Population (Distribution/Abundance, Growth/Regulation, Dynamics) Flashcards
Distribution
large scale geographic range over which a species may occur
Dispersion
spatial arrangement of individuals within a population – depends on location of essential resources, competition, dispersal, and behavioral interactions
what factors alter Nt+1?
The number of individuals in the population at time t, the growth rate of the population and the value for t – i.e. how MUCH time?
Random dispersion
Neutral interactions between individuals (no competition) and neutral interactions between individual and enviro
Regular dispersion
Antagonistic interactions between individuals or local depletion of resources.
Clumped dispersion
Attraction between individuals or attraction of individuals to a common resource
Why and for what types of organisms do you use a mark recapture study?
to determine population abundance, used for mobile organisms
When do you use N = (m*c)/r ?
what does each variable stand for?
for mark recapture studies
N = estimated pop abundance, m = initial count captured and marked,
c = total recaptured, r = marked recaptured
When do you use the exponential growth equation and when do you use the geometric growth equation?
Use exponential when the population growth is continuous (i.e. reproduce year round)
Use geometric when the population grows over discrete time intervals (i.e. growth is not continuous)
How is the per capita rate of increase related to body size?
In general, the bigger the species, the smaller the rate of increase. Exception - Large ectotherms can have a larger growth rate because they can put more energy into reproduction
What is the purpose of a Life table?
Summarize the likelihood that organisms in a population will live/die and/or reproduce at different life stages
Static Life Tables
what are they, and which kinds of organisms is it useful for?
“snapshot” of age specific survival and fecundity in a population over a short period of time. Used for mobile organisms
Cohort Life Tables
what are they, and which kinds of organisms are they useful for?
selects individuals born at the same time and keeps records from birth until at least one dies. Used for plants, invertebrates, etc.
For predicting the future population size of a population growing exponentially or geometrically, what key assumptions must be made?
Environmental conditions must remain constant
No immigration or emigration
No genetic structure in birth/death – i.e. no predisposition to not be capable of reproduction or to dying sooner
No age or size structure
Continuous growth with no time lags
Explain a type I survivorship curve
probability of survival is great at a young age then decreases with age (ex- humans, large mammals)
Explain a type II survivorship curve
The probability of dying is constant throughout entire life span (ex- animals with high predation rates: birds, mice, etc.)
Explain a type III survivorship curve
survivorship of offspring is low- these organisms produce lots of offspring (ex- fish, coral, plants)
How are age distributions useful?
they indicate if a population is stable, growing, or shrinking
What is carrying capacity (K)
the max number of individuals that can be supported due to limiting resources (birth rate = death rate)
What is the inflection point?
K/2
Demographic stochasticity
randomness associated with birth and death
Environmental stochasticity
random environmental fluctuations
Allee effects
when r or λ decreases because of low population density
effective pop size
number of individuals in a pop who contribute offspring to the next generation
What genetic problems plague small populations?
Inbreeding depression, genetic drift, loss of heterozygosity
Interspecific competition
competition among individuals of 2 or more species
Intraspecific competition
competition among members of the same species
Exploitative competition
use of resources by one or more individuals, thereby reducing the available resources for other individuals (ex: plants competing for resources in soil, etc.)
Interference competition
direct, aggressive interaction between individuals
What is the competitive exclusion principle?
If Niche overlap is high and competition is uneven, the stronger competitor will potentially drive the weak competitor to extinction
fundamental niche
niche space defined only by physical factors and resource requirements (absence of other organisms)
realized niche
niche space determined by combining physical and biological factors (competition, predation, etc.)
What is character displacement
evolution stemming from selection to reduce resource competition between species
(ex- differing finch beak size when competition is present)
Predation
individuals of one species (predator) benefit by feeding on and directly harming another species (prey)
Parasitism
predator (parasite) lives symbiotically on or in the prey (host) and consumes certain tissues; may not necessarily kill the host
Pathogens
parasites that cause disease
Hyperparasitoids
parasites of parasites. they specialize in parasitizing insects that themselves are parasitic on other insects
what is lx on a life table? How do you calculate it?
survivorship - how many individuals make it from birth to age class of interest Nx(interest)/Nx(0)
what is Sx on a life table? How do you calculate it?
survival rate - proportion of individuals of one age class that survive to the next Nx+1/Nx
what is Fx on a life table?
fecundity - average number of offspring produced per female
