2. QUICK REVIEW•What is community?•What is population?
3. Community Interactions• Powerfully affect an ecosystem• Include: – Competition – Predation – Symbiosis
4. Competition• When organisms of the same or different species attempt to use an ecological resource at the same place and the same time – Resource any necessity to life – Plants and animals compete – Winner and losers
5. • Interspecific competition – Competition between two or more speciess – When 2 or more species rely on same limited resource in a community – Ex. Garden plants and weeds – Ex. Grasshoppers and bison – Ex. Lynx and foxes – Ex. African savannah
6. Niche• Each species unique living arrangement in a community• “Role” – Think about a specific position player on a team i.e. pitcher on a baseball team• Ex. Lizards in a rainforest• Includes: – Habitat – Food sources – Time of day organism is most active
7. Rules, rules, rules• Fundamental rule in ecology – Competitive Exclusion Principle • Russian biologist G.F. Gause – Paramecium caudatum vs. Paramecium aurelia – Separately, both thrive in a culture – P. aurelia could gather food more quickly than the P. caudatum, therefore, if they are grown together, P. aurelia will thrive while P. caudatum will die out • 2 species so similar in requirements that the same resource limits both population’s growth, and one species may succeed over another • No two species can occupy the same niche in the same habitat and the same time • Prevents un necessary competition
24. Chemical Warfare• Both predators and prey have evolved toxic chemicals for attack and defense• Spiders and poisonous snakes use venom to paralyze their prey and deter predators• Many plants have evolved chemicals to deter herbivores• Bombardier beetle sprays hot chemicals from its abdomen 30
25. Chemical Warfare 31
26. Coevolutionary Adaptations• Plants have evolved a variety of chemicals to deter herbivores – Example: the toxic and distasteful chemicals in milkweed• Some animals evolve ways to detoxify these chemicals, allowing them to eat the plants – Plants may then evolve other toxic substances 32
27. The monarch butterflyuses deterrent chemicalsof milkweed, acquired by afeeding caterpillar, to makeitself distasteful to itspredators Chapter 27 33
28. Symbiosis• Any relationship where two species live closely together• Symbiosis literally means “living together”• 3 main types – Parasitism – Mutualism – commensalism
29. What type of relationship is this?• Who is helping who?
30. Mutualism• Both species benefit from the relationship• A Happy couple• Flowers and bees – Flowers need bees for pollination, bees need flowers nectar
31. What type of relation ship is going on here?•Who is helping who?
32. Commensalism• One member of the relationship benefits while the other is neither harmed nor helped• One-sided• Rare in nature• Food or shelter• Barnacles on whale• Seaweed on back of crab
33. What type of interaction is going on here?
34. Parasitism• One organism lives on or inside another organism and harms it• Parasite obtains all or part of its nutrients from the other organism• Host – Organism that is harmed in relation ship; the one that provides the nutrients to the parasite• Parasite – Organism that gets its nutrients from the host• Do they want to kill their host? – No, because they need them…they will weaken or hurt the host in some way
35. SymbiosisChapter 27 48
36. Recap• What are the three types of interactions in a community? – Competition – Predation – Symbiosis • What types do we have? – Mutualism – Commensalism – Parasitism
37. Ecological Succession• Do all ecosystems stay the same all the time?• What are some things that cause changes to ecosystems? – Natural and unnatural – Quickly and slowly
38. • Ecosystems are constantly changing in response to human and natural disturbances.• As an ecosystem changes, older habitants die out and new organisms move in, causing more change
39. Ecological Succession• Series of predictable changes that occur in a community over time – Physical environment – Natural disturbance – Human disturbance
40. Primary Succession • Succession on land that occurs on surfaces where no soil exists • Volcanic eruptions • Glaciers melting
41. Stages of Primary Succession• Start with no soil, just ash and rock• First species to populate this area – “pioneer species” – For example, pioneer species on volcanic rock are lichens (LY-kunz) • Lichens made up of fungus and algae that can grow on bare rock • When lichens die, they for organic material that becomes soil…now plants can grow
42. Secondary Succession• Succession following a disturbance that destroys a community without destroying the soil• Natural – hurricane – fires• Human disturbances – Farming – Forest clearing
43. Succession in Marine Ecosystems• Deep and dark• Can succession happen?• 1987 dead whale off of California – Unique community of organisms living in remains – Represents stage in succession in an otherwise stable, deep-sea ecosystem – Whale-fall community
44. Whale-Fall Succession• Begins when large whale dies – Sinks to barren ocean floor – Scavengers and decomposers flock to carcass , our first community • Amphipods • Hagfish • sharks• After a year, most tissues have been eaten – Now, second small community of organisms live here – Body is decomposing, releasing nutrients into the water • Small fishes • Crabs • Snails • worms• Only skeleton remains… – Third community moves in • Heterotrophic bacteria • Decompose oil in bones release of chemical compounds • Who uses these chemical compounds? – Chemoosynthetic autotrophs • In come the crabs, clams, and worms that feed on this bacteria
45. Human Activity and Species Diversity• Land clearing – Farmland – Diverse forest replaced with single crop – Decreases species diversity• Introduced species – Humans move a species from its native land to a new location, intentionally or accidentally
46. Study Intro to Ecology and Community InteractionsTeacher,