Download Evolution Test Review

EVOLUTION
REVIEW FOR TEST
EXPLAIN DARWIN'S THEORY OF NATURAL
SELECTION EXPLAIN HOW ADAPTATIONS ARISE:
• Many of Darwin’s ideas came from exploring the Galapagos' islands and observing life
there.
• HERITABLE VARIATION: Exists in populations.
• OVER PRODUCTION OF OFFSPRING: More offspring than environment can
support.
• COMPETITION: For food, mates, nesting sites, etc.
• DIFFERENTIAL SURVIVAL: Successful traits= adaptations
• DIFFERENTIAL REPRODUCTION: Adaptations become more common in
population.
HOW DO VARIATIONS OCCUR?
• MUTATIONS: random changes to DNA, error in mitosis/meiosis and environmental damage.
• SEXUAL REPRODUCTION: Mixing of alleles, genetic recombination.
EXAMPLES OF NATURAL AND ARTIFICAL
SELECTION:
ARTIFICIAL
NATURAL
MILK QUANTITY
PEPPERED MOTH
COLE CROPS- FROM MUSTARD
DARWIN’S FINCHES
DOGS-WOLVES
WHITE LIZARDS OF NEW MEXICO
INSECTICIDE RESITANCE
EVIDENCES OF EVOLUTION AND AN
EXAMPLE
1. Artificial/natural selection
2. Fossils– ex) Horse, tetropod fish
3. Homologus organs: Similar structures, different functions and show ancestory
ex) Bones in a bat wing or our hands.
4. Genetic code: The DNA sample, blast it, analyze it.
5. Biogeography: Species in a geographic area tend to be more closely linked to each
other.
**We must also remember the continental drift and Pangaea.
DISTINGUISH BETWEEN HOMOLOGS AND
ANALOGOUS STRUCTURES- GIVE AN EXAMPLE
• Homologous: Similar and shows ancestry.
Ex– arm of a human, wing of a bat.
• Analogous: Similar trait, similar environment, doesn’t show ancestry.
Ex– Fins in fish compared to fins in dolphins. Another example is the
wings in squirrels compared to sugar gliders in Australia. (covalent evolution)
WHAT IS ENDEMIC SPECIES? GIVE AN
EXAMPLE
• Species that are found at a certain location but not found to be anywhere
else.
Ex) Marine iguanas in the Galapagos’ Islands.
5 THINGS THAT MUST BE TRUE FOR HARDY
WEINBURG FROZEN NO CHANGE SITUATION:
1. No genetic drift: Very large population size.
2. No gene flow: No migration in or out.
3. No mutation: No chemical change to DNA.
4. Random mating: no sexual selection.
5. No natural selection: Equal survival
KNOW THE HARDY WEINBURG EQUATION
AND PROBLEMS:
KEEP IN MIND FOR HARDY WEINBURG:
• Always start with q2 (the frequency of the recessive condition)
or q (the frequency of the recessive allele) depending on which
is given in the question.
WHAT IS MICROEVOLUTION?
• A small change within the species level.
MICROEVOLUTION CAUSES:
1. Natural selection & Mutations
2. Genetic drift
3. Gene flow (immigration and emigration)
2 TYPES OF GENETIC DRIFT: CHANCE
EVENTS
• FOUNDER: Small group splinters off and starts a new colony
ex) A branch with bugs gets blown to a new island.
• BOTTLENECK: Disaster reduces population to small number and then population recovers and expands again.
Ex) Cheetah
SPECIATION:
• This is the formation of a new species. It caused by isolation ,hybridization and polyploidy.
• Once isolation or separation occurs gene pools diverge because they cannot share their
new random variations with isolated individuals.
• Isolation then breaks down into geographic (allopatric) or reproductive (sympatric)which are still in the same area. The geographic isolation is the most effective when
forming a new species.
ISOLATIONS OR BARRIERS WHICH RESULT
IN NEW SPECIES:
1. GEOGRAPHIC: They are in different areas. Ex) Squirrel separated by canyon.
2. TEMPORAL: Species that breed during different times of the day. Ex) Spotted skunk.
3. HABITAT: Gardner snakes that live in water/land; as well as the tiger and lion.
4. BEHAVIOURAL: Unique behavioral patterns & rituals isolate species. Ex) Blue footed boobie.
5. MECHANICAL: More biological differences (don’t fit together.) Ex) Snails.
6. GAMETE: Egg and sperm do not join together. Ex) Sea urchin.
POST REPRODUCTIVE BARRIERS:
• Prevent hybrid offspring from developing into a viable, fertile adult.
• Reduced hybrid viability.
Ex) Salamander
• Reduced hybrid fertility.
Ex) Mule
• Hybrid breakdown.
Ex) Seeds from plants that have fertile themselves but the plants they grow are infertile.
**Remember that horse and donkey’s make mules, which are sterile.**
SECOND WAY TO GET A NEW SPECIES:
• HYBRIDIZATION
• In rare cases when there is ideal conditions maybe to due habit change, a hybrid does become
a real species.
Ex) Eastern Coyote came from the small Western Coyote and the wolf.
• Also, new species can be formed when there is an accident during meiosis and a whole extra
set of chromosomes form. It usually happens in plants.
Ex) Grey tree frog
MACROEVOLUTION:
• A drastic change, way above the new species level.
Ex) Feather on dinosaurs