Ecology has been sub-divided into different fields so as to understand the subject in a more profitable way. Ecology can be commonly divided into animal ecology and plant ecology. However, two major subdivisions were preferred by ecologists. The whole subject was divided into autecology and synecology. Autecology deals with the study of individual species whereas synecology deals with the study of a group of organisms or population.
Autecology. A study of the individual species in relation to their environment is known as autecology. It includes the study of its geographical distribution, taxonomic position, morphological characters, reproduction, life cycle and behaviour with reference to ecological factors that might influence these activities.
Synecology. A study of the groups of organisms in relation to their environment is called synecology. Here the unit of study are the groups of species. It comprises population ecology, community ecology and study of the ecosystems. Useful subdivisions may also be made according to the habitat, taxonomic divisions and level of organization. Thus the subject can be studied through following branches of ecology:
1. Population ecology. It deals with the growth, trophic structure, metabolism and regulation of a population.
2. Community ecology. It deals with the ecology of different populations in the same habitat and same environmental conditions.
3. Taxonomic ecology. It is concerned with the ecology of different taxonomic groups, viz. microbial ecology, mammalian ecology, insect ecology and so on.
4. Habitat ecology. It includes the study of animals and plants in different habitats. According to habitat, it can be further divided into freshwater ecology, marine ecology, terrestrial ecology, forest ecology and desert ecology.
5. Human ecology. It deals with the effects of human activities on environment and vice versa.
6. Applied ecology. It deals with the application of ecological concepts to human needs including wild life management, biological control, forestry and conservation of natural resources.
7. Chemical ecology. It is concerned with the chemical affinity or preferences shown by different, organisms.
8. Physiological ecology (ecophysiology). Physiological adaptation according to ecological conditions are dealt in ecophysiology.
9. Palaeo-ecology. It deals with the environmental conditions and life of the past ages. Palaeontology and radioactive dating have aided significandy in the study of palaeo-ecology.
10. Evolutionary ecology. It deals with evolutionary problems like speciation and segregation.
11. Gynaecology (ecological-genetics). Relationship of environment with genetic variability are considered in gynaecology.
12. Eco-geography. It studies the geographical distribution of plants and animals in different environments—collectively called as biomes.
13. Pedology. It deals with the study of soil and refers to its nature like acidity, alkalinity, humus contents, mineral contents, soil types and so forth.
14. Ethology. It is the study of animal behaviour in different environments under their natural conditions.
15. Sociology. When ecology and ethology are combined it becomes sociology.
16. System ecology. When the structure and function of an ecosystem is analysed using applied mathematics, statistics or computer, it is called as system ecology.