Survey methods and Structure Flashcards
Absolute Population size
Actual abundance
Relative population size is the
number of individuals in one time or place relative to another
ie # of cougar tracks in one area
why is relative population size hard to interpret
because animals may be more active in one area than another
Quadrat based methods
what is it?
what are they best used on?
-best used on immobile organisms
-sample portion of an area and draw inferences abt larger habitat
Line Transect method
what is this commonly used on
-observation of individuals from a transect line
-walking along a line and observing shit
bird studies
Mark-recapture
-capture and marking organisms, releasing them, cathing them again later
-used for mobile organisms
Mark recapture formula
proportion marked in the first sample should equal the proportion marked in second sample
(#marked 1st catch* total # of second catch)/ (# marked 2nd catch)
Species distribution modeling
-predicts species distribution based on conditions it is known to occupy
-incorporatesinfor abt niche
-use to decipher changes in distributions due to climate change
-lots of citizen science
Population Structure is the description of
Demographic Characteristics of pop
survival, age, sex distribution, and dispersal
what is a fundamental descriptor of population
pattern of survival and mortality among individuals
life tables
-bookkeeping device to track birth and death in populations
survival can be estimated from:
life tables
Survivorship Curve:
what is it based on
graphic summary of pattern of survival in a population, based on life table data
3 ways to estimate patterns of survival
- cohert life table
- static life table
- Age distribution
Cohert life table
identify individuals (cohort) born at same time and keep -records from birth to death
-provides MOST accurate data, however VERY DIFFICULT to keep track
Static life table
what does it require
-Record age at death of large # of individuals over narrow window in time
-requires accurate estimate of age at death. Through dissections or counting growth rings etc.
Age Distribution
what does it assume
Calculate difference in proportion of individuals in each class
-assumes differences in numbers from one age class to next due to mortality
-Simplest method
Major assumptions of age distribution
-population size must not change, and NO dispersal
-very strict for a natural population
what type of scale is survivorship curve is type 2?
oh yes i know this answer, it is a logarithmic scale
what type of scale is survivorship curve 1 and 3?
they are arithmetic scales
Type 1 survivorship curve
- high survival of young
-most individuals survive to old age
annual plants, humans, rotifers, large vertebrates
Type 2 survivorship curve
-chance of surviving remains constant throughout life
birds, water snakes
Type 3 survivorship curve
-High death rates of young. those that reach adulthood survive well
-fish, trees, and other plants
What does age distribution of a population reflect?
-the history of survival, reproduction and growth potential
- by studying can make predictions about future
what does lots of young in a population mean?
population is stable, young individuals to replace dying ones
What does a population dominated by middle and older trees mean?
the decline of young mfs means a decline in population as not as many mfs to replace
Sex ratio
relative frequency of each sex type in pop
can change depending on relative fitness of diff sex
in species with 2 sexes, most pops sex ratio near 1:1 why is this?
because if it is off of 1:1, then one sex has higher chances of reproducing, so it will level off
