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Last updated: 08/18/98 Designed by: Davis's Ent. |
Read the DISCLAIMER before proceeding. Biology 1720 - Ecology Outline Notes for Professor Abbott With Interjections by Ricky
Introduction to Ecology Definitions: Oikos: Home or place to live ECOLOGY: the body of knowledge concerning the economy of nature--the investigation of the total relationship of the animal, both to its inorganic and organic environment... (Haeckel). ECOLOGY: the study of interactions of organisms with one another and with their physical environment (Smith). ECOLOGY: the study of interactions of organisms and their environment (Campbell). Facets of Ecology Organismal Ecology - Behavioral, physiological, and morphological ways in which organisms survive in their abiotic environment Population Ecology - Factors affecting population size and composition Ecosystem - Involves abiotic and biotic factors
Community Ecology - Consisting of... Distribution of Organisms Biosphere - Portion of earth inhabited by life Terrestrial Biomes - Distinct combination of plants and animals, each characterized by a uniform life of vegetation F.E. Clements & V. Shelford, 1939- Classified world plant formations At least 9, depending on classification Largely determined by temperature and moisture interactions Distribution of Organisms Abiotic Factors :
Water - Availability and adaptations to lack of water Sunlight- Can we say, "Photosynthesis!" Wind- Affects temperature (wind chill). Also seed dispersal Rocks & Soil- Mineral content, pH Catastrophes- Adaptations to catastrophe... Yes they can do it! Climate- Global patterns, seasons, etc... Terrestrial Biomes 1. Tropical Rain Forest 2. Tropical Grassland/Savanna 3. Desert 4. Chaparral 5. Temperate Grasslands 6. Temperate Deciduous Forest 7. Temperate Rain Forest 8. Taiga/Boreal Forest 9. Tundra Tropical Rain Forests
Tropical Grasslands/Savanna
Deserts
Chaparral
Temperate Grasslands/Prairies
Temperate Deciduous Forests
Temperate Rain Forests
Taiga/Boreal Forests
Tundra
Elevation & Latitude
Aquatic Ecosystems Marine Systems - average 3% salt - cover 75% of Earth s surface - average depth > 3 km (2 mi) - Marianas Trench (11 km, 7 mi) - critical O2 supply - <10% of life occurs in oceans - barriers between microhabitats not sharply defined The Oceans 1. Neritic Zone - - area along coast and continents/islands - <300 m below surface - most diverse area
2. Surface Zone - - primarily includes plankton (at mercy of current) and nekton (can fight current) - 40% of all photosynthesis on earth occurs here - light is a limiting factor
3. Abyssal Zone - - depths >1000 m - cold temperatures - high atmospheric pressures (10 m=1 atm) - darkness - lack of food - life still exists
Freshwater Systems (<1% saline) - inland lakes account 1.8% Earth s surface - running waters, 0.3% - strongly connected with terrestrial systems - marshes/swamps act as intermediates Lentic Systems 1. Littoral Zone - - shallow are along shore
2. Limnetic Zone - - sunlit areas away from shore
3. Profundal Zone - - below limits of light Thermal Stratification - occurs in Temperate regions
Summer - - epilimnion (photic) forms with warmer water at surface - cooler hypolimnion (aphotic) lies below (4°C) - abrupt thermocline between the two - epilimnion is O2 rich/nutrient poor
Winter - - temperature of epilimnion drops to 4°C - mixes with hypolimnion (Fall Overturn) - a layer of cooler, lighter water freezes forming ice at surface - below ice (0°-4°C) plants and animals survive
Spring - - ice melts & surface water warms up - at 4°C it mixes with water below (Spring Overturn) - mixing results in nutrients formerly confined to depths returning to surface and O2 from surface is carried to depths. Eutrophic Lakes - abundance of minerals & organic matter - O2 supply can be easily depleted
Oligotrophic Lakes - organic matter & nutrients are scarce - often deep with characteristic "blue water" - hypolimnion is always O2 rich - susceptible to nutrient pollution because of naturally limited quantities - fertilizer runoff, sewage, detergents = algal blooms - O2 supply depleted killing fish & other organisms Lake Pollution - Accumulation of Toxins: DDT, PCB, toxic metals - Nutrients : P (sewage/Agricultural run-off), N (cultural eutrophication) - Thermal : power stations (decrease O2, increase productivity of bacteria) - Sediment : erosion - Acids/Bases : industrial byproducts (smelting, petroleum refining), Acid Rain
