BIOL 3060 - PRINCIPLES OF ECOLOGY

STUDY QUESTIONS

Fall 2006

 

I. Ecology as a science

1.       Define ecology; how and why has the definition changed since the late 1860s?

2.     What biological subdisciplines comprise the field of ecology? How does physiological ecology differ from ecosystem ecology?

3.     What is the scientific method? Why is ecology considered a “science”? Is it always so? Under what conditions are ecologists not “scientists”?

4.     Give examples of general ecological questions that could be asked using a(n) a) descriptive, b) functional, and c) evolutionary approach.

5.     Define the following: Holism/reductionism, Empirical/theoretical, Patterns/processes, Inductive/deductive logic, Null/alternative hypothesis, Prediction/observation, Applied research/basic research, Natural experiment/controlled experiment, Conceptual model/mathematical model.

6.     What are the “levels of organization” in ecological systems? What is the difference between a population and a community? An ecosystem and a community? A species and a population?

 

 

II. Climate

1.       What are the 3 main elements of climate? How does climate and geography interact to produce abundance and distribution patterns of organisms in the Biosphere?

2.     Describe the phenomena of latitudinal heating and light patterns. Why is there more light and higher temperature at the Equator and progressively less light and lower temperature as one moves toward the poles?

3.     What is the “Greenhouse Effect” and how does the atmosphere influence heating of the Earth’s surface? How and which human activities accelerate the rate of increase of “Greenhouse Gasses” in the atmosphere?

4.     Describe the basic relationship between temperature and precipitation patterns across the Earth. Why is atmospheric humidity so much more uncomfortable in summer than in winter?

5.     What is wind? What is a “Westerly”? A “Trade wind”? What is the “Jet Stream”? How do Westerlies and Trade winds influence global water circulation and precipitation patterns?

6.     Describe the basic relationships between precipitation patterns and topography? What is a rain shadow and why is vegetation different on the windward (vs. lee) side of a mountain/mountain range? Why are longitudinal differences in continental precipitation patterns so much greater in Western (vs. Eastern) North America? Why are areas further from the oceans generally drier than areas close to the oceans?

7.     What is “aspect” and why is it important climatologically and ecologically?

8.     Discuss some ways that differences in “microclimate” arise. What environmental factors influence temperature, light and/or humidity on a “micro” scale?

9.     List and discuss the main types of temporal variation in climatic conditions.

10.  What is the difference between predictable vs. unpredictable climatic variation? What is the evolutionary significance of these 2 sources of environmental variation?

11.  Define and/or explain the ecological significance of the following: Southern Oscillation, El Niño/La Niña, Monsoon, Tsunami, Hurricane, Tornado, Drought.

 

III. Aquatic and Terrestrial Environments

1.       Compare and contrast aquatic vs. terrestrial habitats in terms of physical properties and ecological significance. How can low thermal variation (i.e. high stability) in aquatic (vs. terrestrial) ecosystems be considered both a “pro” and a “con” to an organism?

2.     Define the following terms: specific heat/viscosity, PAR, GPP/NPP, Production/Respiration, Biomass/Energy, input/output, entropy, biomass.

3.     How is that biological systems maintain a high degree of organization (order) while the universe tends toward low organization (disorder)? How can these 2 conflicting statements be reconciled?

4.     What is the solar constant and why is it important in understanding the functioning of the biosphere? How (in)efficient is the transformation of light energy to biomass?

5.     What is photosynthesis and why is this process important to autotrophs? Heterotrophs? Which organisms undergo cellular respiration, and why is this process important in efficiency of energy transfer from autotrophs to heterotrophs?

6.     Describe the hydrologic (water) cycle, including definitions of the terms precipitation, evapotranspiration, evaporation, sublimation, infiltration, interception, throughflow. What factors influence the amount of overland flow in a terrestrial system? How can urban development by humans increase overland flow in natural ecosystems?

7.     List the primary sources of nutrients for biotic life. Define the following terms: essential nutrient/nonessential nutrient, macronutrient/micronutrient, detritus, organic matter/inorganic matter, parent material/soil, weathering.

 

IV. Physiological Ecology

1.       1. What is a “limiting factor”? List as many limiting factors as you can, and describe how one might determine how an environmental factor can be shown to be limiting.

2.     What is a “condition”? What is a “resource”? Explain how a condition in one environment could be considered a resource in another.

3.     Define Liebig’s “Law of the Minimum”. How might this principle apply to understanding the relative importance of essential macronutrients in an agricultural field?

4.     List and describe the 3 types of responses of individual organisms to limiting factors. Which of the responses describe nonlinear relationships between response and limiting factors? Give a practical example of each type of response.

5.     Define the following terms: threshold, inflection point, asymptote, zone of tolerance, poikilotherm/homeotherm, ectotherm/endotherm.

6.     Describe a typical relationship between metabolism, body temperature, and environmental temperature for an ectotherm. How does this relationship differ for an endotherm?

