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60 Cards in this Set
- Front
- Back
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Thomas Malthus
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-Died before origin
-Noted that more offspring are born than can survive -There are "checks" that cause deaths-->Darwin's Natural Selection |
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Lamarck
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Inheritance: If parents changed, the future child would be affect-->acquired trait
-Was a victorian naturalist (environment effected spp, studied spp diversity; God created the spp) |
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James Hutton and Charles Lyell
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-Lyell continued Hutton's ideas
-Observed rock layers, giving Earth a much older age-->dating scheme |
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Wallace
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-Sent his manuscript to Darwin, which most likely pushed Darwin to publish
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4 Components of Evolution by Natural Selection
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1. There is variation amongst individuals-->phenotypic variation
2. the variations in individuals are inherited (some) 3. More individuals are born than can survive to reproduce 4. Some variants survive and reproduce at higher rates than others. OUTCOME: The composition of the population changes from one generation to the next |
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Types of Mutations
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-point (substitution) mutation
-insertions and deletions (indels) -chromosome inversions -gene duplication -genome duplication |
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Point (substitution) Mutation
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One nucleotide changes to another
-typically during replication -creates new alleles. Synonymous (doesnt change amino acid it codes for) vs. nonsynonymous (potentially changes amino acid coded for) |
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Insertions/Deletion Mutation (Indels)
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-adding or deleting a set of nucleotides (other than a multiple of 3-->frame shift-->loss of function)
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Chromosome Inversion
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-a rearrangement in which a segment of a chromosome is reversed end to end
--crossover problems |
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Gene Duplication
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-Duplicating a region of DNA, usually by crossover in meiosis due to misalignment
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Genome Duplication
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-mostly seen in polyploid plants
-addition of a complete set of chromosomes |
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Processes that Cause Changes in Allele Frequency
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-Mutations
-Drift: increase freq. of one phenotype to another randomly -Selection -Migration |
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Why is there variability if natural selection moves to stop that?
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-phenotypic plasticity
-neutral theory: differences do not have an effect on survival -balance theory: multiple alleles can exist under normal selection -selection changes over time and space (never long enough to eliminate variation) |
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Frequency-Dependent selection
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rare phenotypes do well while common phenotypes decrease
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Overdominance
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when the heterozygote is the most fit genotype
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Underdominance
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When the heterozygote is the least fit phenotype
-unstable -one allele will get lost as the other becomes the only one |
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gene flow
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migration, transfer of gametes that effect allele frequency
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Things effecting gene flow
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-how many new individuals are introduced
-how different new genes are from current population |
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Genetic Drift
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-Change in the frequency of a gene in a population at random
-Totally random |
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Mechanisms of Drift
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-persistently small populations
-bottleneck: an event that reduces the genetic variation in a population -founder effect:loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population |
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Short Tandem Repeats
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-Usually noncoding DNA- marks of variation
-More different copies, more different alleles are -internal measure of genetic variability |
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Anisogamy
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-refers to the size of gametes being unequal
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Primary Sex Traits
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internal organs
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Secondary Sex Traits
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come about from sexual selection
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Theoretical Batemen Gradient
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the theory that females almost always invest more energy into producing offspring than males invest, and therefore in most species females are a limiting resource over which the other sex will compete
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Intrasexual Selection
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-male-male competition in most cases
--combat, resource defense, sperm competition |
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Intersexual Selection
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-mate choice by females in most cases
--costs: lose time, energy involvement, risk of being eaten --Direct and indirect benefits |
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Direct Benefits of Intersexual Selection
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-benefits females
-parental care -nuptial gifts -territory access -->replenishing females cost for having offspring |
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Indirect Benefits of Intersexual Selection
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-benefit offspring
-mostly genetic benefits -->good genes, compatible genes, sexy sons |
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Compatible Genes
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-the best gamete for a female depends on her own genotype
-->female's preferences depend on their genotypes -->There is not always a universally good or bad male |
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Zahavi Handicap Hypothesis
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-signals have to be costly or they wouldn't have a meaning: can afford to have signals/ornaments because youre strong enough to deal with the cost
-->informative for the female |
