Download Slide 1

• Friday…wear comfortable clothes to go
outside!!
• Permission slips needed for Friday as well
• TODAY:
– Work on model…comp lab 618 around
• Darwin and the Beagle:
http://www.sciencechannel.com/tv-shows/greatestdiscoveries/videos/100-greatest-discoveries-darwinsstory/
• Bird Mating Dance:
https://www.youtube.com/watch?v=wCzZj21Gs4U
• Spider Mating Dance:
https://www.youtube.com/watch?v=V8-CbmM8pf8
• 10 top weird mating dancing:
– https://www.youtube.com/watch?v=kxuijR_KdPg
• Write the equation for photosynthesis.
– 6CO2 + 6H2O ------> C6H12O6 + 6O2
Agenda:
-Warm-Up
-Collect lab
homework
-Evolution video
clips
-Evolution stations
notes
-Socrative review
game
• Write the equation for cellular respiration.
– C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy
• In which organelle does photosynthesis occur
in?
– chloroplast
• In which organelle does cellular respiration
occur in?
– mitochondria
• Go to the website below:
– m.socrative.com
• The classroom you are joining is:
– CINO
Choose your color and begin the review 
• For MUCH of history, people believed:
– Frogs developed from falling drops of rain
– Mice arose from sweaty underwear
• Spontaneous generation is the incorrect hypothesis
that nonliving things are capable of producing life
• “All living beings come from seeds of the
plants or animals themselves”
• However, if someone were to demonstrate
even 1 exception to this hypothesis, then
Redi’s hypothesis would be rejected.
• John Needham’s experiment involved
placing a broth into a bottle, heating it
and then sealing it.
• Days later, Needham found the presence
of life, and eventually announced that life
had been created from nonliving material.
• This supported the incorrect idea that life
could come from nonliving things.
What he did:
1st experiment
Boiled flasks with broth
(chopped hay in water)
Sealed the flasks after
boiling (airtight)
What he found:
There was NO bacterial
growth in the flasks with
airtight seals
What he did:
•Used swan-necked flasks
•Flasks allowed in air, but
trapped dust (and microbes) in
the curve because they
couldn’t overcome gravity
•Boiled broth to force the air
out
•Broke the necks off of some of
the curved flasks
• Descent with
Modification
• the slow , gradual
change in a population
of organisms over time
Charles Darwin
• Born Feb. 12, 1809
• Joined Crew of HMS
Beagle, 1831
• 5 Year Voyage around
world
• Avid Collector of Flora &
Fauna
• Astounded By Variety of
Life
• During His Travels, Darwin Made Numerous
Observations And Collected Evidence That
Led Him To Propose A Revolutionary
Hypothesis About The Way Life Changes Over
Time
• Patterns of Diversity were shown
• Unique Adaptations in organisms
• Species Not Evenly Distributed
• Australia, Kangaroos, but No Rabbits
• S. America, Llamas
• Production of more individuals than can be
supported by the environment leads to a
struggle for existence among individuals
• Only a fraction of offspring survive each
generation
• Survival of the Fittest
• Individuals who inherit characteristics most
fit for their environment are likely to produce
more offspring than less fit individuals
• Called Natural Selection
• The unequal ability of individuals to survive and
reproduce leads to a gradual change in a
population, with favorable characteristics
accumulating over generations (natural selection)
• He believed that new species evolve
• Darwin’s process of natural selection has four components.
– Variation. Organisms (within populations) exhibit individual variation
in appearance and behavior. These variations may involve body size,
hair color, facial markings, voice properties, or number of
offspring. On the other hand, some traits show little to no variation
among individuals—for example, number of eyes in vertebrates.
– Inheritance. Some traits are consistently passed on from parent to
offspring. Such traits are heritable, whereas other traits are strongly
influenced by environmental conditions and show weak heritability.
– High rate of population growth. Most populations have more offspring
each year than local resources can support leading to a struggle for
resources. Each generation experiences substantial mortality.
– Differential survival and reproduction. Individuals possessing traits
well suited for the struggle for local resources will contribute more
offspring to the next generation.
• Malthus (If human population grows unchecked, there
will be insufficient space and food for everyone.
Darwin applied this thought to animal and plants.)
• Lyell (Geologist who instilled in Darwin knowledge of
how Earth changes, which influenced how Darwin
thought about life changing.)
• Wallace (Publishing his own thoughts on evolution
pushed Darwin to do the same.)
• Jean-Baptiste Lamarck, 1809
• One Of First Scientists To
Understand That Change
Occurs Over Time
• Stated that Changes Are
Adaptations To Environment
acquired in an organism’s
lifetime
• Said acquired changes were
passed to offspring
• Idea called Law of Use and
Disuse
• If a body part were used, it got
stronger
• If body part NOT used, it
deteriorated
• Blacksmiths & Their Sons
(muscular arms)
• Giraffe’s Necks Longer from
stretching)
• Inheritance of Acquired Characteristics
• Proposed That By Selective Use Or Disuse Of
Organs, Organisms Acquired Or Lost Certain
Traits During Their Lifetime
• These Traits Could Then Be Passed On To
Their Offspring
• Over Time This Led To New Species
Clipped ears of dogs
could be passed to
offspring!
