EcologyEcologyChapters 3-6Chapters 3-6

1

Organisms and their Organisms and their environmentsenvironments

2

What is ecology?

• Study of interactions among organisms and their environments

• Includes relationships between living and nonliving

3

Aspects of ecologyAspects of ecology

4

Biosphere

• Portion of the Earth that supports life

• Extends from high in the atmosphere to the bottoms of the oceans

• Thin, but diverse

5

Abiotic factors

• Nonliving parts of the environment

• Air currents, temperature, moisture, light, soil

• Determine which species can live in an area

6

Biotic factors

• Living parts of the environment

• All organisms inhabiting an environment

7

Levels of organizationLevels of organizationDependence on others for food, shelter, reproduction, or protectionDependence on others for food, shelter, reproduction, or protection

8

Species

• A group of organisms that can interbreed and produce fertile offspring

9

Population

• All organisms of the same species inhabiting a certain area

• May compete for food, water, or other resources

10

• Some species have adaptations that decrease competition• Different forms during development frogs

• Different colors for closely related species cichlid fish

11

Community

• Collection of interacting populations in a certain area

• Changes in one population causes changes in others

12

Ecosystems

• Interactions of biotic and abiotic factors in a certain area

• Terrestrial, freshwater, marine

• Energy flows between populations and the environment self-sustaining

13

Organisms in Organisms in ecosystemsecosystems

14

Habitat

• Place where an organism lives

• Contains organisms of different species

15

Niche

• Role and position of species in an environment

• How it meets it’s needs food, shelter, reproduction

• Includes interactions with biotic and abiotic factors

16

Niche cont.

• One species = one niche

• Advantageous decrease in competition

• Competition arises with overlapping niches

17

Predator/prey relationships

• Predators are carnivores and omnivores

• Prey are herbivores

18

SymbiosisSymbiosis Relationships in which there exists a close association among organisms of Relationships in which there exists a close association among organisms of different speciesdifferent species

19

Commensalism

• One species benefits and the other neither benefits or is harmed

• Sharks and pilot fish

20

Mutualism

• Both species benefit

• Ants and acacia trees

• Humans and bacteria

21

Parasitism

• One species benefits and the other is harmed

• Dogs and fleas

• Humans and tapeworms

22

Symbiosis: a review

23

Nutrition and energy Nutrition and energy flowflow

24

How organisms obtain How organisms obtain energyenergy

25

Autotrophs producers

• Use energy to synthesize their own nutrients

26

Phototrophs use energy from the sun

27

Producers

28

Chemotrophs use energy from chemical compounds

29

30

Heterotrophs consumers

• Obtain energy and nutrients from the environment

31

Herbivores plants only

32

Carnivores animals only

33

Omnivores both plants and animals

34

Scavengers carrion and refuse (clean-up)

35

Decomposers break down dead and decaying organic matter (recycle nutrients)

36

Matter and energy flowMatter and energy flow

37

Food chains patterns of flow

• The arrows indicate the direction of energy flow• Grass Mouse Owl

38

• Energy is lost at each level in the form of heat food chains only have up to 5 levels

• Levels are called trophic levels

39

Food webs represent all possible feeding relationships

• Made of overlapping food chains

• More realistic most organisms depend on more than one species for food

40

41

42

Ecological pyramids

• Show relative amounts of energy or matter by trophic level

• Initial source of energy is the sun

• 10% rule only 10% of the available energy is passed from one trophic level to the next

43

Energy Pyramid:

Shows the relative amount of energy available at each trophic level.Only part of the energy that is stored in one trophic level is passed on to the next level.

