Download howard notes evol bio 1

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AP Biology Notes: Evolutionary History & Mechanisms chpt 22-26
GOD
Pre-cursor: Evolutionary Theory vs. “Intelligent Design Theory”
A. Science is a tool not a god
Everything in the universe
1. as a “god” –“science has all the answers”
2. as a tool – limited by senses
B. Intelligent Design –
1. I Cor 1:18-21
2. Faith? Heb 11:1-3
a. There will never be scientific proof!!
3. age of Earth???????? Gen 1:1-3
What science can deal with.
C. Evolutionary Theory is not the Devil!
1. It is the best explanation of the data using science as a tool
a. God? Science does NOT include God in its evaluation because God is beyond the
limitations of science
2. Christians force the evolutionary theory into the mold of anti-God – in reality it is a
scientific theory created by following the scientific method
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Evolutionary Biology
I. History
A. The Men
1. Linnaeus –Swedish naturalist --binomial nomenclature – taxonomic system
2. Hutton – 1795 Scottish geologist – created gradualism- profound change is produced
by a slow, continuous process (no instantaneous or miraculous changes)
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3. Lamarck –1809 English –museum of natural history fossils (he was WRONG, but 1st to
say orgs evolve)
a. 1st to create a theory of evolution
1) use/disuse –“if you don’t use it you lose it” or if you use it a lot it becomes
more pronounced
2) inheritance of acquired char. – some change acquired during lifetime can be
passed on to offspring
3) natural transformation – offspring of each generation slightly changed (more
complex)
4. Cuvier – paleontology—study of fossils
a. catastrophism –each boundary between fossil strata corresponded to a catastrophe
of some kind that resulted in extinctions
b. he established extinctions as fact
5. Lyell – uniformitarianism (goes hand-in-hand with gradualism)
a. uniformitarianism says geologic processes that happened in the past are the same
as are happening now (same type & rate ---no catastrophes)
b. anti-catastrophism
6. Darwin (1809 – 1882) born the same day as Abe Lincoln
a. 1831-36 – voyage on the HMS Beagle as a naturalist (had a
crappy journey – seasick, caught Chaga’s disease) went to the
Galapagos Islands!!!
b. came back & married cousin 1839 married into the
Wedgewood China family $$$$$
c. 1859 - publishes book “On the Origins of Species…” to
explain how adaptations can lead to a change in a pop over time
On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the
Struggle for Life.
d. Darwin’s theory of natural selection
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1) overproduction of offspring – always more offspring are produced than can
survive
2) variations occur between individuals in a pop
3) limited envr. Resources creates a
a) “struggle for survival” – some variation allows for one org to survive better
than another
b) “survival of the fittest” – that org passes these traits on to the offspring
4) inherited favorable char. become more common
a) “descent with modification” – over TIME variations can differentiate 1 group
of orgs from another
II. Modern theory of evolution (neo-Darwinism)
A. Terms
1. population –gp of interbreeding orgs of the same species in the same geographic area
2. species – orgs of the same kind that can mate & have viable offspring
3. evolution –change over time
4. microevolution – pop change from 1 generation to the next
5. macroevolution – patterns of changes in groups of related species over broad periods
of geologic time
6. fossil – remains of orgs that were buried quickly so that decomp was stopped/slowed
– in sedimentary rock
7. gene pool—all genes in a pop at any 1 time
B. Natural Selection
1. pops produce vast #’s of offspring
2. pop sizes remain stable
3. envr. resources are limited – just because pops grow larger doesn’t mean there’s more
food, light, water….
4. competition for survival – which org is best able to get the limited resources
5. variation among individuals
6. most variations are heritable
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7. survival of the fittest
8. evol. occurs as favorable traits accumulate in a pop over time
C. Kinds of natural selection p.458
original pop
evolved pop
directional
selection
stabilizing
selection
diversifying
selection
1. stabilizing selection – eliminates individuals w/extreme traits – the common traits are
the best adapted (gets rid of the extremes)
2. Directional Selection – favors individuals at 1 end of the spectrum (extreme traits)
these traits are best adapted
3. diversifying/disruptive selection – envr favors the extremes of
a trait
4. sexual selection – produces sexual dimorphism
a. sexual dimorphism- difs in male & female secondary sex
characteristics (antlers, coloring, plumage…)
b. male competition – strength contests – winner gets chance to
mate
c. female choice- (intersexual selection) – females choose mate
based on some masculine characteristic (may reflect overall health of male?)
