Observation of a ZZW female in a natural population: implications for avian sex determination.
Avian sex determination is chromosomal; however, the underlying mechanisms are not yet understood. There is no conclusive evidence for either of two proposed mechanisms: a dominant genetic switch or a dosage mechanism. No dominant sex-determining gene on the female-specific W chromosome has been found. Birds lack inactivation of one of the Z chromosomes in males, but seem to compensate for a double dose of Z-linked genes by other mechanisms. Recent studies showing female-specific expression of two genes may support an active role of the W chromosome. To resolve the question of avian sex determination the investigation of birds with a 2A: ZZW or 2A: ZO genotype would be decisive. Here, we report the case of an apparent 2A: ZZW great reed warbler (Acrocephalus arundinaceus) female breeding in a natural population, which was detected using Z-linked microsatellites. Our data strongly suggest a role of W-linked genes in avian sex determination.
Arit
D
D
Department of Animal Ecology, Lund University, Ecology Building, S-223 62 Lund, Sweden.
Bensch
S
S
Hansson
B
B
Hasselquist
D
D
Westerdahl
H
H
D000818:Animals; D005260:Female; D005838:Genotype; D018895:Microsatellite Repeats / Q000235:genetics; D019105:Random Amplified Polymorphic DNA Technique; D012730:Sex Chromosomes / Q000235:genetics*; D019849:Sex Determination Processes; D020308:Songbirds / Q000235:genetics*; D013548:Sweden; D014314:Trisomy / Q000235:genetics*