General Ecology (BIO 160) Study Guide
(updated: 5/2/10)




This study guide is intended to help you focus your study efforts by providing you with specific learning objectives and key terms used in the course.  The learning objectives and terms are listed by lecture or lab to make it easier to organize your study efforts.


Student Learning Objectives


The following is a list of learning objectives for lectures and selected labs that you must achieve in order to do well in this course.


The nature of ecology

Explain what the science of ecology is about

Give an example of what ecologists do

Describe the different hierarchical levels of organization in ecology

Explain how nature is variable in both time and space

Explain how ecologists study the natural world

Explain some of the common misconceptions we have about nature and how ecological studies have better informed us about our influence on the environment


Adaptation and evolution I

Explain why adaptation is essential for the continued existence of biological organisms

Explain why species are not "perfectly adapted" to their environment

Explain why an organism's adaptations to the environment represent a compromise between competing demands by the organism to grow, survive and reproduce

Explain the process of natural selection and describe the role of genetic variability, heritability, and selection

Describe one documented example of natural selection

Explain how natural selection is a necessary and logical consequence of Darwin’s four postulates

Illustrate the three types of selection in a graph and explain how each can arise and how they affect phenotypic variation in a population

Compare and contrast genotypic variation and phenotypic variation

Explain how and why phenotypic plasticity occurs

Explain how reciprocal transplant experiments can be used to distinguish between genetic and environmental variation in a population


Adaptation and evolution II

Explain how speciation can occur and why islands tend to have higher rates of speciation

Describe the process of allopatric speciation and explain how it occurs

Explain the role of mutation and recombination in evolution

Describe the selective forces that can change allele frequencies in populations and explain how they do this

Explain the importance of Hardy-Weinberg equilibrium as a null model for understanding the forces that alter allele frequencies in populations

Explain the role of migration and genetic drift in terms of how it affects allele frequencies in a population

Explain why small populations are more susceptible to genetic drift

Explain how founder effects and population bottlenecks reduce genetic diversity in a population and increase the vulnerability of populations to extinction


Climate I & II

Describe the major factors that determine global climate

Explain how temperature and precipitation vary globally

Explain how climate varies seasonally and how this variation occurs

Explain how solar radiation can drive global air circulation

Explain why rising air cools

Draw an illustration of a Hadley cell and explain the factors driving its circulation at each step

Explain how Hadley cells are responsible for creating deserts at 30oN and 30oS latitude

Explain the coriolis effect and how it influences wind patterns and ocean currents

Draw a diagram of global air and ocean circulation patterns and explain how they occur

Explain the causes and climatic consequences of the El Niño effect

Explain how topography can modify local climates : e.g., N/S slope effect and rainshadow effect



Describe the three types of rock parent material and rock weathering

Describe the sources of biological inputs and the role of decomposition

Explain how soils form

Describe the importance of soil color in determining soil conditions

Describe the importance of soil texture in characterizing soil fertility and drainage

Explain how soil clay particles affect soil fertility

Describe a typical soil profile and explain how soil horizons form

Explain the characteristics of the selected soils in relation to the biomes in which they occur


Life histories

Explain how species' life histories are selected for by natural selection

Explain how the principle of allocation leads to trade-offs among reproduction, growth, and survival

Describe the "big three" allocation strategies and be able to explain two examples of different allocation strategies in observed in organisms

Explain the concept of r-K selection in terms of the principle of allocation and how the allocation “strategy” of a species is selected for by environmental factors

Describe the traits of an r-strategist and a K-strategist and be able to give an example of each

Explain the relationship between r- and K-selected species and the environmental conditions in which they typically occur

Draw a population growth curve of a typical r- and K-selected species and explain the nature of each


Properties of populations

Explain the difference between the distribution and geographic range of a population

Describe how abiotic and biotic factors can determine the distribution of a population

Explain how clumped, random, and regular dispersion patterns can arise in a population and how to distinguish them based on a variance-to-mean ratio

Be able to calculate the population size and density of stationary organisms using data collected using the quadrat method

Be able to calculate the population size and density of mobile organisms using the mark-recapture technique and how this estimate can be biased by violating its assumptions