7.     What is a thermoneutral zone? Upper versus lower temperature threshold?

8.       Summarize the physiological and ecological advantages and disadvantages of endothermy and ectothermy.

9.     Define Bergmann’s and Allen’s rule. For which general group of organisms do they apply, and why? Why might small-bodied organisms (and species) be more restricted to lower (vs. higher) latitudes?

10.      What is acclimation (or acclimatization) and how might it be adaptive for an organism? Why might organisms (and species) with greater acclimation abilities be found more often in higher (vs. lower) latitudes?

11.     What is a biome? List and discuss the major biomes on the Earth and highlight the climatic and vegetational characteristics that differentiate them. Why are some biomes more distinctive than others?

12.      Discuss the pattern of changes in the distribution of organisms (animals and plants) as one hikes from a lower to higher altitude in a topographically variable region (e.g., from a desert floor to a mountain summit). Why do such changes occur?

14.      What is the interaction between temperature and relative humidity in terrestrial environments? How can high relative humidity in tropical environments promote organism survival relative to conditions in temperate environments?

 

V. Evolutionary Ecology

1.   Why should evolution be included in the science of ecology? How do the 2 subdisciplines relate to each other?

2.     Define and differentiate between the following terms: trait/adaptation, fitness/condition, phenotype/genotype, evolution/natural selection, differential mortality/differential reproduction, species/population, abiotic agent of selection/biotic agent of selection, gene/allele, meiosis/mitosis.

3.     What are the 4 main tenets of evolution?

4.     Provide an example of an organism in a natural population showing an adaptation for a particular environment, and discuss how that adaptation may shower higher or lower fitness in a new environment. How and why is fitness organism- and environment-specific? Why is it that only populations, and not  individuals, evolve?

5.     Differentiate between the 3 main types of selection and provide a hypothetical or real example of how each type might work.

6.     What is a niche? What factors operate to define the difference between a fundamental vs. realized niche?

7.     Why is a niche considered by some ecologists to be a “n-dimensional hypervolume”? How is this characterization useful in terms of understanding how and which environmental factors influence the abundance and distribution of species?

 

VI. Population Ecology

1.       What is a “population,” and what is the difference between “population size” and “population density” as measures of the abundance of organisms? Which of the previous terms are considered estimates?

2.     What 4 life history parameters affect population growth? Which parameters contribute to negative population growth and which to positive growth?

3.     Define the following symbols: r, Ro, N, No, dN/dt, K, bo, do.

4.     Differentiate between exponential vs. logistic growth in terms of graphical relationships and formulas showing key functions. Which of these 2 population growth models is considered more realistic for natural populations, and why? Is it possible for a population to show both exponential and logistical growth? If so, how?

5.     What is carrying capacity and how does this parameter influence population growth? How might one empirically determine what level of N is close to or at the carrying capacity of the environment?

 

VII. Life History

1.       What is “demography” and what factors influence the life history or demographics of a population?

2.     Define the key parameters that are measured when constructing a life table. How are life tables useful in describing populations?

3.     Differentiate between the following symbols: bx vs. dx; dx vs. qx; ax vs. bx; lxbx vs. Σ(lxbx). What is a “cohort”?

4.     Why is it important to display “age-specific” life history parameters in life tables for most populations?

5.     Why are demographic data for males frequently omitted from life tables?

6.     What are the limitations of life tables in terms of accurately describing population size changes over time? What factors (or parameters) that often are missing from life tables are important in describing population growth? 

7.     (From Lab) What is a “survivorship curve”? Define the 3 types of survivorship curves and give an example of a type (species) of organism displaying each type of curve. From the life table examples discussed for the 2 species in lecture, which type of curve is displayed by which species?    

8. What is “age structure” and how can this attribute be used to understand population demographics? Give an example of and explain how age structure data can be used to assess which survivorship curve (I, II, III) applies to a given population. Can size structure (i.e., size class) data be used for the same purpose? Why or why not?  

 

VIII. Biotic Interactions: Competition and Other Interactions

1.       Compare and contrast the 7 types of interspecific interactions discussed in lecture and give a practical example of each. Which of these interactions are considered “symbioses”, and why?

2.     Define competition and list and discuss its fundamental features. Would interspecific or interspecifc competition be expected to have the greatest impact on a particular individual in a population? Why?

3.      Define the following terms: density-dependence, exploitation/interference, resource, competitive dominant/subordinant, undercompensated density dependence/overcompensated density dependence, fundamental niche/realized niche, character displacement (see text).

4.     What is a resource use curve and how is it useful in determining the likelihood of interspecific competition?

5.     What is the “competitive exclusion principle”? Give an example of how has this principle been demonstrated in simple lab experiments and under more complex

6.     What are the Lotka-Volterra competition models, and what factors influence the densities of 2 competing populations within these models?

7.     Discuss at least one case study showing that the outcome of interspecific competition depends on environmental conditions (i.e., is “context dependent”).

8.     What types of patterns (observations) suggest the potential for interspecific competition? Why are correlations (graphing abundance of 1 species in terms of another) considered weak evidence for competition? Why are experiments (field or lab) more useful than correlations in documenting interspecific competition?

