Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Symbioses - Mutualism Symbioses • Symbioses - species living in close association • Parasitism +,- parasite benefits, host harmed • Commensalism +,0 or 0,0 can have positive effect for one species or for neither • Mutualism +,+ both species benefit Mutualism • Definition - the individuals in a population of each mutualist species grow and/or survive and/or reproduce at a higher rate when in the presence of individuals of the other. Each benefits (+,+) General Features of Mutualisms 1. The life cycle of most mutualistic species is very simple (in contrast to parasites) 2. There is no conspicuous dispersal phase for most endosymbionts (endomutualists) 3. Populations of most mutualists are stable in size - no epidemics as seen in parasites 4. The ecological range (niche breadth) of organisms in mutualisms usually appears to be greater than that of either species alone 5. Host specificity is usually flexible 6. Within populations of mutualists, the number of endosymbionts per host is relatively constant Two types of Mutualism • Facultative - each partner gains a benefit but is not dependent on the other - the vast majority of mutualisms are facultative. • Obligate - one or both partners is dependent on the other and cannot survive without the other. Mutualisms Involving Links in Behavior Greater Honeyguide Honey Badger Ants and Acacia Trees Beltian bodies (yellow) on Acacia leaves Ant larvae inside Acacia “horn” Pollination Mutualisms Pollination syndromes among the phloxes Honeybee covered with pollen Honeybee pollinating beebalm – Monarda sp. With visible light with UV light Nectar guides for honeybees Cyrtid fly pollinating a composite Caralluma – carrion fly pollinated Erysimum – butterfly pollinated Hummingbird pollination Greater double-collared sunbird Episcia – moth pollinated Bat pollination Hammer Orchid and Wasp Figs and Fig Wasps Figs and Fig Wasps Mutualisms involving Culture of Crops or Livestock Leaf-cutter Ants – genus Atta Diagram of Leaf-cutter ant colony nest Human Agriculture Sustainable Dairy Industrial Wheat Digestive Mutualisms Involving Gut Inhabitants Ruminant with multiple stomachs Ruminant by-products Termite Mound Western Australia Termites Mycorrhizae Ectomycorrhizae Ectomycorrhizae VAM – Vesicular Arbuscular Mycorrhizae Nitrogen Fixing Mutualisms Red Clover – A Classic Legume Normal Nitrogen Fixation Legume Root Nodules Rhizobium root nodules on a bean plant Animal-Algae Mutualisms Healthy Coral Reef - Indonesia Coral polyp with zooxanthellae - a dinoflagellate, Symbiodinium Coral polyp – coral animal is green, Zooxanthellae is red Endosymbiotic Origin of Eukaryotes Lynne Margulis Endosymbiotic Origin of Eukaryotes Endosymbiotic Origin of Eukaryotes • The earliest eukaryotes acquired mitochondria by engulfing alpha proteobacteria. • The early origin of mitochondria is supported by the fact that all eukaryotes studied so far either have mitochondria or had them in the past. Mitochondria have their own DNA and replicate themselves during cell division. • Later in eukaryotic history, some lineages of heterotrophic eukaryotes acquired an additional endosymbiont—a photosynthetic cyanobacterium—that evolved into plastids. • This hypothesis is supported by the observation that the DNA of plastids in red and green algae closely resembles the DNA of cyanobacteria. • Plastids in these algae are surrounded by two membranes, presumably derived from the cell membranes of host and endosymbiont. Stromatolites on coast of Western Australia