Intro to Ecology. Chapter 18

Transcription

1 Intro to Ecology Chapter 18

2 Interdependence: A Key Theme in Ecology Ecology- study of the interactions of living organisms w/ one another and w/ their physical environment (soil, water,weather) Interdependence: 1 change can affect all species in an ecosystem

3 Ecological models help to explain the environment

4 Ecologists recognize a hierarchy of organization in the environment

5 A) Biosphere: broadest, most inclusive, thin layer around Earth where life exists B) Ecosystems: all organisms and the nonliving environment

6 C. Community: interacting organisms living in an area D. Population: all the members of species that live in one one time E. Individual organisms of a single species

7 Immigration: movement into a population Emigration: movement out of a population

8 carrying capacity - the # of individuals the environment can support - population growth becomes stable - humans have expanded the carrying capacity

9 18.2 Ecology of Organisms Habitat: place where an organism lives Biotic factors: living things that affect the organism Abiotic factors: nonliving things (climate, sunlight, ph)

10 Why It Rains Where It Does Latitudes: * 30 o north and south the air is dry because it lost almost all moisture in the tropics * Most of the Earth s great deserts occur near 30 o north and south latitude.

11 At 60 o north latitude, the air is rising and cooling and losing moisture and the great temperate forests occur as a result.

12 Rain-shadow Effect: Mountains force approaching air up, cooling it, and causing precipitation on the windward side. Areas on the leeward side are dryer. Vegetation varies with rainfall. (windward) (leeward)

13 Organisms in a Changing Environment Acclimation: organisms can adjust their tolerance to abiotic factors Control of Internal Conditions Conformers: organisms that do not regulate their internal conditions, change w/ environment Regulators: use E to control their internal conditions

14 Escape from Unsuitable Conditions Some species survive by becoming dormant or by migrating Dormancy: state of reduced activity Ex- drought Migration: seasonal movement Ex- birds

15 Niche: way of life, or role in an ecosystem Earthworm Niche

16 18.3 E Transfer Consumers Producers (autotrophs) photosynthetic, make carbs by using E from sun obtain E by eating other organisms or organic molecules from organisms (herbivores, omnivores, carnivores, detritivores, decomposers)

17 Detritivores- organisms that obtain E from organic waste and dead bodies at all trophic levels Ex- vulture and worms Decomposers- cause decay, release nutrients back into the environment (recycle) Ex: fungi and bacteria

18 Food Chain: single pathway of E transfer

19 Food web: network showing all paths of E transfer

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21 -1 st Trophic Level producers (a) use sunlight to make food (b) absorb nitrogen and minerals Ex--algae

22 -2 nd Trophic Level herbivores (a) animals that eat plants (b) primary or 1 st order consumers (c) Ex cows, horses, caterpillars,etc. (d) Must be able to breakdown cellulose of plant cell walls.

23 -3 rd Trophic Level carnivores (a) animals that eat herbivores (b) 2 nd order consumers (c) Ex tigers, wolves, snakes (d) *This level also contains the omnivores that eat both plants and animals (bears and humans).

24 -4 th Trophic Level carnivores (a) tertiary consumers (top carnivores) (b) Carnivores that eat carnivores. (c) 3 rd order consumers (d) Ex hawk eats a snake

25 Feeding Trophic Consumer Type Level Level Top carnivore 4 th 3 rd Carnivore 3 rd 2 nd Herbivore 2 nd 1 st Producer 1 st

26 Energy Pyramids - about 10% of E available at one trophic level is transferred to the next trophic level - 90% of available E is lost at each level - E transfers Btwn trophic levels are inefficient - Large amts of E are released and lost as HEAT in each E transfer

27 E Loss Limits the # of Trophic Levels in an Ecosystem - Most terrestrial ecosystems only involve 3-4 trophic levels - Too much E is each level to allow more

28 18.4 Ecosystem Recycling Materials Cycle Between Organisms and Nonliving Environment

29 A) Water cycle: evaporation, transpiration, and precipitation

30 Water cycles in 2 ways: (a) Nonliving Sun heats up surface water & it evaporates Water vapor condenses in the atmosphere and falls to Earth as precipitation large part of it seeps into the soil and becomes groundwater

31 (b) Living Water is absorbed by plant roots and enters the plant Transpiration occurs from leaves

32 1 Water, compared to all of the other nonliving components in ecosystems, has the greatest influence on an ecosystem s inhabitants. 2 Its availability often determines the diversity of the ecosystem.

