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Evolution
A change that times place in a group of organisms over time, usually in gene frequency.
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Natural Selection
- Any consistent difference in fitness (reproductive success) among phenotypically different classes of biological entities.
- - 4 levels -> genetic, individual, population, species
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Creationism
species are static and created by a higher source; against Darwinian science
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Uniformitarianism
Lyell; idea that processes that created the earth are still happening today
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Catastrophism
punctuated equilibrium; attributed new species in area to very dramatic event; assumed supernatural (like the flood)
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Progressionism
thought life was wiped off the face of the earth and brought back more complex than before
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Natural theology
Study of nature to get closer to the creator
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Divine Watchmaker
theory that if something complex was found (like a watch) someone had to have made it and put it there
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Transmutation
- Lamarck; theory that species became more complex because they want to
- 1. environmental changes invoke changes
- 2. changes in activity caused by needs
- 3. changes in habitat result in more/less use of parts and bigger/smaller parts
- 4. all changes are heritable
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Microevolution
small changes with in a species
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Macroevolution
causes big changes above the species level
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Significance of Darwin
- 1. species can and do change overtime (NS)
- 2. Man's place in the natural world
- 3. helped to form scientific community separate from religion and politics
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inclusive fitness
the fitness of gene measured by its effect on survival and reproduction of the organism and its genes borne by the individual's relatives
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kin selection
individual favoring survival of those closely related
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Intrasexual selection
- competition with in species -> males vs. males, females vs. females
- - big secondary characteristics
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Intersexual selection
- convincing opposite to mate
- - bright colors, plumage...
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Ways to change gene frequency
- 1. gene flow
- 2. genetic drift
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Pre-adaptation
- trait that is used for something and useful for something else later if that environment changes
- ex. penguins "fly" with wings under water
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Founder effect
- few individuals are taken from large founder population and are isolated until they produce their own population and look different over time
- - why species look different on islands
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Biological Species Concept
- - Mayr
- species where interbreeding is possible but reproductive isolation occurs between other species
- -exception - asexual, fossils, bacteria
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Modern species definition
- genetically based, heritable change in a population or species
- - not individuals
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Phylogenetics
branching in tree, search for common ancestor
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taxonomy
- hierarchy
- - KPCOGS
- Lineauus latin names
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character states
- different features of organisms used to show relatedness
- -morphological, genetic, embryology, physiology, behavior, biochemical
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pleisiomorphic
- an ancestral state
- ex. tail, 4 limbs
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apomorphic
- a derived character state
- ex. increased brain size
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monophyletic groups
goal of phylogeny; a set of species derived from a single, common ancestor
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synapomorphic
shared, derived traits; most helpful in determining phylogeny
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3 reasons species look similar - william hennig
- 1. uniquely derived character states
- 2. ancestral character states
- 3. homoplasious character states
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homoplasy
trait developed from convergent evolution
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convergent evolution
developing the same traits at the same time as other species after they split off
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autapomorphic trait
multiple changes that occur with in one species/lineage
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molecular clock
as time passes, you get mutations and changes in the structures of genes
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cladogenesis
origination of branches
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anagenesis
- changes that happen with in a lineage
- -lumpers - include more individuals in few groups
- - splitters - more groups in split
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homology
- same trait developed from common ancestor
- ex. forelimps
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vestigial characteristics
- characteristics that are not used but are ancestral
- ex. appendix, wings in birds that don't fly
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convergence
- evolution of similar features independently in different evolutionary lineages
- - by different developmental pathways
- ex. vertebrate vs. octopus eye
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Geographic distributions
- where species are located
- ex. marsupials only in sa and australia
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intermediate forms
- forms from ancestral states that still remain and haven't changed
- ex. pelvis in snakes
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homoplasy
- no common ancestor; traits that show up not because of common ancestor
- ex. color, loss of trait, beak size
- - leads to analogous structures -> bird and bat wings
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Batesian mimicry
harmless mimics something poisonous
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mullerian mimicry
- two toxic species that look alike
- mimicry rings - protection for all toxic species that look alike from predators
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parallel evolution
