At every level of biological organization, be it molecular, cellular, organismic, population or interspecies, equilibrium patterns emerge. The concept of evolutionary stable strategies in natural populations is well accepted in biological circles. Artificial selection, the foundation of livestock and poultry breeding programmes, can disrupt these patterns and can have major implications in production systems. Accordingly, responses of animals to their environments are easier to evaluate when viewed as aims and strategies for survival. Nature is dynamic, and maintenance of variation within and between populations enhances their adaptation to environmental changes and associated stressors. Thus, conservation of genetic variation allows for ecological niches to be filled, in both the short and long term.

1. Adaptation 63
2. Animal welfare 6313
3. Birds 937
4. Breeding 96
5. Chickens 1761
6. Nutrition 122
7. Physical environment 154
8. Production 13
9. social interactions 13
10. Stress response 150