13.1 Briefly summarize the history of evolutionary thought.

Evolution: _____________________________________
__________________________________________________.

Modern definition: a _________ change in the characteristics within a ___________ from one generation to the next.

Idea as old as ancient____________.
Charles Darwin

18___, ____ years old

Served on H.M.S. _________ : “Ship’s Naturalist”

Around-the-world voyage lasting ______ years.

Aristocrat so could socialize with ______.

Despised by the____________________.

Sought to provide evidence and mechanism for evolution
13.1 Explain how Darwin’s voyage on the Beagle influenced his thinking.
Geology (Rock Strata or layers)

Cuvier (anatomist/archeologist) reassembled fossil bones o Stated: o Past organisms differed greatly from any living species. o Some organisms had become ___________. o Deeper, older strata hold fossils that are increasingly different from living species. o “C____________”: sudden geologic catastrophes caused extinction of large groups of organisms at certain points in the past. (Geologic change and extinction occurred).

Lyell (geologist) o Shared some of Cuvier’s ideas o Laws of nature in past same as today: o “____________________” o Lyell’s geologic evidence fit with Darwin’s o evidence from biology.
Biology

Lamarck
’s Ideas on Evolution o Died the year Darwin set sail. o Supported change over time. o Spontaneous generation for simple life. o Simple life becomes more complex. o Acquire Traits thru experience or behavior then pass those traits on to offspring. o “Inheritance of ______________ Characteristics”
Darwin’s Competition:
Scientists don’t argue that evolution occurs, but HOW it happens or it’s mechanism .

1830-1835 Voyage of the Beagle

1830 _______ ________ _________turns 7 years old, grows up to be a biologist and also sails around the world.

Both Darwin and _______ arrive at the same conclusions.

1858 Both present ideas to scientists in London.
 1859 Darwin publishes: “_________________________”

1835

1858 = 23 years
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13.1 Describe the ideas and events that led to Darwin’s
1859 publication of The Origin of Species.
http://wps.aw.com/bc_campbell_concepts_6/83/21320/545806
3.cw/index.html
13.2 Explain how the work of Thomas Malthus and the process of artificial selection influenced Darwin’s development of the idea of natural selection.
Thomas Malthus: Wrote an essay on ________ populations:
More individuals are born than can ________to __________.
Artificial Selection: _______________________________
_______________________________________________.
13.2 Describe Darwin’s observations and inferences in developing the concept of natural selection.
Observation #1: Variation within a population
Observation #2: more offspring produced than can survive
Inference #1: Must fit in and survive, reproduce, pass on genes
Inference #2: Unequal survival rate causes favorable traits to accumulate, “survival of the fitness”
13.2 Explain why individuals cannot evolve and why evolution does not lead to perfectly adapted organisms.
Individuals do not evolve:

They can ___________________to
 ________ _____________with…
 varying degrees of success: “____________”
Evolution does not lead to perfectly adapted organisms:

Not ________ oriented

NS results from environmental factors that vary
 from _______ to ______ and ________ to _________
 “____________” will vary

Adaptations are _________________
 ex. bluefooted boobie’s feet o work great in water o clumsy on land
13.3 Describe two examples of natural selection known to occur in nature.
Notes three key points about how natural selection works.
Thousands of experiments document evolution in action.
Example #1: Ground Finches’ beaks

20 year study
 changes in beak size
 eat small seeds
 in dry years, fewer seeds, birds eat more large seeds
 birds with larger, stronger beaks have the advantage
 average beak size in population increases.
 during wet years, opposite happens.
Example #2: Pesticide resistance
Mrs. Loyd
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Three Key points:
1. N.S. is ___________ not ____________.
2. Contingent on time and space: N.S. favors characteristics that fit _________, ___________ environment.
3. _______________ evolutionary change can occur in a _________ time.
13.4 Explain how fossils form, noting examples of each process.
Fig. 13.4 A-F
A. Skull of H. erectus: actual remains
B. Ammonite casts: minerals replace organic molecules, harden, refilled, hardens, turned out of a mold.
Petrified trees.
C. Dinosaur tracks: trace fossils: footprints, burrows, other traces that represent behavior.
D. Fossilized organic matter of a leaf: actual remains preserved by omitting bacteria and fungi from growing.
E. Insect in amber: fossilized tree sap (actual)
F. Ice Man: frozen (actual)
G. La Brea tar pits (actual)
H. Peat bogs: Tolund Man (actual)
13.4 Explain how the fossil record provides some of the strongest evidence of evolution.
The Fossil Record: the sequence in which fossils appear within layers of sedimentary rocks.
 Strata: layers
 Superposition: oldest is________, youngest is __________
 Fossilization is a __________ event o hard parts fossilize best and most often o soft parts (skin, feathers) fossilize least often.
 Speciation requires __________ time (on geologic time scale)
 Fossil record is ______________as one should expect.
 ________________ is oldest fossilized life form
 Transitional fossils: fig. 13.4H o Terrestrial mammals to whales o Vestigial pelvis o Shared ankle bone design unique to: pigs, hippos, cows, camels, and deer.
Mrs. Loyd
 cloyd@waukee.k12.ia.us
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Evidence of Evolution:
 Fossils ( “Comparing Primate Fossils” Activity)
 biogeography: Wallace established biogeography (the study of the past and present geographical distribution of organisms) by studying the distribution of animal species around the world.
 comparative anatomy o homologous features: Blast Animation
“Homologous Structures” o ____________ features o embryonic development:

