26. Number of breeding pairs
Averageclutchsize
(a) Decreasing birth rate with increasing density in a
population of great tits
0 10 20 30 40 50 60 70 80 90
8
9
10
11
12
Figure 19.8a
Figure 19.1 An ecologist styding a population of black-browed albatross in the Falkland Islands, east of the tip of South America
Table 19.1 Life Table for the U.S. Population in 2004
Figure 19.5 Exponential growth of a rabbit population
Figure 19.5a Exponential growth of a rabbit population
Figure 19.6 Logistic growth of a seal population
Figure 19.7 Comparison of exponential and logistic growth
Figure 19.8a Density-dependent regulation of population growth
Figure 19.9 Space as a limiting resource in a population of gannets
Figure 19.10 Weather change as a density-independent factor limiting growth of an aphid population
Figure 19.11b Population cycles of the snowshoe hare and the lynx
Figure 19.11a Population cycles of the snowshoe hare and the lynx
Figure 19.13 Collapse of northern cod fishery off Newfoundland
Figure 19.19 Five centuries of human population growth, projected to 2050
Table 19.3 Population Trends in 2008
Figure 19.22a Families in India (left) and the United States (right) display their possessions.
Figure 19.22b Families in India (left) and the United States (right) display their possessions.
Figure 19.24 A pronghorn antelope racing across the North American plains
Student Misconceptions and Concerns
1. Students may not appreciate the energy and effort that goes into the generation of their food and products they use daily. A simple analysis of packaging materials will reveal some of the daily investment in convenience. Consider some small task for your students to do to best estimate their ecological footprint. See Teaching Tip #5 below for a list of web sites where your students can calculate their ecological footprint.
2. We often grow tired and frustrated by the long list of problems caused by humans. Many feel helpless. You might consider referencing these web sites for basic ideas on what individuals can do to start to make a difference.
1) www.calacademy.org/exhibits/california_hotspot/what_you_can_do.htm
2) www.dep.state.pa.us/earthdaycentral/96/business/FS1977.htm
3) www.nwzaa.org/project-pages/green6.html
Teaching Tips
1. You might surprise your class by noting that more people are alive today than have ever lived before and died. An examination of Figure 19.19 reveals why this is true.
2. The US government’s Census Bureau sponsors a US and World population clock at (www.census.gov/main/www/popclock.html ) for the most recent estimates of US and world human populations.
3. Medicare and Social Security will be increasingly impacted as the US population ages. By contrast, you might want to discuss the occupational outlook for professions that will address the growing needs of the elderly and the opportunity to invest in companies that will capitalize on these changes.
4. The United States has an ecological footprint greater than the land of the United States. Consider asking your class to explain how this is possible, and what this means to other countries. If you spend some time doing various conversions, you will find that the average ecological footprint of a person in the United States is about equal to the area of 18 football fields with end zones. This was calculated using the following figures.
a) 1 football field with end zones is 57600 square feet (360 x 160 feet)
b) 1 acre = 43560 sq. feet
c) 2.47 acres = 1 hectare = 107,593 square feet
d) 1.87 football fields in 1 hectare = 107,593 (1 hectare) sq. feet / 57600 sq. feet (football field with end zones)
e) 17.6 football fields = 9.4 hectare x 1.87 football fields = average ecological footprint of each US citizen.
5. Many web resources are available for students to calculate their ecological footprint. A few of them are noted below.
www.earthday.net/footprint/
www.footprintnetwork.org/en/index.php/GFN/page/calculators/
www.ecologyfund.com/ecology/res_bestfoot.html
www.ecologicalfootprint.org/Global%20Footprint%20Calculator/GFPCalc.html
www.myfootprint.org/en/visitor_information/
