notes evolution may
TRANSCRIPT
![Page 1: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/1.jpg)
Chapter 16Population Genetics
OBJECTIVES: • Relate the study of genetics to that of
population genetics and discuss factors that can affect gene-pool equilibrium
• Explain the Hardy-Weinberg model• Discuss evolution through natural selection• Explain genetic drift and contrast its effects
on large and small populations.• Discuss the role of quantitative traits in
microevolution.
![Page 2: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/2.jpg)
Population Genetics
Recall: variation among individuals allows populations to adapt to new environmental conditions or to be selectively bred for desirable traits.
![Page 3: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/3.jpg)
2 Types of Evolution
• Microevolution: change within a species. Occurs over dozens or hundreds of generations*
• Macroevolution: Much longer time period. Results in a new species
![Page 4: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/4.jpg)
A More Precise Definition
Microevolution is a change in the genetic composition of
populations.
Studied by population geneticists.
![Page 5: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/5.jpg)
Gene poolAll alleles in a population
of organisms.
![Page 6: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/6.jpg)
Allele frequency
Percentage of a particular allele in one population.
Ex: In a population of pea plants that are all homozygous for purple flowers, allele freq.
for purple flowers is 100%
A change in an allele frequency is an indication of evolutionary
change.
![Page 7: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/7.jpg)
Allele Frequencies within Beetle Population
![Page 8: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/8.jpg)
Polymorphic Populations
• Have 2 or more alleles for a particular trait.
• Ex: humans are polymorphic for blood type.
• Ex: apple trees are polymorphic for fruit color.
![Page 9: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/9.jpg)
Hidden Genetic Variations
• Mutation in non-coding regions of DNA
• Silent mutations code for the same amino acid
• Unseen polymorphisms
![Page 10: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/10.jpg)
The Hardy-Weinberg ModelAn idealized mathematical model of
gene pools.
•Mathematician Godfrey H. Hardy
•Physicist Wilhelm Weinberg
![Page 11: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/11.jpg)
Use allele freq. to calculate genotype freq.
Allele frequency p and q,
p + q = 1
In the next generation:
p2 + 2pq + q2 = 1
Homozygous p: p2
Heterozygous: 2pq
Homozygous q: q2
![Page 12: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/12.jpg)
Hardy-Weinberg Equilibrium
Allele and genotype frequency will stay constant in the absence of
disturbing influences.
p2 + 2pq + q2 = 1
![Page 13: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/13.jpg)
Hardy-Weinberg Model
Makes some assumptions about the population. No “disturbing influences.”
• random mating • no mutation (the alleles don't change) • no migration or emigration • infinitely large population size• no selective pressure for or against
any traits.
![Page 14: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/14.jpg)
Hardy-Weinberg Equilibrium
Predictions of the model1. Predicts allelic and genotypic
frequencies 2. Genetic variation remains in the
population (unless selective pressures)
Good news for Darwin! (Assumed blending inheritance.)
![Page 15: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/15.jpg)
Genetic equilibrium: a constant state of allele
frequencyThe following conditions must be met in order that genetic equilibrium not be
disrupted.1)No natural selection
2)Random mating
3)No migration
4)No mutation
5)Large population sizeNote: does not occur in nature.
So, why use Hardy-Weinberg model?
![Page 16: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/16.jpg)
Quick Quiz
1. Would a change in allele frequencies be more likely to produce microevolution or macroevolution?
2. What is the difference between gene pools and allele frequencies?
3. Why does the concept of gene pools apply to populations but not to species?
![Page 17: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/17.jpg)
A Normal Distribution results
from Stabilizing Selection: Natural
selection that favors average individuals in a
population.
![Page 18: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/18.jpg)
Normal Distribution
IQ
![Page 19: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/19.jpg)
![Page 20: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/20.jpg)
Directional Selection in Peacocks
Females only mate with males with the largest tails. Over time, tails have gotten continually larger due to this selective pressure.
![Page 21: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/21.jpg)
Peppered Moths: color variations
![Page 22: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/22.jpg)
![Page 23: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/23.jpg)
1850: allele frequency was 95% light, 5%
dark
1900: allele frequency 95% dark, 5% light
![Page 24: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/24.jpg)
Disruptive Selection: Natural
selection that favors either extreme trait.
