1)      What is a population?

Ø  Individuals of the same species in the same place at a given time

)      What is the difference between population size and population density?

Ø  Population Size = the actual # of individuals in the population

Ø  Population Density = shows the spread of the population—the distribution of the species over a certain area

1)      To what does the word “range” refer?

Ø  The areal extent of a species, or population

Ø  Ask yourself: Where is the species located? This is the range of the species

Ø  Remember: the range can be clumped, random, or even.

·   Clumped = Resources are clumped together, so species is forced to interact—social interactions and limited dispersal

·   Random = Resources are randomly distributed, so species can be more spread out

·   Even = Resources are even, so species competition is exhibited, along with territorial interactions

1)      What affects population size?

Ø  Death rates, birth rates, immigration (moving to a different place), and emigration (moving out of a place)

 When does population density begin to decrease?

Ø  When death rates are higher than birth rates

1)      Remember your equation: dN/dt = rN

Ø  In words: Change in population size over time is equal to the intrinsic growth rate times the size of the population, or the number of individuals in the population.

1)      We have seen that populations begin to grow exponentially, but end up decreasing of leveling off at some point in time. What prevents continued exponential growth? (Hint: Common sense things—what would cause a decrease in population size?)

Ø  Disease, predation, limited resources/competition, catastrophic events—floods, hurricanes, tornados, drought, fires, etc.

1)      What does (K-N)/N describe?

Ø  Describes how growth slows in populations as the population size approaches carrying capacity (K).

Ø  Describes competition.

1)      What is intraspecific competition?

Ø  Competition between individuals of the same species

Ø  Acts to increase death rate or decrease birth rate in a population

1)      What does the static life table tell us?

Ø  It tells us about mortality and survival rates of a population, but doesn’t tell us if population is increasing, decreasing, or remaining the same.

1)      What does the cohort life table tell us?

Ø  It follows a group of individuals, usually females, and measures survival and fecundity (reproduction) rates.

1)      What is R₀?

Ø  The net reproductive rate (whether or not individual is being replaced; generally, talking about females)

Ø  If R₀>1, then population is increasing

Ø  If R₀<1, then population is decreasing

Ø  If R₀=1, then population is remaining the same

1)      What is the difference between an “r-selected” species and a “k-selected” species?

Ø  R-selected: semelparous (one big-bang reproduction), small body size, easily dispersed, short lifespan (which is probably why they reproduce all at once and at young ages), poor competitors, can live in disturbed areas, fast-growing

Ø  K-selected: iteroparous (reproductive episodes, not all at once), long lifespan, large body size, not easily dispersed, great competitors, live in stable habitats, slow-growing

1)      So, which one are we: K or R?

Ø  K-selected species

1)      What is interspecific competition?

1)      What is interspecific competition?

Ø  Competition between individuals of different species

1)      What is the difference between community and population?

Ø  Population is made up of only one species, whereas a community is composed of multiple species

1)      What effect does interspecific competition have on diversity?

Ø  Can decrease diversity and can cause local extinction

Ø  Remember Gause’s Competitive Exclusion Principle: no two species can coexist if they use the same resources in the same fashion. One will out-compete the other!

1)      How have species evolved to get around Gause’s Principle?

Ø  Species have evolved to diverge in species use. Therefore, some species may be able to coexist in the same environment as long as one species is willing to find a new resource.

1)      What is interference competition? Exploitative Competition?

Ø  Interference: blocking access to resources—so this would be your territorial species, which would defend their territories by blocking another species’ access to resources

Ø  Exploitative: using a common resource—so species are trying to out-compete each other

Ø  Heterogeneity = emigration/immigration, prey refuge, variation in prey defenses, more species, predator, or prey—escape from extinction

1)      Does predation decrease or increase diversity of a community?

Ø  BOTH!!!!

Ø  Predators can cause local extinction, decreasing diversity

Ø  OR, predators can increase diversity by reducing competition between prey species

1)      REMEMBER the Pisaster experiment!!

Ø  Diversity was decreased once predator was removed because interspecific competition became an issue.

Ø  Predation can decrease competition between species, causing increase in diversity!

Ø  SO PREDATION INTERACTS WITH COMPETITION!

1)      What is an ecosystem?

Ø  Biological community plus the physical environment (abiotic and biotic factors of living space)

1)      What are some abiotic factors of ecosystems?

Ø  Energy, nutrients, climate, pH, etc

1)      With the ecosystem approach:

Ø  Focus on energy flow through trophic levels

Ø  Ignore individual populations

Ø  Focus on how nutrients and other physical environmental factors affect energy flow, productivity, and biomass

Ø  Producers make their own food—plants

Ø  Consumers have to eat other things—primary consumers would eat producers, so they would be considered herbivores; the rest would be carnivores

1)      What are the laws of thermodynamics?

Ø  First, energy is conserved; not created or destroyed—just cycled

Ø  Second, energy or entropy conversions are inefficient because the transfer requires the loss of heat

1)      Remember: higher trophic levels have lower biomass and lower energy….can you think of a reason for this?

Ø  Energy lost as heat during conversions, so by the time you get to the top, there is less energy and not as much biomass as there was at the bottom of the web.

1)      What affects productivity?

Ø  Light, temperature, and precipitation (all positively related to productivity, so as one increases, productivity will also increase)

Ø  The type of primary producers

Ø  The type of consumers

Ø  Quality of the biomass available

1)      What is the main reservoir for nitrogen?

The atmosphere

1)      Since nitrogen gas is not readily used by most organisms, what must happen to the nitrogen?

Ø  Various soil microbes must fix the nitrogen gas, via nitrogen fixation, into inorganic forms that can be used by other organisms, such as plants

1)      Is the carbon cycle usually limiting to productivity, like nitrogen?

Ø  NO

1)      Which element has important implications for climate change and global warming? And, where is this element located, primarily?

Ø  Carbon—located in fossil fuels and carbonate rock