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Evolution Notes
I. Early Earth and the Origin of Life
A. Origin of the Universe (15 BYA)
1. Many theories exist
2. Most scientists favor the __________________________________ which state
that the universe began as a dense concentration of matter smaller than a speck
of dust which exploded outward violently.
B. Origin of the Sun (10 BYA)
1. Clouds of molecules, made of hydrogen gas, began to grow in mass which
increased their gravity, which in turn, attracted more hydrogen to increase their
mass.
2. These clouds increased to such a huge mass, that it’s gravity smashed hydrogen
molecules together, triggering a ______________________________. We call
these fusion reactions clouds _____________ and one formed our __________
C. Origin of Earth
1. Clouds of matter caught in the Sun’s gravitational field began forming
___________________
2. Solid matter collected into a dense core and radioactive decay melted the
matter into a ball of molten rock that we call ________________________
3. Conditions of Early Earth Prevented Life
a) ____________________________________________________________
b) ____________________________________________________________
c) ____________________________________________________________
d) ____________________________________________________________
e) ____________________________________________________________
D. The Antiquity of Life
1. Life Appeared relatively early in Earth’s history
a) Fossils of prokaryotes have been recovered from _____________________
that are 3.5 billion years old.
b) The oldest eukaryotes are 1.5 billion years old
2. Multicelled organisms arose 700 million years ago.
E. Spontaneous generation of Life: _________________________________
1. Abiogenesis is NOT evolution
2. Russian Biochemist _________________________________ introduced a
plausible theory of chemical development of life in 1927
F. Abiogenesis: Oparin/ Haldane Model:
1. Abiotic synthesis and accumulation of small organic molecules:
________________, _______________________, and _________________
2. The joining of monomers to form polymers
3. The formation of __________________________- groups of abiotically
produced molecules able to maintain an internal environment
4. Origin of heritable Material
A) DNARNAprotein model most likely evolved from a simpler model
B) One hypothesis proposes ______to be the first genetic material
C) DNA was later favored due to its stability
G. Evidence to Support the Oparin/Haldane Model
1. __________________________ & ________________________ constructed
a primitive earth machine with methane, Ammonia, water vapor and hydrogen
in the atmosphere which produced organic molecules
2. Various experiments have produced all 20 amino acids, ATP, sugars, and
DNA and RNA bases
3. _____________________________ produced ______________________
abiotically produced polypeptides
a) Clay, hot sand and rocks can contain metals which will catalyze
condensation reactions .
b) Pyrite can provide a charged surface or free electrons to support bonding
between molecules
4. When mixed with cool water, proteinoids self-assemble into ______________
surrounded by a selectively permeable membrane.
5. ______________________________ form spontaneously from drops of
polypeptides, nucleic acids and polysaccharides
6. _________________can base pair in the presence of zinc
7. RNA is ________________________________c- it can catalyze the
formation of mRNA, tRNA, and r-RNA by itself
8. RNA fold is determined by its sequence
a) This provides a mechanism for natural selection
b) Stability and catalytic activity would be favored
E. Origin of Eukaryotes
1. __________________________________- eukaryotes evolved by
specialization of internal membranes derived from the prokaryotic plasma
membrane
a) Most endomembrane structures are believed to have differentiated from
the plasma membrane invaginations
b) Double membrane organelles (chloroplasts & mitochondria) may have
involved secondary invaginations or more complex folding
2. _________________________________l- certain prokaryotic species called
endosymbionts lived within prokaryotes
a) Focuses mainly on chloroplasts and mitochondria
b) ______________________________ are thought to have descended from
endosymbiotic photosynthesizing prokaryotes living in larger cells
c) ______________________________ are postulated to be descendants of
prokaryotic aerobic heterotrophs that may have been parasites or
undigested prey of larger cells
3. Evidence for the Endosymbiont model
a)
b)
c)
d)
Appropriate size to be descendants of eubacteria
Replicate by splitting as do prokaryotes
Contain their own DNA and ribosomes similar to prokaryotes
Replicate independent of the cell
II. Evidence of Evolution
A. __________________________- any preserved remnants or impression left by
an organism that lived in the past
1. Fossil Formation
a) Some fossils are found as thin films pressed between layers of sandstone
and shale and retain organic material
b) Most fossils form from the mineral rich hard parts _________________,
_________________, or _____________________because other substances
decay rapidly
c) Other fossils found by paleontologists are replicas, casts or molds left when
corpses where covered by sand or mud
2. Limitation of the Fossil Record (Fossilization requires a series of improbable
events)
a) The organism must die at the right time in the right place in an
________________________________________to avoid decaying
b) Geological events must form the fossil and then the fossil must escape
geological events such as erosion, pressure and heat
c) Finally, the fossil must be found by someone who knows what they are
doing
3. Ramifications of Fossilization:
a) _______________species never leave fossils
b) _______________ formed fossils have probably been
destroyed
c) Only a ______________________ number of existing fossils have been
found
d) Therefore, the fossil record is composed of organisms that were
___________________, ________________________, lived a long time
and had hard _______________ or _____________________.