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5. artificial selection – directional selection carried out by humans
D. Evidence for Evolution
1. biogeography – study of the distribution of orgs
a. related orgs live close to each other
b. island species are related to species on the nearest continent
2. Paleontology – study of the fossil record
a. provides evidence that the variety of species that’s inhabited the Earth has
changed over time
1) strata – geological processes form layers or strata of rock
2) each stratum has its own fossils
a) Law of Superposition- oldest layer of rock is on the bottom – type of
RELATIVE DATING
b) Absolute dating – estimated from amt/ratio of radioactive isotope in
specimen
3. Comparative Anatomy – allows classification of orgs (taxonomy)
a. Homologous structures – evolved from common original structure
1) same structure different function
2) divergent evolution – evolution used 1 structure & modified it for dif. purposes
(ex forelimbs of mammals)
b. Analogous structures – evolved from dif original structures, but due to similar envr.
have a similar function
1) convergent evolution – evolution used multiple structures & modified them for
the same purpose (ex wings of bats & birds)
c. parallel evolution – 2 related species that have diverged then made similar
evolutionary changes via dif paths
& reconverged
d. coevolution – one species evolves in response to another species evolving
(predator/prey relationships)
e. vestigial structures – structures that functioned in ancestral orgs but are reduced
in structure & function in descendant
1) serve little or no purpose in currently existing species – nat. selection has
selected for orgs w/in the pop that have reduced or absent forms of the structure (for
metabolic efficiency?) ex: muscles that move the ears
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4. Embryology – reveals similar stages in development among related species
a. similarities in
ontogeny help establish phylogeny
evolutionary relationships
“ontogeny recapitulates phylogeny”
5. Molecular Biology
a. DNA comparison or AA sequence in like proteins—more closely related species
should have more similar dna or more similar AA sequences. ----They’re starting to use this to
modify the standard taxonomy of many orgs!
E. Population Genetics –
1. Darwin’s explanation not well accepted until it was combo’d with Mendelian genetics
(early 1930’s) –genetics explains the variations in populations
2. Variations in a pop caused by:
a. mutations
b. sexual reproduction – allows offspring to be dif from parents (not clones), crossing
over, independent assortment of chromosomes, random fertilization
c. diploidy – allows recessive genes to be carried in pop
d. polymorphism – maintaining stable frequencies of more than 1 phenotype in a pop
1) heterozyg. advantage- being heterozygous for a trait is “better” than being
homozyg.--- heteroz for sickle cell anemia gives immunity to malaria
2) frequency-dependent variation- teeter-totter effect over time – least common
phenotype becomes advantageous & thus most common---- then conditions change slightly &
what was MOST common becomes least & back & forth
e. outbreeding – opposite of inbreeding
f. neutral variation – variation with no selective advantage
3. changes in allele frequencies (gene frequencies) caused
by:
a. natural selection
(b. mutation – more commonly these are harmful)
c. genetic drift – RANDOM changes in gene frequencies
1) bottleneck effect – disasters (flood, fire…) occur killing off most of a pop & by
chance certain alleles/genes will be over represented (& some entirely absent) *this usually
decreases variation in a pop
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2) founder effect- small # of the pop colonize a new area & are isolated *this
usually decreases variation in a pop
d. gene flow –genetic exchange due to migration –
1) immigration – orgs entering a region
2) emigration – orgs exiting a region
e. non-random mating – choose mates based on individual traits or nearness
1) inbreeding- mating w/relatives
4. Hardy-Weinberg Equilibrium =
genetic equilibrium (no evolution)
*occurs when allele frequencies in a
pop remain constant
*to study pops where changes occur
you must have the “norm”
to compare
them to!
a. to have a Hardy-Weinburg equilibrium….
1. no natural selection
2. no mutations
3. no gene flow
4. no genetic drift
5. random mating
6. LARGE pop
It would seem that almost no population would ever
be in equilibrium given these assumptions.
However, in practice
A. mutation rates are small to negligible.
B. population size will still give a good fit to HardyWeinberg even if the population is fairly small,
say 100 individuals.
C. Also, since the equilibrium is established after
one generation, the population will come back to
equilibrium within one generation after being
disturbed
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p2+ 2pq + q2 = 1 (frequency of genotypes must add up to 1)
p + q = 1 (frequency of both alleles must add up to 1)
p = frequency of allele A (dominant)
q = frequency of allele a (recessive)
Roger Rabbit Lab!