![Page 25: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/25.jpg)
Disruptive Selection in Snails
Limpets with light-colored shells blend in with light rocks and sand. Dark shells blend in with dark rocks.
Limpets with medium-colored shells are easily seen on both rocks and eaten by birds.
![Page 26: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/26.jpg)
Disruptive Selection in Spiders
• When spiders are small, they are not as easily seen by predators.
• When spiders are large, they are often too big to be eaten.
• Spiders in the middle are the most vulnerable to predators.
![Page 27: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/27.jpg)
![Page 28: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/28.jpg)
Other Factors Affecting Gene Pools
• Gene Flow: Migration to a new population, organism may bring new alleles with it.
• Mutation: If beneficial, will be favored by natural selection and gradually increase in frequency
• Genetic Drift: Spontaneous changes in allele frequencies. Small populations only.
![Page 29: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/29.jpg)
Other Factors Affecting Gene Pools
• Inbreeding: Gradual increase of homozygotes. Ex: California Condor
• Population bottleneck: Population size reduced for a few generations. Inbreeding results. Ex: Buffalo in the 1800’s.
• Inbreeding increases frequency of harmful recessive alleles. Leads to Inbreeding Depression: reduced fertility and survival.
![Page 30: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/30.jpg)
Did you know…
The average human is estimated to have 7 alleles that would be lethal if they were homozygous? In inbred populations, inheriting 2 of these alleles is more likely.
(BSCS Biology: A Molecular Approach)
![Page 31: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/31.jpg)
Population Genetics
CONCEPT REVIEW:
• Evolution results from a disruption in genetic equilibrium.
• The normal distribution of variations in a population can be changed by natural selection, gene flow, mutations, and genetic drift
![Page 32: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/32.jpg)
Chapter 18Diversity and Variation
Outcomes• Explain homology and give examples
of homologous structure• Describe how the general
characteristics of the 5 kingdoms differ.
![Page 33: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/33.jpg)
The 5 (or 6) Kingdoms
• Archaebacteria• Eubacteria• Protista• Fungi• Plantae• Animalia
Bacteria/monera
![Page 34: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/34.jpg)
Bacteria
• Prokaryotes• First organisms to evolve
![Page 35: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/35.jpg)
Protista
• Earliest eukaryotes. • Usually single celled. • No organ systems• Nucleus developed• Mitochondria, flagellates, and
plastids became incorporated.• Ex: amoeba, paramecium, algae
![Page 36: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/36.jpg)
Fungi
• Usually multicellular (except yeast)• Eukaryotic• Heterotrophs• Evolved from fungus-like protists
(slime molds)• Ex: mushroom, mold, yeast
![Page 37: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/37.jpg)
Plantae
• Multicellular, with complex body systems (roots, stem, leaves)
• Autotrophs• Eukaryotes• Evolved from photosynthetic
bacteria• Ex: Flowering plants, Conifer,
Mosses, Ferns
![Page 38: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/38.jpg)
Animalia
• Multicellular with complex systems• Heterotrophic• Eukaryotic• Ex: Fish, Amphibian, Reptile, Bird,
Mammal
![Page 39: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/39.jpg)
![Page 40: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/40.jpg)
There are still lobe-finned fish today called mudskippers. 34 species have
been identified. Unlike those we evolved from, most of today’s species have only 2 appendages (front lobe-
fins)
![Page 41: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/41.jpg)
![Page 42: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/42.jpg)
Fish to Amphibians
![Page 43: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/43.jpg)
![Page 44: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/44.jpg)
Reptiles to Birds
![Page 45: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/45.jpg)
Reptiles to Birds
![Page 46: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/46.jpg)
Evolution
of
Mammals
![Page 47: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/47.jpg)
Eventually, some mammals returned to the
water.
• Today’s whales had an ancestor similar to a wolf.