44

Natural cyclesNatural cyclesRecycling of matter and energyRecycling of matter and energy

45

Water cycle pattern of water movement

46

47

Carbon cycle

48

Nitrogen cycle

49

Communities Communities

50

Living in the communityLiving in the community

51

Limiting factors

• Biotic or abiotic factors that restrict numbers, reproduction, or distribution of organisms

• Through interdependence, factors that limit organisms populations may have an indirect effect on another

52

Limiting factors:

• Food availability

• Predators

• Moisture

• Soil pH

• Sunlight

• Temperature

53

Ranges of tolerance

• Ability to withstand fluctuations in limiting factors

• Varies between species and individuals

54

SuccessionSuccession Natural changes and species replacements taking place in an ecosystemNatural changes and species replacements taking place in an ecosystem

55

Occurs in stages

• May take decades or centuries

56

Primary succession new sites

• Pioneer species first to arrive• Colonize bare rock turns to soil

• Lichens and mosses

• Thin soil allows grasses soil gets deeper

57

Primary succession cont.

• Grasses give way to shrubs deeper soil

• Eventually trees can colonize

• Climax community stable, mature community that changes little• Disrupted only by natural disasters

58

59

Secondary succession

• Soil present

• Sites devastated by natural disasters or human intervention

60

• Faster than primary

• Pioneer species are different

• Can also happen to ponds

61

62

Biomes Biomes Large groups of ecosystems sharing the same type of climax communitiesLarge groups of ecosystems sharing the same type of climax communities

63

Aquatic biomesAquatic biomesMarine and freshwater (75%)Marine and freshwater (75%)

64

Marine biome 97% (largest)

• Contains largest amounts of biomass plankton

• Most stable (unchanging) biome

65

66

Freshwater biome 3%

• Lakes only top few feet warmed by sun• Limiting factor

• Decomposers at bottom recycle nutrients

• Running water contains more O2

67

Estuaries

• Mixing of fresh and saltwater

• Salinity changes with tide increases biodiversity

• Used as breeding grounds by many species

68

69

Terrestrial biomesTerrestrial biomes

70

Tundra

• Circles the poles, tops of mountains

• Treeless thin soil supports only grasses and shrubs

• Cold temperatures slow decay slow nutrient recycling

• Short growing season limiting factor• Permafrost permanently frozen ground

71

72

Taiga (coniferous forest)

• Just south of the tundra

• Cone-bearing trees• Pine, fir, hemlock, and spruce

• Warmer and wetter than the tundra

• Harsh winters, short and mild summers

• No permafrost

73

74

Desert driest

• Sparse plant life

• Plant adaptations:• Spines instead of leaves

• Extensive root systems

• Rapid growth and development

• Thick tissue water conservation

75

76

Grassland interior of continents

• Not enough rainfall to support trees

• Includes prairies, steppes, and savannas

• Largest terrestrial biome

• Breadbaskets fertile soil

77

78

Temperate deciduous forest

• We live here!

• Broad-leaved hardwood trees that lose their leaves annually

• Soil composed of top layer (humus) and bottom layer (clay)

• More rainfall than taiga

79

80

Tropical rainforest

• Warm, wet, constant temperature and humidity

• Highest in biodiversity• Year-round growing conditions

• Multitude of possible habitats

• Soil poor in nutrients quickly absorbed by plants

81

82

Population biologyPopulation biology

83

Principles of population growth

• Population growth increase in size of population over time

84

Not linear J-shaped curve

85

Exponential growth

• As population increases, growth rate increases• Initial growth is slow due to small number of reproducing

organisms

86

87

Principles cont.

• Limiting factors eventually stop growth• Food supply

• Living space

88

Carrying capacity

• Number of organisms of 1 species the environment can support• Under births exceed deaths

• Over deaths exceed births

• Would be infinite without limiting factors

89

Carrying Capacity

90

Patterns of reproductive Patterns of reproductive growthgrowthDepend on environmental conditionsDepend on environmental conditions

91

Unpredictable environments rapid life histories

• Small body size

• Rapid growth and development

• Early reproduction

• Short life-span

• Mice

92

Stable environments slower

• Large body size

• Slow growth and development

• Reproduce slowly

• Long life-span

• Sea turtles

93

94

Environmental limitsEnvironmental limits

95

Density-dependent factors

• Increased effects as population size increases

• Disease

• Competition

• Parasites

96

Density-independent factors

• Not related to population size

• Temperature

• Droughts

• Storms

97

Organism interactions Organism interactions limit population sizelimit population size

