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What are the major components of climate?
- 1. Light
- 2. Temperature
- 3. Winds
- 4. Ocean Currents
- 5. Percipitation
How does temperature vary with latitudes?
There tends to be a higher level of solar radiation near the equator, and lower levels near the poles
How does the tilt of the Earth's axis affect temperature?
To show that an abiotic factor limits distribution of an organism:
- 1.Determine which stage of the life
- cycle is most sensitive;
- 2.Identify the physiological
- tolerance range for this life-cycle phase;
- 3.Show that the range of the abiotic
- factor where the organism lives is permissible for sites within the geographic
- range, and lethal for sites outside of the geographic range.
What is evolution?
the change in allele frequency in the population from one generation to the next.
What is adaptation?
An inherited characteristic (trait) of an organism that enhances its survival and reproduction (fitness) in specific environments. (Angry birds and camouflage)
What are the 4 mechanisms of evolution?
1. Mutation: Random change in nucelotide sequence of a gene
2. Migration/Immigration: Individuals move into or out of a population, moving their alleles with them
3. Genetic Drift: Change in allele frequency due to random chance
4. Gene Flow: Differential survival and reproduction reflecting individual interaction with the environment
3 requisites for evolution by natural selection?
- 1. phenotypic variation
- 2. heritability
- 3. trait must increase fitness.
What are the 3 types of natural selection?
- 1. Directional: Mean moves toward one extreme value
- 2. Disruptive: Mean is at intermediate values
- 3. Stabilizing: Mean moves toward both extreme values.
Constraints on adaptation?
- historical factors - lack of genetic variation
- genetic factors - mutation/immigration can add maladaptive alleles
- environmental factors - best phenotype may change variable
- physical constraints
General steps in speciation?
- 1. Geographic (or other) barriers prevent populations from interbreeding.
- 2. Independent evolution of isolated populations leads to reproductive barriers
- 3. If populations are unable to interbreed, then speciation is complete
What is Reproductive isolation?
Reproductive barriers prevent two individuals from distinct species from interbreeding to produce viable and fertile hybrid offspring.
Allopatric speciation vs Sympatric speciation
- Allopatric speciation: Physical separation of a population interrupts gene flow. Genetic
- divergence results from mutations and genetic drift.
- Sympatric speciation:No physical barriers! Two groups encounter each other, but do not
What are 2 types of reproductive barriers?
1.Prezygotic barriers: prevent the sperm from fertilizing the egg
2.Postzygotic barriers: follow successful fertilization and reduce hybrid fitness
Types of prezygotic barriers?
- •Temporal isolation: Mating/flowering occurs during different seasons or at different times of day
- •Habitat isolation: Populations
- live in the same area, but in different habitats and so do not meet
- •Behavioural isolation: Little or no sexual attraction exists
- between populations
Types of postzygotic barriers?
- Mechanical isolation
- Gametic isolation: Only sperm from the same species is able to successfully fertilize the egg
- Hybrids have reduced viability
- Reduced hybrid fertility
- Hybrid breakdown
Adaptation may result in rapid speciation if a group of organisms diversifies in different environments
Ectothermy vs Endothermy
Ectothermy: animals acquire heat from external environment. Ectotherms regulate body temperature through behavioural or physiological means
Endothermy: animals control their own body heat through metabolism. Endotherms regulate temperature through changes in metabolic rate, evaporative cooling, skeletal muscle contractions (fur, fat, feathers prevent heat loss)
Advantages of Ectothermy?
- 1.Lower metabolic requirements; can live in environments where food or O2 is scarce
- 2. can withstand more fluctuation in body temperature
- 3. Can be smaller
Disadvantages of Ectothermy?
- 1. movement is restricted by external
- 2. cannot survive in extreme climates
- 3. Upper limit on body size
Advantages of Endothermy?
- 1.Less affected by external temperature
- 2.Can live in colder habitats
- 3.Muscles can provide more sustained activity
Disadvantage of Endothermy?
- 1.Energetically expensive; endotherms require a lot of food and O2
- to maintain temperature
- 2. Lower limit on body size
Life History; Ideally an organism would:
- 1. Reproduce asexually
- 2. Reproduce asap
- 3. Reproduce continuously
- 4. Produce many offsprings.
When to mature?
(success small/success large) = mating success x survival to maturity x breeding lifespan
A slight increase in brood size would mean that semelparous organisms have higher fitness than iteroparous organisms.
When will semelparity be favoured?
Semelparity will be favoured when adult survival is low/uncertain and/or juvenile survival is high.
What are the 3 patterns of dispersion?
- 1.Random: Occurs when no attractive or repulsive forces between individuals. Environment is relatively homogenous (ie. Consistent in biotic and abiotic conditions.)
- 2. uniformand
- 3. clumped
What are the 3 assumptions of mark-recapture?
1.Marked and unmarked individuals have equal probability of capture
2.Marked individuals are not more likely to die than unmarked individuals
3.Marked animals are not lost or overlooked
3 types of survivorship.
- Type I: high survival until physiological maximum is reached
- Type II: relatively constant mortality over lifespan
- Type III: high mortality in juvenile stages
Life/Fecundity Table Variables
- •x = age/class
- •nx = number alive at age x
- •lx = proportion surviving at start of interval x
- •dx = number dying from x to x+1
- •qx = death (mortality) rate from x to x+1
- •bx = mean number of females born to each female in age group x