Lotic Systems - rivers and streams - organisms adapted to flowing water - streamlining - flattening - suckers, silk-fasteners - heavily affected by pollution run-off Ecological Succession - ecosystems are dynamic - replacement of one community by another - often progressing to a stable terminal climax - climax community - community that would exist if left undisturbed - succession is continuous and worldwide in scope Primary Succession - lifeless terrain - lava flows, receding glaciers, new pond - soil generation (physical & chemical weathering) - pioneer community (lichen & moss) - acidic secretions help break down rocky substrate and add to the accumulation of soil - xeric vs. hydric Secondary Succession - succession of vegetative species - caused by physical (human) or biological modifications - clear cutting of forests Ecosystem - the biotic community and its abiotic environment functioning as a system. - provides a scientific context for evaluating environmental issues. - Environmentalism (Environmental awareness) Population Ecology Basic Requirements of all Organisms 1. Food 2. Shelter 3. Air 4. Reproduction
Populations - a group of individuals of the same species.
Community - several to many populations of different species.
Biotic Components - Producers (autotrophs) - organisms that make their own food, and I don’t mean with a microwave
- Consumers (heterotrophs) - organisms that live on other organisms
Primary Consumers - those that eat producers as food (herbivores) Secondary Consumers - those that eat herbivores or other primary consumers Decomposers (detritivores) - those that eat non-living organic material returns organic material to inorganic Energy Flow - Source : Sun - Forms : Radiant energy, chemical bonds in organic molecules (carbohydrates) Trophic Levels : steps of NRG transferal - Level 1 - green plants - Level 2 - herbivores - Level 3 - carnivores - Level 4+ - carnivores - Level ? - Ecological Pyramids - progressively smaller numbers of organisms at successive trophic levels. - "pyramid of biomass" - "pyramids of energy" - "pyramids of numbers" - occasionally some pyramids can be inverted - pyramids of energy can never be inverted Nutrient Cycling C, N, O, H, P Carbon Cycle - CO2 makes up 0.03% of the atmosphere - CO2 is incorporated into organic molecules then released during respiration - long term sinks include oil, gas and coal - CO2 in the atmosphere is increasing - burning of fossil fuels - global climate changes (greenhouse effect) Nitrogen Cycle - 78% of Earth s atmosphere - total amount of fixed N2 in soil, oceans and organisms is only 0.03% of above - few organisms can convert atmospheric N2 into forms used by organisms - naturally occurring as NN - cleavage is catalyzed by proteins - used for synthesis of proteins & nucleic acids - various free-living bacteria convert N2 to ammonia - some bacteria are symbiotic with legumes - denitrification - - in its absence all N2 would eventually become fixed Ammonification- breakdown of organic matter to produce ammonia - picks up H+ in acidic soils (NH4+) - Nitrosomonas bacteria - convert NH3 to NO2 - Nitrobacter - convert NO2 to NO3 Phosphorous Cycle - representative of other mineral cycles - needed for : ATP Cell Membranes Phospholipids Bones Teeth Shells - source : Phosphates as phosphorous anions exist in soil only in small amounts - insoluble; existing as certain forms of rocks - other sources-- guano - weathered out of soils & transported by rivers & streams to oceans - geologic cycling from ocean floor - decomposing phosphatizing bacteria convert dead organic matter to dissolved phosphates - generally a net loss Species Diversity - a function of : 1. Number of species (species richness) 2. Evenness (relative abundance) - tends to increase with area & proximity to equator Niche - functional role in ecosystem (occupation)
- habitat- the place where an organism lives (address)
Population Distributions 1. Clumped
2. Even
Clumped Even Random Minimum Viable Population - - threshold number of individuals that will ensure the persistence of subpopulations
Population Growth - growth rate = (birth rate + immigration) – (death rate + emigration)
- affected by : age, length of life, etc. Population Size - Density-Dependent Factors : - have increasing effect as population size increases 1. Availability of nutrients 2. Competition for resources 3. Predation, paratism, disease Density-Independent Factors - effect population irregardless of size 1. climactic factors (temperature and wind) 2. natural disasters Carrying Capacity (K) - - the number of individuals a particular environment can support
