Theory of Evolution “Nothing in biology makes sense EXCEPT in the light of evolution.” -...
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Transcript of Theory of Evolution “Nothing in biology makes sense EXCEPT in the light of evolution.” -...
Theory of Evolution
““Nothing in biology makes sense Nothing in biology makes sense EXCEPT in the light of evolution.” EXCEPT in the light of evolution.”
--Theodosius DobzhanskyTheodosius Dobzhansky
Early Evolutionary Thought
James Hutton Suggested
Gradualism Gradual change
over a long period of time leads to species formation
Early Evolutionary Thought
Gould and Eldredge Suggested Punctuated
Equilibrium A successful species may
stay unchanged for long periods of time.
Major environmental changes may have caused evolution to occur in spurts
Early Evolutionary Thought
Jean-Baptiste Lamarck, 1809 Suggested the Law of Use and
Disuse One Of First Scientists To
Understand That Change Occurs Over Time
Organisms Could Change The Size Or Shape Of Organs By Using Them Or Not Using Them
Early Evolutionary Thought Lamark
Stated that Changes Are Adaptations To Environment acquired in an organism’s lifetime
Said acquired changes were passed to offspring If body part NOT used, it deteriorated
Early Evolutionary Thought
Thomas Malthus Wrote that human
populations are able to increase faster than what the food supply can.
We do not because of disease, war and famine.
Early Evolutionary Thought
Charles Darwin Naturalist aboard the HMS Beagle
Traveled for 5 years around the world Made observations and collected
samples Eventually landed on the Galapagos
Islands where he made several observations that impacted his Theory of “Descent with Modification”.
Natural Selection
When visiting on the Galapagos Islands Darwin noticed: Individuals that have physical or
behavioral traits that better suite their environment are more likely to survive and reproduce.
This theory is called Natural Selection
Natural Selection Finches
Darwin noticed that there were a number of different types of finches
All finches had physical traits that allowed them to adapt to their environment.
For example if a finch lived on a part of the island that was abundant in flowering plants then the finches beak would be long and thin so that it could drink nectar.
Natural vs. Artificial Selection
Natural Selection A mechanism for change in populations. Occurs when organisms with favorable variations
survive, reproduce, and pass their variations to the next generation.
Organisms without these variations are less likely to survive and reproduce.
Artificial Selection Breeding organisms with specific traits in order to
produce offspring with identical traits
Evidence of Evolution
Anatomy Homologous
Structures Structural features with
a common evolutionary origin
Can be similar in arrangement, in function, or in both.
Evidence of Evolution
Analogous StructuresBody parts of
organisms that do not have a common evolutionary origin but are similar in function
Evidence of Evolution
Vestigial Structures Body structure in a
present-day organism that no longer serves its original purpose, but was probably useful to an ancestor.
Evidence of Evolution Embryology
Study of the earliest stage of growth and development of both plants and animals
The embryos of a fish, a reptile, a bird, and a mammal have a tail and pharyngeal pouches
suggest evolution from a distant, common ancestor
Fish Reptile Bird Mammal
Pharyngealpouches
Pharyngealpouches
Tail Tail
Evidence of Evolution
Biochemistry Provides strong
evidence for evolution. Comparing the same
hemoglobin protein in several species reveals a pattern.
Species that share a common ancestor more recently have fewer amino acid differences.
Adaptations
Three major adaptations exist in nature: Mimicry
A structural adaptation that enables one species to resemble another species.
Because a yellow jacket looks so much like a honeybee it’s predators often mistake it for it’s twin and stay away.
Adaptations
Camouflage Adaptation that enables
species to blend with their surroundings
Because well-camouflaged organisms are not easily found by predators, they survive to reproduce.
Adaptations
Physiological Adaptations Changes in an organism’s metabolic
processes Evolve much more rapidly. For example, some of the medicines
developed during the twentieth century to fight bacterial diseases are no longer effective
Antibiotic Resistance
When the population is exposed to an antibiotic, only the resistant bacteria survive.
The bacteria in a population vary in their ability to resist antibiotics.
The resistant bacteria live and produce more resistant bacteria.