Ecology Notes for Population Growth & Ecology Study Guide Exam 2
4. Population Growth
∙ Current population size=previous population size + (birthsdeaths) + (Immigrantsemigrants)
∙ Cohort life tables are good for plants and sessile organisms. To make the table, fill in the number alive and the fecundity (number of eggs/offspring). o Mortality rate=1survival rate.
o Survivorship=number alive/number that started in the cohort o Survival rate of age class 0= survivorship of age class 1/survivorship of age class 0. Therefore, Survival rate of age class 1=survivorship of age class 2/survivorship of age class 1
∙ Linear graph of a life table indicates that the population is limited by the rate of growth
∙ Exponential graph of a life table indicates that the population is limited by carrying capacity. We also discuss several other topics like Who is johannes kepler?
If you want to learn more check out What are the four major categories of macromolecules?
∙ Net Reproductive Rate (Ro): average number of offspring produced by an individual over their lifetime.
∙ (Ro) > 1 means the population is growing; <1 population is declining; =1 population is stable We also discuss several other topics like What does the 4th amendment protects?
∙ Geometric rate of increase (lamda) = future population size / current population size and this is used for populations with nonoverlapping generations. Increased fecundity will increase the geometric growth rate
∙ When generations overlap, Generation time (T): average time from birth to when the organism reproduces
∙ When the per capita rate of population growth (r) is >0 the population is growing; r<0 population is declining; r=0 population is stable
∙ r selected species have shorter generation times
∙ Body size has a positive correlation with generation time. Human populations grow exponentially.
∙ Densitydependent factors: regulate the population and include disease, predation, competition Don't forget about the age old question of What is the goal of personality psychology?
∙ Densityindependent factors: influence the growth rate of the population and examples are natural disasters.
∙ A logistic population growth curve (Sshaped) reflects the carrying capacity (K): the theoretical max population number. The population grows rapidly then slows and growth stops and stabilizes at the carrying capacity (K).
∙ As a population approaches K, the rate of increase approaches 0. Ecology Study Guide 2
1. Population Distribution and Abundance
∙ What questions would population ecologists ask and what
experiments would they use? We also discuss several other topics like What is the meaning of a multi unit torso?
∙ What is a population and what are its characteristics?
∙ What is a niche? How do fundamental and realized niches compare?
∙ What are the 3 basic patterns of distribution in a population? Why
would populations be patterned in this way?
∙ If given characteristics of organisms in a population, can you predict We also discuss several other topics like It is a type of unemployment that the portion of unemployment that is due to time delays in
matching available jobs and workers, what is it?
their spatial distribution?
∙ How could you measure the abundance and density of a population? ∙ What factors influence species abundance and density? How might
niche characteristics and body size influence population range? 2. Life Histories
∙ What is Life History Evolution? List some life history traits and their
∙ What is the Principle of Allocation?
∙ What are some examples of intrinsic tradeoffs? Do they have a positive or negative correlation? Why are they positively or negatively
∙ How are life history tradeoffs linked to population range expansion? ∙ What are species ranges and migration patterns? Give examples.
∙ What is fecundity? How does fecundity compare with offspring size? ∙ What traits do Iteroparous organisms have? Semelparous? Give
examples of organisms that are Iteroparous and Semelparous. ∙ What are the predictions and conclusions of the David Reznick study
on the life history of guppies?
∙ What characteristics do r selected and K selected species have? ∙ Compare and contrast r selected and K selected species with regard to:
intrinsic rate of increase, competitive ability, development,
reproduction, body size, reproduction, and offspring.
3. Population Dynamics
∙ What determines current population size?
∙ What influences dispersal and what does it effect?
∙ What is a life table and what does it show you?
∙ What is a cohort?
∙ There are 2 types of life tables: Static life table and Cohort life table. What are the characteristics of each? How are they similar and different? Be able to understand the graphs. Can you draw a graph of
a life table?
∙ Can you estimate a survivorship curve from a life table? Can you
determine life history traits from a life table?
∙ Understand the 3 types of survivorship curves and which types of individuals would demonstrate each one. Example: Humans are Type
∙ Be able to interpret age distribution graphs. Periods of successful
reproduction? Growth potential? Etc.
4. Population Growth
∙ Be able to interpret graphs made from life tables.
∙ Be able to understand how survivorship and birth rate influence population growth? What happens to a population if birth rate
increases? If mortality increases?
∙ What is the geometric rate of increase? What will increase and
∙ Compare and contrast the growth rate in populations with overlapping
and nonoverlapping generations.
∙ How does generation time influence the rate of population growth?
What about carrying capacity?
∙ How do generation overlap and generation time influence population
∙ What limits exponential growth of populations?
∙ What are densitydependent factors? What are densityindependent
factors? Give examples.
∙ Graph population growth over time and identify regions that represent exponential growth, decreasing population growth rate and carrying
∙ Where is the population growth highest in a population on a logistic
∙ Compare growth rate in populations with overlapping and non overlapping generations. (There is a table in the lecture notes)