Symbioses - Mutualism
Jan 29, 2016
Symbioses - Mutualism
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 (+,+)
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
Mycorrhizae – world’s largest organisms?
• The mycelium of some forest fungi can extend enormous distances. In 1992 a single individual of Armillaria bulbosa was discovered that permeates more than 30 acres of forest soil in northern Michigan and was thought to be one of the world's largest living organisms. It may have been spawned by a single spore thousands of years ago. In 1998 another species Armillaria solidipes in the Blue Mountains of Oregon was found to consist of a subterranean mycelial network extending across 2400 acres. It must weigh thousands of metric tons. Its age could be from 2500 to 8400 years old.
Armillaria solidipes
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
Lynn 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
The Nature of Communities and Ecosystems
Sourdough bread – ingredients and final product
Redwood Forest
Scale of Ecosystem – Lake Superior
Scale of Ecosystem – Isle Royale
Scale of Ecosystem – Isle Royale – Forest and Pond
Scale of Ecosystem – Isle Royale Wetland
Scale of Ecosystem – Isle Royale Pitcher Plants
Ecotone – region where two communities/ecosystems grade into each
other
Forest-Marsh Ecotone
Stability
A stable community or ecosystem is one that has the ability to replace
itself – exist in place for more than one generation
Douglas-Fir
Pea Aphids
Life cycle of the Pea Aphid
Components of Stability
2 major components:
1) resistance - the ability of a community or ecosystem to avoid disturbance
2) resilience - the speed with which a community or ecosystem returns to its former state following a disturbance that has displaced it from its initial condition
Ecosystems and Stability
Grassland – South Africa Rainforest – Puerto Rico
Additional Components of Stability
• Local stability describes the tendency of a community to return to its original state following a small disturbance
• Global stability describes the tendency of a community to return to its original state following a large disturbance
Adaptive Capacity of an Ecosystem
Adaptive Capacity of an Ecosystem
Adaptive Capacity of an Ecosystem- Chesapeake Bay
Adaptive Capacity in 3D
Current Adaptive Capacity
From Local vs. Global Stability
• dynamically fragile - a community which is stable only within a narrow range of environmental conditions
• dynamically robust - a community which is stable within a wide range of environmental conditions