Studied by 0 peopleWhat is science?
aims to understand the natural world through observation and reasoning
begins with organisms
classification of all life
human genome sequencing
hierarchical classification?
organisms grouped into clusters
Kingdom > Phylum > Class > Order > Family > Genus > Species
shift from identifying and naming to constructing hypotheses to explain relatedness of species
binomial scientific name?
Genus [capital], Species [lowercase]
how to identify hierarchical classification?
latin
2 parts
lowercase
capitalize
Scientific Method step 1
Observations
scientific method step 2
Hypothesis
what is hypothesis
a possible explanation for an observation
statement
has dependent and independent variables (control variables)
what is null hypothesis
no changes
all the same
what is independent variable?
the experimenter will manipulate to see how it affects the dependent variable
what is the dependent variable?
What is actually being measured/affected in the experiment
scientific method step 3
experiment
tests the hypothesis at a time
includes a control (no part of the experiment)
scientific method step 4
analysis
scientific method step 5
draw conclusions
why are many hypotheses are supported?
it is because of theory
what is theory?
broad explanation
body of interconnected concepts
supported by lots of scientific evidence
Can supernatural be studied?
No
it cannot be studied or explained by science
it cannot be measured
What cannot provide value judgments?
ethics, morals, faith
what is evolution?
challenge in allelic frequencies in a given population over time
darwin’s “descent with modification”
Aristotle’s ideology: scala naturae
scale of nature
‘life may have changed gradually over time, but .. life forms arranged on a ladder of increasing complexity’
Carolus Linnaeus?
scientist who classify life “for the greater glory of God”
developed Binomial nomenclature: Nested classification
long thought to have been created recently and to be unchanging
change is hard to see at the scale of a human lifetime
From static worldview to an evolutionary worldview- what happened?
1700s-1800s: accumulation of fossils showed that life on earth had changed enormously
what is catastrophism?
extinctions (and other major changes on earth) are due to periodic catastrophes (sudden change)
big change
Georges Cuvier (1769-1832)?
french scientist: extinct species were evidence of past catastrophes 1798
James Hutton & Charles Lyell?
scottish geologists
geological evidence that current events were the key to understanding the past
what is uniformitarianism?
processes operating in the world today are the same ones that have operated in the past (constant change)
processing change
what is gradualism?
processes that result in geological change operate slowly (gradually) over huge spans of time
implies much time has passed and earth is VERY OLD
age/time… takes a while
Darwin was not the first to?
propose a theory of evolution
Darwin proposed?
proposed mechanism of evolution: natural selection 1859
Darwin’s perception?
a radical, leftist, atheist who was happy to overthrow the existing worldview
facts are a little more mundane
Extra facts on Darwin
fainted at the sight of blood
went to clergy school
naturalist
took notes in voyage of HMS beagle
in the mainland is not the same in the islands
with Captain Fitzroy
idea came out in ‘59
Buffon’s theory 1749
species change as they spread from their original location
Lamarck’s theory 1809
acquired variation is passed on to descendants
new species come from existing species through environmental forces
change over time
Darwin’s theory
natural selection or genetically-based variation leads to evolutionary change
Darwin’s focus on adaptation
influenced by Thomas Malthus (most significant, made essays)
adaptation to the environment and the origin of new species as closely related processes
natural selection?
the match between organisms and their environment
has to match environment to survive
agricultural selection?
results from generations of human selection for desirable phenotypic traits, they reproduce and pass genes
ex: larger corn ear size
Domestication?
human-imposed selection has produced a variety of cats, dogs, pigeons, etc
breeds developed for specific purposes
dachshunds for badger pursuit
Evidence of evolution: direct observations
nature - soapberry bugs
evolution of drug-resistant bacteria
resist to penicillin 1945, 2 yrs after widely used
resist to methicillin, 2 yrs after widely used
MRSA now resistant to many antibiotics
Evidence of evolution: anatomical evidence
homologous structures
vestigial structures
early embryonic development
molecular evidence
homologous structures?
structures derived from same body part; may or may not have same function
ex: forelimb bones in mammals are same
vestigial structures?
structures have no apparent function, but resemble structures their ancestors possessed
ex: human ear wiggling muscles
evolutionary relicts
early embryonic development?
comparisons of how organisms develop
embryos similar early on → different as develop
humans: glands and ducts
molecular evidence?
DNA relatedness - compare anatomy, genomes, or proteins
more related → less changes
less related → more changes
Evidence of evolution: fossil record
differed from present-day organisms
shed light on new groups
support hypothesis based on DNA
document transition fossils
measured; determines how they move
Animal closest relation to whales?
