what 2 pieces of data are needed to mathematically determine density
number of individuals per unit of area or volume
the number of individuals per unit of area or volume
density
pattern of spacing among individuals within countries of the population
dispersion
what is the impact of immigration on population density
increases
what is the impact of emigration on population density
decreases
what are the 3 types of dispersion patterns
clumped, uniform, random
what do clumped dispersion pattern tell us about the population and its interactions
aggregated in patches
what do uniform dispersion pattern tell us about the population and its interactions
evenly spaced; may result form direct interactions between individuals in the population
what do random dispersion pattern tell us about the population and its interactions
position of each individual is independent of others; in absence of strong attractions or repulsions
in what population statistic do demographers have particular interest? how is the data often presented?
birth and death rates; life tables
age specific summaries of survival patterns of populations
life tables
an age specific summary of the reproductive rates in a population
reproductive table
on what is the life history of an organism based
traits that affect an organism's schedule of reproduction and survival
what 3 variables form the life history of a species
when reproduction begins, how often the organism reproduces, and how many offspring are produces during each reproductive episode
single reproductive episode before death
semelparity
multiple reproductive cycles over the course of the life time
iteroparity
explain how 2 critical factors influence whether a species will evolve toward semelparity or iteroparity
survival rate of offspring and likelihood that adults will survive to reproduce again
what is the advantage of using per capita (over head) birth and death rates rather than just raw numbers of births and deaths
allows to calculate birth and death rates; the number of offspring produced per unit time by an average number of the population
what will the per capita birth and death rates be if a population is demonstrating zero population growth
equal
what does it mean for a population to be in exponential population growth
reached reproduction maximum (intrinsic rate of increase)
what are 2 examples of conditions that might lead to exponential population growth in natural populations
no predators, protected species, humans
maximum population size that a particular environment can sustain/support
carrying capacity
what are 6 examples of limiting resources that can influence carrying capacity
energy, shelter, refuge from predators, water, nutrient availability, suitable nesting sites
in the logistic population growth model, the per capita rate of increase approaches zero as the _____ is reaches
carrying capacity
if the carrying capacity is 1000 and N is 10, the term (K-N)/K is large. explain why a large value for (K-N)/K products growth close to the maximum rate of increase for this population
the environment can sustain more; rate will be high
density dependent selection; selection for life history traits that are sensitive to population; operates on population near density limit imposed by resources and strong competition
K selection
selection for life history traits that maximize reproductive success in uncrowded environments
r selection
a birth/death rate that DOES NOT change with population density
density independent regulation
death rate that rises wit population density; dependent on density of population
density dependent regulation
explain how negative feedback plays an essential role in the unifying theme of regulation of populations. does negative feedback play a role i both density independent and density dependent regulation?
density decreases population growth or else populations wouldn't stop growing; only dependent regulation
increasing population densities intensifies competition for declining nutrients and other resources, resulting in a lower birth rate
competition for resources
can limit population density- territory space becomes resource for which individuals compete
territoriality
impact may be density dependent if transmission rates of a particular one depends on a certain level of crowding in a population
disease
may be did if a predator encounters and captures more food as the population density of prey increases
predation
poisoning organisms
toxic wastes
population too dense0- causes problems with speciation
intrinsic (physiological) factors
what are negative feedback systems of density dependent population regulation
competition for resources, territoriality, disease, predation, toxic wastes, intrinsic factors
explain the importance of immigration and emigration in metapopulations
they link the populations
summarize human population growth since 1650
exponential population growth
when birth rates approach death rates
demographic transition
why do infant mortality and life expectancy vary so greatly between certain counties
reflect quality of life
