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Learn about ecology, biomes, population characteristics, and factors affecting ecosystems in this comprehensive environmental science program.
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PaCES/HIMB Summer Program in Environmental Science David A. Krupp, Ph.D Ecological Principles Part I
Topics to be Studied • Define “ecology” and describe its scope • Define essential terms • Contrast biotic and abiotic factors • Physiological limits and abiotic factors • Biomes • Population characteristics • Population growth
Ecology • Ecology = the study of the interaction of organisms with their environments. • It involves understanding biotic and abiotic factors influencing the distribution and abundance of living things. • The word "ecology" coined from Greek word "oikos", which means "house" or "place to live”.
The Scope of Ecology • Population growth • Competition between species • Symbiotic relationships • Trophic (= feeding) relationships • Origin of biological diversity • Interaction with the physical environment • Ecosystem change • Human impacts on the environment
Some Important Terms • Population • A collection of individuals all belonging to the same species in a defined area and time • Community • A group of interacting populations in a defined area and time
Some Important Terms • Ecosystem • A system composed of the biological community interacting with its surrounding abiotic environment • Biosphere • The entire portion of the Earth in which life occurs; all of the ecosystems of the Earth combined
Biotic Factors • Dispersal • Behavior • Species interactions • Competition for common resources • Predator-prey relationships • Symbiotic associations
Abiotic Factors • Temperature • Water • Light • Salinity • Wind • Currents • Substrate
Physiological Limits environmental gradient
Physiological Limits zone of tolerance
Physiological Limits zones of intolerance
Physiological Limits optimum range
Physiological Limits zones of physiological stress
Biomes • Biomes = major types of ecological assemblages that occupy broad geographic regions of land or water • Aquatic biomes: primarily influenced by depth (light) and temperature • Terrestrial biomes: primarily influenced by temperature and balance between precipitation and evaporation
Aquatic Biomes: Lakes oligotrophic eutrophic
Population Characteristics • Size and density • Dispersion • Survivorship • Population growth • Population age structures
Number of individuals per unit area, per volume or unit of habitat. 5 individuals/m2 15 individuals/m2 Density
Random Dispersion Patterns
Clumped Dispersion Patterns
Uniform Dispersion Patterns
Generation Population Size 1 2 3 4 5 6 7 8 9 10 1 2 4 8 16 32 64 128 256 512 Population Growth
600 500 400 Population Size 300 200 100 0 0 1 2 3 4 5 6 7 8 9 10 11 12 Generation Exponential Population Growth
Immigration Births Deaths Emigration Population Growth Population Size (N)
Population Growth N/t = B - D dN/dt = bN - mN dN/dt = instantaneous rate of population increase b = per capita birth rate m = per capita mortality rate dN/dt =(b - m)N = rN r= b - m
Population Growth dN/dt = rN r = per capita rate of increase Under Optimal Conditions dN/dt = rmaxN rmax = optimal per capita rate of increase
Effects of Different Intrinsic Growth Rates (r) rmax = 0.5 rmax = 1.0
A Paramecium population in the lab Population Growth
A Daphnia population in the lab Population Growth
A sparrow in its natural habitat Population Growth
Density-Dependent Factors • limiting resources (e.g., food & shelter) • territoriality • production of toxic wastes • infectious diseases • predation • stress and other intrinsic factors • emigration
Density-Independent Factors • severe storms and flooding • sudden unpredictable severe cold spells • earthquakes and volcanoes • catastrophic meteorite impacts