ch 16-17 Flashcards
why does genetic drift affect small populations more than large
larger variety of genes- genetic diversity increases
what factors can lead to evolution besides natural selection?
spontaneous mutations (change allele frequency)
genetic drift (change events after allele frequency-anything in nature-finches and cheetahs)
migration (gene flow-genes from lion to other group)
what are the assumptions of the hardy-Weinberg principle
evolution doesn’t change (genetic equilibrium)
what are the 2 equations used in the hardy-Weinberg principle
p+q=p^2+2pq+q^2=1
what is speciation
process by which species are formed
there has to be reproductive isolation
Describe the 3 types of isolation that can lead to speciation
Behavioral Isolation - Courtship rituals keep from interbreeding
Geographic Isolation - separated by physical barrier
Temporal Isolation - reproducing at different times
distinguish between adaptive and convergent evolution
adaptive- a single divides into many different types
convergent- 2 diff. objects look similar because of environment (shark and dolphin)
what is coevolution
when one organism evolves in response to another (predator, prey evolution) Ex: flowers and their pollenators
distinguish between gradualism and punctuated equilibrium
gradualism – when species evolve over time
punctuated equilibrium – only evolve when there are environmental changes
describe how molecular clocks can be used to measure how much time has passed sense organisms shared a common ancestor
they use mutation rates in DNA sequences to estimate the time that two species have been evolving independently
they can tell by silent mutations and comparing common ancestors
where do all the genes come from
copying genes that can occur due to unequal swapping of DNA during crossing over
modifications in existing genes
how can the hox genes lead to evolution
they determine which parts of the body develop and size
A change in them can result in changes in adult animals
describe Darwin’s job as a ship naturalist on the HMS Beagle
he documented organisms encountered on each stop
List the 3 types of natural selection and define them.
- Stabilizing Selection: environment chooses intermediate forms of a trait
- Directional Selection: environment chooses one extreme form of a trait
- Disruptive Selection: environment chooses both forms of a trait
what book did Darwin write
origin of species
what two theories did he describe in his book
– Natural selection
– Descent with modifications
List the 3 types of natural selection and what their graphs look like.
stabilizing – population after really tall
directional – camel humps
disruptive – original population medium, population after selection camel humps
what did Darwin conclude about the finches on Galapagos Islands
they ate something different on each island which affected the beak size
small and short – nuts
small and pointy – insects
explain the term “survival of the fittest”
Survival of the fittest is the members of a species with beneficial traits thriving in an ecosystem and those with undesired traits dying off
What are the 5 conditions that must be met to meet genetic equilibrium? (Hardy Weinberg Principle)
- random mating
- large population
- no migration
- no natural selection
- no mutations
What is genetic drift?
when a chance event causes allele frequency. AKA bottleneck effect. affects small populations more than large.
List evidence for evolution.
- Fossil Record
- Geographic Distribution
- Vestigial Organs
- Homologous Structures
- Analogous Structures
- Embryology
- Molecular Biology
What is Geographic Distribution?
Evidence for evolution dating back to Pangaea, when the continents were all one.
What are vestigial organs?
Structures that no longer serve a function like the appendix.
