Transcript Evolution by Natural Selection

Evolution by Natural Selection
Part 1: Darwin
Part 2: Adaptations
Adaptation Song Youtube
http://www.youtube.com/watch?v=
YX8VQIJVpTg
Who is Charles Darwin?
Part 1
 An English naturalist in the 1800’s
– Studied to be a minister
 Did most of his research while working on the
HMS Beagle as the science officer
– Voyage took 5 years
– Sailed along the coast of South America
– Explored the Galapagos Island chain
• famous for studying the finches
– Collected thousands of specimens (plants and animals),
collected data on weather and ocean currents
How did tortoises and birds differ among
the islands of the Galapagos?
 Each island
had its own
type of
tortoises and
birds that
were clearly
different from
other islands
Darwin’s finches – helped define theory.
 Each bird species evolved from a common finch
from the mainland (C. America).
 All have different beaks depending on feeding
behavior
Phylogeny of the Galapagos Finches
Darwin’s Theory of Evolution
Implications
 Another way of saying this is that there is very little gene
flow between the islands and the mainland.
 Genetic mutations occurred, including beak shape and
neck length, which in turn allowed for varied diets.
8
Charles Darwin’s Theory
Theory of Evolution by Natural Selection
Theory- well-tested explanation that
unifies a broad range of
observations.
Evolution- change in an organism over
time; modern organisms descended from
ancient organisms
Charles Darwin’s Ideas
 Biological evolution is change
in species over time.
– This was not a new idea at the
time
– But there were no good
mechanisms to explain how these
changes occurred
 Natural selection is the
mechanism behind evolution,
and this is what Darwin
contributed.
10
Darwin’s Theory of Natural Selection
 Origin of the Species –
book written for both
scientists and nonscientists. Created
biggest debate of science
vs religion ever…
 Survival of the Fittest –
theory that only the
strongest survive to
reproduce and therefore
are better adapted to the
environment. Basis for
theory of evolution.
 Proposed The Theory of Evolution By Natural
Selection
– Based on 5 key observations
• organisms best adapted to the environment will most likely
survive; “survival of the fittest”
• organisms that survive will mostly likely reproduce
• genetic traits are passed on from parents to offspring who
usually look similar to parents
• more offspring are produced than can survive – the idea of
overproduction to ensure some will survive to reproduce
• organisms compete for needed resources:
a. food
b. water
c. shelter
d. space / territory
e. mates
Artificial selection
Selective Breeding
 Selective Breeding
– Humans and Dogs
– Dogs originated from the Grey Wolf
– Breeding for physical traits
– Many breeds of dogs - all one species
– Human induced and not natural selection
Descent with Modification
 Each living
species has
descended with
changes from
other species
over time
 How have
humans changed?
Natural Selection and Species
Fitness
 Overtime, natural selection results in
changes in the inherited characteristics of
a population.
 These changes increase a species fitness
(survival rate)
 Natural selection does not result in perfection
 Better adapted to the current circumstances
Darwin’s Theory of Evolution
 Selective Breeding- humans choose specific organisms for breeding
because they have useful traits from the natural variation within a
species, hoping to pass on so these traits accummulate in offspring
 Struggle for existence- competition among members of a species for
food, living space, and the other necessities of life.
 Fitness- ability of an organism to survive and reproduce in its
environment.
 Survival of the fittest- individuals that are best suited for their
environment survive and reproduce most successfully.
 Descent with Modifications- principal that each living species has
descended, with changes, from other species over time.
Evidence of Evolution
 Fossil Record
 Homologous Body structures
 Vestigial Structures
 Similarities in Embryology
 Geographic Distribution of Living
Species
Relative
vs.
Absolute
Dating
Carbon-14 Dating
Evidence of
Evolution
Turtle
Homologous Body
Structures
– A body part that is
structurally similar
in 2 or more species
e.g. Wing of bat,
human arm, leg of
turtle
Alligator
Bird
Homologous Body Structures
Vestigial Organs
– traces of homologous organs in other species
– Organ that serves no useful function
e.g. Appendix
Cormorants of Galapagos
Evidence of
Evolution
Similarities in
Embryology
–
In their early
stages of
development,
chickens, turtles,
rats etc. look
similar
Embryological development
The development of pesticide resistance in insects is another example
of real-time evolutionary change.
Natural selection is also
responsible for:
• antibiotic resistance in
bacteria
• herbicide resistance of
weeds
• HIV resistance to antiretroviral drugs
What are Adaptations?
Part 2
Types of Adaptations
 structural:
– a body part or coloration that aids survival

1.) wings, beak shapes, long legs, webbed feet
antlers, etc.


2.) camouflage or protective coloration
* allows an organism to blend in or
hide in its surroundings


3.) mimicry or protective resemblance
* organism looks like or acts like
something it’s not
 Physiological
– the ability to control life functions to
aid survival
 1.) hibernation (slows down metabolism,
breathing, heart rate)
 2.) marine mammals holding breath for long
time
 3.) certain plants in extreme conditions
(salty, dry, underwater)
 Behavioral:
– actions that aid survival
 learned behaviors
1.) behaviors taught to or learned by
experience
2.) example: knowing where the water
hole is or knowing what to eat
 Instincts
1.) behaviors genetically inherited from
parents; “just know how”
2.) example: knowing when to migrate,
sensing danger, mating season
 Traits that help an organism survive
– Helpful, positive physical or behavioral
characteristics
 Allow organisms to:
1. get food/water
2. protect themselves
3. reproduce/find a mate
4. withstand environment