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Answer:
Ecological and ethological approaches to the study of behaviour. The natural history approach of Darwin and his predecessors gradually evolved into the twin sciences of animal ecology, the study of the interactions between an animal and its environment, and ethology, the biological study of animal behaviour.
Obligate symbiotic fungi that form associations with plants by entering their cortical cells without invading the plant cells membrane are called endomycorrhizae and include the genus Glomus. Many plants form associations called mycorrhizae with fungi that give them access to nutrients in the soil, protecting against disease and toxicities. In these associations the fungi are integrated into the physical structure of the root, where the fungi colonize the living root tissue during active plant growth.