Chapter 11 Flashcards
What does the model of population growth assume?
assumes constant environment and unlimited resources
What happens in regards to birth and death as population increases?
birthrate declines and death rate increases
What happens when birth=death?
represents maximum sustainable population size under prevailing environmental conditions
What happens if a population approaches and exceeds carrying capacity?
slows as it approaches K
declines as it passes K
What is density dependence?
negative feedback of population growth
as population increase, resources decreases, which then regulates population growth
What is density-dependent mortality?
slow rate of population growth by increasing mortality
What density-dependent fecundity?
decreased population growth by decreased rate of fecundity
What is density-independent?
factors that influence rate of birth and death
What are density-independent factors (3)?
- predation
- disease
- environmental factors
- moisture causing invasive species
- temperature affecting poikilotherms
- precipitation in deserts
What is competition?
when individuals use a common resource that is in short supply relative to the number seeking it
What is intraspecific competition?
competition in the same species
What is scramble competition?
when growth and reproduction are depressed equally across individuals in a population as intensity of competition increases
can lead to all with insufficient resources
What is contest competition?
when some individuals claim enough resources while denying others a share
only a fraction suffers
What is exploitation?
competition where species do not directly interact, but compete for resource availability
Why does intraspecific competition increases gradually?
first affects growth and development, later survival and reproduction
What is density-dependent growth (2), and what traits might it favor?
inverse relationship between population density and individual growth
- individuals have slow growth due to limited resources at high densities
- may favor traits that increase an activity, like faster movement
What is self-thinning?
progressive decline in density and increase in growth of remaining individuals
How can intraspecific competition reduce reproduction?
reduced weight gain under high density increases age at reproduction
How might increased crowding cause stress?
- stress can suppress growth, reproductive function, and sexual activity
- can also increase young and fetal mortality
What might cause animals to disperse? (2)
stress
sub-adults are often driven out due to adult aggression
Why is dispersal not an effective method for population regulation?
since it is a response to overcrowding
How might soical behavior limit population?
- limit number of animals in a habitat, access to resources, and access to mates
- ex- at high densities, wolves may be forced to leave a pack and have a higher chance of mortality
How might group structure limit population?
- group structure for defense can be based on aggression and dominance
- settled by fighting and threats
What is a home range, and what does it vary?
- area animal uses
- varies with resources
How might home ranges change?
- in mammals, related to body size
- carnivores, males, and adults have larger home ranges
What is territory?
home range an animal defends
How might plants be territorial, and what kind of distribution will it create?
- plants can eliminate others by depleting sunlight and taking up more water and nutrients
- usually creates a regular spatial distribution
What is the Allee effect, and 2 examples?
- function to reduce birth rate and survival at low population
- dispersed species difficulty finding mate
- less likely for pollination to occur between plants far from each other