Reproductive Strategies R-strategists: (insects, some small mammals, weeds) - typicall short lived - early and single stage reproduction (semelparous) - rapid development - small body size - large number of offspring (low survival) - minimal parental care - use temporary habitats - inhabit ustable or unpredictable environments - environmental resources are rarely limiting - mortality is density-independent - exploit relatively incompetitve situations - tough and adaptable - means of wide dispersal K-Strategists: (large mammals, deer, elephants; trees) - typically long lived - delayed and repeated reproduction (iteroparous) - slower development - larger body size - few offspring, seeds, eggs (high survival) - parental care in animals; seeds with stored food in plants - competitive species with stable populations - specialists, users of particular environments - environmental resources are limiting - populations are at or near carrying capacity - mortality results from density-related factors - not very adaptable - lack means of wide dispersal Competition - Intraspecific - two or more organisms attempt to use a limited resource - Interspecific - interactions between individuals of different species
Competitive Exclusion Principle - Paramecium, G.F. Gause - no two species can occupy the same niche - resource partitioning - Barnacles, J.H. Connell - Warblers, MacArthur Species Interactions
Predation + - Parasitism + - Competition - - Commensalism + O Mutalism + +
Social Interactions - social dominance based on intraspecific aggressiveness and intolerance - pecking order (alpha, beta, omega) - best food/mates - territoriality Biodiversity - Viruses 1,000 - Bacteria 4,760 - Fungi 47,000 - Algae 27,000 - Protozoa 31,000 - Plants 250,000 - Invertebrates 9990,000 - Insects 750,000 - Chordates 45,000 - total number of known, described species: 1.4-1.6 million - Erwin (1988), 30 million - Stork (1997) , 5-15 million - greatest concentration is found in tropical rain forests
"The diversity of life forms, so numerous that we have yet to identify most of them, is the greatest wonder of this planet." E.O. Wilson (1988) Extinction - natural process - today - highly accelerated - destruction of habitat - introduction of exotic species (predators) - pest control and hunting- Evolutionary Ecology - Adaptations 1. Structural Unpalatability - thorns, spines, small seeds 2. Chemical Deterrents - plants - secondary compounds (poison ivy) - animals - unpalatable, sprays, odors, bites 3. Aposematic Coloration - advertising poisonous nature - bright warning colors/patterns 4. Aposematic Sound - moths imitating birds 5. Crypsis - blend in with surroundings - twigs, bird droppings, etc... - disruptive coloration 6. Deceptive Markings Mimicry - Mullerian - F. Mueller, 1878 - resemblance of two or more species of unpalatable organisms - share burden of predator learning experience - yellow & black coloration of Hymenoptera - Monarch/Viceroy - Batesian - W.H. Bates, 1857 - unprotected species (mimic) resembles those that are distasteful (model) - both exhibit aposematic coloration - unprotected mimics will be protected if they are scarce - beetles, flies and moth mimics of wasps/bees Human Populations
- populations have grown exponentially in the last century Human Growth Rates - 1970, growth rate was 3% annually, population doubles in 23 years - 1996, growing 1.7% annually, population doubles in 40 years - currently 6 billion - resources must double to accommodate growth - currently 6 billion - resources must double to accommodate growth Environmentalism Rachel Carson - Silent Spring, 1962. - an influential study of the damages of insecticides. - brought environmental concerns to the attention of the public.
- as a result: - National Environmental Policy Act (1969) - Endangered Species Act (1975, 82, 94) - Clean Water Act (1977, 81, 87, 94) Environmentalism cont... - current concerns : - acid rain - population growth - greenhouse effect - habitat destruction—species extinction Impact on Environment - Nuclear Power - Chernobyl, 5,000-75,000 cancer deaths - Global Warming (greenhouse effect) - Pollution - acid rain - pesticides / herbicides / fertilizers (problem when abused) - ozone depletion - Loss of Biodiversity
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