Biology Standard 6: Ecology!

1. Biology Standard 6: Ecology! The student will demonstrate an understanding of the interrelationships among organisms and the biotic and abiotic components of their environments.

2. B-6.1 Explain how the interrelationships among organisms (including predation, competition, parasitism, mutualism, and commensalism) generate stability within ecosystems. Key Concepts: • Ecosystem: • stable ecosystem • Predation: • predator, prey • Competition: • niche • Symbiotic relationships: • parasitism, mutualism, commensalism • An ecosystem is defined as a community (all the organisms in a given area) and the abiotic factors (such as water, soil, or climate) that affect them.

3. A stable ecosystem is one where… • population #s of each organism • fluctuate at a predictable rate • supply of resources in physical environment • fluctuates at a predictable rate • energy flows through ecosystem • at a fairly constant rate over time • These fluctuations in populations and resources ultimately result in a stable ecosystem!

4. Organisms in an ecosystem constantlyINTERACT! • interactions among the organisms generate stability within ecosystems

5. Predation • interaction between species in which one species (the predator) eats the other (the prey) • helps regulate the population within an ecosystem thereby causing it to become stable • Fluctuations in predator–prey populations are predictable • At some point: prey population grows so numerous that they are easy to find, so predator population…

6. A graph of predator–prey density over time shows how the cycle of fluctuations results in a stable ecosystem. • As prey population increases, predator population increases. • As predator population increases, prey population decreases.

7. Competition • relationship that occurs when 2 or more organisms need same resource at same time • can be among members of same or different species • usually occurs with organisms that share the same niche • ecological niche: • role of an organism in its environment • including type of food it eats • how it obtains its food • how it interacts with other organisms • 2 species with identical ecological niches cannot coexist in the same habitat!! • usually results in a decrease in population of a species less adapted to compete for a particular resource

8. Symbiotic Relationships • exist between organisms of 2 different species that live together in direct contact • balance of ecosystem is adapted to symbiotic relationship • If population of 1 or other of the symbiotic organisms becomes unbalanced, populations of both organisms will fluctuate in an uncharacteristic manner. • Symbiotic relationships include • Parasitism • Mutualism • Commensalism

9. Hornworm caterpillar host will eventually die as its organs are consumed by wasp larvae. Parasitism + • symbiotic relationship in which one organism (the parasite) benefits at the expense of the other organism (the host • Some parasites live within the host • tape worms, heartworms, bacteria • Some parasites feed on the external surface of a host • aphids, fleas, mistletoe • Generally, parasite does not kill the host…WHY? • Parasite-host populations that have survived have been those where neither has a devastating effect on the other. • Parasitism that results in rapid death of host is devastating to both parasite and host populations. • important that host survive and thrive long enough for parasite to reproduce and spread Parasitism _

10. Mutualism • symbiotic relationship in which both organisms benefit • Because 2 organisms work closely together, they help each other survive. • For example: • bacteria, which have the ability to digest wood, live within the digestive tracts of termites • plant roots provide food for fungi that break down nutrients the plant needs

11. Commensalism • symbiotic relationship in which one organism benefits and the organism is not affected • For example, • barnacles that attach to whales are dispersed to different environments where they can obtain food and reproduce • burdock seeds that attach to organisms and are carried to locations where they can germinate Our eyelashes are home to tiny mites that feast on oil secretions and dead skin. Ø Eyelash mites find all they need to survive in the tiny follicles of eyelashes. +

12. REVIEW! • EXPLAIN how the interrelationships among organisms generate stability within ecosystems • cause-and-effect model showing how predation, competition, parasitism, mutualism, and commensalism affect the stability of an ecosystem • summarize how a stable ecosystem is obtained • identify or illustrate the roles of various organisms in an ecosystem (predator, prey, parasite, host) using pictures, diagrams, or words • interpret a graph of predator/prey numbers over time • explain how the numbers of various organisms fluctuate in an ecosystem to maintain stability • exemplify biological relationships • explain how a significant change in the numbers of a particular organism will affect the stability of the ecosystem • classify a symbiotic relationship as mutualism, parasitism, or commensalism • summarize each of the types of biological relationships • compare how various types of biological relationships affect the organisms involved

13. B-6.2 Explain how populations are affected by limiting factors (including density-dependent,density-independent, abiotic, and biotic factors). Key Concepts: • Population: • population density • Limiting factors: • density-dependent • density-independent • Abiotic • Biotic • A population is a group of organisms belonging to the same species that live in a particular area. Populations can be described based on their size, density, or distribution.

14. Population density • measures the number of individual organisms living in a defined space • Regulation of a population is affected by limiting factors that include • density-dependent • density-independent • Abiotic factors • Biotic factors

15. Density-dependent • Limiting factors that operate more strongly on large populations than on small ones. • Competition • Predation • Parasitism • Disease • triggered by increases in population density (crowding)

17. Density-independent • Limiting factors that occur regardless of how large the population is and reduce the size of all populations in the area in which they occur by the same proportion • abiotic (such as weather changes) • Human activities (such as pollution) • natural disasters (such as fires)

18. Abiotic and biotic factors • Abiotic factors • chemical or physical • water, nitrogen, oxygen, salinity, pH, soil nutrients and composition, temperature, amount of sunlight, and precipitation • Biotic factors • all the living components of an ecosystem • bacteria, fungi, plants, and animals • A change in either may decrease size of a population if it cannot acclimate, adapt to, or migrate from the change. • A change may increase size of a population if that change enhances its ability to survive, flourish or reproduce.

