Transcript Similarities in DNA

What is Evolution?
Evolution is change over time
The scientific theory of evolution explains how
living things descended from earlier organisms.
Think about the whale evolution lab, and the human
skull evolution gizmo. What was used to determine
how something evolved from something else?
What evidence supports evolution?
1)
2)
3)
4)
Fossils
Similarities in DNA and protein structures
Similar body structures
Embryonic development
Fossils
Scientists use fossils to examine:
how well adapted an early human species was for walking
upright
how well adapted an early human species was for living in hot,
tropical habitats or cold, temperate environments
the difference between male and female body size, which
correlates to aspects of social behavior
how quickly or slowly children of early human species grew up.
Evidence of Evolution
Homologous Structures
Structures derived from a common ancestral structure (that may or may not be
used for the same function in the species in which it occurs) are called
homologous structures.
Similarities in DNA
DNA in our cells reflects each individual’s unique identity and
how closely related we are to one another. The same is true for
the relationships among organisms.
DNA shapes how an organism grows up and the physiology of
its blood, bone, and brains.
DNA is especially important in the study of evolution. The
amount of difference in DNA is a test of the difference between
one species and another – and thus how closely or distantly
related they are.
Similarities in DNA
While the genetic difference between individual
humans today is minuscule – about 0.1%, a
difference of 3.1% distinguishes us and the African
apes from the Asian great ape, the orangutan.
Similarities in DNA
The strong similarities between humans and the African
great apes led Charles Darwin in 1871 to predict that Africa
was the likely place where the human lineage branched off
from other animals – that is, the place where the common
ancestor of chimpanzees, humans, and gorillas once lived.
The DNA evidence shows an amazing confirmation of this
daring prediction. The African great apes, including
humans, have a closer kinship bond with one another than
the African apes have with orangutans or other primates.
Hardly ever has a scientific prediction so bold, so ‘out there’
for its time, been upheld as the one made in 1871 – that
human evolution began in Africa.
Similarities in DNA
The DNA evidence informs this conclusion, and the fossils
do, too. Even though Europe and Asia were scoured for
early human fossils long before Africa was even thought of,
ongoing fossil discoveries confirm that the first 4 million
years or so of human evolutionary history took place
exclusively on the African continent. It is there that the
search continues for fossils at or near the branching point
of the chimpanzee and human lineages from our last
common ancestor.
Evidence of Evolution
Section of Cytochrome c Protein in Animals
The table shows the sequence of amino acids in one region of a protein,
cytochrome c, for five different animals. Each letter corresponds to a
different amino acid in the protein.
Embryonic development
https://www.youtube.com/watch?v=uAZmLYWEPGk
Scientists infer evolutionary relationships by comparing the early
development of different organisms.
Evidence of Evolution
Similarities in
Development
These four organisms
all look similar during their
early development. What
are similarities and
differences among them?
Darwin
Darwin hypothesized that species change over many
generations and become better adapted to new conditions.
Adaptations are traits, physical or behavioral, that increase an
organisms ability to survive and reproduce.
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Darwin’s Theory
Galápagos Finches
The structure of each
bird’s beak is an
adaptation to the type
of food the bird eats.
Match each finch to
the type of food you
think it eats.
Natural Selection
The process by which individuals that are better adapted to their
environment are more likely to survive and reproduce than other
members of the same species.
Three things cause natural selection:
1) Variation
2) Competition
3) Overproduction
Darwin proposed that, over a long time, natural selection can
lead to chance. Helpful variations may accumulate in a species,
while unfavorable ones may disappear.
Darwin’s Theory
Factors That Affect Natural Selection
What are the factors of natural selection that affect a group of sea turtles
over time?
Darwin’s Theory
Relate Cause and Effect
Identify the factors that cause natural selection.
Natural Selection
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Darwin’s Theory
Loggerhead Sea Turtle Data
Do you think clutch size influences the survival rate of offspring?
Darwin’s Theory
Environmental Change
When copper contaminated the soil surrounding the monkey flowers,
the environment changed. What do you think the area will look like in
ten years?
Biodiversity and Extinction
The map shows
the ranges of Kaibab and
Abert’s squirrels.
A new species can form
when a group of
individuals remains
isolated from the rest of
its species long enough to
evolve different traits that
prevent reproduction.
What factors affect biodiversity?
1) Area – the larger the area, the more biodiversity
2) Climate – climates with warm temperatures and lots of
rainfall are more diverse than cold, dry climates.
3) Genetic diversity – organisms in a healthy population have
diverse traits such as color and size. Genetic diversity helps
species survive changes in the environment.
4) Niche diversity – coral reefs have many niches, allowing
many species to live on them.
Biodiversity and Extinction
Park Size
The dark green area represents three different park
plans. Which plan supports the most bio-diversity?
Biodiversity and Extinction
Extinction usually occurs when a species is unable to adapt within a
changing environment.
Different categories:
Endangered
Threatened
Extinction and Human Activities
Extinction is usually a natural process that occurs gradually.
Nowadays, scientists believe that human activities are
accelerating extinction rates.
decreasing habitat
hunting
climate change
Biodiversity and Extinction
Florida Panthers
This pie chart shows the causes of death for Florida panthers between
1997 and 2007.