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Process of Evolution
CHAPTER 15
Key Concepts
15.1 Evolution Is Both Factual and the Basis of Broader Theory
15.2 Mutation, Selection, Gene Flow, Genetic Drift, and Nonrandom Mating Result in
Evolution
15.3 Evolution Can Be Measured by Changes in Allele Frequencies
15.4 Selection Can Be Stabilizing, Directional, or Disruptive
15.5 Genomes Reveal Both Neutral and Selective Processes of Evolution
15.6 Recombination, Lateral Gene Transfer, and Gene Duplication Can Result in New
Features
15.7 Evolutionary Theory Has Practical Applications
Intro
In 1918-1919 there was an unusually high death rate associated with the influenza pandemic
This flu virus had an interesting evolutionary nature as soldiers contracted a virus that was
especially intense to the human immune system.
Viruses are continually changing and therefore humans need to build up resistance but will
never truly be immune as these viruses continue to change
Flu vaccines continually change – top 5 from the previous year.
Evolution is Both Factual
and the Basis of Broader
Theory
15.1
Background
Evolution is the change in genetic composition of populations over time.
Evolutionary change is observed in laboratory experiments, in natural populations, and
in the fossil record.
These underlying genetic changes drive the origin and extinction of species and fuel the
diversification of life.
Watching Evolution in Real Time
Evolution
Evolutionary theory is the understanding and application of the processes of evolutionary
change to biological problems.
Applications:
◦ Study and treatment of diseases
◦ Development of crops and industrial processes
◦ Understanding the diversification of life
It also allows us to make predictions about the biological world.
Evolution
Theory—in everyday speech, an untested hypothesis or a guess
Evolutionary theory is not a single hypothesis
It refers to our understanding of the processes that result in genetic changes in populations over
time and to our use of that understanding to interpret changes we observe in natural
populations.
Darwin
Even before Darwin, biologists had suggested that species had
changed over time, but no one had proposed a convincing mechanism
for evolution.
Jean-Baptiste Lamarck presented strong evidence for the fact of
evolution but his ideas were not convincing
In the 1820s, Charles Darwin was interested in geology and natural
history, but despite his passion, his father wanted him to become a
doctor
Darwin
It was because Darwin required surgery, he was not given anesthesia, he became nauseated and
he gave up the idea of medicine and decided to take up a career as a clergyman in the Church or
England
Because Darwin always had a passion for the sciences, he gravitated towards a botanist named
John Henslow who recommended Darwin for a position on the HMS Beagle to survey the world
HMS Beagle
In 1831, Darwin began a 5-year
voyage around the world on a
Navy survey vessel, the HMS
Beagle.
Whenever possible, Darwin went
ashore to study rocks and observe
and collect plants and animals
From here he explored the
Galapagos islands, west of
Ecuador.
The Voyage of the Beagle
3 Min - Theory of Evolution
Crash Course – Natural
Selection
Bozeman - Natural Selection
Bozeman - Examples of Natural
Selection
The Making of a Theory:
Darwin, Wallace, and Natural
Selection — HHMI
BioInteractive Video
The Framework
From the observations and insights made on the voyage and new
ideas from geologists, like Charles Lyell, about how the Earth has
been shaped by slow acting forces that are still active today.
From this Darwin developed a framework of an explanatory theory
for evolutionary change:
◦ Species are not immutable, they change over time
◦ Divergent species share a common ancestor (descent with
modification)
◦ The mechanism that produces change is natural selection; the
increased survival and reproduction of some individuals compared with
others, based on differences in their traits.
Darwin
In 1858, Darwin received a paper from Alfred Russel Wallace with an explanation of natural
selection nearly identical to Darwin’s.
Both men are credited for the idea of natural selection.
Darwin’s book, The Origin of Species, was published in 1859.
Natural Selection Animated Tutorial
Bozeman - Evolution
Modern Synthesis
By 1900, the fact of evolution was established, but the genetic basis of evolution was not yet
understood.
Then the work of Gregor Mendel was rediscovered, and during the 20th century, work continued
on the genetic basis of evolution.
A “modern synthesis” of genetics and evolution took place 1936–1947.
Milestones in the Development
of Evolutionary Theory
What Darwin Never Knew – 2hr must watch!
Watson and Crick
The structure of DNA was established by 1953 by
Watson and Crick.
In the 1970s, technology developed for
sequencing long stretches of DNA and amino acid
sequences in proteins.
Evolutionary biologists now study gene structure
and evolutionary change using molecular
techniques.
Watson and Crick Video