Transcript Ecology
Ecology Chapters 3-6 1 Organisms and their environments 2 What is ecology? • Study of interactions among organisms and their environments • Includes relationships between living and nonliving 3 Aspects 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 organization Dependence 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 ecosystems 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 Symbiosis Relationships in which there exists a close association among organisms of different 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 flow 24 How organisms obtain energy 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 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 cycles Recycling of matter and energy 45 Water cycle pattern of water movement 46 47 Carbon cycle 48 Nitrogen cycle 49 Communities 50 Living 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 Succession Natural 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 Large groups of ecosystems sharing the same type of climax communities 63 Aquatic biomes 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 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 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 growth Depend 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 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 limit 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 growth 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 Conservation 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 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 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 migration Often species can’t reestablish themselves 118 Abiotic issues • Can change climate • Dust Bowl in Oklahoma 119 120 Habitat degradation Damage 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 conservation 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! 146