Explain how the type of age distribution (or age structure) of a population can determine its growth potential

Explain why the distribution of populations on the landscape is patchy and how this patchiness affects the movement of individuals in a population

Compare and contrast the different types of movement in populations : dispersal, immigration, and emigration


Population growth

Explain the exponential and logistic growth models and what circumstances can lead to each in a population

Draw and appropriately label an exponential and logistic growth curve

Explain how and why the instantaneous per capita growth rate (r) is affected by population size (N)

Explain how births and deaths determine the instantaneous per capita growth rate (r) and how changes in r (via birth and death rates) regulate population growth

Explain how age structure can influence a population's instantaneous per capita growth rate (r)

Explain what a life table is and what it tells us about survivorship

Be able to construct a life table given information about a population's age-specific survivorship and birth rate

Draw and appropriately label a graph of type I, II, and III survivorship curves, explain how they occur, and give an example of each

Explain each of the components (terms) of a life table and be able to calculate: nx, lx, and the net reproductive rate (Ro)

Explain what the net reproductive rate (Ro) tells you about the growth rate of a population


Population regulation

Explain what determines a population's carrying capacity (K) and how a population's K could change

Be able to write out and interpret the exponential and logistic growth equations

Explain how population growth rate (dN/dt) in the logistic model is influenced by the relationship between population size (N) and carrying capacity (K)

Explain how the instantaneous per capita growth rate (r) is influenced by population size (N)

Explain how population growth can be regulated by its own density (i.e., density-dependent regulation)

Be able to give an example of density-dependent regulation

Explain how population growth can be regulated by density-independent factors and provide an example

Explain the phenomenon of self-thinning and how it relates to density-dependent regulation

Be able to compare and contrast density-dependent versus density-independent regulation in terms of expected mortality patterns




Explain how and why populations exist as metapopulations in nature

Explain how birth and death rates within subpopulations and immigration and emigration among subpopulations contribute to determining the size of a metapopulation

Explain the relationship between movement among subpopulations and colonization rate of new patches

Explain the relationship between movement among subpopulations and extinction rate within patches

Explain how movement among patches influences the balance bewteen colonization and extinction of patches

Explain the relationship between patch isolation and colonization, and patch size (area) and extinction

Explain the source-sink model of metapopulation dynamics

Be able to make predictions about the dynamics of a metapopulation based on the source-sink model and what you know about patch quality, the instantaneous per capita growth rate (r) of source and sink populations, and movement among patches



Explain how competition results in a negative effect on each individual in the interaction

Compare and contrast exploitation and interference competition and give an example of each

Explain how exploitation competition can affect plant and animal performance (e.g., growth, survivorship, density, etc.)

Explain the basis for the competitive exclusion principle and what it predicts for complete competitors

Describe Gause's 1934 experiment testing the competitive exclusion principle and its interpretation

Explain the concept of the niche

Explain the difference between the fundamental and realized niche

In Joseph Connell's (1961) study, describe the role of competition in determining the realized niche of the two barnacle species

Explain the concept of resource partitioning and how it acts to reduce competitive interactions among species

Explain how character displacement can result as a long-term evolutionary outcome of interspecific competition and provide an example of its occurrence in nature

Explain how a keystone predator can prevent competitive exclusion and increase species diversity in a community


Predation and herbivory

Describe some key adaptations predators have evolved for capturing prey

Describe some key adaptations prey have evolved to counteract predation

Explain the selective advantage of crypsis, warning coloration, mimicry, and chemical and physical defenses in prey

Explain how and why some swallowtail butterflies exhibit Batesian mimicry

Explain how and why some species exhibit Müllerian mimicry

Explain why some chemical and physical plant defenses are selected for evolutionarily

Describe how herbivores can affect the distribution of plants

Explain how certain factors can increase the persistence of predator-prey systems such that they do not result in extinction of both predator and prey (e.g., Gause and Huffaker experiments)

Diagram (as a graph) the Lotka-Volterra predator-prey model, explain its predictions about predator-prey population dynamics, and describe some of its assumptions

