10/11 quiz Flashcards
what is the purpose of survivorship curves?
to assess patterns of survival in a population
what group of individuals does a survivorship curve follow?
a single generation - a cohort
what is plotted on survivorship curves?
the number of individuals still alive at that stage
type I curve
most individuals survive until old age
typically produce few offspring and have parental care
why do type I curves have low offspring mortality?
able to have parental care bc most individuals live until old age
type II survivorship curve
individuals have a constant chance of being killed at any point in life
small birds and mammals that are killed heavily by predation
type III curve
individuals have a low chance of survival when young, but survive well if they can make it to adulthood
typically lots of offspring but no parental care
what are factors that can impact survivorship curves?
habitat quality and sex
what’s something to note about survivorship curves?
the y-axis is logarithmic
how can habitat quality impact survivorship?
food quality and predation
how can sex impact survivorship?
differences by sex, such as competition for mates
what are dispersion patterns?
patterns of spacing among individuals
what are the three types of dispersion patterns?
clumped, uniform, and random
what influences cause clumped dispersion?
positive biotic interactions (btwn individuals)
common resources
what influences cause uniform dispersion?
negative biotic interactions (competition and territoriality)
what influences cause random dispersion?
absence of biotic interactions
not very common
example of clumped dispersion
penguins
to conserve heat and to be social
example of uniform dispersal
shrubs
example of random dispersion
dandelions in lawn
plenty of resources and can thrive anywhere
census
all individuals in population counted
when do censuses work best?
when individuals are large and easy to count
why are censuses inherently inaccurate in the US?
its too large of a population and territory
what does population estimation work well with?
sessile species using quadrats
can leave permanent markers to come back to
what does mark-and-recapturing do?
allow for sampling of mobile species
how do mark-and-recapture samplings work?
mobile species are marked with a band, tattoo, or radiotracked
what mathematical model does mark-recapture sampling use?
Lincoln Index
N = nM/R
what do the variables in the lincoln index mean?
N : estimated population size
n : total number of individuals captured in first census
M : number of individuals captured during second census
/
R : number of marked individuals recaptured during second census
what are the assumptions of the lincoln index?
equal chance of recapture for all individuals in population
ratio between marked and unmarked individuals remains constant
individuals don’t lose their mark
population is closed
what is meant by ratio staying constant with respect to marked and unmarked individuals?
we are neglecting death and predation
what is meant by all members of pop having an equal chance of recapture?
no one is “trap shy” or “trap happy”
what is meant by the population being closed?
no immigration or emigration
what are the factors that influence population size?
births, death, immigration, emigration
what is the first mathematical model for population growth?
N(t+1) = N + (births - deaths) + (immigration - emigration) all at time t
assumptions for the first population growth model
all individuals are identical (no age, genetic, or evolutionary differences)
birth and death rates are constant
no immigration or emigration
habitat is perfectly uniform
what are the modeling options if we are working with non-limiting resources?
if discrete generations -> geometric growth
is overlapping generations -> exponential growth
what is the modeling option if we are working with limiting resources?
logistic growth
how do populations grow?
in proportion to their size
what is the geometric growth model used for?
populations that vary due to seasonal changes in birth and death rates
many birds and mammals
what is lambda in geometric growth?
population growth rate constant
what value of lambda makes a population INCREASE?
greater than one
what value of lambda makes a population DECREASE?
less than one
what value of lambda makes a population STABLE?
equal to one
example of organism with discrete generations
emerald ash borer
new generation of adults each spring, all adults die that summer
no generational overlap
how do we calculation geometric growth for more than a year of change?
make lambda to the power of the year
5 year change -> N(0) * lambda^5
what are conditions in which geometric and exponential growth can occur?
when a new habitat or geographic range are established
exploiting temporarily favorable conditions
recovery after protection
loss of predator or competition
example of establishing a new habitat
killer bees on new continent
virtually unlimited resources
example of exploitation of temporarily favorable conditions
dandelion in empty lawn
can reproduce anywhere and has lots of resources
example of recovery following protection
whooping cranes
n = 22 -> 505
what are examples of organisms that use exponential growth models?
bacteria, many pest species, and humans
what does dN/dt mean?
instantaneous population growth rate
change in population over change in time
what does r mean?
per capita population growth rate
constant
what does r numerically represent?
birth rate - death rate
= ln(lambda)
what is r when population is increasing?
greater than zero
what is r when population is decreasing?
less than zero
what is r when population is stable?
equal to zero
how can we use the exponential growth model to calculation population size?
integrate growth over time