Introduction to Ecology

Transcription

1 Introduction to Ecology 3.1 What is Ecology 3.2 Energy, Producers, and Consumers 3.3 Energy Flow in Ecosystems 3.4 Cycles of Matter p Climate 4.2 Niches and Community Interactions 4.3 Succission 4.4 Biomes 4.5 Aquatic Ecosystems p

2 Key Terms Biosphere Population Community Ecology Ecosystem Biome Biotic factor Abiotic factor Autotroph Primary producer Photosynthesis Chemosynthesis Heterotrophs Consumer Carnivore Herbivore Scavenger Omnivore Decomposer Detritivore Food chain Food web Phytoplankton Trophic level Ecological pyramid Biomass Biogeochemical cycle Nutrient Nitrogen fixation Denitrivication Limiting nutrient Weather Climate Microclimate Greenhouse effect Tolerance Habitat Niche Resource Competitive exclusion principle Predation Herbivory Keystone species Symbiosis Mutualism Parasitism Commensalism Ecological succession Primary succession Pioneer species Secondary succession

3 Review? How can a constantly changing environment might affect evolution? Populations can evolve by natural selection With respect to heritable traits that favor reproductive success and survivorship in each particular environment Can humans have an impact on the environment?

4 Objectives Identify a key theme in ecology Describe an example showing the effects of interdependence upon organisms in their environment. Identify the importance of models to ecology State the five different levels of organization at which ecology can be studied

5 What is Ecology? (house/ study of) Ecology is the study of interactions between organisms and the living and nonliving components of their environments. Each of the variety of organisms on Earth depends in some way on other living and nonliving things in its environment. Ecology is a broad science that involves collecting information about organisms and their environments, observing and measuring interactions, looking for patterns, and seeking to explain these patterns.

6 Organisms and their Environment All organisms interact with other organisms in their surroundings and with the nonliving things in the environment The survival depends on the interactions This is called the interconnectedness or interdependence The things you need to survive

7 Ecological models Ecology is complex thing to study Used ecological models to represent or describe the components of an ecological system Helps to study environmental interactions and make predictions Can not always account for influences or variables in an environment

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9 The Science of Ecology Ecology is the scientific study of interactions among and between organisms and their physical environment. Interactions within the biosphere produce a web of interdependence between organisms and the environments in which they live.

10 Studying Our Living Planet The biosphere consists of all life on Earth and all parts of the Earth in which life exists, including land, water, and the atmosphere. The biosphere extends from about 8 km above Earth s surface to as far as 11 km below the surface of the ocean.

11 Levels of organization Biosphere- thin volume of earth and its atmosphere that supports life Ecosystem- all of the organisms and the nonliving environment found in one place Community-all the interacting organisms living in an area Populations- all the members of a species that live in one place at the same time Web cd 34 a, holtclip

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13 Objectives Compare abiotic factors with biotic factors and list two examples of each Describe two mechanisms that allow organisms to survive in a changing environment Explain the concept of the niche

14 Ecology of Organisms The place where an organism lives is its habitat. But why does it live there and not elsewhere? What parts of its habitat does it use? The answers to these questions depends on an organism s evolutionary history, its abilities, and its needs

15 Ecosystem components Factors that influence an organism into two types 1. Living components- biotic factors 2. Nonliving factors- abiotic factors (changing) a) Temperature b) Humidity c) ph d) Salinity e) Oxygen concentrations f) Amount of sunlight Web cd 34 b

16 Organisms in a changing environment Each organism is able to survive within a limited range of environmental conditions Tolerance curve- helps to determine an organisms performance versus values of an environmental variable (temps, salt) May still survive but performance limited Some organisms can acclimate, adjust tolerance levels

17 Control of internal conditions How do they deal with environments changing daily? Two ways 1. Conformersorganisms that do not regulate their internal conditions, they change as their external environments changes 2. Regulators- use energy to control some of their internal conditions over wide variety of environmental conditions

18 Escape from unsuitable conditions Escape them temporarily Ways- 1. Hide underground or shade till cool 2. Active at night when cooler (desert species) 3. Long term- dormancy, reduce activity (bears) 4. Migration- move habitat (birds)

19 The niche to nest The specific role or way of life of an organisms in its environment Includes: 1. Range of conditions 2. Resources 3. Ways to obtain resources 4. Number of offspring 5. Time of reproduction 6. Predator/prey

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21 Two different types of species 1. Generalist- species with broad niches, can tolerate range of conditions and use a variety of resources ex. Opossum feeds on eggs, fruits, dead animals 2. Specialist- narrow niches, ex koala only feeds on eucalyptus trees *More than one- some species have more than one niche during a lifetime (caterpillars eat leaves, butterflies eat nectar)

22 Objectives Summarize the role of produces in an ecosystem Identify several kinds of consumers in an ecosystem Explain the important role of decomposers in an ecosystem Compare the concept of a food chain with that of a food web Explain why ecosystems usually contain only a few tropic levels

23 THINK ABOUT IT What happens to energy stored in body tissues when one organism eats another? Energy moves from the eaten to the eater. Where it goes from there depends on who eats whom!

