Chapter 53 Ecology Flashcards
what is a population
group of individuals of a single species in the same general area
how are populations described
by their boundaries and their size
what is population ecology
how biotic and abiotic factors affect population density, dispersion, and demogrpahics
what is density
of individuals in a particular area
what is dispersion
pattern of spacing among individuals within boundaries of a population
what is demography
study of birth/death/ migration rates of a population over time
is it practical to count all individuals in a poulation
no
what do ecologists use to count population
sampling techniques to estimate densities and total populations
or the mark-recapture method
what is the mark recapture method
capture, tag and release individuals in a population
density is the result of what
interplay between processes that add individuals to a population and those that remove individuals
what is immigration
influx of new individuals from other areas
births increase populations
what is emigration
the movement of individuals out of a population, and deaths decrease the populaiotn
what is the pattern of dispersion determined by
spacing among individuals within the boundaries of a population
what can differences in spacing show
biotic and abiotic factors affecting individuals
what influences the spacing of indivuals
envirionmental and social factors
what are the 3 types of dsitribution
clumped, uniform
what is the most common pattern of dispersion
clumped
what is ciumped dispersion
individuals aggregate in patches
what is an example of clumped dispersion
insects and salamanders are clumped under the same log
what can influence clump dispersions
mating behavior and group predation or defense
what is a benefit of clumped dispersion
more individuals into groups can increase the effectiveness of predation or defense
what is uniform dispersion
evenly spaced, that results from direct interactions between individuals in the population
why do animals show uniform dispersion
antagonistic social interactions
what is territoriality
the defense of a bounded physical space against encroachment by other individuals
what is random dispersion
unpredictable spacing that occurs in the absence of strong attractions or replusions among indivudals or where key physical or chemical factors are relatively constant
what is demography
study of key characteristics of populations and how they change over time
what is a life table
summarizes the survival and reproductive rates of individuals in specific age-groups within a population
what is a cohort
a group of individuals of the same age from birth until all the individuals are dead
how do you build the life table
determine the proportion of cohort that survives from one age-group to the next
what is a survivorship curve
a plot of the proportion of numbers in a cohort still alive @ that age
what is the description of a type 1 survivorship curve
low death rates during early and middle life and a sharp increase in death rates later in life
where is type 1 found
in large mammals
type 2 curve
constant death rate over organisms life span
type 3 species
high death rates for the young and lower death rate for survivors
- produce a lot of offspring but can’t take care of them
what can be used to estimate the number of breeding females
direct counts, mark-recapture, molecular tools like DNA profiling
what is the exponential model
describes populaiton in an idealized, unlimited environment
what is the equation for population growth
dN/dt = rN
- N: pop size
the bigger the rate of constant….
the faster the rate of population
why do large populations grow faster than smaller ones
they have more individuals
population with larger r….
grows faster than one with smaller r
can a population keep growing and growing
no because there won’t be a lot of resources
what is the logistic population growth
pop growth approaches 0 as the populaiton size nears the carrying capacity
what is the equation for the logistics model
dN/dt = rN (K-N/K)
what shape does a logistics model have
sigmoid (s-shape)
what does life-history comprise
the traits that affect its schedule of reproduction and survival
what are the 3 components of an organisms life history
the age, how often the organism reproduces, and how many offspring are produced per reproductive episode
the age at first reproduction varies with
the type of species it is
