evolution Flashcards
what is the evidence of evolution?
fossil record
biochemical evidence
comparative anatomy
observable events
biogeography
what is paleontology
study of fossils
ex of remains
bones, teeth, shells
ex of traces
footprints, burrows
why is the fossil record incomplete??????
fossils are rare, not alll organisms become fossils, the yonly form in sedimentary rock
the compariso of fossils from different layers shows
life on earth has changed, number of life forms increased
what are the 2 models of evolution
gradualism
punctated equilibrium
gradualism
gradual change over a long period of time leads to species formation
punctuated equilibrium
periods of rapid change in a species separted by by periods of little or no change
biochemical evidence
uses amino acids to determine common ancestors
closeley related species
exebit few amino acid differences
species that have lots of different species
shared common ancestor more recnetly
what is the strongest evidence
amino amino acid sequencing
phylogentic tree
shwows number of amino acid differences
homologous structures
similar genes (appearance) different function
homologus structures show
organisms past and present
anologous structure
same in function, not in structure..
vestigial structures
structures that are present that do not have a purpose
embryolgoy
simillar embryos show relationships to common ancestor
biogeography
organisms living in different conteinemnts may be simillar bcof common ancestor
observable events
changes in spcies over time that has been observered.
migration of species can change
the allele frequnecy
mutations can effect allele frequency by
adding a new allele or changing amout of present alleles
genetic drift
random changes in allele frequency due to population size
what is founders effect
occurs when few induviduals form new community
what does founders effect result in
reduced genetic variation
non random sample of genes
bottleneck affect
when population size is greatly reduced for one generation
bottleneck effect results
reduced genetic variation
non random mating
having limited number of possible mates
non random mating effects
allele frequenciy bc
- limited geography
- limited traits
- can be closley related
types of selection
stabilizing selection
directional selecion
disruptive selection
sexual selection
stabilizing selection
a type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait value
directional selection
occurs when individuals with traits on one side of the mean in their population survive better or reproduce more than those on the other.
disruptive selection
specific type of natural selection that actively selects against the intermediate in a population, favoring both extremes of the spectrum.