![Page 48: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/48.jpg)
Chapter 19Changes in Species
Outcomes:• Cite evidence from fossils, ecology,
and homologies that support the theory of evolution
• Discuss the genetic and molecular evidence for evolution
• Discuss isolation mechanisms that can cause speciation
• Describe the patterns in evolution such as punctuated equilibrium
![Page 49: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/49.jpg)
Fossils
as evidence of evolution
![Page 50: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/50.jpg)
Fossils are the preserved remains or imprints of ancient organisms.
![Page 51: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/51.jpg)
Fossils: the only evidence we have that tells us directly about life in the
past.
This extinct dragonfly had a wingspan of 3 feet!
![Page 52: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/52.jpg)
Life first appeared on earth more than 3 billion years ago.
Fossils of algae and diatoms
![Page 53: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/53.jpg)
Millions of now extinct creatures lived on earth before humans came along.
![Page 54: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/54.jpg)
Some fossils are the actual preserved remains of the organism
![Page 55: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/55.jpg)
Soft-Tissue Fossils
Ice in the Arctic has preserved some fossils for 1,000s of years.
In 1999 a wooly mammoth was discovered intact.
Can it be revived by crossing with an elephant? Different #s of chromosomes (58 and 56), but 95% similar DNA.
![Page 56: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/56.jpg)
Scientists have found 250,000 species of extinct orgnisms
Estimate that only 1 in 10,000 have been found.
![Page 57: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/57.jpg)
Evolution of the Horse
In these pictures, there appears to be a straight line progression from the first horse ancetor to the modern horse species.
Such a progression implies an evolutionary
goal, since there is a trend toward larger body
size and fewer toes.
![Page 58: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/58.jpg)
Evolution of the Horse
However, evolution rarely follows a straight line to a
goal.
Remember,
There are no goals in evolution !
![Page 59: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/59.jpg)
1) homologous2) vestigial 3) analogous
Evidence for Evolution:
Body Structures
![Page 60: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/60.jpg)
Homologous Structures: Traits that are similar in different species because they share a common ancestor.
Note how the bones have adapted to different niches
This is evidence of a common ancestor.
![Page 61: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/61.jpg)
![Page 62: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/62.jpg)
Vestigal Structures: No longer used.
The Human “Tailbone”
This is evidence that humans evolved from an ancestor that
had a tail.
![Page 63: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/63.jpg)
appendix
Vestigal Organ: human appendix
![Page 64: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/64.jpg)
![Page 65: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/65.jpg)
A whale has a pelvic bone too,
and tiny leg bones.
![Page 66: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/66.jpg)
Analogous Structures: structures that are similar in function but are not inherited from a common ancestor.
NOTE: Analogous structures indicate that organisms are not related.
![Page 67: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/67.jpg)
Embryology is also used as Evidence of Evolution: Similar development of the embryo is
evidence of a common ancestor
All three embryos have “gill pouches” in the folds of the neck. All three have
tails.
![Page 68: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/68.jpg)
![Page 69: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/69.jpg)
Perhaps the clearest biochemical
evidence of the common origin of living things is the genetic code. The
same nitrogen bases of adenine, thymine,
guanine, and cytosine exist in
every form of life.
![Page 70: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/70.jpg)
In addition, the genetic code itself – the codons for the amino
acids – is almost universal.
![Page 71: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/71.jpg)
The genetic code is the same in every known organism. Every organism uses the same base
codes for amino acids
![Page 72: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/72.jpg)
Degree of RelatednessCan be determined by
• Amino acid sequence• Homologous proteins• Nucleotide sequence• Homologous genes.
![Page 73: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/73.jpg)
More Genetic Evidence: Pseudogenes
Gene duplication: produces multiple copies of DNA sequences.
Pseudogenes: gene copies that don’t function, so aren’t subject to natural selection.
Mutations occur unchecked. According to natural selection, these non-
coding sections should accumulate mutations faster than functional genes – and they do!
![Page 74: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/74.jpg)
Amino Acid Sequence• Can be used to determine
relatedness
![Page 75: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/75.jpg)
How fast do evolutionary changes take
place?
![Page 76: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/76.jpg)
Based upon Darwin’s theory it has long been
believed that evolutionary changes were slow and gradual: Gradualism.