33 B) Carbon Cycle: C is returned to environment in 4 ways: 1) CO 2 in the atmosphere and H 2 O is used in photosynthesis to build organic molecules 2) CO 2 and water are products of cellular respiration

34 3) Decomposers release CO 2 into the atmosphere when they break down dead organisms 4) Combustion- CO 2 is released when plant material is burned Ex: plant material (wood), fossil fuels (coal, oil, gas)

35 C) Nitrogen Cycle

36 1) Atmospheric N (N 2 ) is very difficult to remove and use directly - most organisms are incapable of doing so

37 2) N fixation converting N 2 to nitrate 3) Bacteria in soil or (Nitrogen-fixing Cyanobacteria) root nodules of legumes are the only organisms that can do this (nitrogen-fixing bacteria)

38 4) N Cycle 4 stages (a) Assimilation absorption and incorporation of N into plants and animals (b) Ammonification production of ammonia by bacteria during the decay of N containing organic matter. many animals excrete N in urine & dung then another type of bacteria turns it back into ammonia.

39 (c) Nitrification production of nitrate (NO 3- ) from ammonia (d) Denitrification conversion of nitrate to N 2. growth of plants is often limited by the availability of nitrate and ammonia in the soil.

40 D) Phosphorus Cycle 1) P in rocks and soil contains calcium phosphate and when it is dissolved in water it becomes phosphate ions (PO 4- ) 2) Absorbed in plants, it is used to build organic molecules (DNA & ATP) Animals eat plants and reuse P

41 3) When plants and animals die, bacteria change P back to phosphate ions 4) P added to lakes from detergents and fertilizers can cause photosynthetic algae to grow rapidly (algal bloom) When algae die, bacteria feed on it, and use the dissolved O 2. Animals living in the lakes will suffocate

42 Community Ecology Chapter 20

43 20.1 Species Interactions Predation: interaction where 1 organism (predator) captures and eats all or part of another organism (prey) predators and prey have individual adaptations

44 Prey Adaptations Mimicry: species resembles another species or object Many plants produce secondary compounds as a chemical defense

45 Competition May cause competitive exclusion (elimination of 1 species in community)

46 Effect of Competition on 2 Species of Barnacles

47 Competition may drive the evolution of niche differences among competitors character displacement: evolution of differences in a characteristic due to competition resource partitioning use specific part of resource to avoid competition

48 Ex: a warbler (bird) & niche (temp, humidity, nesting time, type of food, where it finds food) - different warblers feed on only portions of the tree; reduces competition

49 Symbiosis A) Parasitism: 1 species (parasite) feeds on, but does not always kill, another species (host) One organism helped, one organism harmed (+ -)

50 B) Mutualism: both species are helped (+ +)

51 C) Commensalism: 1 species benefits, and the other is not affected (+ 0)

52 SUMMARY Interaction Effect on 1 st species Effect on 2 nd species Predation Benefits Harms Parasitism Benefits Harms Mutualism Benefits Benefits Commensalism Benefits No effect

53 20.2 Patterns in Communities Species richness (diversity): # of species in a community greatest near equator, and larger areas support more species predation can promote species richness Species evenness: relative abundance of each species

54 Community Stability & Species Richness Disturbances: can alter a community by eliminating or removing organisms or altering resource availability Species richness may improve a community s stability Areas of low species richness may be less stable

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56 Successional Changes in Communities Ecological succession: change in the species composition of a community over time 2 types

57 Complexity of Succession Community proceeds thru a series of stages until it reaches a stable end point (climax community) Primary- lichens and mosses climax community Secondary- weeds climax community

58 Primary succession: assembly of a community on newly created habitat occurs in areas that lack soil Bare rocks, lava flow areas, glacial areas, newly formed islands

59 Pioneer plants- 1 st plants to return to a changed area (a) Usually small and fast growing, quickly replaced by another species (b) Makes ground more hospitable for the life that follows

60 Steps of Primary Succession 1) Lichens- break down rock and help form soil

61 2) Mosses & Ferns- grow in extremely poor, thin soil

62 3) Grasses & Wildflowers grow in a thicker soil layer w/ an ability to absorb & hold water

63 4) Shrubs & Trees thicker, richer soil

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65 Forest fires, abandoned field occurs in areas where the original ecosystem has been cleared by a disturbance Secondary succession: change in an existing community following a disturbance