Developmental basis of limblessness and axial patterning in snakes
Article Abstract:
The distribution of three Hox proteins, HOXC6, HOXC8 and HOXB5, has been analyzed to establish whether changes in Hox gene expression in the paraxial and lateral plate mesoderm are responsible for the morphological transformations seen in the python trunk. It was established that expansion of Hox gene expression domains in both paraxial and lateral plate mesoderm could be the mechanism which shifted the whole snake trunk towards a thoracic/flank identity and was directly responsible for the lack of forelimb development during snake evolution.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1999
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A hormonal mechanism for parental favouritism
Article Abstract:
A competitive study of canaries and cattle egrets shows that hormonal favoritism may be a common mechanism for bird mothers to influence sibling competitiveness. While hen birds influence competitiveness by depositing increasing amounts of testosterone in the yolks of successively laid eggs, egret mothers deposit more androgens in the first eggs of their clutches. This adds a potential hormonal enhancement to the advantage caused by earlier hatching. Androgens may enhance a chick's begging behavior, growth rate and aggression.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1997
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