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40 Cards in this Set
- Front
- Back
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Define Evolution
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A change in Allele frequencies over time
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What are the mechanisms of evolution?
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1. Selection
2. Genetic Drift 3. Migration |
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What are the three types of selection?
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Artificial, Natural & Sexual selection
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What is heritability and how is it measured?
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Heritability (h2) is measured as the slope of a regression line between the parent and offspring values for a trait.
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What is Artificial Selection?
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Artificial selection is when humans decide which individuals genes are passed on to offspring.
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What is Sexual Selection?
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Sexual selection is individuals who experience the most matings will reproduce more.
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What is Natural Selection?
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Natural selection is when nature decides which individuals will reproduce more.
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What is Genetic Drift?
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Genetic Drift are changes in allele frequencies due to change.
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Name 2 types of Genetic Drift and define each.
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The Founder Effect: when a subset of a population begins somewhere else reducing the amount of variation in the genes.
The Bottleneck Effect: A disaster reduces the number of individuals to a small subset. |
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Why are males the competitive sex and females the choosey sex?
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Because females invest much more energy into reproduction than males.
Ex: Egg size, raising offspring, caring for offspring. |
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What is fitness?
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Fitness is the number of copies of genes, which are passed on to future generations.
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What are the modes of selection?
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Directional, Stabilizing and Disruptive
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What is the evidence that evolution is responsible for diversity of life on Earth?
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1. Artificial Selection : diversity in dog breeds.
2. Homology among skeletons. 3. Fossils |
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How is the age of rock determined?
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The age of a rock is determined by using radiometric dating.
radiometric dating: calculating the proportion of atoms that have decayed. |
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What is a species?
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A species is a group of organisms that have the potential to breed with each other and produce live, fertile offspring.
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What are the necessary steps for speciation to occur?
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The necessary steps are:
a) reproductive isolation of populations. (no cross-mating) b) Genetic divergence between isolated populations. |
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What is Allopatric Speciation?
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Allopatric speciation is when reproductive isolation occurs due to geographic barriers.
Genetic divergence occurs to genetic drift |
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What is Sympatric Speciation?
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Sympatric speciation is when there is reproductive isolation due to differences in mating behavior.
Mate in different parts of habitat. |
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Under what circumstances does stasis occur?
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Stasis occurs when an organism remains unchanged for long periods of time because there is a lack of genetic variation, stabilizing selection, constant environment.
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Under what circumstances does adaptive radiation occur?
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Adaptive radiation is rapid diversification followed by long periods with less change.
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What is punctualism?
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Punctualism is the idea that evolution is quick followed by times of no change.
"Evolution by JERKS." |
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What is gradualism?
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Gradualism is the idea that changes in evolution are continuous and gradual.
"Evolution by CREEPS." |
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What is the endosymbiont hypothesis?
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The endosymbiont hypothesis states that certain organelles, such as Mitochondria and Chloroplasts came from other micro-organisms when merged with a prokaryote.
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How do we interpret evolutionary trees?
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Evolutionary trees are interpreted by:
1. Assuming the simpler explanation is more likely than a complex one. 2. Choose a set of traits to compare among the individuals. 3. Construct all possible trees. 4. The most likely tree will be the one with the fewest genetic transitions. |
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How do we determine which possible evolutionary tree is the most parsimonious?
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By counting the number of genetic transitions. The lower the number, the more likely it is to be true.
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When and where did modern humans evolve?
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Modern humans evolved ~6 million years ago in Africa.
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What is the relationship btw humans and chimpanzees?
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Humans and Chimpanzees share a common ancestor from ~ 6 m.y.a.
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What are the different mating systems which animals exhibit?
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Monogamy, Polyandry & Polygyny.
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Under what circumstances does Monogamy evolve?
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Monogamy evolves when male fitness increases if he helps raise the offspring.
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Under what circumstances does Polyandry evolve?
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Polyandry evolves when there is high food abundance and precocial care of the young.
precocial = born in an advanced state, able to mostly provide for itself. |
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Under what circumstances does Polygyny evolve?
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Develops when males monopolize mating opportunities.
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What are the types of Polygyny?
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1. Female Defense
2. Resource Defense 3. Scramble Competition 4. Leck |
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What is Female Defense Polygyny?
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Females are in clusters, and males compete for these clusters.
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What is Resource Defense Polygyny?
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Females are distributed based on resource availability. Males defend territories with resources and wait for females.
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What is Scramble Competition?
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When both resources & females are scattered. Males compete with other males to receive access to females.
Selects for persistence, endurance and perception. |
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What is Leck Polygyny?
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Males display near each other on small territories and females choose mate.
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What is Polygamy?
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When one has multiple mates.
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What is a group selectionist argument?
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The argument is that an individual of a population will sacrifice their own reproductive success for the good of the group.
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What is wrong with these types of arguments?
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Aniamsl behave for the good of themselves, not the species.
Selection occurs at an individual level, rather than at the level of the group to which it belongs. |
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Under what situations would we expect animals to behave altruistically towards relatives and non-relatives?
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They'll behave altruistically towards relatives when it increases their fitness.
They'll behave altruistically towards non-relatives when/if it is a form of reciprocal altruism. "You help me now, I'll help you later." - VERY RARE. |