- have similar conditions that involve similar developmental pathways
- ex. maxillped in crustaceans
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evolutionary reversal
- resemble ancestor of another species
- ex. frogs that have regained the character state of having teeth
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convergent
share the same structure but derived by different developmental pathways
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parallel evolution
same structure derived by same developmental pathways
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Mosaic evolution
species evolve piecemeal; pieces of species change overtime and some stay stagnant
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endothermy
ectothermy
- -body temp regulated inside (mammals)
- -body temp regulated outside (reptiles, fish)
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saltationism
quick jumps in evolution with short-terms of stability
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gradualism
continuous, long-term stability; things change gradually with time
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individualization
- bodies of organisms consist of modules, compartmentalization
- ex. teeth in reptiles all look the same
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heterochrony
- evolutional change in the timing or rate of developing events
- -localized or large scale
- ex. horns that keep growing (localized)
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paedomorphosis
- maintaining juvenile characteristics through life
- ex. salamanders
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peramorphosis
- developing exaggerated adult features and maturity
- ex. human brain
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allometry
- differential growth in different parts of an organism
- y=bxa
- - exaggerated characteristics can result
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progenesis
change in development time
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neoteny
change in rate of development
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heterotrophy
- change of where genes are expressed in the body
- ex. light emitting organs
- ex. photosynthetic stems
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adaptive radiation
- rapid, divergent evolution of numerous related lineage
- -not moving towards trend/direction
- - see this at edge of species range/colony
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LUCA
- last universal common ancestor
- #1 on tree
- ex. all living things use L a.a. isomers
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Miller-Urey experiment (1953)
replicating conditions of early earth to try to form organic from inorganic substances
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Peptide nucleic acid (PNA)
stable, simple, could have been precursor to RNA
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Cenozoic
- Quaternary:
- 1. Holocene
- 2. Pleistocene
- Tertiary:
- 1. Pliocene
- 2. Miocene
- 3. Oligocene
- 4. Eocene
- 5. Paleocene
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Mesozoic
- 1. Cretaceous
- 2. Jurassic
- 3. Triassic
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Paleozoic
- 1. Permian
- 2. Carboniferous
- 3. Devonian
- 4. Silurian
- 5. Ordovician
- 6. Cambrian
- precambrian
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endosymbiosis
- structure derived from an organism within another
- ex. chloroplasts, mitochondria
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background rate
average rate of extinctions overtime, mass extinctions are spikes in background rates
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vicariance
- separation/ barrier of population; speciation occurs because of separation or geological barrier
- -null hypothesis
- -split occurs AFTER separation of species
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Dispersal
- when a population moves from an area where they do well to where they may not do so well (ex. seeds)
- - dispersal model -> split occurs BEFORE separation of species
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Wallace Effect
- island species
- - flying animals are more capable of dispersal to islands
- - human introduced species do well on islands
- - species are related to mainland species
- -endemic species on islands only found there
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Autochonthous
group arises within a geographical region
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Allochthonous
group arises from somewhere else (dispersal)
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Phylogeography
- tracking lineages of genes based on geographical distribution
- - can be used when no fossil record present
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Phylogeography for homo sapiens hypotheses
- 1. Multiregional - archiac humans from africa, asia, eurp give rise, large diff between genes, alot of gene flow
- 2. Replacement - archaic humans moved out of africa and dispersed, small diff in genes
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community convergence
- similar in similar species
- ex. birds have similar beaks if they eat similar foods
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Island Biogeography
- - linear relationship between the size and distance of the island from the mainland and the number of species on the island; bigger islands have more species
- far and small = smallest equilibrium
- large and near mainland = largest equilibrium (constant rate of species)
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biodiversity
number of species you find in an area and how they are distributed
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richness
evenness
- - number of species
- - how species are distributed
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singletons
- species rise and go extinct at the same time
- - just one fossil is found
- ex. soft bodied animals
- - usually excluded from species numbers
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pull of the recent
greater tendency to find species that are new to the fossil record, looks like there's more diversity now because it's easier to count them
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diversification rate
S-E = R
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density dependent/independent
- dependent - biotic factors - predation, competition
- independent - abiotic factors - weather, natural disasters
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volatile species
- species with high turnover rates, high origination rates, high rates of extinction
- - highly specialied
- - low or variable population size
- - low geographic range and dispersal ability
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adaptation
change in response to surroundings, change for the BETTER from previous form, increase in fitness
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fitness
ability to survive and reproduce
