Chapter 5: Population Dynamics Flashcards
define carrying capacity and explain what happens if population density rises
amount of available resources such as food habitat and water.
when population density increases the have to compete for these resources as there is a fixed carrying capacity
what is population dynamics
how the ecological interactions (biotic and abiotic) affect fluctuations in population size
what is abundance in population dynamics
the density or population size in an ecosystem
what are 5 characteristics of r-selected species
large amounts of offspring little parental investment unstable environments small size mature quickly reproduce once low life expectancy type 3 survivorship pattern
e.g rats and mice
what are 5 characteristics of K-selected species
small number of offspring lot of parental investment high survivorship stable environment larger size mature slower reproduce multiple times high life expectancy type 1 or 2 survivorship pattern
e.g elephants and humans
what is population density and how is it measured for grass
population density is the amount of a species in a unit of area
grass is measured in dry mass as it is hard to distinguish separate organisms
population/area
what is the difference between total abundance and population density
total abundance is the amount of species in an area while population density is the amount of species/area
define population composition and give 3 examples
the different characteristics of a population
e.g age structure, sex ratios, fertility rate and offspring per female
what does distribution mean
where physically the different members of a species are located
calculate the growth rate as a number and percentage of a population of 1000 individuals, where every year, 100 individuals are born, 65 immigrate, 37 die and 25 emigrate
Growth = (b + i) - (d + e)
Growth = (100 + 65) - (37 + 25)
Growth = 103/1000 or +10.3%
name and explain the 3 types of distribution
Random: individuals are randomly spaced and are not effected by the location of other individuals
Uniform: individuals are evenly spaced therefore they are effected by the position of other individuals
Clumped: resulting from social behaviour such as schools or herds, the group makes up a population of it’s own
what is a quadrat and when are they used
a quadrat is a grid with a known area. Organisms are counted within the quadrat
used for species that don’t move much such as starfish or plant density in grasses
if 35 individuals have been counted in a 10 1m^2 quadrats
what is the average density and abundance of the species
population size
____________________________ x total number of quadrats
area
= (35/1) * 10
=3.5
what is a transect and when are they used
a transect is a line dividing community so that both size and density can be estimated
they are used for immobile or slow moving species
capture - recapture
in the first sample 20 individuals were marked, in the second sample 50 individuals were recaptured and of those 10 were marked. what is the total population
N=(M*n)/m
total population = (20*50)/10
total population = 1000/10
total population = 100