1972: scientists Stephen Jay Gould and Niles Eldridge advanced a different explanation
about the rate of evolution called
Punctuated Equilibrium
![Page 77: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/77.jpg)
•Punctuated Equilibrium:
populations remain genetically stable for long periods of time, interrupted by brief
periods of rapid change.
•sudden changes in the environment
•increased mutation rate.
stasis
![Page 78: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/78.jpg)
Speciation is the evolution of one or more species from a
single common ancestor species.
![Page 79: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/79.jpg)
Patterns of Evolution
![Page 80: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/80.jpg)
How do species remain separate?
(1) Potential mates do not meet. Grizzly and Polar bears.
(2) Potential mates meet but do not breed. Nocturnal and diurnal birds. Leopard frog populations that breed during different months.
(3) Potential mates meet and breed, but do not produce viable offspring.
![Page 81: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/81.jpg)
Divergent Evolution:
Occurs when isolated populations of a species evolve independently.
![Page 82: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/82.jpg)
Divergent evolution is responsible for polar bears. A northern population of grizzly bears became isolated from
others of the species and adapted to the Arctic regions.
Grizzly Bear Polar Bear
![Page 83: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/83.jpg)
Coevolution:
Interactions with other organisms effect
evolution.
Coevolution is responsible for mimicry
one of the most fascinating topics in biological evolution.
![Page 84: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/84.jpg)
CoevolutionThe pronuba moth and the
yucca flower
Depend on one another for
reproduction.
![Page 85: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/85.jpg)
CoevolutionThe Orchid Fly
![Page 86: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/86.jpg)
Coevolution: Cactus and Galapagos Tortoise
Saddleback shell
![Page 87: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/87.jpg)
Cleaner Wrasse
Sabre Toothed Blennie
![Page 88: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/88.jpg)
Adaptive Radiation: Many diversely related species from one common ancestor
![Page 89: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/89.jpg)
Polyploidy in PlantsIf plants inherit an extra chromosome
from parents, they are said to be polyploidy.
Often, these plants can only mate with other polyploids, or use asexual reproduction.
![Page 90: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/90.jpg)
Convergent Evolution:
Unrelated species display similar features. No common ancestor.
How does this happen?
![Page 91: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/91.jpg)
Convergent Evolution
![Page 92: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/92.jpg)
Disruptive markings make it hard for predators to single out
a victim.
![Page 93: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/93.jpg)
Similar niches usually contain similar evolutionary pressures (selective
pressures).
If ancient niches were similar to modern niches then organisms today could resemble organisms now long
extinct.
![Page 94: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/94.jpg)
Similar niches found on different continents can produce organisms
that are fairly similar.
![Page 95: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/95.jpg)
Modern dolphins and prehistoric ichthyeosaurs (marine reptiles) look very
similar due to the types of niche they inhabited.
![Page 96: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/96.jpg)
. .
..
.
Analogous structures can be caused by niches. Similar niches create similar body forms.
![Page 97: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/97.jpg)
.
..
Note how similar niches created long necks in both sauropods and giraffes.
![Page 98: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/98.jpg)
.
Similar foods (similar niches) create similar teeth in herbivores.
![Page 99: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/99.jpg)
Similar foods (similar niches) create similar teeth in carnivores.
![Page 100: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/100.jpg)
![Page 101: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/101.jpg)
![Page 102: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/102.jpg)
Quick Quiz
1. What are isolating mechanisms, how do they operate?
2. What is polyploidy? What is its connection to speciation?
3. Explain the statement: “Populations evolve, not individuals within a population.”
![Page 103: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/103.jpg)
Origin of Species
Concept Review:
• New species can develop when populations become separated and isolated.
• Similar traits can develop in unrelated species occupying comparable niches.
• Interactions with other organisms affect evolution.• Many diverse species can evolve from one ancestral species.
![Page 104: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/104.jpg)
Chapter 17The Origin of Life
Objectives:• Describe the origin of the universe and
probable conditions on early Earth• Evaluate hypotheses about the origin
of life and identify the probable characteristics of early life-forms
• Distinguish between chemical and biological evolution
• Describe the fossil record for prokaryotes and eukaryotes.
![Page 105: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/105.jpg)
The Origin of Life
•Can’t be observed
•Inferences
•Probably needed energy, C, H, O, N, and lots of time.