III. Speciation – formation of a new species (chpt 24)
A. speciation occurs via 2 means
1. allopatric speciation- a geographic barrier separates 2 pops of the same species
(rivers, mts, desert)
a. genetic drift etc… allows for variation & over time if enough variation occurs then
the 2 pops will be unable to mate & have offspring--- so a new species occurs
b. adaptive radiation –
new species branch off of parent species
“rapid” evolution of many species from 1 parent ancestor
2. sympatric speciation – new species form w/out geographic/geologic barriers
a. polyploidy speciation – mainly in plants (generally detrimental in humans & other
animals) meiosis mess up creates polyploidy gamete
polyploidy zygote
which can’t mate
w/original pop
b. hybridization – (mainly in plants) – 2 dif but closely related species mate along a
geographic boundary & create viable offspring--- offspring have some variation that’s
advantageous so hybrids develop along geographic boundary
(whitetail deer escape faster going down hill mule deer escape faster going up hill
hybrids – neither)
c. balanced polymorphism - multiple variations of a particular trait --- (ex. dif colors)
1 variation works best in a slightly dif habitat than another so orgs w/that particular variation
tend to stay together & mate ultimately leading to a new species
B. Reproductive Isolation (no physical barriers) – prevention of breeding between species
1. prezygotic barriers – prevention of fertilization or prevention of mating
a. habitat isolation – orgs don’t ever meet
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b. behavioral isolation – orgs don’t recognize mating behavior in other species
(elaborate courtship rituals)
c. temporal iso. – species breed at dif times of the day or during dif seasons
d. mechanical iso – anatomically incompatible
e. gametic iso1) male gametes can’t survive in female (internal fert)
2) female gametes don’t chemically “recognize” male gametes (protein ID)
2. postzygotic barriers – occurs after fert
a. reduced hybrid viability – zygote fails to develop
b. reduced hybrid fertility – offspring are sterile
c. hybrid breakdown – hybrids are okay but the hybrids offspring are not (due to a &
b above)
IV. Origin of Life (chpt 26)
A. Earth & Atmosphere – formed 4.5 billion years ago (bya)
1. primordial atmos. –
1st existing atmos – formed from gases vented from Earth’s
interior
a. consisted of – CO CO2 H2 N2 H2O HCl S HCN
(very little O2)
2. primordial seas – 1st existing sea – as Earth cooled, gases condensed to create seas
w/many minerals – sometimes called “primordial soup”
3. complex molecules formed in seas
a. E to catalyze reactions – came from UV light, lightning, heat used to catalyze rxns
forming amino acids, acetic acid…
b. 1920’s Oparin & Haldane – theorized
that primordial atmos & seas (w/out O2) allowed all of these chem. rxns & formations & since
the seas & atmos are dif today it no longer occurs
c. 1953 Miller & Uray – tested Oparin’s theory
1) created conditions of primordial atmos in lab – H2O H2
CH4 NH3 - & were able to produce AA’s & other organic cmpds w/heat &
electricity
4. polymers formed from monomers through dehydration
synthesis (polymers formed by removal of water)
a. proteinoids – abiotically produced proteins – how?— by letting
AA’s dry out on a hot substrate (like a rock)
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5. protobionts – aggregates/clumps of abiotically produced molecules
a. precursors of cells
b. some had membranes that enclosed an area where chem. rxns occurred
???????And then a miracle occurs ----otherwise known as
“spontaneous generation”???
Louis Pasteur
read pp. 521-2 “Debate about origin of life abounds”
p.517
6. primitive prokaryotes formed –no nucleus, heterotrophic
7. Autotrophic prokaryotes formed (through mutation?) ex:
cyanobacteria
8. O2 & O3 layers formed –due to autotrophic orgs – O2 atmos formed then UV light
converted O2 to O3 blocking out the UV light & making atmos more
hospitable (& ending abiotic syn of organic mlcls)
9. Eukaryotes formed via endosymbiosis!
a. endosymbiotic theory – says eukaryotes (w/nucleus)
formed from symbiotic relationships between prokaryotes
b. evidence1) mitochondria & chloroplasts have their own DNA
2) ribosomes of mito. & chloro are genetically
similar to bacterial ribosomes
3) M & C – reproduce independently inside the cell via binary fission – like
bacteria!
4) M & C have double membranes – caused by
endocytosis
5) thylakoid membranes in C’s are like membranes in
cyanobacteria
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V. History of Life p.512-
A.
life originated 3.5 to 4 billion years
ago (bya) -
1. oldest fossils in Australia – similar
to bacteria today – they form stromatolites (fossilized
bacteria p.513)
2. prokaryotes dominated 3.5 – 2.0 bya
B.
O2 accumulates 2.7 bya due to
autotrophic prokaryotes
C.
eukaryotes showed up 2.1 bya -
larger & more comples than prokaryotes
D.
multicellular eukaryotes 1.2 bya
E.
animal diversity explosion 543 mya
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F.
plants, fungi, animals colonized land 500 mya