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Sex and death: CHD1Z associated with high mortality in moorhens

journal contribution
posted on 2002-12-01, 00:00 authored by Patricia LeePatricia Lee, P Brain, D Forman, R Bradbury, R Griffiths
Sex ratios in clutches of moorhens (Gallinula chloropus) in Britain were measured on 83 chicks using the sex-linked CHD1 gene (Chromo-helicase/ATPase-DNA binding protein 1). Among birds, the female is the hetero-gametic sex (Z and W chromosomes), and the male is homogametic (two copies of the Z chromosome). We report variation among the PCR-amplified fragments of the CHD1Z, and the death of nearly all heterozygous male chicks (92%). In contrast, survivorship among females and homozygote males was 54–60%. Mortality in male heterozygotes was significantly higher than that of male homozygotes (P < 0.001). Chick and egg biometrics were not significantly different between these males. The CHD1Z was unlikely to be directly responsible but may have been hitchhiked by the causal gene(s). The observations appear to follow a classic underdominance (heterozygote inferiority) pattern, but raise the paradoxical question of why one form of the Z chromosome has not been fixed, as is expected from evolutionary theory. We discuss possible explanations and include a survey of British populations based on skin specimens.

History

Journal

Evolution

Volume

56

Issue

12

Pagination

2548 - 2553

Publisher

Wiley

Location

London, England

ISSN

0014-3820

eISSN

1558-5646

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2002, Wiley