24 Energy transfer All organisms need energy to carry out essential functions, such as growth, movement, maintenance and repair, and reproduction. In an ecosystem, energy flows from the sun to autotrophs, then to organisms that eat the autotrophs, and then to organisms that feed on other organisms. The amount of energy an ecosystem receives and the amount that is transferred from organism to organism affect the ecosystem's structure.

25 Producers Autotrophs- make their own food, plants, some protists and bacteria Most are photosynthetic use sunlight to make food Chemosynthesis- breakdown molecules to produce carbohydrates

26 consumers Heterotrophs- can not make own food, eat other organisms Grouped based on types of food they eat: 1. Herbivores- eat producers (antelope) 2. Carnivores- eat other consumers (lion) 3. Omnivores- eat producers and consumers (grizzly bear) 4. Detritivores- consumers that feed on wastes, dead organisms (vulture) 5. Decomposers- break down organisms (bacteria, fungi)

27 Decomposers and Detritivores in Food Webs At the same time, the decomposition process releases nutrients that can be used by primary producers. They break down dead and decaying matter into forms that can be reused by organisms, similar to the way a recycling center works. Without decomposers, nutrients would remain locked in dead organisms.

28 Energy Flow Transfer of energy from one organism to another Trophic levels- organism s position in a sequence of energy transfers Food chain- single pathway of feeding relationships between organisms in an ecosystem that results in energy transfer Food web- interconnected food chains Web cd 37 c, d, e Fig: 18.9, 18.10, 18.11

29 Food Chains A food chain is a series of steps in which organisms transfer energy by eating and being eaten. Food chains can vary in length. An example from the Everglades is shown.

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31 Food Webs In most ecosystems, feeding relationships are much more complicated than the relationships described in a single, simple chain because many animals eat more than one kind of food. Ecologists call this network of feeding interactions a food web. An example of a food web in the Everglades is shown.

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35 Limitations on trophic levels Only 10% of the energy available at one trophic levels is transferred to the next trophic level not enough to support more levels Higher tropic levels contain less energy support fewer organisms

36 Pyramids of Biomass and Numbers The total amount of living tissue within a given trophic level is called its biomass. The amount of biomass a given trophic level can support is determined, in part, by the amount of energy available.

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41 Objectives List four major biogeochemical cycles Summarize three important processes in the water cycle Outline the major steps in the carbon cycle Describe the role of decomposers in the nitrogen cycle Summarize the major steps of the phosphorus cycle

42 Ecosystem Recycling As energy and matter flow through an ecosystem, matter must be recycled and reused. Substances such as water, carbon, nitrogen, calcium, and phosphorus each pass between the living and nonliving worlds through biogeochemical cycles.

43 Recycling in the Biosphere Unlike the one-way flow of energy, matter is recycled within and between ecosystems. Elements pass from one organism to another and among parts of the biosphere through closed loops called biogeochemical cycles, which are powered by the flow of energy.

44 4 major cycles 1. Water cycle 2. Carbon cycle 3. Nitrogen cycle 4. Phosphorus cycle Web cd 37 f, g, h,

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48 Ecosystem Diversity Coral reefs are among the most diverse and productive marine ecosystems on Earth.? How do animals take advantage of a CR?? Why CR community is so rich in number and kinds of organisms? A: as a home, food, protection, growth A: many opportunities for food, safety, interactions, resources

49 Objectives Identify two types of predator adaptations and two types of prey adaptations Identify possible causes and results of Interspecific competition Compare parasitism, mutualism, commensalisms, and be able to give examples

50 Species interactions Just as populations contain interacting members of a single species, communities contain interacting populations of many species. Many species have specific types of interactions with other species. This chapter introduces the five major types of interactions among species: predation, competition, parasitism, mutualism, commensalisms, These categories are based on whether each species causes any benefit or harm to the other species in a given relationship