19. REVIEW! • explain how populations are affected by limiting factor • cause-and-effect models of how each limiting factor (including density-dependent, density-independent, abiotic, and biotic factors) can affect a population in an ecosystem and in turn, the entire ecosystem. • summarize how limiting factors (as listed in the indicator) affect population size • exemplify or classify each type of limiting factor (as listed in the indicator) • compare density-dependent limiting factors to density-independent limiting factors and biotic limiting factors to abiotic limiting factors • infer the result of a change in a limiting factor on the size of a population

20. B-6.3 Illustrate the processes of succession in ecosystems. Key Concepts: • Ecological succession • Primary succession: • pioneer species • climax community • Secondary succession • ecological succession: series of changes in an ecosystem when one community is replaced by another community as a result of changes in abiotic and biotic factors • two types: primary and secondary

21. Primary succession • occurs in an area that has not previously been inhabited • Bare rock surfaces from recent volcanic lava flows • rock faces that have been scraped clean by glaciers • a city street

23. Beginning of primary succession • depends on presence of unique organisms that can grow without soil and facilitate process of soil formation • Lichens (mutualistic relationships between fungi and algae) • some mosses • Break down rock into smaller pieces • Among the most important pioneer species (the first organisms) in the process of primary succession • At this stage of succession there are the fewest habitats for organisms in the ecosystem. • Once enough soil and nutrients: • small plants, such as small flowers, ferns, and shrubs, grow • plants break down rock further, provide more soil • Then seeds of other plants and small trees are able to germinate and grow • Over time more species grow and die. • decomposed bodies add nutrients to soil • larger plant species able to populate area

24. Ch-Ch-Ch-Ch-Changes! • As the species of plants change, • species of animals able to inhabit the area also change! • organisms in each stage may alter ecosystem in ways that hinder their own survival but make it more favorable for future organisms • In this way, one community replaces another over time.

25. As long as no disturbances occur... • composition of species perpetuates itself • climax community of a particular area is determined by limiting factors of the area • As scientists have studied changes in ecosystems • found that processes of succession are always changing ecosystems

26. Secondary succession • begins in area where there was a preexisting community and well-formed soil • abandoned farmland • vacant lots • clear-cut forest areas • open areas produced by forest fires • similar to later stages of primary succession • after soil has already formed • Something halts the succession (fire, hurricane, human activities) • destroys established community but soil remains intact • When disturbance is over, ecosystem interacts to restore original condition of community

27. Succession is a continual process • Some stages (and organisms that compose communities that characterize these stages) may last for a short period of time, while others may last for hundreds of years. • Any ecosystem disturbance will affect rate of succession in a particular area • Usually secondary succession occurs faster than primary succession because soil is already present • When disturbances are frequent or intense • area will be mostly characterized by species present in early stages of succession • When disturbances are moderate • area will be composed of habitats in different stages of succession • succession occurs in all ecosystems • forest succession • pond succession • coral reef or marine succession • desert succession

28. Which is primary?Secondary?

29. REVIEW! • illustrate the processes of succession in ecosystems • show how one biological community replaces another community • identify communities that characterize the stages of succession • explain the environmental conditions that are necessary for pioneer species to survive; • infer what type of organisms will be present in a given area in the future based on the a description of the area’s current species • exemplify the conditions for primary and secondary succession • summarize the processes of primary and secondary succession

30. B-6.4 Exemplify the role of organisms in the geochemical cycles (including the cycles of carbon, nitrogen, and water). Key Concepts: • Geochemical cycles • Carbon cycle • Nitrogen cycle: • elemental nitrogen, nitrogen fixation, denitrifying bacteria • Water cycle (hydrologic cycle) • Role of organisms in the geochemical cycles

31. Geochemical cycles • movement of a particular form of matter through living and nonliving parts of an ecosystem • Earth is a closed system and must continually cycle its essential matter • Matter changes form but is neither created nor destroyed; it is used over and over again in a continuous cycle. • Organisms are an important part of this cycling system! • Matter placed into biological systems is always transferred and transformed. • Matter, including carbon, nitrogen, and water, gets cycled in and out of ecosystems.

