1 Introduction 1
1.1 The class Aves 1
1.2 General features of the avian karyotype 1

2 The avian genome 6
2.1 Genome size 6
2.2 Genome structure 9
2.2.1 Composition of the avian genome 9
2.2.2 The localization of heterochromatin and satellite DNA 9
2.2.3 Genome organization 13

3 Karyotypic features of special interest 14
3.1 Microchromosomes 14
3.2 Nucleolar organizers (NORs) 15
3.3 Sex-chromosomes 16
3.3.1 Sex-chromosome constitution 16
3.3.2 The Z-chromosome 17
3 .3 .3 The W-chromosome 18
3.3.4 Sex-determining mechanisms and dosage compensation 19
3.4 Meiosis 19

4 Avian cytotaxonomy 20
4.1 Background 20
4.2 The chromosome data 20
4.2.1 The Ratitae 20
4.2.2 Sphenisciformes, Gaviiformes, Podicipediformes, Procellariformes,
Pelecaniformes 22
4.2.3 Ciconiiformes 23
4.2.4 Anseriformes 26
4.2.5 Falconiformes 28
4.2.6 Galliformes 33
4.2.7 Gruiformes 36
4.2.8 Charadriiformes 39
4.2.9 Columbiformes 43
4.2.10 Psittaciformes 45
4.2.1 1 Cuculiformes 49
4.2.12 Strigiformes 50
4.2.13 Caprimulgiformes, Apodiformes, Coliiformes 53
4.2.14 Coraciiformes 55
4.2.15 Piciformes 58
4.2.16 Passeriformes 59

5 Change within the avian karotype -- patterns and mechanisms 78
5.1 Intraspecific polymorphisms 78
5.1.1. Structural variation 78
5.1.2. Heterochromatic variation 80
5.2 Induced and natural cytological abnomralities in domestic species 81
5.3 Chromosomal homology across avian orders 82
5.4 Teh significance of karyotypic cahnge in birds 84

Acknowledgements 87
References 88
Species index 109