51 Predation The relationship between a predator and a prey Predator eats the prey (snake eats mouse) Can affect how each species lives 1. Predator adaptations- Snakes have poor scent, have heat detectors Spiders spin webs Speed of cheetah Predators relies on if they can catch food and prey relies on ability to not get caught

52 Predation 2. Adaptation in animal prey Ability to flee Chemical defenses Mimicry- resembles another species - Batesian- harmless looks like deadly - mullerian- 2 or more dangerous look similar (bees) 2. Adaptation in plant prey- sharp thorns, spines, sticky hairs Secondary cpds- chemical defense (poison ivy)

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54 Herbivore-Plant Relationships An interaction in which one animal (the herbivore) feeds on producers (such as plants) is called herbivory. Herbivores, like a ring-tailed lemur, can affect both the size and distribution of plant populations in a community and determine the places that certain plants can survive and grow. For example, very dense populations of white-tailed deer are eliminating their favorite food plants from many places across the United States.

55 Keystone Species Sometimes changes in the population of a single species, often called a keystone species, can cause dramatic changes in the structure of a community. In the cold waters off the Pacific coast of North America, for example, sea otters devour large quantities of sea urchins. Urchins are herbivores whose favorite food is kelp, giant algae that grow in undersea forests. A century ago, sea otters were nearly eliminated by hunting. Unexpectedly, the kelp forest nearly vanished. Without otters as predators, the sea urchin population skyrocketed, and armies of urchins devoured kelp down to bare rock. Without kelp to provide habitat, many other animals, including seabirds, disappeared. Otters were a keystone species in this community.

56 Competition 1. Interspecific competition- type of interaction in which two or more species use the same limited resources (plants and sunlight) Web cd 37 A 2. Competitive exclusion- one species gets eliminated from the community due to resources 3. Reduce niche size- interactions with other species, -fundamental- potentially use, -realized niche- what is actually used

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58 The Competitive Exclusion Principle The competitive exclusion principle states that no two species can occupy exactly the same niche in exactly the same habitat at exactly the same time. If two species attempt to occupy the same niche, one species will be better at competing for limited resources and will eventually exclude the other species. As a result of competitive exclusion, natural communities rarely have niches that overlap significantly.

59 The Competitive Exclusion Principle In the experiment shown in the graph, two species of paramecia (P. aurelia and P. caudatum) were first grown in separate cultures (dashed lines). In separate cultures, but under the same conditions, both populations grew. When organism were put in the same culture one species dies off. However, when both species were grown together in the same culture (solid line), one species outcompeted the other, and the less competitive species did not survive.

60 Competition 4. Character displacement- evolution of differences in a characteristic due to competition, way to reduce niche overlap, finches 5. Resource partitioning- when similar species coexist each species may avoid competition with others by using a specific part of an available resource (warbler eating insects at diff parts of tree)

61 Dividing Resources Instead of competing for similar resources, species usually divide them. For example, the three species of North American warblers shown all live in the same trees and feed on insects. But one species feeds on high branches; another feeds on low branches, and another feeds in the middle.

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63 symbiosis Close long term relationship between two organism 3 major examples 1. parasitism- one is harmed/ one benefit mutualism- both benefits 3. commensalisms- one is helped/ one is neither helped or harmed

64 Examples 1. Tapeworms live in the intestines of mammals, where they absorb large amounts of their hosts food. Fleas, ticks, lice, and the leech shown, live on the bodies of mammals and feed on their blood and skin. 2. The sea anemone s sting has two functions: to capture prey and to protect the anemone from predators. Even so, certain fish manage to snack on anemone tentacles. The clownfish, however, is immune to anemone stings. When threatened by a predator, clownfish seek shelter by snuggling deep into an anemone s tentacles. 3. Barnacles often attach themselves to a whale s skin. They perform no known service to the whale, nor do they harm it. Yet the barnacles benefit from the constant movement of water that is full of food particles past the swimming whale.

65 Objectives Describe the factors that affect species richness in a community Explain how disturbances affect community stability Distinguish between types of succession and explain why succession may not be predictable

66 Patterns in communities The investigating of community properties and interactions is and active area of ecology. Which properties are most significant in structuring a community? What determines then umber of species in a community? How do communities recover from disturbance? These questions are central to a study of communities.

