Unit D Populations Flashcards
What is a gene pool?
All of the genes that occur in a certain population
What does P represent?
The frequency of gametes with the dominant allel
What does Q represent?
The frequency of gametes with the recessive allel
What is frequency measured between?
0 and 1
What must the total frequency of both alleles equal?
Must equal one
P + Q = 1
What must the frequency of genotypes equal?
Must equal one
P^2 + 2PQ + Q^2 = 1
What does P^2 represent?
The frequency of homozygous dominant genotype
What does Q^2 represent?
Frequency of homozygous recessive
And
recessive phenotype
What does 2PQ represent?
Frequency of heterozygous individuals
What does P^2 and 2PQ add up to?
Add to dominant phenotype (individuals that display dominant trait)
What are 5 conditions in HW frequency?
Large population
Random Mating
NO Mutation
NO Migration
NO natural selection
What does HW frequency mean?
If following conditions are constant, then the gene frequency stays the same after each generation…. Is said to be in genetic equilibrium or not evolving
What are eight factors that affect gene pool?
Natural Selection
Genetic Drift
Gene Flow
Non Random Mating
Bottle neck Effect
Founder Effect
Migration
Mutation
What is natural selection?
Indiviuduals best suited to the enviroment reproduce and gene frequenct changes to fit gene.
What is genetic drift?
Change in allel frequency due to chance —-> random
Natural selection is not a driving factor
What type of population is more susceptible to genetic drift?
Small populations
What is gene flow?
Movement of genes to one population to another
What is non-random mating?
When individuals choose mates based of gene/phenotype
What is a bottle neck event?
An event greatly reducing the population. Therefore reducing population leading to variation
Allel frequency changes
What is the founder effect?
Part of a population becomes isolated, new population looks like founders
What is Migration?
Various types:
Immigration: Indie moves into a population
Emigration: Indie moves out of a population
Results in change in allel frequency
What condition must be meet for movement to be considerd migration compatared to gene flow?
During migration an indie moves and stayes
Gene flow only the genes move
What is mutation?
Can result in new allels
Can change allel frequency
What are abiotic interactions?
Interactions that occur between nonliving factors
What are biotic interactions?
Between living organisims, can lead to cooperation or competition
What are the two types of biotic interaction?
Intraspecific
Interspecific
What are intraspecific interactions?
What does it lead to?
Between the same species ex: Mates, food, area
Leads to evolution (sexual selection)
What is interspecific interaction?
Between different species
Symbitoic relationships can develop - may led to evolution
What is Gause’s Principle?
The law of competitive exclusion
What is the law of competitive exclusion
Two populations cannpt occupy the same niche
Overtime one will become better suited and the other eliminated
What are the three types of symbiotic relationships?
Mutalism
Commensalism
Parasitism
What is mutalism?
Both organisms benefit
What is commensalism?
One benefits, the other is unaffected
What is parasitism?
One benefits other is harmed
What are defense mechanisms?
Adaptations that prey may employ that adds to the chance of survival for the species
What are mechanical defenses?
Examples include the presenence of armor in animals or thorns in plants - discourage predation and herbivory by discourgaing physical contact
What are two defense mechanism refering to body apperance?
Many species use body shape and coloration to avodi being deteced by predators.
Ex: Walking stick
Ex: Chameleon
Camo
How can coloration be used as a defense mechanism
As a way of warning predators that they are distastful/ posionous
Ex: Monarch Butterfly
Ex: Fire bellied toads
What are two behavioural defense mechanisms?
Warning calls
Playing Dead
What are warning calls?
Some animals sound the alarm when danger approaches. For example oxpeckers will give a loud warning call when predators get too close
What is playing dead?
When faced with danger, some aimals pretend to be dead. This type of adaptation is known as Thanatosis. Since most animals avoid dead or rotting animals
Is often very effective
What is succession?
Observed change in the structure of an ecosystem
What are the two types of succession?
Primary
Secondary
What is primary succesion?
Growth of life where it hasnt before (or where it has all died)
- Valcano
- Glacier retreating
Is typically primary succestion if bare rock is present
What is secondary succession?
Growth were life was before (forest fire)
more common
often in response to natural disaster
What is a pioneer organism?
In order for succession to occur, these organisms need to move into the area
Ex: Lichen/Moss
How are lichen pionner organisms
Lichen can bread down rock creating a layer of organic material (soil)
What is community structure?
Composition of a community, including the number of species in that community and their reletive numbers
What is species richness?
The number of different species in a particular community
What is species diversity?
A measure of community complexity. Is a function of both the numver of different species in the community and their relatice abundances
What is Simpsons Diversity Index?
Measure of how diverse a community is:
Diversity Index = 1-Sum(n/N)^2
What is a foundation species?
Create and define a community, modify the enviroment
What is a dominant species?
Species that are the most abundant or that collectivly have the highest biomass
What is a keystone species?
Species that disproportionately effect the community structre realtive to its biomass/abundance
What are the four factors that affect pop. growth?
Natality
Mortality
Immigration
Emigration
What is Natality?
Birth Rate (Increases pop. size)
What is mortality?
Death Rate (Decrease pop. size)
What is immigration?
Moving into an area (Increase pop. size)
What is emigration?
Exiting an area (Decrease pop. size)
What is change in population reperseted by?
DeltaN = (Natality + immigration) - (Mortality + Emigration)
What is a limiting factor?
Anything that limits population growth
Ex: Avaliable energy, Space
What does density dependent limiting factor mean?
Depends on the population size
What does density independent mean?
Doesnt depend on population size
What is biotic potential?
Highets possible growth rate (w/ no limiting factors)
What is carrying capacity?
Max organism the ecosystem can support
Describe a logistic or s shaped curve.
A logistic curve describes the growth of a population that starts out exponentially but slows as it approaches a carrying capacity due to limited resources.
Can you descrive a exponential curve?
Exponential Growth describes a type of growth where the rate of increase is proportional to the current population size, leading to a rapid, accelerating increase over time.
Describe growth rate.
Change in population over time
gr = Change in pop./Change in time
Describe per Capita growth rate
Per capita growth rate refers to the average rate of growth per individual in the population.
cgr = dN/N
Describe population density
Indies. per area.
Dp = N/A or N/V
What are the three types of population dissipation patters.
Random, clumping, uniform
When does a logistic growth curve occur?
As limits due to density-dependent and density-independent factors are imposed
As you near carrying capacity growth rate slows
What are the two types of populations?
Open and closed populations
What factors affect closed populations?
Only death and birth rate ex: Parks and Labs
What factors affect open populations?
Birth and Death Rate
Migration and emigration
What are R/K selection strategies?
Life strategies for an organism to reproduce
Briefly describe key characteristics of K-selected organisms
-Long lives
Few Offspring
Lots of parental care
Higher Survivorship
Stable environment (Climax community)
Close to carrying capacity
Often large (due to need for time and stable environment)
Describe R-Selected Organisms
Short Lives
Many offspring
Little parental care
Low survivorship
Unstable enviornment
What are population histograms?
Shows the percentage of a population at each age group
What does a population histogram show if its growing?
Wider base, higher % of young people
What does a population histograms show if it’s stable?
Base close to equal with older ages
What does a population histograms show if its declining?
Smaller base in relation to older people
