Ecology Outline PDF

Preview

Summary

David Russell, Xio-Wen Cheng...

Description

Ecology I. Definition: the study of interactions between organisms and their environments II. Population Ecology A. Populations in relation to the environment B. (Population Number)= (Birth+immigration)-(Death+emigration) 1. Simplified to N=B-D C. Population Growth Rate 1. Over time: Change in Number ∆N÷Change in time ∆t a) (Growth rate)x(N)=∆N/∆t 2. Instantaneous: dN÷dt a) (Growth rate)x(N)=dN/dt 3. Per capita Population Growth Rate a) Growth rate [either I.C.1.a OR I.C.2.a] ÷ population size b) Growth rate is constant D. Exponential Growth Model 1. Thomas Malthus 2. Unrealistic most of the time, HOWEVER, does exist when sudden changes occur a) Ex: Tule Elk being recently protected from hunting will grow exponentially for a small period of time

E. Density Factors 1. Dependent Factors a) Death is an independent rate while birth is a rate dependent on factors (1) Pop. too big, density factor will decrease rate of B (2) Pop. too small, density factor will increase rate of B 2. Independent Factors a) Physical factors and Disturbance (1) Ex: Wildfire kills small plants and ruins lots of habitats, but this frees land space and increases the nutrients in the ground for some trees to thrive F. Logistic Growth Model 1. Incorporates density-dependence into equation 2. dN/dt=rN[(Karrying Capacity-N)/K]

3. Populations follow this model when resources are limiting G. Life History Strategies 1. Definition: traits associated with the life cycle of a species 2. r-selection- plants 3. K-selection a) Type I- humans b) Type II- birds

III.

Community Ecology A. Definition: Populations living close enough for interaction between them B. Competition(-/-) 1. Competition for a resource results in local extinction of one species (complete competitors cannot coexist) 2. Ecologically similar species can coexist of they have different niches a) Competition can cause niches to change (1) Fundamental niche- potentially occupied by a species (2) Realized niche- actually occupied by that species 3. Character Displacement a) Past competition between species can cause directional selection in both species (Ex: beak depth in 2 birds)

C. Exploitation (+/-) 1. Definition: one species benefits by eating the other species

IV.

2. Predatory a) Animal eats another animal 3. Herbivory a) Animal eats a plant b) Plant is typically not killed, but growth and reproduction is lowered c) Chemical or mechanical defenses may arise 4. Parasitism a) Parasite takes nutrients from tree or animal (1) Parasites can directly or indirectly affect host population (2) Direct- bacteria poisons and kills host (3) Indirect- bacteria kills food supply for host b) Endoparasite- lives within body of host c) Ectoparasite- lives on exterior of host d) Parasites that are microbes are called pathogens D. Positive (+/+) OR (+/o) 1. Mutualism a) Both species benefit b) Ex: hummingbird and flower (food and fertilization, respectively) 2. Commensalism a) One species benefits and the other is not harmed or benefited b) Ex: Cattle egrets and livestock (easier to find food from backs) Ecosystem Ecology A. The ecosystems (organisms and abiotic factors) in our body change as we grow B. Energy flows and Matter/Nutrient Cycles C. Physical Laws 1. Conservation of Energy 2. Conservation of Mass D. Trophic Levels 1. Autotrophs create energy from themselves 2. Heterotrophs create energy from others 3. Order: sun primary producers, primary consumers, secondary consumers, tertiary consumers, all becomes detritus and decomposed by detritivores a) Detritus- nonliving matter b) Decomposers connect everything by recycling the organic material back into the ecosystem (1) Prokaryotes and fungi (2) Rate of decomposition is limited by temperature, moisture, and nutrients

E. Production 1. Primary Production (PP): amount of light energy converted into chemical energy by autotrophs in a given time a) Chemoautotrophs are primary producers in some ecosystems b) Energy max is set by amount of photosynthesis (1) Sun is limited when reaching the Earth (2) Only a fraction of the sun hitting the Earth is usable 2. Gross Primary Production (GPP) a) Definition: total PP in an ecosystem b) Is the conversion of chemical energy from photosynthesis per unit of time (light energy converted to chemical energy) 3. Net Primary Production (NPP) a) Definition: GPP-energy used by primary producers for Respiration (1) Energy per unit area per time (J/m2×yr) (2) Biomass per unit area per time (g/m2×yr) b) Only available to consumers c) Standing crop is total biomass of photosynthetic autotrophs d) Each ecosystem varies in NPP contribution F. Efficiency 1. Energy transfer between trophic levels is 5-20% (avg around 10%) 2. Secondary Production: chemical energy in food that is converted to new biomass 3. Production Efficiency: the energy stored in food that is not used for respiration a) PE=Net secondary production x 100% / Assimilation of primary production 4. Trophic Efficiency is multiplied over the length of the food chain 5. Biomass pyramids show energy transfer between trophic levels

G. Biogeochemical Cycles (Energy Flows, Nutrients Cycle) 1. Involves biotic and abiotic factors

2. Water Cycle a) Doesn’t follow the general model b) Solar energy, evaporation, movement, precipitation, runoff/groundwater/evapotranspiration/ back to ocean c) Evapotranspiration (1) H2O molecules use cohesion (stick to other H2O) and adhesion (stick to the walls) travel the inner tubes of roots and veins travelling through the tree and leaves (2) The water is evaporated upward and provides water to the top of the tree (3) Excess is removed and evaporated from the top and put back into the clouds to be cycled (4) Droughts in rainforests occur when the trees are removed and there is not more water to evapotranspire

3. General Model of Chemical Cycling a) 4 reservoirs defined with 2 characteristics; organic or inorganic materials, and are those materials usable or unusable

4. Carbon Cycle (Global Cycle) a) CO2 is taken up through photosynthesis and released through respiration b) Burning of fossil fuels contributes to the amount of CO2 in

atmosphere

5. Nitrogen Cycle (Global Cycle) a) N2 enters system through 2 ways (1) Atmospheric deposition: usable N2 is added to soil by rain or dust (2) Nitrogen Fixation: Prokaryotes convert N2 to ammonia that can be used to process other organic compounds (a) N2 is too strong of a bond and can not be directly used (b) Direct product is ammonia which becomes ammonium in the soil due to ammonification (c) Plants can use ammonium (3) Ammonium becomes nitrate due to nitrification (a) Plants can use nitrate (4) Bacteria use nitrate and release N2 back into the air due to denitrification

6. Phosphorous Cycle (Local Cycle) a) Phosphorous only occurs in phosphate b) Weathering of phosphate from rocks travels down to the ground with rain and precipitation c) Plants use the phosphate, then die and become detritus d) Decomposers break down the detritus and put phosphate back

into the soil where the cycle repeats e) Phosphate also falls to the ground with other sediments and overtime will create new rocks which will start the process over again

7. Humans affect nutrient cycling by removing the nutrients from one area and moving them to another 8. Succession a) Only one can happen at a time, secondary succession is usually due to man clearing an area down to the soil b) Primary Succession: starts with the absence of soil (1) Bare rock (2) Pioneer Species (lichens and moss) (3) Decomposition (4) Grasses grow on new soil (5) Nutrients increase and shrubs form (6) Increases in soil allows trees and other larger plants to grow

c) Secondary Succession: starts with soil (1) Annuals (weeds) (2) Perennials (weeds and grass) (3) Shrubs (4) Young pine forest (5) Mature forest...