![Page 106: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/106.jpg)
The Big BangThe Expanding Universe
• Edwin Hubble, 1920. The Hubble Telescope was named for him.
• Wavelengths of light can be measured, spread out as objects move farther away
• The rate of expansion is known, used to calculate the time when universe was tiny.
![Page 107: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/107.jpg)
The Big Bang
• 15 billion years ago• Universe was condensed into a tiny
“singularity”• An infinitely hot, dense mass.• When it exploded, The Big Bang,
hurled energy and mass into space.• What was there before the Big
Bang?
![Page 108: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/108.jpg)
Early Earth
• 4.6 Billion years ago• Meteorites and the oldest rocks
from the Moon confirm this
![Page 109: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/109.jpg)
History of the EarthEra Million Years Ago First evidence of
Cenozoic 7-565
Human-like apesPrimates
Mesozoic 140220235
Flowering PlantsMammalsDinosaurs
Paleozoic 300360400430520
ReptilesAmphibiansLand AnimalsLand PlantsVertebrates
Precambrian 210025003500
EukaryotesFree O2 in atmosphere by prok.Prokaryotes
![Page 110: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/110.jpg)
The Early Atmosphere
• Gasses from volcanoes: N2, CO2, H2O, H2, CO, probably methane (CH4)
• No O2
• No ozone layer – intense radiation, extreme temperature changes.
![Page 111: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/111.jpg)
The First Living Things
• Anaerobic Organisms• 1 billion years later, some
photosynthetic organisms began releasing free oxygen.
![Page 112: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/112.jpg)
How did those living things come to be?
3 possible explanations:1. Life originated on some other planet,
then traveled to Earth through space.2. Life originated by unknown means on
Earth3. Life evolved from nonliving
substances through interaction with their environment.
2 of these cannot be tested, only one can be stated as a hypothesis. Which one?
![Page 113: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/113.jpg)
Chemical Evolution Life evolved from nonliving
substances • Small, inorganic molecules were
heated via cosmic radiation, volcanoes, radioactivity and lightning.
• Gasses in the atmosphere react, forming organic compounds
• Compounds accumulate in oceans, forming a hot soup
• Life evolved by chemical reactions and transformations in the organic soup
![Page 114: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/114.jpg)
Chemical EvolutionThe oceans became “soup” of
organic compounds
![Page 115: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/115.jpg)
The Heterotroph Hypothesis
The first living things were probably heterotrophs that fed on organic compounds in the ocean.
With no competition, autotrophs would not have an advantage over heterotrophs
![Page 116: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/116.jpg)
The Heterotroph Hypothesis(or Oparin-Haldane
hypothesis)3 Requirements1. There had to be a supply of
organic molecules, produced by nonbiological processes.
2. Some processes had to assemble those small molecules into polymers such as nucleic acids and proteins.
3. Other processes had to organize the polymers into a system that could replicate itself
![Page 117: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/117.jpg)
Evidence for the Heterotroph Hypothesis
Stanley Miller’s experiment in 1950. Early Earth conditions were simulated in an airtight apparatus.
• Water vapor• Lightning• CH4, NH3, H2O, H2After circulating for a week, new
compounds were found in the water, including some amino acids.
![Page 118: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/118.jpg)
More recent experiments have produced the 5 bases of DNA and RNA too.
![Page 119: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/119.jpg)
Other Sources of Organic Molecules
• Meteorites from space – amino acids have been discovered
• Volcanic vents – release gases at high temperatures
Remember 1st requirement: There had to be a supply of organic molecules, produced by nonbiological processes.
![Page 120: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/120.jpg)
The rest of the hypothesis:
#2. Some processes had to assemble those small molecules into polymers such as nucleic acids and proteins.
Clay – repeating crystalline structure that could attract then connect monomers
#3. Other processes had to organize the polymers into a system that could replicate itself
RNA – Can form spontaneously. Can reproduce itself. Probably came before DNA
![Page 121: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/121.jpg)
Biological Evolution• When did chemical evolution become
biological evolution?• When organic molecules became living things• Self reproduction, mutation that can be
inherited, and natural selection = life• Cells? Today all living things are made of cells.• It is unknown when/how cell membranes
developed.• The first living things may have had
membranes, or not. They may have been DNA, RNA, proteins…who knows?
