Chapter 10 - Populations, Communities, Ecosystems

Notes for Chapter 10:
Populations, Communities, and Ecosystems

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Case History: Backhoe Biology
Visit Wetland Ecosystem Team website at University of Washington

RQ 10.1: Describe the only wetland in the U.S. with a street
address, 1676 Lincoln Avenue, including an explanation
of the notion of "mitigation" to preserve lost habitat.

I. Populations
terms: population, birthrate, death rate, survivorship curve,
age structure, cohort

a) Population Properties and Survival

RQ 10.2: Describe, in words, how the contrasting survivorship
        curves of the green alga, Ulva, and the red alga, Gigartina
        (recently reclassified as Macrocarpus), translate into each
        species' "strategy" for reproductive success.

    b) Counting Organisms - Important, Difficult
        terms: mark-and-recovery (capture/recapture) technique,
            density, population dynamics

RQ 10.3: Describe how an ecologist might estimate population
numbers of a mobile marine organism, such as a hermit
crab, with a "capture/recapture" experimental design.

c) Counting Organisms - Important, Difficult

II. Communities
        terms: community, abiotic and biotic components
            Note: Species tend to characteristically be found
         with other species, and we typically name this assemblage a
            community for the most common conspicuous species, such
            as the Macoma baltica community (see Fig. 10.6).

RQ 10.4: What is the distinction between a population and
a community?

a) The Role of Species in Communities
terms: habitat

        1) Each species appears to have a niche in its community
            that is not identical to that of any other species.
        terms: ecological niche, competitive exclusion principle
            (or Gause's principle)
            Note: Gause did his original competition experiments
                observing the ciliate species, Paramecium aurelia
                and P. caudatum. For more details, click here.

RQ 10.5: What are the theoretical requirements for two
species to coexist, i.e., what does it mean for two
species to have an "identical niche"?

2) Each species appears to use resources in different ways.
terms: resource partitioning (niche separation)

RQ 10.6 (Fig. 10.8 and 10.9): Using the example in
    the text of butterfly fishes of the Great Barrier Reef,
    characterize the gradients along which resources appear
    to be partitioned, allowing for coexistence of many
    species in close proximity.

         Featured organisms and locality (Fig. 10.8, 10.9):
          Butterfly fishes More Links - 1 - 2 - 3 - 4 - 5 - 6
              Great Barrier Reef More Links - 1 - 2 - 3 - 4 - 5 - 6 - 7

3) Competition shapes and separates species.
terms: character displacement, congeneric species

RQ 10.7 (Fig. 10.10): Following the example in the
    text, explain why two species might show greater
    differences in parts of their geographic range where
    they coexist than in regions only occupied by one of
    the species.

Featured organisms (Fig. 10.10):
Hydrobia: H. ventrosa and H. ulvae

b) The Number of Species in a Community
terms: epifauna, infauna, microenvironments

         Featured organisms (Fig. 10.11):
          Euphausids ("krill")
                    More links: 1 - 2 - 3 - 4 - 5 - 6

RQ 10.8: In general, where do closely related species
live, relative to each other?

III. Ecosystems
terms: ecosystem

a) Ecosystems on Land and in the Oceans
terms: producers, consumers, decomposers

    b) Ecosystem Components
        terms: photosynthesis vs. chemosynthesis of producers,
           autotrophs are "primary" producers, consumers and
            decomposers are heterotrophs, trophic levels,
           food chain, food web, top carnivores,
            trophic pathway

    RQ 10.9 (Figs. 10.14 and 10.15): What is a self-sustaining
        ecosystem? Are marine ecosystems typically self-sustaining?
        If not, which ones are not and why not?

    RQ 10.10: Descripe a food web path that starts with organisms
        deriving energy from sunlight. Use a specific example and
        characterize the organisms by their position in the food web,
        using appropriate terminology.

Click link to return to Lecture Schedule
or Lecture Notes by Chapter
Back to Chapter 9
Forward to Chapters 11 (in part) and 13