Download presentation
Presentation is loading. Please wait.
1
Population Ecology Chapter 19
2
Understanding Populations (Ch. 19.1)
What is a population? Group of organisms that belong to the same species and live in a particular place at the same time. What classifies a group to be considered a population? Population Size -- # of individuals Population Density – how crowded is it Dispersion (clumped, even or uniform, random)
3
Also known as even dispersion.
4
Population Dynamics Populations are dynamic…meaning they change in size and composition over time. Birth Rate Death Rate (Mortality) Life Expectancy Age Structure – distribution of individuals among different ages in a population. Survivorship Curves – mortality rate data of different species tend to conform to 1 of 3 curves.
5
AGE STRUCTURE GRAPHS
6
SURVIVORSHIP CURVES Type I = Likelihood of dying is small until late in life Type II = Some species the probability of dying doesn’t change throughout life Type III = Many organisms are very likely to die when young
7
Measuring Populations (Ch. 19.2)
Demographers study population dynamics. The size of a population depends on four factors: birth, death, emigration, and immigration. 1. Emigration- movement of individuals out of a population. Immigration- movement of individuals into a population. Growth rate = birth rate – death rate Total Growth rate = (B – D) + (I – E)
8
Population Growth Type 1
Exponential Growth…”J” shaped curve. The larger the population gets, the faster it grows.
9
Population Growth Type 2
Logistic Growth…”S” shaped curve. Builds on the exponential model but takes into account limiting factors. Carrying Capacity- number of individuals the environment can support over a long period of time.
10
Population Regulation
Density Dependent --- A factor that has an increasing affect as a population increases. Examples --- disease, competition, parasites, and food. Density Independent --- affects all populations no matter what their size or density is. Examples – temperature, floods, storms, drought, and habitat destruction.
11
Human Population Growth (Ch. 19.3)
Hunter-gathers (500,000 years ago). Growth of population was very slow due to small populations and a high mortality rate. Agricultural Revolution (10,000 – 12,000 years ago). Population began to grow fast because of increased food supply. Bubonic Plague ( )…wiped out 25% of Europe’s population. 1650…Mortality rates decrease…reason = better sanitation and hygiene, control of disease, better sources of food, improved economics. World War II…kaboom!
12
World Population Distribution Today
Asia – 60.5% Africa – 13.4% Europe – 11.9% Latin America – 8.5% North America – 5.2% Oceania - .5% US Statistics: Growth Rate = .9% Fertility Rate = 1.9 Literacy Rate = 99% GNI Per Capita = $47,000
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.