Biology 2483A Lecture 14: "Mutualism & Commensalism"
25 Aug 2013
School
Department
Course
Professor
Document Summary
Ant farmers nourish, protect, and eat the fungal species they grow, forming a relationship that benefits both. In the 1990s, a parasitic fungus (escovopsis) was discovered that attacks the fungal gardens of leaf-cutter ants. Ants respond to escovopsis by increasing garden weeding rate and also enlist the help of other species (the ants carry a bacterium that makes chemicals that inhibit escovopsis and also secrete compounds that promote cultivated fungal growth). The bacteria also benefit as a third mutualist as it live in crypts on the ant"s exoskeleton and obtains a food source from the ant"s glandular secretions. Positive interactions (also known as facilitation) occur when neither species is harmed and the benefits of the interaction are greater than the costs for at least one species. Mutualism involves a mutually beneficial interaction between individuals of two species (+/+). Commensalism is where individuals of one species benefit, while individuals of the other species do not benefit and are not harmed (+/0).
