Transcript Chapter_53
Community Ecology The study of the interactions between the species in an area. Succession-good link for review http://www.restoringearth.co. uk/education/science/geogra phy/ecology/succession/succ ession.shtm Almost chameleons half of the world’s chameleon species live on the island of Madagascar. Go to pbs. org Type in chameleons and find out why they really change color! Community Hypothesis 1. Individualistic 2. Interactive Individualistic Hypothesis H.A. Gleason Community as a chance assemblage of species because of similar abiotic requirements. Interactive Hypothesis F.E. Clements Community as a linked assemblage of species that function as an integrated whole. Predictions Individualistic - fuzzy borders Interactive - sharp borders Robert Whittaker – tested the two ideas against each other. Results If abiotic factors form a continuum, then borders are fuzzy. Individualistic Hypothesis is correct. Comment Abiotic factors may form sharp borders. Ex: soil types Result – the Community may look very much like the Interactive Hypothesis. Interspecific Interactions Interaction between species. May be positive, negative, or neutral. Ex: 1. Coevolution 2. Predation 3. Mimicry 4. Competition 5. Symbiosis Coevolution When two species have reciprocal evolution to each other. Ex: Flowers and their pollinators. Predation (+/-) Predator and prey relationships. Ex – Lynx and Hares Predation Often results in interesting defenses or adaptations. Ex: Plant defenses Cryptic coloration Aposematic coloration Cryptic Coloration A passive defense where the prey is camouflaged against its environment. Aposematic Coloration The use of conspicuous colors in toxic or unpalatable organisms to warn off predators. poison arrow frogs Homework – Chapters 53, 55 Chapter 52 - today Chapter 52 – Fri. 4/25 Aquatic Productivity – wait until data is posted Reading Mimicry Defense mechanism where the mimic has a resemblance to another species, the model. Types: Batesian Mullerian Batesian Mimicry Palatable species mimics an unpalatable model. Hawk moth larva Snake Mullerian Mimicry Two unpalatable species resemble each other. Cuckoo Bee Yellow Jacket Competition When two species rely on the same limiting resource. Intraspecific competition usually more severe than Interspecific competition. Why? Competitive Exclusion Principle Predicts that two species with the same requirement can not co-exist in the same community. One species will survive and the second will go extinct. Ecological Niche The n-hyperspace of requirements for a species. How a species “fits into” an ecosystem. Species can not have niche overlap, the Competitive Exclusion Principle Niche Types 1. Fundamental - what a species is theoretically capable of using. 2. Realized - what a species can actually use. Resource Partitioning A way that species avoid niche overlap by splitting up the available resources. Ex: Anolis lizards A. distichus A. insolitus Symbiosis When two different species live together in direct contact. Types: 1. Parasitism 2. Commensalism 3. Mutualism Parasitism (+/-) Parasite harms the host. Parasites may be external or internal. Well adapted parasites don't kill the host. Parasitic behavior: A female Nasonia vitripennis laying a clutch of eggs into the pupa of a blowfly (Phormia regina) Commensalism (+/o) One partner benefits while the other is unchanged. Ex. – Cattle and Egrets Mutualism (+/+) Both partners benefit from the interaction. Ex: Pollinators and flowers Acacia Tree and Ants Succession Changes in species composition over time. Succession Stages Sere: unstable stage usually replaced by another community. Climax: stable stage, self-reproducing. Succession Types 1. Primary 2. Secondary Primary Succession Building a community from a lifeless area. Ex: volcanic islands glaciated areas road cuts Comment The first example of primary succession was worked out on the Indiana Dunes. Stages: Open Beach Beach Grasses Conifers (Junipers and Pines) Oaks Beech-Maple forest (Climax) Secondary Succession Where a community has been disturbed and the soil is mostly intact. Ex: Cutting down a forest Blow-outs on the Dunes Causes of Succession 1. Autogenic Factors 2. Allogenic Factors Autogenic Factors Changes introduced by the organisms themselves. Ex: toxins acids Allogenic Factors Outside disturbances Ex: Fire Floods Prairie Restoration Project Upland, IN Biogeography Study of the past and present distributions of individual species and communities. Range Limitations 1. Lack of dispersion. 2. Failure to survive in new areas. 3. Retraction from former range area. Proof Fossil Evidence Pollen Studies Transplant Experiments Islands Special cases in Biogeography. Must be colonized from other areas. Island Species Factors Island size. Distance from mainland. Island Size Small islands hold few species. Why? Fewer niches available for species to occupy. Distance from Mainland Closer islands have more species. Why? Easier for colonization. Comment Islands tend to have high numbers of Endemic species Why? Adaptive Radiation and Evolution of new species. Summary Know the two hypothesis of community structure. Know the various types of interspecific interactions. Know the Competitive Exclusion Principle and Niche Concept. Summary Know some examples and causes of succession. Know how island communities are shaped.