4. Fossil Dating
a) Relative Dating
1) Younger strata is deposited on top of older
2) Strata from different sites can be correlated by similar fossils known as
_______________________________
3) Geologist have formulated a sequence of geologic periods by comparing
many different sites
b) _______________________________: Not errorless. +/- 10%
1 ) ____________________________________: uses C14 which has a
half- life of 5730 years. Useful for dating organic matter less than
50,000 years old
2) K40 has a half life of 1.3 billion years old
3) Living organisms synthesize L-form amino acids which decay to D-form
over time
B. _______________________________- the geographical distribution of species
1. Islands with similar environments in different parts of the world are not
populated by closely related species, but rather species related to organisms
form the nearest main land
2. South American tropical mammals are more closely related to South
American dessert animals than to African tropical animals
3. Australia has a diversity of marsupials in an environment that could easily
support placentals
C. ______________________- reflects the branching genealogy of the tree of life
1. Different taxonomic levels are related through descent from a common
ancestor
2. Organisms thought to be closely related on the basis of anatomical features
reveal common hereditary background
D. ___________________________________- Anatomical similarities between
groups of the same taxonomic category show evidence of common descent
1. Forelimbs of mammals are ____________________________________structures that are similar due to descent from a common ancestor
a) Although the limbs re used for different functions, it is obvious that the
same skeletal elements are present
b) It is logical then that the foreleg, wing, flipper or arm is similar due to a
common ancestor
2. _____________________________- rudimentary organs of little or no use to
an organism that were valuable to the ancestral form. I.e. hip bones in snakes
E. ___________________________________- Closely related organisms go
through similar stages in their embryonic development
1. All vertebrates (Fishes, Amphibians, reptiles, birds and mammals) go through
an embryonic stage in which they posses gill slits on the sides of their throats
a) As development progresses, gill slits develop into divergent structures, In
humans, they form the _________________________________ that
connect the middle ear and throat.
b) Supports conclusion that all vertebrates descended from a common aquatic
ancestor
2. Comparative embryology can often establish homology among structures that
are so altered later in development that their common origins can’t be
determined by their fully developed forms
F. _______________________________- Organisms with similar proteins and
DNA have similar ancestors
1. The closer two species are taxonomically, the higher the percentage of DNA
they share
2. Even taxonomically distant organisms share some DNA and protein. This
substantiates the idea that all life forms are related to some extent
III. Mechanisms of Evolution
A. Natural Selection: Charles Darwin
1. All species have such a great potential fertility that their population size would
_______________________________________ if all individuals born would
reproduce successfully
2. Most populations remain __________________ except for seasonal fluctuations
3. Natural Resources are ___________________
a) Production of more individuals than the environment can hold leads to a
____________________________
b) Only a fraction of the original offspring survive
4. Individuals of a population vary extensively in character
5. Variation is due to ____________________________, _____________________,
___________________________, and _________________________
a) Survival is not random, but depends on the hereditary constitution of the
individual
b) Organisms with favorable traits will live longer and have ________________
offspring than those with average or poor traits
c) Favorable traits will ____________________________ over generations
B. Population Genetics
1.
Individuals do not evolve. Therefore, populations must be studied.
2. ____________________________- a group of interbreeding individuals of the
same species that share a common geographic area
3.
____________________________l- total aggregate of all the genes in a
population at any one time.
4.
___________________________________________ Equations used to
calculate gene and genotypic frequencies at genetic equilibrium. I.e. No evolution
is occurring
a) Gene Frequencies
1) ____________ = Frequency of the Dominant Gene
2) ____________ = Frequency of the Recessive Gene
3) Therefore:
P+q=1
All the dominant gene + all the recessive genes = All the genes
b) Genotype Frequencies
Hardy-Weinburg Notation
1) PP or _________
Homozygous Dominant
2) Pq + qP or _________
3) qq or __________
Therefore:
Genotypes
p
q
p
P2
Pq
q
qP
q2
Heterozygous
Homozygous Recessive
P2 + 2Pq + q2 = 1
All the Homozygous Dominant + All the Heterozygotes + All the Homozyous
Recessives = All the Population
c) Hardy-Weinburg Equilibrium will be maintained if the following conditions
are met:
1) Infinitely large population size. This eliminates gene frequency change
due to chance called _________________________
2) No immigration or emigration. Organisms entering or _______________
3) ____________________________________________ The rate at which
A mutates to a is equal to the rate at which a mutates to A
4) ______________________________The chances of any one genotype mating
with another genotype is equal to its frequency within the population
5) ______________________________ All genes are neutral with each one
having the same survival value.
C. Causes of Microevolution- the change in gene frequencies within a population
1. __________________________- change in gene frequency due to random chance
2. ______________________________- following a natural disaster, the small
remaining population is unlikely to represent the genetic make up of the original
population
3. _______________________________- genetic drift that occurs when a few
individuals colonize a new habitat
4. ___________________________-immigration or emigration of individuals
disproportionately
5. ______________________- introduces new alleles into the population and
immediately changes the gene pool
6. _________________________________
a) Individuals selecting mates that are geographically neighbors can lead to
_____________________________
b) ____________________________________- individuals having a mating
preference.