Hippopotamuses
evidence of evolution: biogeography
plate tectonic
convergent evolution
what is biogeography?
study of species geographic distribution
different geographical areas exhibit similar plants and animals even though organisms may be distantly related
plate tectonic?
shifting continents drift isolated organisms, promoting divergence
convergent evolution?
parallel evolutionary adaptation in similar environments
Similar forms evolved in different, isolated areas because of?
similar selective pressures in similar environments
analogous structures?
similar function, not same form (evolutionary-ancestral traits)
divergence?
moving apart from each other
Genetic variation?
differences in alleles of genes found within individuals in a population
raw material for natural selection
meiosis creates variation. why?
independent assortment
recombination
random fertilization
independent assortment?
shuffles chromosomes
recombination?
shuffles genes on chromosomes
meiosis metaphase phase 1
random fertilization?
picks two cards out of the deck at random
one couple can create >70 trillion unique combinations (not including crossing over)
Raw material?
no selection takes place without heritable variation
How do you get raw material?
Mutation & Recombination
Mutation?
a heritable change in DNA
has to be inherited
0.003 === 64== mutations per genome per cell generation
recombination?
a molecule (DNA/RNA) is broken and then joined to a different one [crossing over]
population genetics?
study of properties of genes in a population
gene pool?
sum total of all the genes in a population at a given time
all alleles at all loci (locations within)
who is Mendel 1860s?
he showed that inheritance is caused by “particles” that are passed unchanged from generation to generation according to the rules of probability
plant breeding experiments
Mendel’s Laws?
Law of segregation
Law of independent assortment
Law of dominance
Law of segregation?
pair of alleles separate during cell divisions for any particular trait (assumes diploidy)
Law of independent assortment?
separate genes for separate traits are passed independently of one another
Law of dominance?
one allele masks other allele
RR or rr
how many chromosomes combinations in humans?
8 million
True breeding cross P1
1 Homo dominant, 1 Homo recessive [Rr]
F1 generation
100% heterozygous
F2 generation genotypic ratio
1:2:1
Phenotype
physical characteristics/appearance
Genotype
actual genetic typing
homologous chromosomes?
2 copies of alleles of the gene for a given individual (genotype)
homozygous alleles?
alleles are the same
AA, aa
heterozygous alleles?
alleles are different
Aa
population-level variation describe as?
allele frequencies (one)
genotype frequencies (two)
Hardy-Weinberg Principle?
genotypic frequencies remain constant from generation
to generation under constant conditions
Conditions of the Hardy-Weinberg Principle?
No mutation takes place
No gene flow (no immigration [in] or emigration [out])
Random mating is occurring
Large population size
No natural selection = no change
a way to examine changes in allele frequency = null hypothesis (no change)
Hardy-Weinberg Principle Equation
p + q = 1
p = homo dominant
q = homo recessive
pq = heterozygous
In reality, most populations will not meet all 5 assumptions/conditions. why?
Meiosis & Sexual Reproduction alone will NOT change allele and genotype frequencies in a population (will NOT cause evolution)
what process/processes cause changes to the frequencies?
evolution results in the change of a population’s genetic composition
5 agents of evolutionary change
Mutation
Gene flow
Genetic drift
Nonrandom mating
Selection
Agent Mutation
totally random
ultimate source of genetic variation
makes evolution possible
rates generally low
other evolutionary processes usually more important in changing allele frequency
Agent Gene flow
movement of alleles from one population to another
random
drifting of gametes or immature stages
mating of individuals from adjacent populations
Agent Genetic Drift
describes how allele frequencies fluctuate unpredictably
random-uncommon alleles are vulnerable
bottleneck effect
founder effect
Bottleneck Effect?
catastrophic event reduces population size
survivors are a random genetic sample of original
results in loss of genetic variability
parent population gone
Founder effect?
small number of individuals drift from population
can lead to the loss of alleles in isolated populations
foundling
parent population is still there
isolation
Agent Nonrandom Mating
Assortative mating
Disassortative mating
Assortative mating?
phenotypically similar individuals mate
increases homozygosity
Disassortative mating?
phenotypically different individuals mate
increases heterozygosity
Agent Selection
some individuals leave behind more progeny than others
rate = favorable phenotype/behavior
non random
natural selection
artificial selection
what is the result of evolution by natural selection?
populations become better adapted to their environment
organisms start to blend in their environment
Conditions for natural selection?
Variation must exist in population
Variation must result in numerical differences of offspring survival
Variation must be genetically inherited
Natural selection is not equal to evolution. why?
Evolution is a subset to natural selection
Natural selection is a process (4 other processes)
Evolution = historical record of change through time
what is fitness?
individuals of one phenotype leave more surviving offspring in the next generation than individuals with an alternative phenotype
what relative concept is misleading?
the most fit phenotype = one that produces, on average, the greatest number of offspring
components of fitness?
traits favored for one, a disadvantage for others - variation
number of offspring per mating - heritability
sexual selection = more successful at mates
survival!
selection favors phenotypes with the greatest fitness. why?
phenotype with greater fitness usually increases frequency
Note
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