Population Dynamics Flashcards
p + q =
1
5 things to maintain hardy weinberg equilibrium
- large population: losing an individual’s genes (genetic drift) has less of an effect on large populations that small ones
- random mating: mating by individuals is not determined by pheno/genotypes
- no mutations: changing alleles present in the pool
- no migration: movnt of alleles in/out (gene flow)
- no natural selection: no env’t factor favoring one genotype over another
p=
frequency of dominant allele in population
q=
frequency of recessive allele in population
p^2
% of homozygous dominant individuals (trait)
q^2=
% of homozygous recessive individuals (trait)
2pq=
% of heterozygous individuals (trait)
mutation (agent of gene pool change)
random changes in genetic sequences. A source of genetic variation for natural selection
gene flow (agent of gene pool change)
movement of individuals (alleles) from one population to another (immigration/ emigration)
non-random mating (agent of gene pool change)
preferred phenotypes, increases those genotypes in pool
Genetic drift (agent of gene pool change) 2 types
change in allele frequency in a breeding pop. due to random events. Small pop. may loose certain alleles (lack of mates, predation, etc): will have a greater impact on smaller groups
- Founder Effect: a pop (gene pool) that’s formed by a small group of individuals (founders) that carry a representation (limited gene pool) of the original pop’s genes
- Bottleneck Effect: quick reduction in pop (starvation, disease) causes a “bottleneck”, surviving pop produces less variant offspring
natural selection (agent of gene pool change)
some individuals are better able to survive & reproduce than others. The offspring carry the successful genes
speciation and 2 types of isolation
formation of a new species (lack of production of viable offspring)
- Geographic isolation
- Reproductive isolation
geographic isolation
separation of individuals of the same species by physical barriers (ie sea, mountains)
- gene flow between 2 groups stops
- eventually individuals of one pop. can no longer interbreed with the other
reproductive isolation
organisms in a pop can no longer mate to produce offspring, even though they live in similar envt
ex mutations not shared, mating seasons differ, reproductive organs
relationship where both organisms (of different species) benefit
mutualism
eg. bees and flowers
commensalism
one organism benefits, the other is unaffected
eg. shark and remora
parasitism
one organism benefits and the other (host) is harmed
eg. tapeworm and buffalo
intraspecific competition
between members of the same species
interspecific competition
between members of different species
6 defense mechanisms (against competition and predation)
- camouflage
- mimicry
- biochemical (bitter/ toxic)
- armor (thorns)
- warning coloration
- behavioral
succession
process of replacement of organisms by a more successful group following a disturbance
pioneer species re/colonize (moss) –> intermediate/ seral species more successful and replaces pioneers –> community stabilizes when climax (most successful) community presides (hardwood trees)
primary succession
occurs where there was no pre-existing soil
- glacier retreat, volcanic eruption
secondary succession
occurs where soil has pre- existed before disturbance
ie fire/ earthquake
carrying capacity (K)
the amount of individuals an envt can support based on resources etc
environmental resistance
all the limiting factors that keep a pop from growing at its biotic potential, and determine the carrying capacity
biotic potential
the max rate at which a pop can increase its size
density dependent
effect increases as population increases
tend to be biotic
ie food suppy, disease, competition
density independent
effect is the same regardless of pop size
tend to be abiotic
ie climate, natural disaters
4 phases of carrying capacity graph
- lag phase (slow/ no growth)
- growth phase: exponential rise in pop
- plateau/ stationary phase: climax community
- decline phase: resources lack
uniform pop distribution
order/ territories: competiton for resources
random pop distribution
no order, attraction, or repulsion among members (lots of resources)
clumped pop distribution
order; grouped in patches around an attraction
ie. watering holes/ to protect from predation (bison)
J-shaped curve graph (exponential or unrestricted growth)
r selected species (closed pops)
S shaped graph (logistic or restricted)
K selected species (open pops)
characteristics of r selected species
J shaped graph - small bodies - numerous - many offspring, no care for offspring - high mortality rate - reach reproductive age early - short life span eg bugs/ bacteria
characteristics of K selected species
S shaped graph - large bodies, fewer in #s - few offspring, which require care - low mortality rate - reach reproductive age late, long life span eg mammals, reptiles
