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48 Cards in this Set
- Front
- Back
Directional selection
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ONE of the extremes of phenotype s are selected against
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Disruptive selection
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both of the extremes of phenotypes are selected for
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Stabilizing selection
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both extremes of phenotypes are selected against
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Example of directional selection
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industrial revolution, moths and lichen
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Example of disruptive selection
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Singer fish and sneaker fish; good singer, small testes/ bad singer big balls
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Example of stabilizing selection
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Birth weights - better to stay in middle
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Balanced polymorphism
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Different phenotypes exist at relatively stable frequencies over long term
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Sexual selection
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Traits that benefit reproduction will stay around even if detrimental
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Examples of sexual selection
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Deer antlers
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2 mechanisms of sexual selection
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male competition/female choice
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Differential parental investment
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female reproductive success limited by resources; male reproductive
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2 implications of the Darwinian paradigm
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females are choosy and males are less discriminating
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What are the evolutionary mechanisms (3)
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1. Genetic drift
2. Gene flow/migration 3. Mutation |
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Genetic drift occurs by what?
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bottleneck effect
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Founder effect
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group picks up and fragments off
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Gene flow includes migration of what?
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individual alleles
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Mutation is the only way to get new ?
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genetic material
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3 types of mutation
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1. silent
2. missense 3. frameshift |
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Define silent mutation
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no effect due to mutation
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Why does silent mutation show no effect?
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1. Alot of DNA is non-coded
2. redundancy built into system |
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Define missense mutation
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point mutations: change in letter at one point to mess everything up
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Define frameshift mutation
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mutation that causes entire frame to shift. caused by sun, smoking, naturally
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Evolution can only act on ____
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existing structures
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Define phylogenetics
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study of evolutionary relationships
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Define monophyletics
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all individuals in your group includes all points and comes from common ancestors
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Define paraphyletics
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when a group is left out
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What does "ontogeny recapitulates phylogeny" mean?
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We share traits with ancestors that define our chordates
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4 characteristics of a chordate
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1. notochord
2. dorsal hollow nerve cord 3. pharyngeal pouches 4. post-anal tail |
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pnedomorphosis
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retention of larval characteristics in adult form
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What type of rock are most fossils found in?
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sedimentary
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Endosymbiosis
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one bacteria engulfs many others and keeps them as slaves
ex. mitochondria |
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Name four tools for reconstructing phylogenies
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1. morphology
2. development 3. fossils 4. molecular data |
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What law states the simple steps are more likely than many, complex ones
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Parsimony
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What is an ancestral character and what is another name for it?
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Unites all species in cladogram
- Symplesiomorphy |
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what is the node?
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point of divergence
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Define synapomorphy
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derived characteristics
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Define homologous characteristics and example
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characteristics due to common ancestry
example: hair |
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Define analogous characteristics and example
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similar characters that arose independently
example: the wings of a bat are analogous to wings of a duck |
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Define polyphyletics
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group that includes multiple evolutionary lineages
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Define species
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A group of related organisms or populations in which genes are actually, or potentially, exchanged through interbreeding
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What are 3 problems with the definition of species?
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1. often based on morphology
2. what to do with asexuals 3. can't get a fossil to have sex |
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Define allopatric speciation
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seperated by physical barriers and evolve separately - if joined again can't reproduce
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Define sympatric speciation
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occurs due to reproductive barriers not physical
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Define pre-zygotic barriers
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habitat isolation - move to new area and develop new niches
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Post-zygotic barriers
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occurs by new alleles arising (mutation) - two species can't reproduce with each other
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Allopolyploidy
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Chromosomal duplication between two species
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Darwin believed in slow, gradual speciation
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gradualism
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Gould believed in what?
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Punctuated equilibrium - short periods of rapid change and long periods of stasis
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