Name 5 cases of evidence for evolution
- Fossils
- Embryological Development
- Homologous structures
- Vestigal organs
- DNA
Define homologous structures
structures that are similar, but modified for different functions (whale fin, bat wing)
Define analogous structures
structures that have similar function, but different ancestry (wings: fly vs bird)
What is the book Charles Darwin wrote to propose natural selection called?
Origin of Species
What does the first postulate in the Origin of Species state?
organisms in a population vary in traits
What does the second postulate in the Origin of Species state?
traits can be passed on to offspring
What does the third postulate in the Origin of Species state?
more offspring are born than the environment can support.
What does the fourth postulate in the Origin of Species state?
offspring with traits that are helpful for survival and/or reproduction live and mate
Change in populations (heritable) traits over time is called what?
natural selection
What is a factor that makes a trait favorable
selective pressure
How equipped an organism is for survival and reproduction is called?
fitness level
Define adaptation
inherited traits that increase organisms’ chances of survival
What are the types of adaptation?
behavioral, structural, physiological, ornamental, coloration
Describe structural adaptations
physical structures that increase an organism’s fitness level
Describe coloration
camouflage or mimicry
Describe ornamental adaptations
structures that attract mates
Describe physiological adaptations
changes in the body to increase fitness level (ex. immunity)
Variations of a gene are know as _____.
alleles
All of the alleles in a population are known as ____ ____.
gene pool
The percentage of an allele in the gene pool is know as _______ ________.
allelic frequency
When allele frequencies do not change is known as _______ __________.
genetic equilibrium
What is stabilizing selection?
when selection favors an average variation
What is directional selection?
selection favors one extreme variation
What is frequency dependant selection?
The fitness level of a given trait varies depending on how many organisms in the population have that trait
What is sexual selection?
traits allow organisms to attract mates
Sexual selection leads to ______ _________.
sexual dimorphism
Define sexual dimorphism
differences between the sexes (size, color, etc)
Define Intrasexual Selection
Members of the same sex compete for mate
Intersexual Selection
Member of one sex choose mates, usually based on particular traits, ornaments or behaviors
What is genetic drift?
chance events that change allele frequencies
What are the two types of genetic drift?
bottle neck effect and founder effect
Describe the bottle neck effect
a sudden random event in the environment can cause the population size to drop
Describe the founder effect
a small portion of the populations is isolated and starts a new gene pool
Random changes in DNA can change allele frequencies. The term for this is _______.
mutations
Define speicies
organisms capable of interbreeding and producing healthy, fertile offspring
What is speciation?
the evolution of a new species
Speciation due to geographic isolation is called
Allopatric Speciation
Speciation despite living in the same geographic area is called
Sympatric Speciation
What is geographic isolation?
when a physical barrier divides a population, creating a new species.
What is reduced hybrid fertility
Two species can mate, but offspring are sterile
Behaviors such as different courtship rituals prevent two species from mating. This is known as what?
behavioral isolation
Morphological differences prevent species from reproducing. This is know as what?
mechanical isolation
The time line of breeding prevents species from mating. They mate during different times of day or seasons. This is know as what?
temporal isolation
Incompatible gametes prevent two species from mating. This is know as what?
gametic isolation
What is reduced hybrid viability
Two species can mate, but offspring are not healthy and die.
What is hybrid breakdown?
Two species can mate, but when the Hybrids have offspring, the offspring are either sterile or unhealthy ( no grandkids)
When change happens over time, this is called
gradualism
What evolution happens in quick bursts with long periods of no evolution in between, this is called
punctuated equilibrium
Species with a common ancestor become increasingly different. The term for this is called
Divergent evolution
Divergent evolution is also known as what?
adaptive radiation
Divergent evolution deals with _________ structures.
homologous
Unrelated species become similar. The term for this is called
Convergent evolution
Convergent evolution deals with ________ structures.
analogous
Species evolve in response to each other. This is known as
Co-evolution
o get the population to change the ____ ____ must change.
gene pool
What is the Hardy-Weinberg Equation?
Equation that shows the frequency of each genotype we would expect to see based on the allele frequencies in the population.
If the genotype frequencies in the actual population match the proportions in the equation, then this means what?
the population is in Equilibrium and not evolving
For a population to stay in equilibrium, five things must be true.
- No Mutations
- Random Mating (no sexual selection)
- No Natural Selection
- No Gene flow
- Very Large Population (no Genetic Drift)
Define allele frequency
the proportion of each allele found in the gene pool
Define gene pool
all of the alleles in a population
