison of sex ch

Ref: Bachtrog et al., Nature Rev Genet 2014: Evolutionary genetics of ZZ-ZW avian sex determination and DMRT1 dosage.

View Details