Bio 2 Final

Ch 1 - 5

What 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?

1. latin
2. 2 parts
3. lowercase
4. 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?==

1. Law of segregation
2. Law of independent assortment
3. 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?

1. No mutation takes place
2. No gene flow (no immigration \[in\] or emigration \[out\])
3. Random mating is occurring
4. Large population size
5. No natural selection = no change


1. 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

1. Mutation
2. Gene flow
3. Genetic drift
4. Nonrandom mating
5. 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==

1. Assortative mating
2. 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?

1. Variation ==must exist== in population
2. Variation must result in ==numerical differences== of offspring survival
3. 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