______ _________
 ______ o vestigial features
Molecular biology



AA sequence in proteins
Chromosomes (
(“Biochemical Evidence” activity)
“Comparing Primate Fossils” Activity)
Important molecules: Cytochrome c highly conserved.
Mrs. Loyd
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13.6 Explain how evolutionary trees are constructed and used to represent ancestral relationships.
 Darwin was the first to view the history of life as a tree, with multiple branchings from a common ancestral trunk to the descendant species at the tips of the twigs.
 Fig. 13.6 Evolutionary Tree http://163.16.28.248/bio/activelearner/17/ch17summary.html
 Homologous structures, both anatomical and molecular, can be used to determine the branching sequence of such a tree.
 Genetic Code: (A, T, C, G) is a homology shared by all species because they date to the deep ancestral past.
 Characteristics that evolved more __________ are shared only within smaller groups of organisms. (Tetrapods all share basic
_____ ______ __________ but their ancestors do not.
THE EVOLUTION OF POPULATIONS
13.7 Define the gene pool, a population, and microevolution.
Gene Pool : The total collection of ___________________at any one time. Used to study evolution at the population level.
Population : A group of individuals of _____________species living in the same _________at the same _________.
Microevolution : Evolution on its _________scale, occurring in the gene pool of a population. When the relative frequencies of ________in a population change over a number of _______.
13.8 Explain how mutation and sexual recombination produce genetic variation.
Mutation: A chance event, not a mechanism (controlled by genes.)
New alleles originate by a change (mutation) in the
______________ sequence of DNA.
 Ultimate source of genetic variation
 Most mutations occur in ______ _______ and are not passed on.
 Only mutations in ____________ are passed on.
 C________________ mutations: o that delete, disrupt or rearrange many gene loci are usually harmful. o Duplication of part of a chromosome is an important source of genetic variation.

Extra genes that can be mutated.
 Olfactory receptor genes in mammals allows for greater range of scent detection.

Mice = 1,300 receptors
 Humans = 1,000 receptors
Sexual Recombination
Fresh assortments of existing alleles:
 C______________ during Prophase I.
 I____________________________________ Metaphase I of meiosis
 S____________________________
 R
Review Questions:
1. What is the ultimate source of genetic variation?
2. What is the source of most genetic variation in a population that reproduces sexually?
1. mutation
2. Unique combinations of alleles resulting from sexual reproduction.
Mrs. Loyd
 cloyd@waukee.k12.ia.us
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13.8 Explain why prokaryotes can evolve more quickly than eukaryotes.
 Prokaryotic mutations can multiply rapidly due to ______ ___________ rate.
Bacteria are _____loid, one gene per character, a new allele can have
___________________ effect.
 Mutation Rate: o Animals and plants average 1/100,000 genes per generation. o Considered a low mutation rate. o Long time spans between generations, o ___ploid genomes prevent most mutations from significantly affecting genetic variation in plants and animals from generation to generation.
13.9, 10 EXTRA CREDIT: Hardy-Weinberg 3 pts. max.
Do: Objectives 13.9, 10 and
Proce ss of Science: “How Can Frequency of Alleles Be Calculated?” (13.9) See:
“Student Media” on Objective Sheet.
DUE: Submit online for credit before test day.
MECHANISMS OF MICROEVOLUTION
13.11 Define genetic drift and gene flow. Explain how the bottleneck effect and the founder effect influence microevolution.
Genetic _________: A change in the gene pool of a population due to chance.
 The __________ the population, the greater the effect.
 Alleles may be ________ to the population due to chance
 This __________ variation by such losses.
 Examples are: o B___________ Effect o F___________ Effect
________________ Effect:
 Catastrophe may kill indiscriminately and leave few survivors.
 Reduced gene pool variation affects population
 Less variation reduces popul ation’s fitness
________________ Effect:
 When a few individuals colonize as isolated island or other new habitat.
 The smaller the group, the less likely the genetic makeup will represent larger population they left.
 Genetic difference between large pop. and founder pop. is founder effect.
Gene ______:
 Allele frequencies can change as a result of ______ individuals move
_____________________a population.
 Gene flow reduces _________________ between populations.
 Compare to similarities in a closed society like the Amish.
13.11 Explain how genetic bottlenecks threaten the survival of certain species.
 Ice age: Human population estimates 600 breeding individuals at one time in S. Africa. Genetic variation between individual humans about
30% less than between individual chimpanzees.
 Florida panther
 African cheetah
 Illinois greater _____________________reduced by agriculture and development from millions in 19 th C. to 50 individuals in 1993. Flocks from neighboring states added into Illinois flock. Regained hatching success from 50% to 90% due to added alleles.
FOUNDER EFFECT example

1814, 15 people founded British colony, Tristan da Cunha on island in
Atlantic.