9.     Is a pattern of low (or no) resource overlap for 2 species occurring in the same habitat evidence for competition in the past? If so, how might this process work??
 

IX. Biotic Interactions: Predation

1.       What is “predation” and how does it differ from competition, parasitism, and the various types of symbiosis? Compare and contrast the different types of predators in terms of their typical prey. What is a “parasitoid” and how does it differ from a predator?

2.     What are the Lotka-Volterra predation models, and what factors influence the densities of a predator and prey species within these models? What are the equations, primary assumptions, and graphical representations of the L-V models? What attributes of prey affect population growth rates of predators and visa versa?

3.     What are the 3 types of predator functional responses? How are these responses similar to each other and how do they differ? How can a disproportionately high functional response be explained? How can a disproportionately low functional response be explained? What is “predator satiation”? Inverse density dependence? Which of the 3 functional responses can be thought to produce non-stable fluctuations in predators and prey and which response(s) as producing stable fluctuations (i.e., oscillations)?

4.     What is a numerical response? How does it differ from a functional and a total response? What is “predator saturation”? Why are functional and numerical responses often asymptotic?     

5.     What is “polyphagy” (or a “polyphagous” species), and why is this the typical situation for most species of predators?

6.     How might an ecologist go about determining whether predators have a strong impact on their prey?

7.     Describe several examples of studies of predator-prey interactions? Under what environmental conditions can predators and their prey coexist?

8.     How did Huffaker (1958) successfully produce stable predator-prey cycles for his mites? What factors did he manipulate?

9.     What elements of the MacLulich (1937) lynx-hare study suggested strongly coupled predator and prey cycles? What were the problems with this study? How could the study have been improved?

 

X. Community Ecology

1.       What is a “community” and how does it differ from a “population”? An “assemblage”? An “association”? A “guild”? Compare and contrast “community structure” and “community organization”. What types of questions might be asked using these 2 approaches?

2.     What is the difference between absolute and relative abundance?

3.     Why must community studies involve the delineation of a boundary, and how are they “scale-dependent”?

4.     Compare and contrast the organismic (Clementsian) and individualistic (Gleasonian) views of community organization? How can gradient analysis be used to test these opposing schools of thought? What is the limitation of gradient analysis in this context?

5.     (From lab): What is “diversity” and what variables are important determinants of a diversity index? What is “evenness”? Define each of the following: ln S, H’, J, (piln pi).  What is a “morpho-species”? Using a frequency distribution graph, illustrate and compare a diverse/even community with an undiverse/uneven community. What is the advantage of using a diversity index to characterize a community?

6.       What types of community patterns in richness or diversity occur across altitudinal, depth, and latitudinal gradients? Cite some empirical examples of these relationships from the notes or the text book. For each pattern propose an alternative hypothesis (and its null counterpart) that might explain the pattern. For example, why might one expect to find fewer species at/near a mountain summit than near its base?

7.      Define and discuss the 4 major hypotheses accounting for latitudinal diversity patterns across the Biosphere. Discuss the strengths and weaknesses of each hypothesis in terms of explaining diversity patterns.

8.     Define or differentiate between the following pairs of terms: primary/secondary succession, climax/pioneer species, competitive exclusion/niche diversification, negative/positive association.

9.     Differentiate among the 3 types of succession. Which type is considered short term? Which type(s) involve(s) primarily sessile organisms and which type(s) also include mobile species? Which type relates only to the influence of abiotic factors on communities?

10.     Differentiate between an “early” versus a “late” successional species in terms of life history characteristics. Which type of species is typically the better competitor? The better disperser? The species with the highest self-maintenance ability? Using a practical example, cite a possible mechanism that would allow one type of species to be a better competitor than the other.  

11.      Compare and contrast between the facilitation, tolerance, and inhibition models of succession. Which of these has been considered historically to be the primary model explaining succession? What is the “resource-ratio” succession model, and how does it differ from the above models?

12.     Differentiate between “equilibrial” vs. “nonequiblibrial” communities and the forces or factors that produce patterns in such communities. Would a community structured by predation be considered an equilibrial or a nonequiblibrial community? Why or why not?

13.     What is a keystone species? How could a single species produce a positive (or negative) effect on species richness or diversity in a community?

 

XI. Ecosystem Ecology

1.       What is an ecosystem? What “ecosystem-level” factors regulate populations and communities in an ecosystem?

2.     Define and differentiate between the following terms: biomass/productivity, primary/secondary productivity, grams/m2 vs. grams/m2/year, grams/m2 vs. kcal/m2, necromass/biomass, NPP/GPP, producer/consumer/decomposer, food chain/web.

3.     Why are large carnivores so rare in natural ecosystems?

4.     What is an “energy pyramid” and how does it help answer question 3 above?

5.     What is “ecological efficiency” and how is it measured? What 3 sources of efficiency comprise ecological efficiency and what does each measure? Give some examples for how these different types of efficiency vary among organisms (e.g., animals vs. plants, vertebrates vs. invertebrates, endotherms vs. ectotherms).