Evolution - Unit 8 Flashcards
What was Lamarck’s theory of Evolution?
Lamarck hypothesized that species evolve through use and disuse of body parts and the inheritance of acquired characteristics (giraffe example)
What are the two main ideas about evolution that Darwin came up with?
- Descent with modification explains life’s unity and diversity
- Natural selection is a cause of adaptive evolution
What is artificial selection?
Selecting and breeding individuals with desired traits
What two observations did Darwin come up with about artificial selection, natural selection, and adaptation?
- MEMBERS OF A POPULATION OFTEN VARY IN THEIR INHERITED TRAITS
- ALL SPECIES CAN PRODUCE MORE OFFSPRING THAN THE ENVIRONMENT CAN SUPPORT, AND MANY OF THESE OFFSPRING FAIL TO SURVIVE AND REPRODUCE
What two inferences did Darwin come up with about artificial selection, natural selection and adaptation?
- Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals
- This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations
Overproduction of offspring leads to _____.
competition
Adaptations must be _____.
heritable
Darwin never used the word evolution he used the phase, _______.
Decent with modification
What does the phrase Decent with Modification refer to?
The phrase refers to the view that all organisms are related through descent from an ancestor that lived in the remote past
What is a Gene Pool?
all of the alleles of all of the individuals in a population
What is Allele Frequency?
a measure of how common an allele is in a population.
How do you calculate the allele frequency?
Calculate by taking (# of specific allele)/(total number of alleles in population) (part/whole)
Where does genetic variation come from? (2 places)
- Mutation
2. Recombination
What is recombination?
Crossing over during Meiosis.
What is microevolution?
observable change in allele frequency of a population over time (is small scale)
What is Directional Selection? (Natural selection)
An “extreme” phenotype that was once rare is now more common. The “mean” value of the trait shifts over towards the more advantageous trait.
What is stabilizing selection? (Natural Selection)
The intermediate (“average”) phenotype is favored. Extreme phenotypes may be lost all together. (decreases genetic diversity)
What is Disruptive Selection? (Natural Selection)
Occurs when both extremes are favored, and intermediates are selected against
What are the 3 other mechanisms of Evolution besides natural selection?
- Gene Flow
- Genetic Drift
- Sexual Selection
What is gene flow?
The movement of alleles from one population to another that increases genetic variation.
What is genetic drift?
Genetic drift is a change in allele frequencies due to chance (Random)
Which populations are more affected by genetic drift? Big or small?
Small populations are more affected by genetic drift
What are two causes of genetic drift?
Two causes of genetic drift are the Bottleneck Effect and the Founder Effect
What is the Bottleneck Effect?
genetic drift that occurs after an event greatly reduces the population size (e.g. overhunting)
What is the Founder Effect?
genetic drift that occurs after a small number of individuals colonize a new area
What is sexual selection?
It is certain traits increase mating success
Usually its a ____ selecting a _____.
Usually its a female selecting a male. (as u should queen)
Traits what become exaggerated because of sexual selection are not always best for survival. True or false?
True
What are Transitional Fossils?
Transitional Fossils exhibit traits common to both the ancestral group and the group that descended from it.
What is a Homologous structure?
Homologous structures are similar in structure but different in function.
Are Homologous structures evidence of a common ancestor?
Homologous structures ARE evidence of a common ancestor.
What are Analogous Structures?
Analogous structures have a similar function, but a totally different structure.
Are Analogous Structures evidence of a common ancestor?
Analogous structures are NOT evidence of a common ancestor.
What are Vestigial structures?
Vestigial structures are remnants of organs or structures that had a function in an early ancestor. (like whales hip bones)
What is Convergent Evolution?
evolution towards similar characteristics in unrelated species
What is Divergent Evolution?
related species evolve in different directions and become increasingly different
What is Coevolution?
two or more species evolve in response to changes in each other
What is an Evolutionary arms race?
coevolution can occur in competitive relationships
predators and prey
What is Adaptive Radiation?
When many new species arise from a single common ancestor.
What is Behavioral isolation?
Differences in courtship rituals or other behaviors prevent two species from attracting mates
What is Geographic isolation?
Two populations are physically separated by a barrier like a river, mountain, etc and cannot interbreed
What is Temporal isolation?
Differences in mating times/seasons prevents two species from interbreeding