![Page 122: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/122.jpg)
Prokaryotic Fossils
3.5 Billion years old. Single-celled prokaryotes.
Suggest life was already diverse and thriving.
Probably methanogens:Use CO2 to oxidize hydrogen
![Page 123: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/123.jpg)
Fossils of Eukaryotes• 2.1 Billion years old• Lynn Margulis of UMass, Amherst
developed the endosymbiont hypothesis: Chloroplasts and mitochondria were once free-living prokaryotes. Photosynthesis and respiration of the small cells have benefited the host cells.
• Mitochondria probably evolved from aerobic, heterotrophic purple bacteria.
• Plastids probably evolved from autotrophic cyanobacteria.
![Page 124: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/124.jpg)
Endosymbiont Hypothesis
The evidence: Both have their own DNA and ribosomes, which are similar to other bacteria. Also both have a double membrane; their outer membranes may have evolved from vacuoles when host cells took them in.
![Page 125: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/125.jpg)
Evolution of Eukaryotes
![Page 126: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/126.jpg)
Quick Quiz
1. Why is it believed that methanogens might have been the first organisms?
2. How might mitochondria and plastids have originated?
3. What evidence supports the idea that mitochondria and plastids originated from free-living prokaryotes?
![Page 127: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/127.jpg)
Chapter 20Human Evolution
Outcomes:• Describe how modern humans
differ from other primates• Evaluate the techniques used to
study evolutionary relationships in humans
• Compare early hominids with Homo erectus and Homo sapiens
• Give reasons for the difference in the gene pools of modern human populations.
![Page 128: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/128.jpg)
![Page 129: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/129.jpg)
What are Primates?
• Opposable Thumbs• Fingers and toes have nails, not
claws• Flexible shoulder and hip joints• Binocular, 3-D vision for accurate
depth perception• Color vision
![Page 130: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/130.jpg)
Humans vs. Other Primates
• Bipedal: Hands are free• Have a hippocampus: brain region
for memory and learning. Absent in most primates (not chimps and gorillas)
• More fine motor control in hands• Language, well developed vocal
chords
![Page 131: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/131.jpg)
Molecular SimilaritiesHuman vs. Chimpanzee
Protein Number of amino acids
Amino-acid difference
Hemoglobin 579 1
Myoglobin 153 1
Cytochrome C 104 0
Serum Albumin 580 7
![Page 132: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/132.jpg)
Molecular Similarities Among Primates
Species compared
Difference in DNA sequence (%)
Estimated time since divergence
Chimpanzee vs. Bonobo
0.7 3 million years
Human vs. Chimpanzee
1.6 7 million years
Human vs. Gorilla
2.3 10 million years
Gorilla vs. Chimpanzee
2.3 10 million years
![Page 133: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/133.jpg)
Early Hominids
• Lived in Africa• Genera in Hominid family: Homo
and Australopithecus (larger teeth, smaller brains).
![Page 134: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/134.jpg)
The Hominids
![Page 135: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/135.jpg)
Hominids – The Human-like Primates
![Page 136: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/136.jpg)
Comparing SkeletonsSkeletal fossils – clues to how
organism moves, eats, behaves.Footprint fossils – How organism
moved, how heavy it was.Who was Lucy?
![Page 137: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/137.jpg)
Comparing SkeletonsSkeletal fossils – clues to how
organism moves, eats, behaves.Footprint fossils – How organism
moved, how heavy it was.Who was Lucy?
Australopithecus afarensis found in Ethiopia, 1974
![Page 138: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/138.jpg)
The First Humans
![Page 139: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/139.jpg)
Hominids
![Page 140: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/140.jpg)
“Hence, both in space and time, we seem to be brought somewhat near to
that great fact - that mystery of mysteries - the first appearance of new beings on this
earth.”Charles Darwin
![Page 141: Notes Evolution May](https://reader034.vdocuments.us/reader034/viewer/2022051513/5477cd98b4af9fa2108b49cb/html5/thumbnails/141.jpg)