32. Carbon Cycle • Carbon = one of major components of biochemical compounds of living organisms • proteins, carbohydrates, lipids, nucleic acids • Found in • Atmosphere • In many minerals and rocks • Fossil fuels (natural gas, petroleum, and coal) • In the organic materials (compose soil, aquatic sediments)

33. Organisms play a major role in recycling Cfrom 1 form to another: • Photosynthesis: • Photosynthetic organisms take in CO2 from atmosphere and convert it to simple sugars • Respiration: • Organisms break down glucose • C is released into atmosphere as CO2 • Decomposition: • When organisms die, decomposers break down C compounds • Enrich the soil or aquatic sediments • are eventually released into atmosphere as CO2 • Conversion of biochemical compounds: • Organisms store C as carbs, proteins, lipids, and nucleic acids • When animals eat plants and animals, some compounds used for energy • others converted to cmpds suited for predator’s body • other compounds (methane, other gases) released to atmosphere

34. Other methods of releasing stored C: • Combustion: • Burning wood or fossil fuels releases CO2 into atmosphere • were formed from once living organisms! • Weathering of carbonate rocks • Bones, shells fall to ocean/lake bottom • incorporated into sedimentary rocks (calcium carbonate) • Sedimentary rocks weather and decompose • C released into ocean, eventually into atmosphere

36. Nitrogen Cycle • Nitrogen • critical component of amino acids • needed to build proteins in organisms • found in • atmosphere as elemental nitrogen (N2) • in living organisms (as proteins and nucleic acids) • in organic materials that compose soil and aquatic sediments

38. Organisms play a major role in recycling N from one form to another: • Nitrogen-fixation: • Nitrogen-fixing bacteria convert elemental N found in air/dissolved in water into forms available for use by plants • found in soil, root nodules of plants, aquatic ecosystems • Intake of N into the organisms: • Plants take in the N through their root systems as ammonia or nitrate • N enters the food chain! • Decomposition: • Decomposers return N to soil • organism dies • animal waste products • Denitrification: • Denitrifying bacteria break down N compounds in soil • Release elemental nitrogen, N2, into atmosphere

39. Water Cycle (Hydrologic cycle) • Water • necessary for life processes of all living organisms! • found in • Atmosphere • On surface of Earth • Underground • In living organisms • water cycle driven by Sun’s heat energy • causes water to evaporate from water reservoirs (the ocean, lakes, ponds, rivers) on Earth and also from organisms

40. Organisms play a role in recycling water from one form to another: • Intake of water into the organisms: • Organisms take in water and use it to perform life functions • Photosynthesis • transport of nutrients • Transpiration: • Plants release water back into atmosphere through transpiration • evaporative loss of water from plants • Respiration: • All organisms metabolize food for energy • Produce water as a by-product of respiration • Elimination: • Most organisms need water to assist with elimination of waste products

42. REVIEW! • exemplify the role of organisms in geochemical cycles • give examples of the ways that organisms are involved in nutrient cycles, such as the nitrogen cycle, the carbon cycle, and the water cycle • summarize the ways that organisms are a vital part of each cycle (carbon, nitrogen, and water) in various ecosystems • interpret a diagram, description, or illustration of an ecosystem in order to describe how various organisms play a major role in the cycling of nutrients • explain the role of various organisms on the carbon, nitrogen, and water cycles

43. B-6.5 Explain how ecosystems maintain themselves through naturally occurring processes (including maintaining the quality of the atmosphere, generating soils, controlling the hydrologic cycle, disposing of wastes, and recycling nutrients). Key Concepts: • Atmosphere: • ozone layer, greenhouse effect, sink • Geosphere: • soil erosion, deposition • Hydrologic cycle • There are naturally occurring Earth processes that help ecosystems maintain the materials necessary for the organisms in the ecosystem.

44. Earth systems are interconnected • Biosphere • Portion of Earth inhabited by life • Atmosphere • Hydrosphere • Geosphere • All must interact efficiently in order for an ecosystem to maintain itself.

45. Maintaining the Quality of the Atmosphere • composition of Earth’s atmosphere is mostly result of life processes of organisms which inhabit Earth (past and present) • Photosynthetic organisms need to produce enough oxygen for themselves and all other organisms on Earth • maintain balance of atmospheric CO2 and O2 • Oxygen produced through photosynthesis is also responsible for the atmosphere’s ozone layer • prevents much of the Sun’s ultraviolet radiation from reaching Earth’s surface • protects biosphere from harmful radiation

46. Maintaining the Quality of the Atmosphere, cont’d. • normal cycling of O2 and CO2 • occurs as plants produce more O2 (photosynthesis) than they consume (respiration) • animals use this O2 (for cellular respiration) and release CO2 • used by plants in photosynthesis • Nitrogen is maintained in the atmosphere through the N cycle

47. Maintaining the Quality of the Atmosphere, cont’d. • Water is maintained in atmosphere through water cycle • water vapor condenses in atmosphere • impurities (dust and particulates) removed from atmosphere • fall to Earth with precipitation • air is cleaned after a rain or snow fall

48. Greenhouse effect • normal warming effect when gases trap heat in atmosphere • Greenhouse gases trap heat energy & maintain Earth’s temperature range • carbon dioxide, oxygen, methane, and water vapor • Don’t allow heat to pass through very well • heat that Earth releases stays trapped under the atmosphere

50. Carbon dioxide in the atmosphere • Amount cycles in response to • the degree to which plants and other photosynthetic organisms cover Earth and absorb carbon dioxide • the degree to which oceans cover Earth • salt water of oceans acts as a sink for carbon dioxide, absorbing what plants do not use • converting it to various salts such as calcium carbonate