first set of slides 3/21 population ecology Flashcards
Scientific goal of ecology
understanding the factors that influence the size of populations
general principles of pop. ecology
dispersion/immigration/emigration/births/deaths
Practical goal of ecology
management of populations
the three tyeps of population management to achieve the practical goal
Increase population size
decrease population size
maintain population size
when do we need to increase population size
endangered species
decrease population size for what type of species
pests
maintain population size for
maintain & maximize sustained yield
ex. fisheries management
Population
group of individuals of same species in same area at same time
what makes a population what characterisitcs
-rely on same resources
-interact with each other
-interbreed together
populations are going to be influenced by
boundaries and size
factors that relate to pop. ecology is AKA dynamic biological process are influenced by (give all factors)
Density
Dispersion
Demographics
Density
number of individuals per unit area or volume
ex. 6 rabbits per acre
dispersion
pattern of spacing among individuals within the boundaries of the pop
demographics
factors that are going to affect birth and death rates in a population
what do Sampling techniques help figure out
density and total pop. size
3 different ways to do the sampling techniques for density
-Extrapolation from small samples
-An index of population size (e.g., number of nests will have a certain number of eggs in it )
-Mark-recapture method
why do ecologist do sampling techniques
because its impossible to count all organisms in a population you need to estimate
tag
marking organism so they are identifiable in sampling
process of Mark-recapture method
-Capture, tag, release a random sample of individuals
-after giving species time to Mix back into the population
- Capture a second sample, note how many of them are marked
Population size is estimated by a formula
formula for MArk recapture method
N=sn/x
N
total pop size
s
amount of individuals in first sample
n
amount of individuals in 2nd sample
x
how many individuals from 2nd sample where tagged
Density is when the environment is
adding & removing individuals from a population
adding to pop.
birth immigration
removing to pop.
death emmigration
Population of spacing ( patterns of dispersion)
how individuals are spaced out within the area they live
clumped
diff size clumps
ex. school of fish
random
common with plants and seed randomly placed
uniform
equally dispersed
population spacing provides
insight into the environmental associations
& social interactions of individuals in population
population spacing provides
insight into the environmental associations
& social interactions of individuals in population
population spacin will be influnced by
enviorment and social factors (factors will influnce spacing of individuals in the pop.)
clumped example for what influences it
influnced by enviormental facots per se resource availability
clumped patterns are most
most common
individuals that show uniformity usually are
territoriality
→ territoriality
they have there own bubble no other individuals in there area
uniformity dispersion may
result from direct interactions between individuals in the population
Demography
Factors that affect growth & decline of populations (birth/death rates)
life table
vital statistics & how they change over time
life tables how are they set up
breaks up age specific catagoriess
and look for survival patterns of a paticular organism
Population growth rates
are number of births in relation to the number of death
Factors affecting population growth rate
FYIish
sex ratio (how many females vs males)
generation time ( what age do females reprodouce)
age structure (how females at reproductive age in cohort)
cohort
means in a particular group
Survivorship curves
Graphic representation of life table
how to read Survivorship curves
The relatively straight lines of the plots indicate relatively constant rates of death; however, males have a lower survival rate overall than females.
3 types of Survivorship curves (look at slide 16 to undersand)
I. High death rate in post-reproductive years
II. Constant mortality rate throughout life span
III. Very high early mortality but the few survivors then live long (stay reproductive)
Reproductive Rates
are determined by
sexual reproduction and reproductive table (fertility schedule)
Sexual reproduction
concentrates on
females in a population
Reproductive table (fertility schedule)
is
age-specific summary of the reproductive rates in a population
