Avian Clock gene polymorphism: evidence for a latitudinalcline in allele frequencies Written by PoB, verified by Editorial Team December 26, 2011 Muscicapidae, PasseriformesBluethroat (Luscinia svecica) Science Article 17 abstractIn comparison with most animal behaviours, circadian rhythms have a well-characterizedmolecular genetic basis. Detailed studies of circadian clock genes in