Describe the potential role of predator and prey migration, prey refuges, resources, and disease on predator-prey dynamics

Describe several factors that can modify predator-prey oscillations and how they affect the oscillations

Explain the concept of optimal foraging in terms of the costs and benefits involved in predator foraging


Ecological communities

Define an ecological community and describe one of its unique properties

Compare and contrast the organismic and individualistic concepts of the community and identify the scientists who are associated with advancing each concept

Explain the typical dominance/abundance (relative abundance) patterns that are found in ecological communities

Diagram a rank-abundance curve and explain how it is used to describe a community's species richness and relative abundance of its species

Describe the two components of species diversity and explain what they tell about the structure of a community

Understand how to use the Simpson’s index to describe the species diversity of a community

Explain the concept of a food web in terms of trophic interactions and energy flow

Diagram a simple food web with specific examples of different trophic levels and their trophic relationships

Explain "top down" vs. "bottom up" control in food webs

Explain the concept of a keystone predator, its effect on the food web, and how it can influence other species in the community

Name the scientist who first described a keystone predator and describe the experiment he conducted to show its effects on the food web


Disturbance & Succession

Describe what is meant by a successional sere

Describe the two types of ecological succession, the circumstances under which they occur, and give examples

Compare and contrast the life history traits typically found in early and late successional species and how these traits correspond to the successional stage in which they occur

Describe each of the three characteristics of a disturbance and how they are interrelated

Describe the relationship between the size and frequency of a disturbance

Explain what is meant by the return interval of a disturbance

Explain how the frequency of a disturbance can influence the species composition of a community

Give an example of plant adaptations to fire and explain the functions of these adaptations

Describe the heterogeneous spatial pattern often found for most disturbances

Explain the intermediate disturbance hypothesis and how it influences species diversity in ecological systems

Describe an experiment that tests the intermediate disturbance hypothesis

Explain the concept of patch dynamics and how it affects the successional status and, thereby, the species diversity of ecological communities



Ecosystem energetics

Explain primary production and the relationship between gross primary production, net primary production and respiration in an ecosystem

Explain the different ways that ecologists measure primary production

Explain how temperature, precipitation and soil fertility can influence primary production

Explain why ecosystems and biomes differ in NPP

Explain how energy flows through an ecosystem and identify the different pathways through which energy can flow (i.e., where the energy goes)

Draw an energy flow pyramid that shows the how energy flows from a primary producer to higher consumer levels

Explain why not all of the energy captured by producers is passed on to consumer s and how the amount of energy coming into an ecosystem can influence how many trophic levels and species are supported


Decomposition & nutrient cycling

Explain how eessential nutrients are recycled within ecosystems

Describe which microbial decomposers decompose plant versus animal material

Describe how ecologists measure decomposition rates

Explain what is meant by litter quality and how litter quality influences decomposition rate

Explain how decomposition rate is influenced by temperature

Compare and contrast mineralization and immobilization

Draw a graph showing how nitrogen content of leaves changes during litter decomposition and explain what is happening at each stage in terms of nitroten leaching, mineralization, and immobilization

Biogeochemical cycles

Name the six major essential nutrient elements and describe where they occur in biological organisms

Explain where nutrients come from

Explain how decomposition rate is affected by temperature, precipitation and litter quality and how rates of decomposition can influence soil organic matter content

Be able to describe a biogeochemical cycle using a box-arrow diagram

Explain how nutrients cycle among reservoirs and how reservoir size influences nutrient cycling rate

Explain how biological organisms act as reservoirs of nutrients

Explain how logging of forest ecosystems can affect nutrient retention

Explain how nutrient retention/loss in ecosystems is influenced by biological organisms

Explain how distinct ecosystems can differ in their abilities to retain nutrients


Carbon cycle

Explain the importance of the carbon cycle

Diagram the carbon cycle and describe the identity, relative sizes, and cycling rates of its major reservoirs

Explain the key processes that drive the cycling of carbon among its major reservoirs

Explain the greenhouse effect and how and why it is occurring

Explain how microorganisms altered the concentrations of CO2 and O2 after they evolved on Earth

