Transcript Natural Selection and Speciation Notes

November 9, 2016

Journal: What is a theory? Are theories always true?
EVOLUTION
Evolution Definition
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Process of species changing over time
Charles Darwin: The Father of Evolution
A. Darwin was NOT the first person to
propose evolution…
B. He did propose a way evolution
happens called Natural Selection
Theory of Evolution by Natural Selection
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Over time, the number of
individuals that carry an
advantageous trait in a
population will increase
Steps of Natural Selection
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Overproduction: more offspring than can survive
are produced
Steps of Natural Selection
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Variation: there are differences between the traits
in these offspring
Steps of Natural Selection
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Selection: In a given environment, having a
particular trait can make individuals more or less
likely to survive
Steps of Natural Selection
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Adaptation: Over time, the traits that improve
fitness will become more common.
 Fitness:
The ability for an organism to survive and
reproduce.
Types of Adaptations
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Physical Adaptations
 Warning
Coloration
 Mimicry
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Behavioral Adaptations
 Horned
Lizards
 Octopus
Speciation

The selection of various
adaptations can help
lead to speciation
 The
formation of a new
species

Species – Group of
organisms that are
closely related and can
mate to produce fertile
offspring
How does speciation occur?
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Reproductive Isolation: When two species can no
longer interbreed to produce offspring
 Geographic
Isolation
 Mating Behavior and Timing
Microevolution

Process that cause changes in the inherited traits
observed in a population over time
 Natural
Selection
 Migration
 Mutation
 Mate Choice
 Genetic Drift: Random effects of everyday life that
cause differences in survival and reproduction rates
Macroevolution
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Convergent Evolution: Species in similar environments
have similar adaptations
Macroevolution
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Coevolution: Species that alive in close contact often
evolve adaption to each other
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Adaptive radiation: Over time, species split into one
or more lines of descendants
Gradualism

Evolutionary change comes about gradually over
time
Punctuated Equilibrum
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Rapid change that results in a new species quickly
Extinction

All members of a lineage die off
Tasmanian Tiger
Quagga