Population Ecology

4-1: Population Dynamics Populations are described as follows: Density Spatial distribution Growth rate Would an individual be considered a population?

Population Characteristics Population density – number of organisms per unit of area Spatial distribution Dispersion (availability of resources is the most important factor) Uniform Clumped groups Random Which of these dispersion types would be the easiest to predict?

Population ranges Only certain areas an organism can be located (i.e. Iiwi vs. Peregrine Falcon) A species might not be able to expand its population range because it cannot survive the abiotic conditions found in the expanded region. Is it possible for a population to grow unchecked in size?

Population – Limiting Factors Density-independent factors Population size does NOT matter Usually abiotic Ex. Weather Density-dependent Population size does matter Usually biotic Disease, parasites & competition

Disease – outbreaks can be transmitted faster between individuals Competition – when food and space become limited – fights will break out Parasites – similar to disease

Population Growth Rate Natality vs. Mortality (most important) Emigration vs. Immigration Exponential growth model (geometric growth) No limits Lag phase (slow at beginning) J shaped curve

Logistic Growth Model S shaped curve Includes carrying capacity (population that can be supported by resources

Reproductive Patterns R-strategists Small Short life spans Many offspring Little to no energy spent on offspring An adaptation to unstable environments

Reproductive Patterns K-strategists Large Long life spans Not many offspring Lots of energy spent on offspring An adaptation to stable environments --Carrying capacity demonstration

4-1 HOMEWORK Pretend you are living in the 16 and 17 hundreds. Create an advertisement (possible group of two) urging American settlers to move westward using knowledge gained from the section. Be creative!! Using the 3 dispersion patterns – find organisms that are defined by each and explain why. Create a comic strip from the perspective of any r- strategist Give me a real world example of a density-independent factor and a density-dependent factor. Research this – none from discussion or book allowed.

Section 2: Human Population

Human Population Growth Demography – size, density, distribution, movement, birth & death rates World population expected to double in about 53 years

Technological advances We have learned to alter our environment to change carrying capacity Human population growth rate Although raising in overall population, the percent of increase is dropping Diseases such as AIDS Voluntary population control

Trends in Human Population Growth Demographic transition (U.S. good example) Zero population growth Births + immigration = deaths + emigration Age structure Pre-reproductive (0-20) Reproductive (20-45) Post-reproductive (45 – 80+) Human Carrying Capacity

Trends in Human Population Growth Demographic transition (U.S. good example)

4-2 Homework Comprehension sentences for the chapter – due on day of test Personal feeling about human population growth worldwide using at least 5 terms from the chapter