Unit 4 - Population Dynamics Flashcards
Hardy-Weinberg Principle
1) Large Population
2) Random Mating
3) No Net Mutations
4) No Migration
5) No Natural Selection
Population Distribution Patterns
1) UNIFORM: Area between individuals is equal, space for each individual is maximized. (Territorial species, made-made population).
2) RANDOM: Position of an individual is independent of others. Least common.
3) CLUMPED: Each individual lives close to neighbors, but clumped are spaced according to resources. Most common.
Open Population
Affected by birth, death, immigration, emigration.
Closed Population
Affected by birth and death only.
Changing Allele Frequency
1) Mutations
2) Gene Flow
3) Non-Random Mating
4) Genetic Drift
5) Natural Selection
Mutations
INHERITABLE: occurs in gametes, allele to be passed on. Can provide SELECTIVE ADVANTAGE to some.
Gene Flow
Movement of alleles between population due to MIIGRATION.
Non-Random Mating
Choosing mates based on physical/behavioral traits.
Genetic Drift
Chance event that changes allele frequencies. Usually affects small populations more than large.
–>FOUNDER EFFECT: a few individuals leave original population and form a new one.
–>BOTTLENECK EFFECT: a population size rapidly decreased, leaving a few individuals to repopulate.
Natural Selection
If some alleles have a selective advantage, the frequency of those alleles will increase.
Biotic Potential (r)
Highest possible cgr for a population with unlimited resources and ideal condition.
Determined By:
1) # of offspring per reproductive cycle.
2) # of offspring surviving to reproductive age.
3) Age of reproductive maturity.
4) Life span of individuals and the # of times they reproduce in their lifetime.
Carrying Capacity (K)
Maximum population an environment can sustain.
Exponential Growth
Population growing at biotic potential. J-curve. Closed population.
Logistic Growth
As a population grows, growth rate slows as it approaches K. S-curve. Open population.
Density-Dependent (Biotic)
Arise from population density.
–> Limited food/resources, competition, predation, paasition.
–>Affects big, dense population.
Density-Independent (Abiotic)
Affect population size regardless of size/ density.
–> Temperature, precipitation, natural selection.
All Limiting Factors
Environmental resistance.
–> Environmental resistance determines K, prevents populations from growing at biotic potential.
R-Selected
Takes advantage of favorable conditions. Reproduces close to biotic potential. Short lifespan. Reproductive at early age, man offspring per reproductive cycle. Little to no potential care after birth.
K-Selected
Spends more energy/resources on helping every offspring survive. Big reproductive cycle, few offspring per cycle. Long life-span, takes longer to reach sexual maturity. Potential care after birth.
Sustaintability
Meeting needs whiles keeping enough resources for the future.
Age Pyramids
Triangle: Population growing.
Rectangle: Stable population.
Inverted Triangle: Population declining.
Intraspecific Competition
Within the same species. Density dependent. Organisms avoid competition by dispersing offspring.
Interspecific Competition
Within different species. The more two species niches overlap, the more competition. Density dependent.
Invasive: Can outcompete and wipe out native species.
Defense Against Predators
Protective Coloration: bright colors signal danger to other species.
–> Camouflaged
–> BASTESIAN MIMICRY: An organism resembles another with defense mechanism, despite not having that mechanism.
–> MULLERIAN MIMICRY: Two organisms resemble each other, both have defense mechanism.
Symbiotic Relationships
(+/+): Both Benefit
(+/0): One benefits the other is unaffected
(+/-): One benefits, the other is harmed.
Primary Succession
Building an ecosystem from scratch, in an area with no soil.
PIONEER SPECIES: grow on rock, break down to form soil and eventually forms climax community.
Secondary Succession
Repopulating an area after a disturbance. Can reach climax community faster than primary.
