Download EVOLUTION CLASS PRESENTATION

The Leap to Life
& Evolution
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Charles Darwin
Evidence for Evolution
Mechanisms for Evolution
Natural Selection
Speciation
Charles Darwin
• Traveled around the world on the Beagle
• Most famous stop, the Galapagos Islands
• Observed/recorded many species of
animals.
Wanted to know: “Why do some species
survive, while others become extinct?”
Adaptations - what are these?
Any aspect that enables an organism to respond to a
stimuli & SURVIVE!!
Adaptations can be:
structural
behavioral biological (an internal process).
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Evidence of Evolution
Structural Adaptations
Structural adaptations include any physical features such as
the bill of a bird, the fur on a mammal, teeth, thorns…
Evidence of Evolution
Structural Adaptations
Camouflage
enables species to blend in
with surroundings
Kareius Bicoloratus
Evidence of Evolution
Structural Adaptations
Mimicry
one species resembles another
Evidence of Evolution
Behavioral Adaptations
A behavior that allows better evasion of predators and
survival.
nocturnal herds or large groupings (schools of fish, flock of birds)
migration
hibernation
dormancy
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Evidence of Evolution
Physiological Adaptations
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Changes in metabolic processes
example: new strains of bacterial infections
Evidence of Evolution
Physiological Adaptations
It begins like this...
What other industries would be worried about resistance?
Evidence of Evolution
Physiological Adaptations
Adjustment of the pupil and retina to varying degrees of
illumination.
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A camel produces very concentrated urine to reduce
water loss.
Evidence of Evolution
Fossils
Evidence of Evolution
Anatomy - Homologous Structures
structures with common evolutionary origins
similar in arrangement, function, or both
evidence of evolution from a common ancestor
Evidence of Evolution
Anatomy - Analogous Structures
structures that don’t have a common evolutionary
origin, but have a similar function
Evidence of Evolution
Anatomy - Vestigial Structures
Features that serve no function to an organism,
but were perhaps useful in ancestral species.
Blind fish & Cave dwelling salamanders
Snake pelvis & limb bones/buds
Whale femur & pelvis
Ostrich wings
Evidence of Evolution
Anatomy - Embryos
Similar features during embryological development, although
full development not always of the same structure.
Mammalian ear bones evolved from reptilian jaw bones.
Two bones in reptilian embryos develop into a jaw. The same
two bones develop into an ear in a mammalian embryo.
Evidence of Evolution
Biochemistry
Mutation
Any change or random
error in a DNA sequence.
Mechanisms for Evolution
Genetic Drift
Alteration of allelic
frequencies due to
chance events.
Gene Flow / Migration
The transport of genes
by migrating individuals.
Natural Selection
Why those genes “make it”
• it’s a mechanism for change in
populations
• happens when organisms with
certain variations survive,
reproduce, and pass their variations
to the next generation
Natural Selection
3 Types - Stabilizing
• Favors average individuals
• example: small spiders... hard to find food;
large spiders... easy prey for birds
Small
spiders
Medium
spiders
Large
spiders
Natural Selection
3 Types - Directional
• Favors one of the extremes variations of a
trait
• example: woodpeckers with the longest
beaks can feed on insects deeper inside
of a tree
Short
Beaks
Medium
Beaks
Long
Beaks
Natural Selection
3 Types - Disruptive
• Favors both extremes variations of a trait
• example: dark & light limpets blend easily
with rocks, tan limpets easy to spot for
birds of prey
Light
Limpets
Tan
Limpets
Dark
Limpets
Speciation
• The evolution of a new species.
• Species - group of organisms that can
interbreed to produce fertile offspring
• New Species - when members of similar
populations can no longer interbreed to
produce fertile offspring
Speciation
2 Causes - Geographic Isolation
• Physical barrier divides a
population
• The two populations evolve in
different ways, for different
reasons until they are no longer
populations of the same species
Speciation
2 Causes - Reproductive Isolation
• Formerly interbreeding organisms can no
longer breed and produce fertile offspring
Evolution
2 Types - Divergent
• species that once were similar to an
ancestral species diverge
• occurs when populations adapt to
difference environmental conditions
• can result in new species
Evolution
Divergent
• adaptive radiation
• Darwin’s finches
Evolution
2 Types - Convergent
• evolution in which distantly related
organisms evolve similar traits
• occurs when species occupy similar
environments
Evolution
Convergent
Organ pipe cactus
North & South America
• unrelated and in similar
environments, both
developed similar
attributes
• further evidence for
natural selection
Euphorbia eritrea
Africa