98

Predation

• Both predator and prey populations show a cycle of increases and decreases over time

• Cuts down on competition for resources

99

Effects of crowding and stress

• Competition causes stress

• Results:• Aggression

• Decreased parental care

• Decreased fertility

• Decreased resistance to disease

100

Human population Human population growthgrowth

101

Demography

• Study of human population growth characteristics

• Growth rate, age structure, geographic distribution

102

• Has been increasing exponentially over the last few hundred years

• Elimination of competition, increased food supply, disease control

103

Effects of birthrates and death rates

• Growth = birthrate – death rate

• Can provide clues to a country’s growth

104

Effects of age structure

• Rapid growth higher number of younger people

• China vs. Japan

105

Effects of mobility

• Immigration moving into a population

• Emigration moving out of a population

• No effect of world population

106

Biological Diversity and Biological Diversity and ConservationConservation

107

Biodiversity variety of life in an area

• Tropical regions 2/3 of all land species

• Important due to species interdependence• Effects on 1 population cascade to others

• Predator-prey relationships

• Symbiotic relationships

• Biodiversity brings stability

108

Importance to humans

• Plants cycle O2 and CO2

• Diverse diet

• Provides basis for new species of agriculture

• Improve health digitalis and other medicines

109

Loss of biodiversityLoss of biodiversity

110

Threatened species

• Population size is decreasing rapidly

• African elephant, loggerhead turtles

111

Endangered species

• Population size is so low that extinction is possible

• Florida manatees, California condors, peregrine falcon

112

Extinction

• Disappearance of a species

• Due to natural processes and human activity

• Passenger pigeon, dodo

113

Threats to biodiversityThreats to biodiversity

114

Habitat loss

• Razing forests for agriculture or construction

• Mining coral reefs for building materials or jewelry

• Overgrazing land

115

Habitat fragmentation

• Separation of wilderness areas from other wilderness areas

• Like islands lose biodiversity due to isolation

• Clearing land or building roads

116

117

Biotic issues

Not enough food for large predators migrationOften species can’t reestablish themselves

118

Abiotic issues

• Can change climate

• Dust Bowl in Oklahoma

119

120

Habitat degradationHabitat degradationDamage by pollutionDamage by pollution

121

Global warming

• Increase in global temperature due to high atmospheric CO2 levels

• Pollution and overpopulation

• Gradual melting of polar ice caps and change in global climate

122

123

Acid rain

• Precipitation with low pH

• Sulfur and nitrogen from industry combine with atmospheric water vapor to form sulfuric and nitric acids

• Damages plant tissues

• Changes acidity of soil and lakes

124

125

Effects of acid rain

Habitat destruction Defamation of man-made artifacts

126

Chlorofluorocarbons CFCs

• Break down ozone layer

• Gradual increase in damaging solar radiation

127

128

Fertilizers and animal wastes

• Washed into large bodies of water by runoff

• Cause algal blooms

• Destruction of coral reefs

129

Effects of algal blooms

130

Solid wastes

• Landfills

• Take up space

• Pollute soil and ground water

131

Landfills

132

Pesticides

• Get into the food chain and harm other animals

• DDT and the American bald eagle

133

Biological Magnification

• Toxins increase in concentration in organisms at higher trophic levels

134

135

Introduction of exotic species

• No natural predators

• Out-compete native species

• Zebra mussels, purple loosestrife

136

Strategies of Strategies of conservation biologyconservation biology

137

Legal protection of species

• Endangered Species Act 1973• Prohibits trade of endangered or threatened species

• Clean Water/Air Acts

138

Preserving habitats

• Nature preserves and national parks

• Habitat corridors strips of protected land used by migratory animals

139

140

Reintroduction programs

• Release organisms into areas where the species once lived

• Not always successful• Expensive

• Animals become domesticated

• Gray wolf

141

142

Captivity

• Permanent zoos

• Temporary rehabilitation centers (Sea World)

143

Alternative energy sources

144

145

The End!The End!146