Transcript Muscular System - walker2013

Evolution
Chapter 15
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Two schools of thought
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Creationism – The belief that the universe and
living organisms originate from divine creation
Evolution – A gradual process in which something
changes into a more complex form
Creationism vs. Evolution
Creationism
Evolution
Definition
God created
everything in the
universe
Time of Earth’s
existence
Life started with
More than 4,000
years
God made
animals, plants,
and people
Change of
organisms over a
long period of
time
4.5 billion years
A single cell
organism
Creationism vs. Evolution

Issue # 1: The origin of the earth
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Creation – God (or an intelligent designer) created
the heavens and earth
Evolution – several ideas (have not decided on
one theory)

Solar nebular theory – Hydrogen and helium came
together to form stars. When stars die, they explode
releasing clouds of gas and dust. The dust started to
stick together. Over millions of years, they formed
planets.
Creationism vs. Evolution
Creationism vs. Evolution
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Issue # 2: People believed the earth was flat


Columbus “proved” that the earth is round in the
15th century
Isaiah 40: 21-22 states that the earth has a
circular shape
Evolution
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Evolution – a change in an organism over a
long period of time
Charles Darwin – the father of evolution
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Darwin had some proof to support his theory
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The shape of fossils
Darwin’s time on the HMS Beagle
Darwin’s trip to the Galapagos Islands
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Located off of South America
Evolution
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Endemic species – a species which is only
found in a given region or location and
nowhere else in the world
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Two examples
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Galapagos tortoises and Galapagos finches
Evolution
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Galapagos tortoises
Evolution
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Galapagos finches
Artificial Selection
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Artificial selection –
breeding organisms
with specific traits in
order to produce
offspring with identical
traits
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Man chooses which traits
organisms should have
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Example – dogs and
cows
Artificial Selection
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Example – beef cows vs. dairy cows
Natural Selection
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Natural selection –
Organisms with
favorable variations
survive, reproduce, and
pass their variations to
the next generation
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Selection occurs on its
own or “naturally”
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Example – birds with
long tail feathers
Natural Selection
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Darwin called natural
selection “survival of
the fittest”
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Stronger organisms with
preferred traits lived and
made fertile offspring
Example – Two
populations of fish
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One population is faster
than the other
“X” indicates faster swimmer
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Natural selection would
favor which population?
Natural Selection
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Natural selection would
favor polar bears in the
arctic and grizzly bears
in the taiga.
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Why?
Adaptations: Evidence for Evolution
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Adaptation – any
variation that aids an
organism’s chances of
survival in its
environment
Adaptations in species
develop over many
generations
Adaptations of a frog
Adaptations: Evidence for Evolution

Several forms of
adaptations:

Mimicry – a structural
adaptation that enables
one species to resemble
another species
Adaptations: Evidence for Evolution

Aggressive mimicry – a
technique used by some
animals to lure prey to
them by mimicking
something else

Angler fish
Adaptations: Evidence for Evolution
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Aggressive mimicry
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Golden orb weaver will
weave heavy zig-zag
lines of web to attract
insects
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Found in Australia
Adaptations: Evidence for Evolution
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Aggressive mimicry
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Snapping turtle’s tongue
resembles a worm
Adaptations: Evidence for Evolution
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Camouflage – an adaptation that enables species
to blend with their surroundings
Adaptations: Evidence for Evolution
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Warning coloration – A
protection adaptation
used by some animals
that uses color to alert
other animals to keep
away
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Yellow jacket
Poison dart frog
Other Evidence for Evolution
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Anatomy
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Homologous structures – structures with common
evolutionary origins
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Provides evidence of evolution from a common ancestor
Examples: forelimbs of lizards, whales, humans, and
birds
Other Evidence for Evolution
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Analogous structures – structures that do not
have a common evolutionary origin but are
similar in function
Other Evidence for Evolution
Insect
Pterodactyl
Analogous structures
Bird
Bat
Other Evidence for Evolution

Vestigial structure – a structure in a presentday organism that no longer serves its natural
purpose, but was probably useful to an
ancestor
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Example: appendix
Other Evidence for Evolution
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Embryology – the earliest stage of growth
and development of both plants and animals
Population Genetics and Evolution
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Evolution occurs on populations, not
individuals
Variation coupled with natural selection fuels
evolution
Gene pool – all of the alleles in a population’s
genes
Population Genetics and Evolution
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Natural selection acts on variations
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Stabilizing selection –favors average individuals in
a population
Directional selection – favors one of the extreme
variations of a trait
Disruptive selection – individuals with either
extreme of a trait’s variation are selected for
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Tends to eliminate intermediate phenotypes
The Evolution of Species
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Speciation – the evolution of a new species
Several ways for speciation to occur:
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Geographical isolation – a physical barrier divides
a population
The Evolution of Species
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Reproductive isolation – formerly interbreeding
organisms can no longer mate and produce fertile
offspring
Patterns of Evolution
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Divergent evolution - (adaptive radiation) an
ancestral species evolves into an array of
species to fit a number of diverse habitats
Laysan finches from
the Hawaiian islands
Patterns of Evolution
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Convergent evolution – Unrelated species
evolve similar traits