Ecology - Bio 320, W 2013

Exam 3 Study Guide

Population Ecology

1. Single-Species Systems

   • Def. of population, pop. ecology

   • significance of pop. density and dispersion

   • measuring density - plants vs. animals

     • mark-recapture method for sampling animal populations

   • Population Age structure (population pyramids)

     • difference between a growing, vs. declining, vs. steady population

   • Survival & Mortality

     • Pops. have a mortality rate

     • What is a life table? (briefly)

     • 3 basic types of survivorship curves

   • Relevance of Sillett et al. article (warblers) to general population ecology questions

     • review questions for Sillett article on Homework page

     • importance to issues of global climate change

   • Patterns of pop. growth

     • Exponential growth

     • all pops have potential for explosive growth; why?

     • be able to define terms used in growth equations

       • N, t, B, D, b, d, r, K

       • be able to write the general form of the exponential growth equation & graph the curve

       • assumptions for exponential growth

     • Density-dependent (Logistic) growth

       • equation describing logistic curve, and shape of curve

       • what conditions create the logistic curve?

       • is K fixed for a given species or habitat?

       • what types of factors create K?

         • intrinsic vs. extrinsic

     • Density-independent growth (irregular)

       • what types of species most likely to exhibit density-independent (vs. dependent) growth?

       • be able to draw/graph an example of this type of "growth"

       • what environmental factors most likely to play a role? (biotic? abiotic?)

       • relate pop. growth patterns to survivorship curves

   • Life History Strategies

     • 2 contrasting approaches to reproduction (what are they? describe)

     • r- vs. K-selected species

     • which survivorship curves & pop. growth models most commonly associated with these different strategies?

     • trade-offs inherent to each approach; (cost-benefit analysis)

      

2. 2-Species Systems

   • Types of interactions (table)

   • define symbiosis, & relate to parasitism; distinguish from mutualism

     • but... how might parasitism be related to some forms of mutualism (symbiotic mutualism)?

   • Competition

     • Competetive exclusion principle

     • Resource partitioning

     • barnacle example (Joseph Connell) (Chthamalus & Balanus species)

       • be able to describe the general setting for this study, the problem/question addressed, and be able to interpret figures from this paper

       • which of the above principles is demonstrated?

     • warbler example (Robert MacArthur)

       • be able to describe the general setting for this study, the problem/question addressed, and be able to interpret figures from this paper

       • which of the above principles is demonstrated?

     • if you were given an example of a different study, could you identify which of the 2 above principles it illustrates?

     • how could you tell one from the other in the field?  what kinds of experiments would you have to do?

   • Mutualism

     • examples from the Evolutionary Arms Race video (ants & fungi)

     • why do some (like E.O. Wilson) say mutualism might be just as strong an evolutionary force as competition or predation?

   • Predation

     • food webs & trophic levels

     • how do predators impact populations of their prey species?

     • use the 4 Yellowstone papers  to address different kinds of impacts:

       • give examples from each of the studies, as appropriate...

       • direct vs. indirect effects (of predator on prey, herbivores on vegetation, vegetation on other spp)

       • keystone species

       • trophic cascades

         • top-down effects

         • bottom-up effects

         • 2 examples (lakes, fish & phytoplankton; wolf, elk (or moose) & willow or cottonwood);

           • which type of effect is illustrated in each example?

         • be able to interpret figures related to these, or other, examples

     • Also from the Yellowstone examples, define & give examples of "Alternate Stable States" in ecological communities

Examples / concepts from Tim Seastedt's guest lecture

Community Ecology

1. definition
2. Community structure
   1. Biological structure - dominance, diversity, interactions/food webs
   2. Physical structure - stratification & zonation
3. Dynamics: Spatial Change
   1. Nature of boundaries between communities: discrete (abrupt) vs. continuous (gradual change)
   2. what do these look like if plotted on a graph (figure showing species abundance along an environmental gradient)
   3. describe Clements & Gleason perspectives: superorganism vs. individualistic
   4. environmental vs. biotic determinism; perspectives & scaling issues
   5. Rivet vs. Redundancy Models of community structure, role of dominant species
      • Foundation species - Ellison et al. article (general overview of concepts, species examples, implications of species loss)
      • descriptive models of communities - impacts of species removal
      • sagebrush/cheatgrass example
   6. Fold Model:
      • where is composition unpredictable?  what does the "fold" part of the diagram imply?
      • apply to an example ecological system (e.g. baobab story; sagebrush; other - if I give you a new example)
      • how does this idea relate to the "ball & cup" model (discussed by George SanMiguel) of ecosystem/community resilience in the face of disturbance?
4. Temporal Dynamics:
   1. disturbance: how defined, significance for ecological communities
      • disturbance regimes - frequency & intensity/severity
      • disturbance regimes of SW forest communities
      • "external" disturbance - not part of a regular disturbance regime
      • Yellowstone fires, 1988 - example
        • were the fires part of a disturbance regime, or were they truly an unprecedented natural disaster?
      • what is meant by a “threshold” in community ecology?
      • give an example of an ecological system in the southwest that has been pushed across a threshold by disturbance, and into a new “state”
      • give an example of such a threshold caused by global climate change
      • what sorts of processes can force natural systems across such a threshold? (which type of disturbance?)
   2. define “succession”: 
      • 1^o - when does it occur?  (Hawaii example)
      • 2^o - Clements again & idea of superorganism/community with developmental stages;
        • Early successional species ("pioneers") - biological characteristics? physical needs? examples? relate to invasive exotic spp?
        • Late successional species ("climax spp") - characteristics & needs?  examples?
        • example from Lime Creek burn area
   3. Disturbance & invasion of exotic species - what is the relationship?  what are the likely outcomes? (Tim Seastedt discussed this to some extent)

Landscape Ecology & Human Impacts

• definition
• significance of spatial pattern
• main causes of landscape pattern (3)
• importance of scale: grain & extent
• Spatial arrangement & movement across landscapes
• Habitat "patch" size:
  • patch size & # of species
  • habitat fragmentation
  • edge vs. interior habitat
• Habitat connectivity:
  • examples of three processes that propagated across a landscape in the SW - nature of process, nature of propagation; how do landforms influence propagation?
  • movement & dispersal (% connectance needed to allow movement across a landscape)
  • Missionary Ridge burn example
  • forest history, fire history - how reconstructed (e.g. Dendrochronology & Mtn. Park lab)
• Disturbance - different ways it can impact ecological systems
•  Examples of human impacts on different ecological systems:
  • which systems are resilient in the face of change?
  • which systems are resistant to change?
• Conservation Biology
  • goals of Cons. Bio.; levels of conservation
  • Island Biogeography theory, & predictions/applications to conservation
  • importance of re-creating connections; "corridors" for animal movement between habitat patches

   

• Be able to give examples of ecological impacts of climate change, from each of the major sub-disciplines we've studied - be able to describe at least 2 examples (from 2 different perspectives)

General

• connections between various subfields of ecology
• given a list of questions, which subdiscipline of ecology could best address each question?  (see above, also)
• be able to give a clear definition of each of the subfields we have surveyed this semester
• Lab-related questions:
  • describe forest stand structure at Mesa Verde, and contrast current structure with what it might have looked like 500+ years ago; other points about fire history & behavior from George SanMiguel's tour
  • other ideas regarding forest history & fire impacts from Mesa Verde, Vallecito & our dendrochronology lab
• be able to interpret graphs; or write a good figure caption for a graph; or construct a graph from a hypothetical set of data; or something along those lines!