One of the 15 was a het for retinitis pigmentosa.

In 1960, of the 240 decendants, 4 had
RP, 9 were hets.

Frequency 10x higher than parent population.
Mrs. Loyd
 cloyd@waukee.k12.ia.us
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13.12 Explain why natural selection is the only mechanism that leads to adaptive evolution.
Chance Events:
 G____________ (__________+____________)
 G________________
 M________________
Chance + sorting:
___________ ____________
 chance: random collection of genetic variation
 sorting: some alleles are favored over others.
 sorting makes in adaptive
 improves the match between organisms and their environment.
 environments change
 “fitness” is a moving target
 adaptive evolution dynamic process
13.13 Distinguish between and describe an example of: stabilizing selection :
 ________ common type
 favors _____________ phenotypes
 ___________ environment
 conditions _________ phenotypic variation
 example: human infant weight averages
6.5-9 pounds, extremes have higher infant mortality. directional selection :
 shifts the overall makeup of the popul. by selecting against individuals at one of the phenotypic ___________.
 example: insects exposed to __________ disruptive selection :
 environmental conditions are varied and favors individuals at ______________.
 leads to________________________
_________ phenotypes.
13.14 Define and compare intrasexual selection and intersexual selection.
Intrasexual selection or within the sex usually between males
 “Winner takes _____”
 _____ wins territorial rights to a group of ___________.
 Usually ____________or ritualized
 Example: lions, elk, mountain sheep
Intersexual selection or mate choice
 between ______ and ____________
 __________ choose ______
 Males display adornments o plumage o courtship dance o song o “Choose Me!” o studies show it relates to overall male health
Mrs. Loyd
 cloyd@waukee.k12.ia.us
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13.15 Explain how antibiotic resistance has evolved.
Discovery Channel video clip http://wps.aw.com/bc_campbell_concepts_6/83/21320/545806
3.cw/index.html
13.16 Explain how genetic variation is maintained in populations .
___ploidy : having two sets of chromosomes
 helps to prevent populations from becoming genetically uniform.
 Recessive alleles hide from selection forces as Hets
 Maintains presence of recessive alleles in gene pool
_________ Selection : When natural selection maintains stable frequencies of two or more phenotypic forms in a popul.
 ________zygote advantage : o homozygotes are selected against o NN = susceptible to malaria/ nn = susceptible to sickle-cell
 ________-dependant selection : most common phenotype selected against o scale-eating fish in Lake Tanganika, Africa o attack other fish from behind to steal scales o right-mouthed/left-mouthed o easier to defend against most common attacker o those numbers go down from lack of food o less common #’s go up from greater food
13.16 Explain what is meant by neutral variation.
 Mutations that have no effect, + or -, on the individual
 Mutation occurs in __________ region of DNA
 O ccurs but doesn’t change ___________ significantly
13.17 Give four reasons why natural selection cannot produce perfection.
1.
Selection can act only on ____________ ____________. a.
can use only phenotypes available b.
may not be ideal trait for environment c.
advantageous alleles do not arise on demand d.
extinction happens
2.
Evolution is limited by _____________ constraints. a.
co-opts existing structures and adapts them to new situations b.
Example: environmental changes favor flight; wings would be best but nature must use the parts available. Bats and birds did not evolve a new set of appendages, they changed what they already had.
3.
Adaptations are often _______________ a.
Each organism must do many different tasks but.. b.
…adaptations may be better suited for some tasks than others c.
Example: blue-footed booby uses webbed feet to swim after prey well, but they are clumsy on land.
4.
Chance, natural selection, and the environment
____________ . a.
Chance plays a bigger role than once thought. b.
Example: a storm blows insects out to sea. A few land on an island, many perish. The few that survived may not be the individuals that would be best adapted to the new environment.
Question: Humans owe much of their physical versatility and athleticism to their flexible limbs and joints. But we are prone to sprains, torn ligaments, and dislocations. a. Which one of the four reasons given for why natural selection cannot produce perfect organisms best explains this? b. Explain how your chosen reason applies specifically to humans.
Mrs. Loyd
 cloyd@waukee.k12.ia.us
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