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Runaway Selection
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-modeled by Fisher
-stronger preference for traits creates more intense trait and so on -genes for female preference and male trait are linked |
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Pre or Post-copulatory Sexual Selection
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-sperm competition
-->in some species, males may remove/cause ejection of sperm from female-->females may develop traits to help determine which male sperm succeeds |
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Multiple Matings
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-in some species, having multiple mates can increase litter size
-->insurance of fertilization -->more mates=more genetic variation -->could decrease infanticide |
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Extra-Pair Parentage
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-social monogamy but genetic polygamy
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Rare-sex Advantage
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If one sex is rare in a population, there is some pressure to have offspring of that sex
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Correlated Expression
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(darwin)
-why males and females may both exhibit an ornament. -->females simply inherited the trait, only selected for in males -undermines idea of ornaments being costly-->natural selection should select against it for females if no benefit SO females and males must BOTH be sexually selected in this case |
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Darwin-Fisher Theory
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-see ornaments in one sex and not the other in monogamous situations because:
--differences in female fecundity --better conditioned females arrive first |
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Biological Species Concepts
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species defined by reproductive isolation
--cant test on allopatric populations --can't apply to fossils --not relevant to asexual organisms |
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Morpho Species Concept
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define species based on how they look
--can apply to fossils/asexual organisms --differing ideas of what is different (threshold) |
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Phylogenetic Species Concept
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the populations of each species should share a common ancestor
--would probably double number of species |
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Phyletic Gradualism
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a model of evolution which theorizes that most speciation is slow, uniform and gradual
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Punctuated Equilibrium
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a model of evolution in which change is rapid and tied to speciation events
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Allopatric Speciation
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geographical isolation that interrupts gene flow between two groups
1. Isolation (dispersal: some leave and go somewhere else; vicariance: a change in the landscape causing separation) 2. Divergence 3. Secondary Contact |
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How divergence occurs in allopatric speciation
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-drift
-natural selection -sexual selection |
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Allopatric Speciation--Secondary Contact
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-isolated population comes back into contact
-it species has not been separated for a long time, drive will probably not cause them to fully diverge. -If not totally different, interbreeding can occur and merges groups back together -if more diverged, hybrids wont do well |
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Pre-zygotic Isolating Mechanism
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-hybrids do not do very well
-can lead to evolution of pre-zygotic isolating mechanisms |
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Pre-zygotic Isolating Mechanism
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-arise if you discriminate: will have more viable kids
--mating location, courtship, behavior, physical incompatibility. |
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Sympatric Speciation
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isolation despite close contact
--need to interrupt gene flow between spp in same space |
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What happens to lineages over time?
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1. extinction
2. change/branch 3. persist |
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Why are some species unchanged over long periods of time?
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-little variation
-stable niche -zigzag evolution: change one way, then another, then back, but no net change. |
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Accepted Definition of a Living Organism
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ability to store information and do something
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Ribozyme
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RNA molecules that can catalyze reactions
-possible for them to evolve under selection pressure |
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Oparin-Haldane Model
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-a model of prebiotic evolution and cell formation
-steps: 1. simple molecules assembled to form the biological building blocks (nucleotides, amino acids) 2.Polymerization of the building blocks to form biological macromolecules-->can store information and catalyze reactions 3.macromolecules directed to form other biological structures (e.g. membranes) |
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LUCA
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-Last universal common ancestor
-the most recent organism from which all organisms now living on Earth descend -OR cenancestor -based on commonality of Eucarya/Archae/Bacteria -DNA based -basic machinery for translation |
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Darwinian Threshold
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It has been proposed that there was a universal gene exchange pool until variation got to be enough to slow this down and cause a sort of speciation-->Darwinian Threshold is the point where spread happened
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Problems with Fossil Records
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-not all places on planet have good conditions for fossilizing
-only hard things fossilize -adaptive radiation-->bursts of diversification |
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Why did more complex body plans arise in cambrian era?
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-more O2 content in sea water
-more O2 allowed organisms to accommodate higher MR and larger body sizes -Origin of homeotic loci |
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Homeotic Loci
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help specify the location of cells
-controls cell fate (what genes should be transcribed based on location of cell) |
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Who is most at risk during extinction
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-specialists
-spp with limited dispersal -spp with limited range of niches |
