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Evolution
Genetic change in a
species over time
Charles
Darwin
1831- Ship’s doctor,
HMS Beagle
Travelled around the
world observing
species and collecting
specimens
Darwin Left England in 1831
Darwin returned 5 years later in 1836
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Darwin was influenced by:
1. James Hutton – geologist
The same geologic processes have
occurred throughout Earth’s history
2. Charles Lyell – geologist
Earth’s surface has changed over time,
Earth is millions, not thousands of years old
3. Thomas Malthus – economist
if unchecked, human population
will double every 25 years
(the struggle for survival prevents this)
1859
Book: Origin of Species
Theory: Natural Selection
1. Overproduction occurs in all species
2. Variations occur in all species
3. Struggle for survival- resources are limited,
not all born will survive
4. Survival of the fittest- those best adapted to
their environment will survive and
reproduce.
Fitness: ability of an individual to
survive and reproduce
- central to the process of Evolution
- individuals with low fitness either
die or produce few offspring
Adaptation: Inherited characteristic
that increases an organisms chance
for survival
Adaptations Can Be:
Physical - Speed, Camouflage, Claws,
Quills, etc.
Behavioral - Solitary, Herds, Packs,
Activity, etc.
Evidence of Evolution
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Fossils
Comparative Embryology
Homologous structures
Vestigial Organs
Biogeography
Biochemistry
Fossil Record
• Earth is Billions of Years Old
• Fossils in different layers of sedimentary
rock show evidence of gradual change over
time
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Evidence for Evolution - Comparative Embryology
Embryonic Development:
similarities indicate a common ancestor
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Homologous Structures
Ex: Forelimbs of mammals have the same bones
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Vestigial Organs
not used by us, used by related species
Ex: appendix (koalas need theirs)
Ex: Human coccyx (tailbone)
Ex: hip bones in snakes
Geographic Distribution of
Living Species
Unrelated animals on
different continents
have similar
adaptations to similar
environments.
Ex: deer, kangaroo –
eat the same food,
have same skull and jaw
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Biochemistry – similar DNA and amino acid
sequences indicate a common ancestor
Evolution of
pesticide
resistance in
response to
selection
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Key Concept
Over time, Natural Selection results In
changes in the inherited
characteristics of a population.
These changes increase a species
fitness in its environment
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