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Chapter 8 Population Change
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Principles of Population Ecology Population Ecology Study of populations and why their numbers change over time Population density The # individuals of a species/area or volume at a given time
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Studying Populations How to Study Populations: Quadrats Transects Capture-recapture methods
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Bird bands
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Change in Population Size
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Growth rate Birth rate Death rate Immigration rate Emigration rate r = (b – d) + (i – e) Calculating Population Change
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Maximum Population Growth Intrinsic Rate of Growth Growth rate under ideal conditions J- Shaped Curve (exponential growth)
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Logistic Growth
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Population Crash Overshooting carrying capacity can lead to population crash
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Factors That Affect Population Size Density Dependent Factor Factor whose effect on population changes as pop. density changes Examples: Food Shelter
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Boom-Or-Bust Population Cycles
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Case Study- Predator Prey Dynamics on Isle Royale As wolf population increases, moose population decreases (and vice versa)
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Factors That Affect Population Size Density Independent Factors Factors that affect population size, but are not influenced by changes in population density Examples: Killing frost Severe blizzard Fire
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Reproductive Strategies r-selected species -Small body size - Early maturity - Short life span - Large broods - Little or no parental care - Probability of long term survival is low - Mosquitoes and Dandelions k-selected species - Small broods - Long life span - Slow development - Large body size - Late reproduction - Low reproductive rate - Redwood trees and human beings
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Survivorship
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Some populations fit two curves Herring Gulls Type III & Type II
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Metapopulations A set of local populations among which individuals are distributed in distinct habitat patches across a landscape Source habitats Sink habitats
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Metapopulations
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Human Population Demography Science of population structure and growth Human Population since 1980 is J-shaped curve
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Population Increase in Mexico
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Demographics of Countries
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Demographic Stages
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Fertility Changes in Select Countries
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Age Structure Diagrams
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Worldwide 29% of human population is under age 15 Could cause large increase in birth rates
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