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red queen hypothesis
species must evolve as fast as they can just to keep up with competitors and predators, to maintain the same level of fitness
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Cambrian Explosion
all basic body types emerge during this
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Current extinction causes
- H - habitat loss
- I - introduction of exotic species
- P - population (humans)
- O - Overexploitation
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Lazarus effect
species that was thought to be extinct shows up again
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opportunistic species
take advantage of whatever resources they find
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disaster species
species that do better after a disturbance
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Refugia species
- species that persist in a certain place while others go extinct elsewhere
- ex. species that live in deep ocean are unaffected by disturbance
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neotenic taxa
- species can reproduce but still have larval form
- -heterochrony
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tropical species
-very prone to extinction bc rarely exposed to changes
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3 tiers of extinction
- 1. microevolution - change w/in a species population
- 2. species selection - differential survival of species during "normal" times
- 3. shaping of biota - dramatic change in higher taxa following mass extinctions
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niche
ecological role that individual holds
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fundamental niche
entire range of resources species can use, full range of environmental conditions
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realized niche
narrowed niche than fundamental, most highly adapted area
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competitive displacement
- extinction of a species because of competition, taking over a niche by competition
- - much less common
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incumbent replacement
- species takes over a niche of species that has gone extinct
- - much more common
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key adaptations
- trait that allows colonization of new niche, diversification
- - ex. lungs, wings, amniotes
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adaptive zones
- range of resources used by a group, set of ecological niches
- ex. herbivorous insects
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sympatric
allopatric
parapatric
- - located in the same place, interbreeding
- - barrier separates them
- - mostly separate but have a hybrid zone in between
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subspecies
- a population of species that can interbreed but separated by a large distance
- - speciation in progress
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subspecies clines
a gradual change in allele frequency over a geographic distance
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Bergmans rule
- increase in latitude brings increase in body size
- ex. bears
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Allens Rule
- longer limbs as you move towards the equator
- ex. hares, humans
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Gloger's Rule
- darker coloration in more humid climates
- ex. skin color in humans
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Ecotypes
mosaic pattern of character distribution
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Character displacement
- species that live together look different, where they live apart they look similar
- - niche partitioning
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Gene flow
- change in genes among population or movement of gametes
- -discrete population = islands
- - continuous population = isolation by distance
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4 mechanisms of evolution
- 1. gene flow - homogenizes populations
- 2. NS - adaptive
- 3. genetic drift
- 4. mutation
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Genetic drift
- random change in allele frequency
- - not because of fitness
- - based on chance
- - Kimura
- - most important in small populations
- - null hypothesis of change
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sample
- those that survive and found in next generation
- ex. snails and cows --> starting frequency is probability of becoming fixed and lost
- allele is 20% -> 80% chance of loss, 20% chance of fixation
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Coalescence
process of going back to a common ancestor through gene lineages
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random walk
alleles can be fixed or lost in populations
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heterozygosity
- WANT hetero. to be high in population to show diversity and variability
- -more homozygous means low variability
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effective population size
deals with number of individuals who are actually getting to mate and reproduce
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census size
much larger than effective size, total number of pop.
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population bottleneck
population is drastically decreased and leads to change in allele frequency
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neutral theory of evolution
small proportions of noncoding DNA are affected by NS
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Trade-off
- when species trade a benefit for a possible negative
- ex. frogs who croak loader and longer get more mates but are also recognized by more predators
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teleological
attributing purpose to something
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fitness
- average, percapita rate of increase in numbers
- - proportion of survival for offspring
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sexual selection
type of NS, differences in reproductive rates
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inversion polymorphism
base pairs get switched on chromosome and changes outcome of phenotype
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altruism
helping the group at a cost to oneself
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Is trait adaptive?
- 1. complexity
- 2. design
- 3. experiments
- 4. comparative method
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ESS
- evolutionary stable strategy
- - type of behavior that can not be replaced by alternative
- ex. hawk type of species
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Hamilton's Rule
- rb> c
- r= relatedness
- b = benefit
- c = cost
- C must be less than the relatedness x benefit to be beneficial to organism
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