Describe global warming and some of the evidence to support it

Explain how we know that CO2 and temperature have changed in tandem over the last 400 million years

Describe how global warming (i.e., the greenhouse effect) is likely to affect Earth's ecosystems


Nitrogen cycle

Name the two forms of inorganic nitrogen that are available to biological organisms

Describe the natural and anthropogenic (human-caused) sources and forms of nitrogen that exist on Earth

Diagram the nitrogen cycle and describe the identity, relative sizes, and cycling rates of its major reservoirs

Explain the key biological processes that drive the cycling of nitrogen among its major reservoirs

Explain how and why nitrate leaching occurs

Explain the processes of assimilation, ammonification, nitrification, nitrogen fixation, and denitrification

Explain how ozone protects biological organisms from harmful UV radiation

Explain how combustion reactions (e.g., production of NO2) can destroy the ozone layer



Terrestrial biomes - Lab (will be included on lecture exams)

Describe the location, general climate, and growth form of each of the terrestrial biomes

Explain the relationship between climate and physiognomy of the terrestrial biomes

Identify a particular biome based on its climate (e.g., climate diagram), latitude and vegetation






In order to do well on exams and quizzes, you should understand and know how to apply and use the following terms.


The nature of ecology /Lab 1







scatter plot

scientific method





Adaptation and evolution I


natural selection




stabilizing selection

directional selection

disruptive selection

genotypic variation

phenotypic variation

phenotypic plasticity


reciprocal transplant experiment


Adaptation and evolution II


allopatric speciation

sympatric speciation

population genetics



gene pool

Hardy-Weinberg equilibrium


non-random mating

genetic drift

founder event

population bottleneck


Climate I & II

adiabatic cooling

Hadley cell

Coriolis effect



El Nino effect (El Nino Southern Oscillation: ENSO)



north-south slope effect


rainshadow effect




rock types




rock weathering



soil forming factors

soil texture


soil horizons






Life histories

life history

principle of allocation

allocation strategy



r-K selection




Properties of populations


population structure



dispersion pattern

age structure
age pyramid

population dynamics



quadrat sampling

mark-recapture method



Population growth

population size (N)

exponential growth

instantaneous per capita growth rate (r)





survivorship curves

type I, II, III

cohort life table

life table terms:

nx, lx, bx

net reproductive rate (Ro)



Population regulation

logistic growth

carrying capacity (K)

population regulation

density-dependent regulation

density-independent regulation





metapopulation dynamics

local population

habitat patch

source population

sink population

patch quality




forms of competition






niche concept

fundamental niche

realized niche

competitive exclusion principle

resource partitioning

character displacement

keystone predation


Predation and herbivory





warning coloration

Batesian mimicry

Müllerian mimicry

secondary chemicals


Red Queen hypothesis

predator-prey dynamics



Lotka-Volterra predator-prey model

optimal foraging


Ecological communities


holistic concept

individualistic concept

F.E. Clements

H. A. Gleason

environmental gradient

continuum concept

species dominance

species abundance

rank-abundance curve

species diversity



Simpson’s index

food web

trophic level

trophic pyramid



trophic cascade

top-down control

bottom-up control

keystone predator


Disturbance & succession



primary succession

secondary succession


disturbance regime




return interval


intermediate disturbance hypothesis

patch dynamics



Ecosystem energetics


gross primary production

net primary production

CO2 method

O2 method

actual evapotranspiration (AET)

energy flow pyramid







detrital (detritivore) food chain


Decomposition & nutrient cycling

internal cycle



litter bag method

litter quality

C:N & lignin:N ratio



net mineralization rate


Biogeochemical cycling

biogeochemical cycling

major elements

minor elements


nutrient retention


Carbon cycle

carbon cycle

atmospheric CO2

greenhouse effect

infrared radiation

global warming


Nitrogen cycle

nitrogen cycle

nitrogen fixation





nitrate leaching


ozone layer



Lab: Terrestrial biomes



tropical forest

tropical savanna


temperate shrubland

temperate forest


coniferous forest

tundra (arctic/alpine)