7. __________________ a given phenotype is selected for (increasing gene
frequency) or against (decreasing gene frequency)
IV. Speciation- The Development of New Species
A. Types of speciation
1. ___________________________- the transformation of an unbranched linage
enough to justify renaming it as a new species
2. ____________________________- the branching of one species into two or more
species
B. What is a Species?
1. __________________________________- a species defined by anatomical feature
2. __________________________________- a group of individuals that can
successfully interbreed and produce fertile offspring
C. Reproductive Barriers Produce New Species
1. ________________________________-prevent zygotes from forming
a) _____________________________________- two species having different
habitats in the same area
b) _____________________________________- two species bread at different
times of the day, season, or year
c) _____________________________________- two species don’t recognize the
others behavior used to attract a mate
d) _____________________________________- anatomical incompatibility may
prevent sperm transfer when closely related species attempt to mate
e) _____________________________________- sperm from one species cannot
fuse with the egg of another species
2. ______________________________- prevent the production of a viable, fertile
offspring
a) _______________________________- zygote fails to develop or an
extremely frail offspring dies soon after birth
b) _______________________________- hybrids are viable but sterile due to
different number of structure of chromosomes
c) _______________________________- First generation is viable and fertile,
but successive generations are feeble or sterile
3. __________________________________- the transplantation of alleles between
the gene pools of different species
D. Biogeography of Speciation
1. ______________________________________- occurs when a splinter
population diverges in evolution from ist parent population after becoming
geographically isolated
a) Small populations are the best candidates because genetic drift and isolation
can rapidly change a small gene pool
b) ___________________________________- the emergence of numerous
species from a common ancestor can be easily seen or island chains
2. _________________________________ New species forming without
geographic isolation due to reproductive isolation
a) __________________________- a species arises when it doubles its previous
chromosome number due to failure in meiosis
b) __________________________- a polyploid hybrid is formed from the
contributions of two different species
E. Genetic Mechanisms of Speciation
1. Speciation by divergence
a) Two populations adapt to different environments and accumulate differences
in genotype and phenotype
b) _________________________________- can lead to reproductive barriers.
According to the recognition concept of species, Natural selection would
amplify adaptations that would enhance reproductive success
1) The adaptations may cause recognition problems
2) This can result in speciation
2. Speciation by Peak Shifts
a) Each ______________________________ is an equilibrium in which
allelic frequencies maximize the average fitness of the populations
members
b) Environmental change may redefine the landscape, making new adaptive
peaks possible
c) Non adaptive shifts may destabilize a gene pool through genetic drift,
bottle neck or founders effect and result in a new adaptive peak
F. Gradual and Punctuated Speciation
1. ____________________________________- occurs over a long period of
time by the accumulation of microevolutionary change in the gene pool
2. ____________________________________ – new species arise quickly
following its budding from its ancestral species and then stabilizes for a
relatively long time
V. __________________________________- the origin of taxonomic groups higher
than the species level. Macroevolution is concerned with major events in the
history of life and the origin of new designs
A. The Origin of Evolutionary Novelties
1. __________________________________- a structure that evolved in one
context and became co-opted for another function
2. Development and Macroevolution
a) Changes in the rate or pattern of development can be due to small changes
in regulatory genes, but can result in great morphological differences. An
example is ___________________________.
b) Genetic changes that alter the timing of development may prevent
structures from developing. _________________________________ is a
condition where juvenile structures are found in the adult
B. Difficulties in Interpreting Evolutionary Trends
1. A single correct evolutionary progression cannot be produced by the fossil
record. I.e. Evolution of a horse
2. Evolution has produced many trends even if some branches go against the
trend
3. Evolutionary trends may ______________ or ____________________with
changing conditions
C. Continental Drift and Biogeography
1. Macroevolution has a dimension in space as well as time
2. ________________________________ has had a significant impact on the
history of life by causing major geographic rearrangements affecting
biogeography and evolution
3. The formation of the super continent ______________________ and its
subsequent break up can explain many cases of geographic distribution today
D. Punctuations in the History of Biological Diversity
1. Major Adaptive Radiations
a) Evolution of novel characteristics can open the way to new adaptive zones
allowing many taxa to greatly diversify
1) A large increase in the diversity of sea animals occurred between the
_________________________and _________________________ era
2) This occurred because bones and shells were developed allowing many
groups to diversify greatly
b) Empty adaptive zones can be exploited if the appropriate evolutionary
novelties arise
1) ___________________________ existed for 75 million years before the
first large adaptive radiation
2) Early in the cenozoic, mammals ____________________ out due to the
ecological void created by the extinction of the dinosaurs
2. Mass Extinctions
a) About _____________ have occurred
b) Mass extinctions profoundly effect the biodiversity by elimination of many
species. But also allows other species to radiate out