• Lamarck Did NOT Know how traits were
inherited (Traits are passed through genes)
• Genes Are NOT Changed By Activities In Life
• Change Through Mutation Occurs Before An
Organism Is Born
• Some scientists
believe Earth is about
4.6 billion years old
• Lightening, volcanoes,
meteorites, and UV
light made conditions
intolerable for life
• Atmosphere was also
toxic
 All life forms from common
ancestor
 First organisms primitive,
unicellular type
 Energy sources broke the gas
molecules and simple organic
compounds formed
 Simple molecules washed into
oceans and made larger ones
What makes molecules
organic????
Theory of Chemical Evolution: The formation
of complex organic molecules from simpler
inorganic molecules through chemical
reactions in the oceans during the early history
of the Earth.
• Primitive pre-cells were combination of
polypeptides, nucleotides, and carbohydrates
• Could not use energy or reproduce
• Source of DNA unknown
• Required outside energy source to reproduce
• Similar to present day bacteria
 Autotrophs – capable of making own
food
 Developed when food supply
became scarce
 Photosynthetic organisms evolved
from these autotrophs
 Photosynthesis produced the oxygen
for future organisms
 Oxygen production formed Ozone for
atmosphere
 Blocked UV rays, many new
organisms could evolve
• a group of living
organisms
consisting of
similar individuals
capable of
exchanging genes
or interbreeding.
• Geographic Isolation: The physical separation of
members of a population. This can happen when
an original population’s habitat is divided by a
geographic barrier that can’t be crossed.
• Allopatric Speciation: when species arise as a
result of geographic isolation. “different
homelands”
• Reproductive Isolation: The inability of members
of a population to successfully interbreed with
members of another population of the same or
related species.
• Can occur because of pre-fertilization (different
mating seasons, inability to recognize mating call,
incompatible anatomy, etc.) or post-fertilization
isolation (offspring doesn’t fully develop or is
sterile).
• Sympatric speciation: occurs when two
subpopulations become reproductively isolated
within the same geographic area.
Changes in Earth’s landscape leads to and influences
how the organisms change…
Catastrophism: The belief that the Earth has been
affected in the past by sudden, short-lived, violent
events, possibly worldwide in scope (great floods, rapid
mountain formation, etc.).
Uniformitarianism: The idea that slow incremental
changes, such as erosion, create the Earth's
appearance.
Both have contributed to appearance of Earth today…
Punctuated Equilibrium: Pattern of evolution where there are
long, stable periods of equilibrium (no change) interrupted
by brief periods of more rapid change. When would we see
this???
(May occur when a small population becomes isolated from the main population, or when a
small population migrates to a new environment and organisms evolve to fill new niches, for
example. May follow sudden drastic change to environment or mass extinctions where there
are new niches to fill.)
Gradualism: Pattern of evolution where change is slow,
steady, and consistent. Supported by pattern of many fossil
records.
It seems that both patterns occur, depending on the
situation…
• Also called migration — is any movement of
genes from one population to another.
• Includes lots of different kinds of events, such as
pollen being blown to a new destination or
people moving to new cities or countries.
• If genes are carried to a population where those
genes previously did not exist, gene flow can be a
very important source of genetic variation.
• One of the basic mechanisms of evolution.
• In each generation, some individuals may, just by chance,
leave behind a few more descendents (and genes, of
course!) than other individuals.
• The genes of the next generation will be the genes of the
"lucky" individuals, not necessarily the more fit individuals
• Genetic drift affects the genetic makeup of the population
but, unlike natural selection, through an entirely random
process. So although genetic drift is a mechanism of
evolution, it doesn't work to produce adaptations.
• Founder Effect
– occurs when a new colony is started by a few members of the original
population. This small population size means that the colony may
have:
– reduced genetic variation from the original population.
– a non-random sample of the genes in the original population.
• severe reduction in population size due to
intense selective pressure or a natural
calamity (hunting, hurricane, etc.) which alters
the allele frequency.
If all green beetles are
squashed by chance,
the allele frequency
will be shifted to more
brown.
• Speciation is the formation of new species as a
result of evolution.
• Isolation is the key component needed for
speciation to occur
• Directional Selection
– Natural selection favors one extreme of the population for that
trait
– often happens when environment changes in a consistent waye.g.climate gets colder.
• Disruptive Selection
– Natural selection favors both extremes selected
– Causes species to diverge
• Stabilizing Selection
– Natural selection favors the average for population selected
• Sexual Selection
• Neck of Giraffe
• Antibiotic resistance of
bacteria
• Moth color (melanin)
• Camouflage/Mimics
• Many sexually selected
traits
• When the extremes of
the trait aren’t as well
suited
Examples
• bird clutch size
• Elk Antlers size
• Giraffe neck length
• Tail length in birds
• Causes divergence
within the species
• Occurs when two
different types of
resources in one area
• Results in specialization
for each branched group
• May lead to formation
of new species
• E.g. Darwin’s Finches
• Fossils are direct or indirect remains of
organisms preserved in media such
as sedimentary rock, amber, ice, or tar. Fossils
have been found that indicate organisms
existed well over 3 billion years ago. These
organisms were simple, single-celled
organisms. About a billion years ago,
increasingly complex multi-cellular organisms
began to evolve.
• The higher up you go in
an undisturbed rock
stratum (rock layer), the
younger the rock layers
become and therefore it
is believed the fossils
within these layers,
as compared to lower
rock layers, are also
younger.
• When comparing fossils in undisturbed strata,
fossils can be found in upper strata which,
although different from fossils in lower strata,
resemble those fossils. This suggests links
between modern forms and older forms, as
well as divergent pathways from common
ancestors.