Introduction to Evolution
Introduction to Evolution
A controversial subject- why?
• Religious Beliefs
• Theory vs. fact– a theory is an idea that has some evidence to support it,
but is not accepted as fact
• Evolution means change in living things
• Changes in gene frequencies that are heritable- actually not as controversial
• What is controversial?
• Beginning of life and where man came from
Big Question: Where life came from?
• To answer this scientifically you must answer
• Where organic compounds come from
• How those molecules are chained into polymers
• How self replicating molecules could be originate (so
genetic info can be passed)
• How all these molecules can be packaged into membranes
that have a different chemistry than their surroundings
Aleksandr Oparin
• Oparin (Russian) and Haldane (British) in the 1920’s suggested that
organic compounds could have been formed in the Earth’s ancient
oceans (really a hypothesis- no proof)
Aleksandr Oparin
• "Primordial soup" is a term introduced by
the Soviet biologist Alexander Oparin.
• In 1924, he proposed a theory of the origin of
life on Earth through the transformation, during the
gradual chemical evolution of molecules that contain
carbon in the primordial soup.
• By further transformation, more complex
organic polymers – and ultimately life – developed in the
soup.
Stanley Miller
• Stanley Miller created an experiment that made amino
acids from methane, ammonia, water, hydrogen
atmosphere
• Miller’s experiment was brilliant and it produced 13 of 20
amino acids. He was awarded the Nobel Prize and many
thought this solved the “big question”
• Problems with Miller’s idea- assumes conditions of the
primitive earth which are only theory; also does not
answer how the amino acids become proteins!
• Could organic materials have been brought in from space?
(panspermia)
• Hydrothermal vents- Could they create the chemical “experiment” that
makes life?
• Volcanoes?- They are important in making Nitrogen compounds- Life?
• RNA?- “The RNA World Hypothesis” RNA can self replicate and it can
carry genetic information
SOMEHOW, prokaryotic cells emerge and photosynthesis begins
• This brings about the oxygen atmosphere and stops the creation of new
organics because of chemical changes to the air and water
Endosymbiotic Theory
• Suggests that chloroplasts and mitochondria were once free living
prokaryotes- came to live in other cells
• Beginning of eukaryotic cells• Evidence- they both have their own DNA and ribosomes, have two
membranes, reproduce in a process similar to binary fission, internal
structure of chloroplast is similar to cyanobacteria
Increasing complexity of life
• Because the oldest rocks contain only simple celled
life and the fossil record contains more complex life
as time goes on, it is theorized that life began
simply and became more complex over time
(evolved)
Jean-Baptiste Lamarck
• Inheritance of Acquired
Characteristics
• Organisms changes during their lifetime
• pass on these traits to offspring
Jean-Baptiste Lamarck
• All organisms evolved toward perfection and complexity
• He did not think that species became extinct- He thought they evolved into
different forms
• Environmental change causes an organism’s behavior to change,
which leads to use or disuse of a structure
• structure would become smaller or larger
• would pass this trait on to offspring, leading to change over time
Evolution: Simpson Style
10.2 Darwin’s
Observations
Darwin noticed
the variation
of traits among similar species that he observed
in his travels…
Variation- is the difference in the physical traits of an individual from those of
other individuals in the group to which it belongs
10.2 journey
Darwin’s
Observations
During Darwin’s
he noticed
that the differences among the species seemed well
suited to the animals’ environment and diet
These observations led Darwin to realize that species may somehow be able to adapt to
their surroundings
• An adaptation is a feature that allows an organism to better survive in its
environment.
– Species are able to adapt to their
environment.
– Adaptations can lead to genetic
change in a population.
You either
have it, or you
don’t
Compare these two tortoises.
Note their looks and think about
how their physical adaptations
might relate to their environment.
– Saddle-back tortoises live in
areas with tall plants
– have long necks and legs
• Domed tortoises live in wet
areas rich in mosses and short
plants
• have shorter necks and legs
Adaptation Misinterpretation
• The verb “to adapt” is often misinterpreted
• The organism has no desire or plan to change
• Wishful thinking and careful planning are not the driving forces at work in
evolution by natural selection
• INSTEAD: Pressures from the environment generate modifications in
populations
What adaptations do these animals have?
Why do they need those adaptations?
Camel
Cheetah
Giraffe
Mountain
Goat
Videos: Adaptations
• Lammergeier Vulture
• Waterfall and Pebble Toads
• Ophiocordycepts Fungus