Biol 301 1nd Edition Lecture 16 Outline of Last Lecture I. CompetitionII. ResourcesIII. ConditionsOutline of Current Lecture II. MutualismsIII. Defensive MutualismsIV. Change in MutualismV. Mutualisms Effect on CommunitiesCurrent LectureMutualisms- A mutualism is a positive interaction between two species in which one species receives benefits that only the other species can provide. Mutualisms are common and can affect populations, species, communities, and ecosystems.- Generalists: a species that interacts with many other species.- Specialists: a species that interacts with one other species or a few closely related species.- Obligate mutualists: two species that provide fitness benefits to each other and require each other to persist.- Facultative mutualists: two species that provide fitness benefits to each other, but the interaction is not critical to the persistence of either species.- Many plants rely on mutualisms with fungi and bacteria to help them obtain nutrients.- Mycorrhizal fungi: fungi that surround plant roots and help plants obtain water and minerals.- Endomycorrhizal fungi: fungi characterized by hyphal threads that extend far out into the soil and penetrate root cells between the cell wall and the cell membrane.- Ectomycorrhizal fungi: fungi characterized by hyphae that surround plant roots and enter between root cells but rarely enter the cells. Fungal hyphae provide plants with soil minerals(e.g., nitrogen) and water; plants provide the fungi with sugars from photosynthesis.- Arbuscular mycorrhizal fungi: a type of endomycorrhizal fungi that infects a tremendous number of plants including apple trees, peach trees, coffee trees, and grasses. Arbuscules These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.are branching hyphal structures found within plant cells that help the fungus to provide nutrients to the plant.- Ectomycorrhizal fungi are only known to live in relationships with trees and shrubs.- The mutualism between plants and mycorrhizal fungi goes back more than 450 mya to the time when plants first evolved on land.- Mutualism between plants and fungi involves more than 6,000 species of mycorrhizae and 200,000 species plants.- Mutualistic interactions between plants and bacteria convert unusable forms of minerals into forms that plants can use.- Many plants rely on animals to carry pollen between flowers. Plants have evolved reward mechanisms to entice pollinators to visit their flowers. Some plants have evolved very specific mutualisms with pollinators.- Large plant seeds are typically dispersed by animal mutualists if the animals receive a benefit in return. One of the most common benefits is food in the form of seeds. This benefit only works if plants produce large numbers of seeds and not all seeds that are carried away are consumed. Some plants entice animals to disperse seeds by surrounding seeds with a fruit that contains nutrients. Many seeds with fruit have a hard coat that resistsdigestion; they pass through an animal’s gut unharmed and still able to germinate.- Many protozoans form mutualistic relationships with animals.- Mutualisms also exist between humans and other animals.Defensive mutualisms- Many plants have mutualisms that defend them from enemies.- Some plants defend themselves through mutualisms with endophytic fungi, which are fungi that live inside a plant’s tissue. Endophytic fungi produce chemicals that repel herbivores and provide drought resistance by increasing the concentration of minerals in plant tissue.- Animals also have mutualisms that aid their defense.Change in Mutualism- Each individual participates in a mutualism to improve its own fitness, not that of its partner.- When a species in a mutualism provides a benefit to another species at a cost, but no longerreceives a benefit in return, the interaction can shift to negative interaction (e.g., herbivory, predation).- Cheating occurs when one species receives a benefit but does not provide one in return.- Natural selection should favor cheating, but should also favor mechanisms that enable defense against cheating.Mutualisms effect on communities- The disruption of a mutualism may cause a decline of the species involved and a reduction in their distribution.- A mutualism might cause a change in species diversity.- A mutualism can also change the abundance of species through a chain of interactions.- Mutualisms can also have effects at the level of the ecosystem.- Loss of dispersers can result in a reduction in plant