Chapter 31: An Interactive Living World: Populations and Communities in Ecology
31.1 The Study of Ecology
Ecological Society of America Home Page
The ESA is one of the premier international scientific organizations devoted to the study of ecology. Their Website includes a wide range of resources that will help you understand what ecology is about. What Does Ecology Have to Do with Me? (http://www.esa.org/education/LME/ecologyANDme.php) describes some of the important applications of the science of ecology to current issues; What Do Ecologists Do? (http://www.esa.org/education/career_funding/careers_undergraduate.php) allows you to read profiles of working ecologists.
Keywords: ecology, ecologist
31.2 Populations: Size and Dynamics
This chapter from an On-Line Biology Book provides a good overview of population ecology in a bit more depth than your text.
Keywords: demography, population ecology, population growth
Learn about Logistic Growth by using this java applet that allows you to view changes in the growth curve as you change the values of birth rate and carrying capacity.
Keywords: logistic growth
Spread of Cane Toads in Australia
Just for fun, read about this example of exponential population growthand its consequencesfollowing the introduction of an exotic species into a novel environment with limited environmental resistance. Can you think of other examples of this problem? See Invasive Species: The Nation's Invasive Species Information System (http://www.invasivespeciesinfo.gov/) for more information.
Keywords: cane toads, invasive species
31.3 r-Selected and K-Selected Species
rK Selection: The DevelopmentReproduction Trade-off
An exceptionally lucid explanation of r- and K-selection in the context of selection in different kinds of environments.
r- and K-Selection
This concise lecture also relates the characteristics of r- and K-selected organisms to patterns of population growth and survivorship.
Keywords: K-selection, r-selection
Use data from birth and death dates on cemetery tombstones to construct life tables and survivorship curves for human populations. Data sets are offered at this site and at CEMETERY DEMOGRAPHY (http://academics.hamilton.edu/biology/ewilliam/cemetery/default.html). The Cemetery Demography project is sponsored by the Ecological Society of America.
Keywords: cemetery demography, survivorship curve
31.4 Thinking about Human Populations
Human Populations: Fundamentals of Growth and Environmental Relationships
This web site charts the rise in human population and discusses the impact this has had on the environment.
Keywords: carrying capacity, human population growth
Population and Human Development Data Tables
This page allows you to download data tables containing information on many aspects of human population growth and quality-of-life issues, compiled by the World Resources Institute (http://www.wri.org). A good starting point for discussions about human population growth as a global issue.
Keywords: human population growth
Issues in Ecology
The Ecological Society of America (http://www.esa.org/) produces a publication series that addresses important ecological issues in easy-to-read language.
Welcome to the UN. It's Your World.
The United Nations Website has a wealth of information related to human population, development, and resource use on a global scale. The site is very complex and cumbersome to navigate; some good places to start browsing are the United Nations: Economic and Social Development Web Site (http://www.un.org/esa/), the POPIN Home Page (http://www.un.org/popin/), and the United Nations Population FundUNFPA (http://www.unfpa.org/).
Keywords: human population, United Nations
31.5 Communities: Looking at the Interactions of Many Populations
Begin by reading the article and "case studies" on keystone species at In the Wild: SPOTLIGHT (http://www.bagheera.com/inthewild/spot_spkey.htm). Follow with the slightly more extensive discussions of Elephants as a Keystone Species (http://www.fieldtripearth.org/div_index.xml?id=3). Then read the summaries of current research on Prairie Dogs as Keystone Species in Prairie Ecosystems (http://www.fs.fed.us/rm/sd/prdkeystone.pdf) to understand that, like everything else in science, the designation of an organism as a keystone species must be the result of careful research, not casual observation!
Keywords: keystone species
Nature Insight Biodiversity
This special edition of Nature Insight offers a series of review articles on the topic of biodiversity by prominent scientists.
The Chronicle: October 13, 2000: Have Ecologists Oversold Biodiversity?
The Chronicle of Higher Education hosts this forum that features a controversial critique of a public statement by the Ecological Society of America on the role of biodiversity for ecosystem function, with a series of follow-up commentaries by scientists.
31.6 Types of Interaction among Community Members
Principles of Ecology: Notes and Links
Two Adobe Acrobat files contain a detailed set of lecture notes covering the major types of community interaction (competition, exploitation, mutualism, and commensalism).
Keywords: community ecology, mutualism, predation, parasitism
The LYNX and the HARE, Part 1
This article explains the relationships between lynx, snowshoe hare (their prey), and the plants on which the snowshoe hare feeds. A great example of the complex relationships (and the patterns they produce) characteristic of ecological communities.
Keywords: lynx, predation, snowshoe hare
The Sea Slug Forum: MimicryPhyllidiella, Flatworms, Chromodoris
This is a great place to see (and read about, but thats not as much fun!) mimicry and camouflage in action in an unfamiliar group of animals.
Keywords: camouflage, mimicry
31.7 Succession in Communities
Mount St. Helens
The eruption of Mount St. Helens in 1980 produced a living laboratory of ecological succession that has generated a wealth of new information and ideas. Plants and Animals of Mount St. Helens (http://volcano.und.nodak.edu/vwdocs/msh/p_a/p_a.html) is a good general tutorial about the communities present before and after the eruption. Mount St. Helens National Volcanic Monument (http://www.fs.fed.us/gpnf/mshnvm/) is the official Forest Service Website. Check the photo gallery for before and after photos illustrating the effect of the eruption and patterns of recovery. Finally, Life Returns to Volcanos Blast Zone (http://www.msnbc.msn.com/id/7830509/) is a 20-year "retrospective" interactive article hosted by MSNBC, which reviews what weve learned and how its changed our ideas about ecological succession.
Keywords: ecological succession, Mount St. Helens
Geology of Indiana Dunes National Lakeshore
The dunes of Lake Michigan were an important model system for early ideas about ecological succession. Read why here.
Keywords: dune succession
Glacier Bay National Park and PreserveAlaska
This site explains why Glacier Bay has been an important model system for the study of primary succession.
Keywords: ecological succession, Glacier Bay
Habitats @ nationalgeographic.com
This National Geographic site uses photos and QuickTime video to illustrate the changes that occur from old field to forest. Take them up on their invitation to "join us" in the woods by clicking that link and begin your exploration of a wealth of data and images.
Keywords: ecological succession, old field succession