Transcript Lesson 1 Intro to Evolution Adaptation and - Blyth-Biology11

What is Evolution?
• In biology, evolution is the change in the inherited traits (a.k.a.
genes/alleles, genotypes/phenotypes) of species (or
populations of a species) over time.
• Throughout this unit, you will see that three main processes
determine the rate of evolution:
– 1) variation within a species (i.e. the fact that no one is an
identical clone to another person)
– 2) reproduction: the method of reproduction and the rate at
which a species reproduces will affect how fast it evolves.
– 3) selection: whether natural selection or sexual selection,
you will see that those best suited to their particular
environment will pass on their genes more frequently.
Evolution by Natural Selection
• The most famous
explanation of evolution was
made by Charles Darwin,
who stated that those
organisms best suited to
their environment will be
more successful at passing
on their traits to the next
generation.
• This he called Evolution by
Natural Selection.
Darwin’s Influences
• Charles Darwin did not foresee himself getting into the
field of evolutionary biology.
• He wanted to be a doctor like his father, but he could not
stand the sight of blood and the savagery of surgery.
• He then wanted to be a minister, but he did not want to
study. He preferred riding and shooting to studying.
• He eventually became interested in biology through his
fascination with such exciting animals as barnacles,
beetles and pigeons.
Darwin’s Influences
• He changed his path at college and took more biology
courses as he developed a great love of taxonomy (yes,
the classification stuff we did in the first unit) and studied
intensely under the tutelage of botany professor John
Stevens Henslow.
• Henslow recommended Darwin for work as an unpaid
naturalist on a voyage around the world upon the HMS
Beagle, under captain Robert Fitzroy.
• As you will see, this journey not only changed Darwin’s
life, but also the face of biology forever…
Adaptation and Variation
• Organisms face constant environmental challenges that
limit their ability to survive
– Weather
– Famine
– Competition (food, space and mating)
• Organisms must survive long enough to pass along to
offspring the genetic information that helped them survive
• If not, species will eventually become extinct
• Species do not “choose” to adapt, They either adapt or
die!
Adaptation and Survival
• Adaptation is a structure, behavior, or
physiological process that helps an
organism survive and reproduce in an
environment
• Camouflage
• hibernation
Camouflage
Mimicry
Mimicry: A type of Structural Adaptation
• A harmless species resembles a
harmful species in coloration or
structure
• Viceroy mimics Monarch. Monarch
is toxic, Viceroy is not, birds avoid
both
Development of Adaptations
• Result of gradual accumulative changes that
help an organism survive and reproduce
• Random heritable mutations in DNA
• Variations are structural, functional differences
between individuals of the same species
• Not all variations become adaptations
Peppered Moth: Variation to Adaptation
Pre Industrial Revolution
After Industrial Revolution
The English Peppered Moth
http://www.youtube.com/watch?v=LyRA807djLc
In Class Work
• Pg 299, Q 1-6
Variation Within Species
• Why is there so much variation
Amongst members of human species?
Genetic variation in a population results from the
variety of genetic information in all individuals of
the population
Mutations lead to genetic variation
• Mutations are a permanent change in the
genetic material
• Provide new alleles in a species and source of
new genetic variation when inherited
• Can occur spontaneously or through mutagens
(UV, cigarettes, X-rays)
• Most mutations are benign or harmful
Mutations in gamete cells
• If a mutation occurs in a somatic cell, it
disappears from the population when the
organism dies.
• If mutation is in gametes, can be passed
to future generations as a new allele
Mutations can provide a selective
advantage
• If a mutation is beneficial it becomes a selective
advantage; improves an organisms chance of
survival
• Individuals living in malaria-plagued regions
have a selective advantage of what
genotype?__________
Rapid reproduction and selective
advantage
• Some bacteria can double their population in
under 10 minutes!
• Rapid reproduction means that an allele that
was insignificant in the population may provide a
selective advantage when the environment
changes
• http://www.youtube.com/watch?v=UxHacm6gA0c
Antibiotic Resistance
• Activity 7.2, pg 302
• Thoughtlab pg 312 (Due Wed May 2) all
the questions up to extend further