67 Species richness The number of species in a community, simple count of population Species evenness- relative abundance of each species, takes into account how common each species is in the community Most study species richness

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69 Community stability and richness Disturbances- events that change the community Stability- tendency of a community to maintain relatively constant conditions

70 THINK ABOUT IT In 1883, the volcanic island of Krakatau in the Indian Ocean was blown to pieces by an eruption. The tiny island that remained was completely barren. Within two years, grasses were growing. Fourteen years later, there were 49 plant species, along with lizards, birds, bats, and insects. By 1929, a forest containing 300 plant species had grown. Today, the island is blanketed by mature rain forest. How did the island ecosystem recover so quickly?

71 Succession- changes Ecological succession- gradual regrowth of a community of species Primary- development of a community in an areas that has not supported life previously, sand dune, rock Web cd 37 b Secondary- replace of species that follows the disruption (soil is present) Pioneer species- small, grow quick, reproduce quick, invade disturbed habitats Climax community- stable end pt

72 Primary Succession Volcanic explosions can create new land or sterilize existing areas. Retreating glaciers can have the same effect, leaving only exposed bare rock behind them. Succession that begins in an area with no remnants of an older community is called primary succession.

73 Primary Succession For example, in Glacier Bay, Alaska, a retreating glacier exposed barren rock. Over the course of more than 100 years, a series of changes has led to the hemlock and spruce forest currently found in the area. Changes in this community will continue for centuries.

74 Primary Succession The first species to colonize barren areas are called pioneer species. One ecological pioneer that grows on bare rock is lichen a mutualistic symbiosis between a fungus and an alga.

75 Secondary Succession Sometimes, existing communities are not completely destroyed by disturbances. In these situations, secondary succession occurs. Secondary succession proceeds faster than primary succession, in part because soil survives the disturbance. As a result, new and surviving vegetation can regrow rapidly. Secondary succession often follows a wildfire, hurricane, or other natural disturbance. We think of these events as disasters, but many species are adapted to them. Although forest fires kill some trees, for example, other trees are spared, and fire can stimulate their seeds to germinate. Secondary succession can also follow human activities like logging and farming.

76 Why Succession Occurs Every organism changes the environment it lives in. One model of succession suggests that as one species alters its environment, other species find it easier to compete for resources and survive. For example, as lichens add organic matter and form soil, mosses and other plants can colonize and grow. As organic matter continues to accumulate, other species move in and change the environment further. Over time, more and more species can find suitable niches and survive.

77 Climax Communities Ecologists used to think that succession in a given area always proceeds through the same stages to produce a specific and stable climax community. Recent studies, however, have shown that succession doesn t always follow the same path, and that climax communities are not always uniform and stable. Ecosystems may or may not recover from extensive humancaused disturbances. Clearing and farming of tropical rain forests, for example, can change the microclimate and soil enough to prevent regrowth of the original community.

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79 Ecosystems Biomes 1. Tundra 2. Taiga 3. Temperate Forest 4. Tropical Rain Forest 5. Temperate Grasslands 6. Savanna 7. Chapparral 8. Desert 9. Ocean - Intertidal zone - Neritic zone - Oceanic zone 10. Estuaries 11. Lakes and ponds 12. Rivers and streams 13. FW wetlands Web cd 34 c, d

80 Defining Biomes The map shows the locations of the major biomes.

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83 Weather and Climate Weather is the day-to-day condition of Earth s atmosphere. Climate refers to average conditions over long periods and is defined by year-after-year patterns of temperature and precipitation. Climate is rarely uniform even within a region. Environmental conditions can vary over small distances, creating microclimates. For example, in the Northern Hemisphere, south-facing sides of trees and buildings receive more sunlight, and are often warmer and drier, than north-facing sides. These differences can be very important to many organisms.

84 Solar Energy and the Greenhouse Effect The main force that shapes our climate is solar energy that arrives as sunlight that strikes Earth s surface. Some of that energy is reflected back into space, and some is absorbed and converted into heat.

85 Solar Energy and the Greenhouse Effect Some of the heat also radiates back into space, and some is trapped in the biosphere. The balance between heat that stays in the biosphere and heat lost to space determines Earth s average temperature.

86 Solar Energy and the Greenhouse Effect Earth s temperature is largely controlled by concentrations of three atmospheric gases carbon dioxide, methane, and water vapor. These greenhouse gases function like glass in a greenhouse, allowing visible light to enter but trapping heat through a phenomenon called the greenhouse effect.

87 Solar Energy and the Greenhouse Effect If greenhouse gas concentrations rise, they trap more heat, so Earth warms. If their concentrations fall, more heat escapes, and Earth cools. Without the greenhouse effect, Earth would be about 30 C cooler than it is today.