poulation and community dynamics Flashcards
communities
made up of populations
-consist of gene pools from all the individuals
population genetics
finding gene frequencies
what makes human populations different
-few offspring
-takes along time
-different enviromental effects
-human traits (body weight, size, intelligence)
population sampeling
-representative sample is takne
-trends and frequencies study
-applied to the whole
bigger size means…
more accurate
population
a group of simlar organisms
same PLACE same TIME
gene pool
sum of all the genes that occur in a population
-carries over generation to generation
gene frequencies are associated
with certain populations
species
group of similar organisms that can interbreed and produce fertile offspring
adaptation
a variation that allows an individual to survive better in a given circumstance
heritable adaptation
genetic not learned
evolution
any change in a frequency of a gene/allele
-exists in every population
difference of evolution vs adaptation
evolution is process
adaptation is whats happening
the five pillars of natural selection
-over production
-variation
-competition
-survival of the fittest
-origin of new species (speciation)
fitness depends on
enviromental demands placed on an organism
three types of selection
-directional
-stabilizing
-disruptive
directional (type of selection)
-one extreme is selected against
-fit to enviroment
-results in mean change
stabilizing (type of selection)
-both extremes are selected against (neither extreme)
-mean stays the same, just more narrowed
disruptive (type of selection)
-extreme ends are different enough to survive
-start to creat two new averages…. thus speciation
the hardy weinberg principal
frequency of alleles and genotype remain CONSTANT
-genetic equilibrium
HWP characterized by two competing factors
stability and variability
stability
balanced in equilibrium
variability
change and evolution
nonrevolving gene pool
can never be met in a natural population
dynamic genetic equilibrium
overallthe composition is unchanged even though there is still movement
equation requirements of HWP
-large breeding population
-random mating
-no mutations
-no migration
-equal viability
equilibrium
trait is not evolving
nonequilibrium
trait is evolving
p and q will change
evolutionary change
-changes in the gene pool (natural selection)
-gene pool or enviorment changes alleles (survival of the fittest)
things other than natural selection that causes the gene pool to change
-mutations
-genetic draft
-migration
-non random mating
genetic draft
completely random-not adaptive
-smaller populations tend to be more affected by this
-slow growing populations tend to drift less
speciation
process by which species originate
-so different they cannot interbreed
evolution
change in gene frequency
two types of speciation
geographic speciation and sympatric speciation
geographic speciation
physical barrier stops populations from interacting
sympatric speciation
reproductive/behavioral
symbiosis
close association between different organisms
mutualism
both organisms benefit
-bees and flowers
commensalism
one organism benefits the other is indifferent
parasitism
one organism benefits at the expense of the other organism
interspecific
organism competes with member of different species for some limited rescource
intraspecific
organism competes with a member of its same species for a limited rescource
the more similar the niche is
the more compeition between the organism
gouses principal
competition exclusion principal
-one will eventually be excluded
predator
consumes living organisms, benefiting itself but reducing survival of prey
prey
organism that is consumed
-often results in death or reduced fertility
avoidance mechanisms
passive (cammoflauge, warning colouration)
active (movement, physiological structure)
population dynamics
describing an organism
-kind of an organism
-size
-same place
-same time
population density
number of individuals per unit area
Dp = N/A
population change
overtime individuals reproduce, die or migrate
gr = changeN/changeT
population change negatives
decrease in population
natality
individuals born annually
mortality
individuals dead annually
immigration
movement into existing populations
emigration
movement out of existing population
change in N
(natality + immigration) - (mortality + emigration)
per capita growth rate
how much is the population growing
cgr = changeN/N
population growth patterns
as a species interacts with its enviroment and other species or members of the community patterns emerge
clumped (growth patterns)
individuals are grouped in clumps
-near water source = trees
random (growth patterns)
not real patterns
-not common in nature, dandelions in wind
uniform (growth patterns )
everything is evenly distributed
-happens with no competition
shelfords law of tolderance
too much or too little of an essential factor can both be harmful
law of minimum
various substences are required for growth
-lowest concentration will limit growth
limiting factor determines growth
only as fast as the slowest person
density factors
factors which affect a population as a result of its density
-disease
density independant factors
factors affecting population regardless of its density
-flood, fire, extreme temps
enviromental resistance
all factors that limit population growth
biotic potential
maximum number of offspring that will reach reproductive age
dynamic equilibrium
longterm balance in which populations remain relatively stable
-identifies mature ecosytems
carrying capacity
number of organisms an ecosystem can sustain given its current conditions
growth curves graph
showing changes in population overtime
X on graph
time
(independant/manipulated)
Y on graph
density/ number of organisms
(dependant/responding)
lag phase
slow inital growth
growth phase
exponential
-biotic potential/acceleration
stationary phase
factors that limit growth
-natality/mortality
equilibrium phase
population fluctuates around carrying capacity
death phase
mortality exceeds natality
