Chapter 8 Population Change

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

Studying Populations  How to Study Populations:  Quadrats  Transects  Capture-recapture methods

Bird bands

Change in Population Size

Growth rate Birth rate Death rate Immigration rate Emigration rate r = (b – d) + (i – e) Calculating Population Change

Maximum Population Growth  Intrinsic Rate of Growth  Growth rate under ideal conditions  J- Shaped Curve (exponential growth)

Logistic Growth

Population Crash  Overshooting carrying capacity can lead to population crash

Factors That Affect Population Size  Density Dependent Factor  Factor whose effect on population changes as pop. density changes  Examples:  Food  Shelter

Boom-Or-Bust Population Cycles

Case Study- Predator Prey Dynamics on Isle Royale  As wolf population increases, moose population decreases (and vice versa)

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

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

Survivorship

Some populations fit two curves  Herring Gulls  Type III & Type II

Metapopulations  A set of local populations among which individuals are distributed in distinct habitat patches across a landscape  Source habitats  Sink habitats

Metapopulations

Human Population  Demography  Science of population structure and growth  Human Population since 1980 is J-shaped curve

Population Increase in Mexico

Demographics of Countries

Demographic Stages

Fertility Changes in Select Countries

Age Structure Diagrams

Worldwide  29% of human population is under age 15  Could cause large increase in birth rates