Population Ecology Flashcards
What is a population?
A group of interacting organisms of the same species
What is demographic structure?
Quantified number of individuals of each age/stage
What is population size?
Total number of individuals
What is population density?
How densely packed together individuals are
What is geographic range?
The limits/bounds established by physical limits that species can tolerate
Some examples of geographic range are. . .
Temperature and aridity, encroachment/intrusion of other species
The most basic approach to population growth is. . .
exponential
What does the exponential population growth approach assume?
Assumes that every individual produces two offspring in their lifetime
Growth rate (r) is. . .
the intrinsic rate of natural increase
What is carrying capacity?
The maximum population size that an environment can sustain
What happens to population growth rate as population size increases in an environment with carrying capacity?
The growth rate slows/decreases
What happens when a population reaches carrying capacity?
Growth stops
With the addition of resource limitation, what change do you expect in the number of births as population size increases? In the number of deaths?
Decrease in births, increase in deaths
In real populations, as population size increases and approaches carrying capacity, the amount of intraspecific competition. . .
increases as fewer resources are freely available to each individual
A population of penguins has an annual per capita birth rate of 0.08 and an annual per capita death rate of 0.1. Estimate the net gain or loss of individuals from a population of 1,000 penguins in one year.
20 individuals lost
Populations growing exponentially:
A) have a growth rate (r) that increases with time
B) have a constant r
C) are under density-dependent control
D) add the same number of individuals to a population every generation
E) can continue growing exponentially indefinitely
B) have a constant r
What type of growth does a population under carrying capacity experience?
Logistic growth
What factors can change population size?
Biological and non-biological factors
What factors can regulate population size?
Biological factors
Biological factors are density ________, and nonbiological factors are density ________
dependent; independent
Density affects population regulation by the four factors of. . .
1) territoriality
2) disease
3) predation
4) toxic wastes
How does territoriality regulate population?
Maintaining territory enables individuals to capture enough food to reproduce where space is limited)
How does disease regulate population?
Less dense populations experience slower spread; more dense populations experience faster spread thus increased rate of death > birth
How does predation regulate population?
Predators may concentrate on most abundant prey
How does toxic waste regulate population?
Metabolic by-product accumulates as population grows
What is fecundity?
The number of offspring an individual can have in its lifetime
Metapopulations are. . .
populations of the same species linked together by migration
True or False?
Metapopulations are different but interlinked populations that have their own habitat
True
Genetic exchange between source/sink population depends on the three factors of. . .
1) population size
2) habitat carrying capacity
3) ability of individuals to move between habitats
What is life history?
The theory of how energy is allocated to different aspects of organisms’ survival
Life history traits are traits that. . .
impact survival and reproductive output
Some examples of life history traits are. . .
- size at birth
- age and size at maturity
- number and size of offspring
- reproductive value
- lifespan and senescence
What is senescence?
The decline in fecundity with age
The life history theory explains how. . .
evolution optimizes survival and reproductive characteristics in different populations
Life history trade-off is. . .
the optimization when increase or decrease in evolution leads to negative or opposite effect on life history trait
What are r-selected traits?
Life history traits that maximize growth rate
What are K-selected traits?
Life history traits that are selected for in organisms living at densities near environmental carrying capacity
A population of waterbuck has an annual per capita birth rate of 0.67 and an annual per capita death rate of 0.05. Estimate the net gain or loss of individuals from a population of 10,000 waterbucks in one year.
6200 individuals added
What is reproductive value?
Average number of offspring that will be produced by an individual at a given age
Reproductive value is influenced by. . .
probability of survival and successful reproduction
When is reproductive value the lowest? When is it the highest?
At birth; at peak of sexual maturity
The purpose of a life table is to. . .
study age-specific population characteristics and determine the number of individuals that survive from one group to the next
A cohort life table follows. . .
one group born at the same time until the death of all individuals
The two key assumptions of a cohort life table are. . .
1) population sample of each age class is proportional to actual population
2) age-specific mortality rates remain constant
What is net productive rate (R0)?
The sum of the product of survivorship times fecundity
When R0 > 1, what is happening in the population?
Producing more offspring than losing from death
What are the different types of survivorship curve?
1) Type I
2) Type II
3) Type III
Type I curve represents a population that has a. . .
low mortality rate when young and high mortality rate when old (concave down exponential curve)
Type II curve represents a population that has a. . .
constant mortality rate (negative linear line)
Type III curve represents a population that has a. . .
high mortality rate when young and low mortality rate when old (concave up exponential curve)
The survivorship curve is represented with _______ on the x-axis and _______ on the y-axis
time; number of surviving individuals
What are the four different types of metapopulations?
1) classic
2) mainland-island
3) patchy
4) non-equilibrium
A classic metapopulation is characterized by. . .
- isolated patches of suitable habitat
- adequate migration rate
- occupied and unoccupied patches
A mainland-island metapopulation is characterized by. . .
- the colonization of islands by the mainland population
- systems of patches located near larger mainland
- the assumption that there is no extinction
A patchy metapopulation is characterized by. . .
- isolated populations within range of suitable habitat
- interlinked subpopulations and demographics
A non-equilibrium metapopulation is characterized by. . .
- different patches of suitable habitat that have asynchronous dynamics
- unlinked and independent subpopulations and demographics
Reproductive value increases with onset of. . .
sexual maturity then declines with age
Selection acts most efficiently on ______ reproductive value.
high
What is the dispersal stage in the human life cycle?
Young adults
Post-menopausal human females can no longer produce offspring, but their reproductive value is typically > 0. How can this be?
They care for grandchildren and other close relatives that will eventually produce their own offspring.
The shape of an age structure diagram for a population experiencing rapid growth is a ______.
pyramid (the pyramid indicates many young individuals relative to fewer older individuals)
Imagine that a species of fish used to be a broadcast spawner (producing many eggs that then get no subsequent parental care) but has evolved to be a mouth brooder (holding the eggs in the parent’s mouth until they hatch and then caring for the young for a while). We would expect the survivorship curve of this species to shift
A) from Type I to Type II or III.
B) from Type II to Type I.
C) from Type III to Type I or II.
D) from Type II to Type III.
E) The survivorship type would vary unpredictably.
C) from Type III to Type I or II.
