Ecology

1. Ecology Chapter 18 Intro to Ecology

2. Ecology • Study of interactions between organisms and the living and nonliving components of their environment • All organisms interact with part of their environment • Their survival depends on this Interdependence

3. Factors • Environmental factors separated into 2 categories • Biotic factors: living components • Abiotic factors: nonliving components

4. biotic orabiotic?

5. Levels of organization • Environments and interactions can be studied at many levels • Organism- one member of a species • Population- many members of the same species in the same are • Community- populations of different species living in the same area • Ecosytem- communities+ nonliving components • Biosphere- thin volume of Earth and atmosphere that support life(skin on an apple)

7. niche • Species do not occupy all parts of their environment • Niche: specific role, or way of life, of a species in its environment • Includes range of tolerances and Resources used • Generalists: broad niche (opossums) • Specialists: narrow niches (koalas)

8. Energy transfer • Autotrophs make their own food • They must capture energy & use it to make organic molecules • They are producers • Most photosynthetic • Some chemosynthetic: energy stored in inorganic molecules to produce carbs

9. productivity • Gross primary productivity: rate at which producers capture light energy by making organic molecules • Some organic molecules used for respiration • Biomass: organic material produced • Net primary productivity: rate at which biomass accumulates

11. consumers • Heterotrophs depend upon autotrophs • Consumers: Energy obtained by eating organic molecules from other organisms • Herbivores: eat producers • Carnivores: eat other consumers • Omnivores: eat producers & consumers

12. DETRIVORES • Consumers that feed on ‘garbage’ (known as detritus) • Detritus: waste, recently dead organisms, fallen leaves, etc. • Decomposers: cause decay by breaking down complex molecules into simpler ones

13. Energy flow • When one organism eats another, molecules are metabolized, & energy is transferred • Energy flows from producers  consumers • Trophic levels: indicate an organism’s position in energy transfer sequence

14. Food webs and chains • Food chains: simple, linear feeding relationships • Food webs: many interrelated food chains

15. Energy transfer • Energy is lost as it moves through ecosystems • heat • ~10% of energy is available to next trophic level • b/c energy transfers are limited, there are not many trophic levels in an ecosystem • Also, # of individuals decreases at each trophic level • Higher trophic levels contain less energy, so they support less individuals

17. Consider This • Amount of U.S. grain fed to farm animals: 70% • Pounds of corn and soy required to produce just one pound of pork: nearly 7 • Water needed to produce a pound of wheat: 14 gallons • Water needed to produce a pound of meat: 441 gallons • Of all water used for all purposes in the United States, more than half goes to: livestock production

18. Water cycle

19. Transpiration: water loss by plants through leaves • Evaporation: liquid  water vapor • Condensation: water vapor  liquid

20. Carbon cycle CO2 photosynthesis combustion Respiration Death and decay

21. Nitrogen cycle • Nitrogen in atmosphere is unusable (N2) • Plants can use nitrate (NO3) • Nitrogen fixation: conversion of nitrogen gas into nitrate • Done by nitrogen-fixing bacteria • Bacteria live in roots of plants • Plants supply carbs, bacteria supply nitrogen

22. Ammonification: formation of ammonia in soil by action of bacteria on decaying matter • Nitrification: nitrites and nitrates produced by bacteria in soil • Denitrification: returning of nitrogen to atmosphere

24. Phosphorous cycle • Plants get it from soil • Animals get it from plants • Phosphorous stored in mineral deposits • No atmospheric component

26. Ch 19 Populations

27. Population characteristics • Population size • # of individuals • Population density • # of individuals per unit area • Dispersion • Clumped: individuals clustered together • Uniform: individuals separated by consistent distance • Random: each location independent of others

29. Population growth • Growth rate: amount by which a population changes over a given time • Affected by 4 factors: • Immigration • Emigration • Birth rate • Death rate

30. 2 Types of Growth Curves • Exponential Growth • Ideal Conditions • No Limiting Factors • Constant Growth Rate • “J” Shaped Curve • Logistic Growth • Limiting Factors Present • Falling Growth rate • “S” Shaped Curve • Resources become less available

31. Exponential Growth

32. Exponential Growth Let’s examine bacteria If a species of bacteria can reproduce once every 20 minutes. How many bacteria will there be after one day? • How is this unrealistic?

33. Growth Curves Continued • Under ideal conditions • Growth continues • However there are limiting factors • 1. nutrients • 2. space • 3. competition

34. Logistic Growth

35. Logistic Growth • Population growth slows or stops • Resources become less available

36. Carrying Capacity • Largest number of individuals (species) that a given environment can support Carrying capacity Number of Yeast Cells Time (hours)

37. Limiting Factors • Any factor that causes population growth to decrease Example: • Competition • Predation • Parasitism and disease • Drought and climate extremes • Human disturbances

38. Density-Dependent factors • Limiting factor that depends on population size. Example • Competition • Predation • Parasitism • disease

39. Density-Independent Factors • Affects all populations in similar ways • Regardless of population size Examples • Unusual weather • Natural disasters • Seasonal cycles • Human activities (damming rivers / clear-cutting forests)

40. Ch 20: community ecology • Species interactions govern communities • Five main interactions • Predation • Competition • Parasitism • Mutualism • commensalism

41. Predation • When a predator eats an individual from another species • Relationship between predator and prey influences size of each population • Predator adaptations • Fangs • Venom • Speed • Specific teeth

42. Prey adaptations • Main strategy is avoidance • Speed or camoflauge • Batesian mimicry: harmless species mimics a harful one • Mullerian mimicry: two or more harmful species look similar

43. Competition • Ocurrs when niches overlap • Interspecific: competition between two or more species • Intraspecific: between members of the same species • One species usually gets pushed out or removed from a community • Competitive exclusion

44. Symbiosis • Symbiosis: close, long-term relationship b/w 2 organisms • Parasitism: one individual is harmed; other benefits • Parasites live on or in a host • Mutualism: both individuals benefit • Commensalism: one benefits, other is unaffected

45. Species richness • Number of species in a community • Varies with latitude • Greatest in tropical rain forests because they are very stable

46. Successional changes • Ecological succession: gradual, sequential growth or regrowth of a community • Follows disturbances • Primary succession: development of a community where one has not previously existed • glacial retreat, volcanoes • Secondary succession: sequentil replacement of species following a distirbance • Fires, floods, • Climax community: stable end point following succession