# AP Biology Chapter 53: Population Ecology

### AP Biology Chapter 53: Population Ecology

What two pieces of data are needed to mathematically determine density?
Number of organisms and area of habitat
Density
Number of individuals per unit area
Dispersion
The pattern of spacing of individuals
Formula N=mn/x
n is _____.
Number of second sampling.
Formula N=mn/x
s is _____.
Number released in first sampling.
Formula N=mn/x
x is _____.
Number of marked individuals in second sampling.
Explain the impact of immigration and emigration on population density.
They alter the density of populations and increase gene flow between populations.
Clumped dispersion pattern
Animals group around food (social animals).
Uniform dispersion pattern
Animals are dispersed evenly with aggressive territoralism.
Random dispersion pattern
Organisms are randomly dispersed, just where they land.
Cohort
A group of individuals of the same age.
Population statistic that demographers have a particular interest in?
Birth and death rates (helps create a life table).
Survivorship curve I (one)
Most individuals live to older age. Small number of offspring. Lots of parental care.
Survivorship curve II (two)
Individuals live and die at consistent rate. Medium number of offspring.
Survivorship curve III (three)
Many individuals die during first stages of life but those that survive live long. Large number of offspring. No parenting.
What does a reproductive table show?
Age specific summary of reproductive rates in a population. (Measured by reproductive rates of a cohort.)
On what is the life history of an organism based?
The traits that affect an organism’s schedule of reproduction and survival from birth to death.
What three variables form the life history of a species?
Age of reproduction
How often an organism reproduces
How many offspring per reproductive episode
Semelparity
Single reproductive episode before death (release eggs) can wait for right conditions, release a lot survival rate of offspring is low.
Iteroparity
Multiple reproductive cycles over the course of its lifetime more dependable environments.
Two critical factors for determining if a species will evolve toward semelparity or iteroparity.
Survival rate of offspring
Likelihood that the adult will survive to reproduce again
Explain the effect of offspring care on parental survival in kestrels.
There appears to be a negative correlation between brood enlargements and parental survival.
What is the advantage to using per capita birth and death rates rather than just the raw numbers of births and deaths?
Per capita gives average of the number of offspring per individual and number of deaths per unit of time.
What will the per capita birth and death rates be if a population is demonstrating zero population growth?
They will be equal.
What does it mean for a population to be in exponential population growth?
A population that is growing without limitation of resources.
What are two examples of conditions that might lead to exponential population growth in natural populations?
Excess of food and water (resources)
Free to reproduce as often as possible
What is carrying capacity?
Maximum population size that an environment can sustain.
What are six examples of limiting resources that can influence carrying capacity?
Space
Water
Food
Mate availability
Shelter
Predator
In the logistic population growth model, the per capita rate of increase approaches zero as the _____ _____ is reached.
Carrying capacity
K-selection
Density-dependent selection, have few offspring, parent heavily
R-selection
Density-independent, lots of babies, no parents
Density-independent regulation
Provides regulation by reducing birth rate and increasing death rates (competition for food)
Density-dependent regulation
Regulation of population regardless of population density (lightning strikes and there is a fire)
Explain negative feedback’s role in the regulation of populations.
It keeps the population at or near carrying capacity through affecting birth and death rates in a large (close to K) population.
Negative feedback mechanism: Competition for resources
Organisms compete for food and water (Mice have a limited insect supply)
Negative feedback mechanism: Territoriality
Organisms compete for space by fiercely defending an area (Mountain lions have large territories)
Negative feedback mechanism: Disease
Diseases increase death rates by killing weak organisms (Bats have fungus)
Negative feedback mechanism: Predation
Predators control prey population and vice versa (Number of foxes and rabbits in field fluctuate together)
Negative feedback mechanism: Toxic wastes
Some organisms (bacteria/yeast) make toxic wastes that kill some population (Yeast makes alcohol which builds up until death)
Negative feedback mechanism: Intrinsic factors
Hormonal/physiological changes in animals based on food (If women are nutrient deficient they stop menstruating)
Importance of immigration and emigration in metapopulations.
A metapopulation is when two or more populations are linked, it is important to have constant immigration and emigration.
Human population growth since 1650.
We have been exponentially growing until lately. We have slowed down. (2.2% in 1962, 1.2% in 2009)
Demographic transition
Movement from high birth and death rates to low (This has happened in both Mexico and Sweden since 1750)
Afghanistan
Large younger population (Prediction: explosive growth rate)
United States
Even number from 0-55 (Prediction: grow slowly)
Italy
Less children than adults (Prediction: no growth)
Why do infant mortality and life expectancy vary so greatly between certain countries?
They reflect a quality of life and parental choices.
Can the world’s population an ecological footprint that is currently the average American’s footprint?
The average American footprint is 10 and it is unsustainable at 1.7 (Over using resources!)