Transcript Evolution 2016

Evolution Vocabulary
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Endosymbiotic Theory
Evolution
Convergent Evolution
Coevolution
Punctuated Equilibrium
Descendant
Ancestor
Fossil
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Homogolous Sturcture
Vestigial Structure
Analogous Structure
Embryology
Biogeography
Hominid
Candidate Fossils
ORIGINS OF LIFE
Theories of the Origin of Life
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Abiogenesis
 Primordial
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soup
Endosymbiotic theory
Hydrothermal vents
Panspermia
Abiogenesis
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= "non biological origins“: hypothetical
generation of life from non-living matter.
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Spontaneous generation
Primordial Soup
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Famous Miller-Urey experiment (1953) suggested
that lightning might have helped create the key
building blocks of life on Earth in its early days.
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millions of years, larger and more complex
molecules could form.
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Electric sparks can generate amino acids and sugars
from an atmosphere loaded with water, methane,
ammonia and hydrogen.
Endosymbiosis
Deep-Sea Vents
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The deep-sea vent theory
suggests that life may have
begun at submarine
hydrothermal vents
These vents spew key hydrogenrich molecules. Their rocky nooks
could then have concentrated
these molecules together and
provided mineral catalysts for
critical reactions.
Even now, these vents, rich in
chemical and thermal energy,
sustain vibrant ecosystems.
Panspermia
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= life did not begin on Earth at all, but
was brought here from elsewhere in
space
Rocks regularly get blasted off Mars by
cosmic impacts, and a number of
Martian meteorites have been found on
Earth that some researchers have
controversially suggested brought
microbes over here, potentially making
us all Martians originally.
Key Concept
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Evidence of common ancestry among
species comes from many sources.
Evidence for evolution came from
several sources.
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Fossils provide evidence of evolution.
 Fossils
in older layers are more primitive than
those in the upper layers.
Paleontology provides evidence to
support evolution.
The study of geography provides
evidence of evolution.
Island species most closely resemble nearest
mainland species
 Populations can show variation from one
island to another
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Embryology provides evidence of
evolution.
Identical larvae, different adult body forms
 Similar embryos, diverse organisms
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The study of anatomy provides
evidence of evolution.
Homologous structures are similar in
structure but different in function.
 Homologous structures are evidence of a
common ancestor.
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Human hand
Mole foot
Bat wing
The study of anatomy provides
evidence of evolution.
Analogous structures have a similar
function.
Human hand
Mole foot
 Analogous structures are NOT evidence of a
common ancestor.
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Fly wing
Bat wing
Structural patterns are clues to the
history of a species
• Vestigial structures are remnants of organs or structures
that had a function in an early ancestor.
• Ostrich wings are examples of vestigial structures.
Molecular & genetic evidence
support fossil & anatomical evidence
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Two closely-related organisms will have similar DNA
sequences.
Humans share a common ancestor
with other primates.
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Primates are mammals with flexible hands and feet,
forward-looking eyes and enlarged brains.
Anthropoids are humanlike primates.
So why are humans so advanced?
BRAINSTORM with a shoulder partner about what
makes us more advanced than other primates and
organisms
So why are humans so advanced?
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Bipedal means walking on two legs.
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foraging
carrying infants and food
using tools
HUGE brains!
 Language
 Use of tools
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NATURAL SELECTION
Or, how did we get here….
Natural Selection
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Natural selection is a mechanism by which
individuals that have inherited beneficial
adaptations produce more offspring on average
than do other individuals.
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Heritability is the ability of a trait to be passed down.
There is a struggle for survival due to overpopulation
and limited resources.
Darwin proposed that adaptations arose over many
generations.
Natural selection explains how
evolution can occur.
• There are four main principles to the theory of natural
selection.
– variation
– overproduction
– adaptation
– descent with modification
ADAPTATION
DESCENT
VARIATION
OVERPRODUCTION
with
MODIFICATION
Variation
1. Reproduction occurs with variation
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This variation is heritable (traits inherited from parents)
Variation
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Variation is a difference in a physical trait.
 Galápagos
tortoises that live in areas with tall plants
have long necks and legs.
 Galápagos finches that live in areas with hard-shelled
nuts have strong beaks.
Overproduction
2. Overproduction of offspring (too many babies!)
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There is competition among living things
More are born or hatched or whatever, than survive and
reproduce
Adaptations
3. An adaptation is a feature that allow
an organism to better survive in its
environment.
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Species are able to adapt to their
environment.
Adaptations can lead to genetic
change in a population.
Descent with Modification
4. Selection determines which individuals enter the
adult breeding population
 This
selection is done by the environment
 Those which are best suited reproduce
 They pass these well suited characteristics on to their
young
 Fitness
describes how reproductively successful an
organism is in its environment.
This lecture keeps evolving…..
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Survival of the Fittest means those who have the most
offspring that reproduce
‘Descent with modification from a common ancestor,
NOT random modification, but, modification shaped
by natural selection’
Natural selection acts on existing
variation.
• Natural selection can act only on traits that already exist.
• Structures take on new functions in addition to their
original function.
five digits
wrist bone
Other Evolutionary Theories
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Lamarckism
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Inheritance of acquired characteristics
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E.g., giraffes really wanted leaves, so they stretched their necks
and…..
‘Cave dwelling fish don’t use their eyes so they disappear’
‘We don’t use our appendix so it is disappearing’
Mechanisms of Change
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Gene Flow
 Migration
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& Emigration
Genetic Drift
 Bottleneck
Effect
 Founder Effect
 Speciation
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Non-random mating
 Sexual
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Selection
Genetic Recombination
Gene flow is the movement of
alleles between populations.
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Gene flow
 occurs
when individuals join
new populations and
reproduce.
 keeps neighboring
populations similar.
 Low gene flow increases
the chance that two
populations will evolve into
different species.
bald eagle migration
Migration & Emigration
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Gene flow moves alleles from one population to
another.
Genetic drift is a change in allele
frequencies due to chance.
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Genetic drift causes a loss of genetic diversity.
It is most common in small populations.
A population bottleneck can lead to genetic drift.
 It
occurs when an event
drastically reduces
population size.
 The bottleneck effect is
genetic drift that occurs
after a bottleneck event.
Genetic Drift
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Genetic drift has negative effects on a population.
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less likely to have some individuals that can adapt
harmful alleles can become more common due to chance
Genetic drift changes allele frequencies due to chance alone.
Founder effect
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The founding of a small population can lead to
genetic drift.
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It occurs when a few individuals start a new population.
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The founder effect is genetic drift that occurs after start of
new population.
Sexual selection occurs when certain
traits increase mating success.
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Sexual selection occurs due to
higher cost of reproduction
for females.
 males
produce many sperm
continuously
 females are more limited in
potential offspring each cycle
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Sexual selection selects for traits that improve
mating success.
Types of Sexual Selection
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There are two types of sexual
selection.
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intrasexual selection:
competition among males
intersexual selection: males
display certain traits to females
Genetic Recombination
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Mutations produce the genetic variation needed for
evolution.
Exit Slip
There are many different species of birds, but they all
have different songs. Explain what kind of
mechanism of change this is and how it works.
Vocab
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Evolution
Natural selection
Variation
Fitness
Adaptation
Descendant
Vestigal structure
Homologous structure
Analogous structure
Vocabulary
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Natural Selection
Frequency
Genetic Recombination
Gene Flow
Genetic Drift
Speciation
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Non-random mating
Behavioral Isolation
Geographic Isolation
Variation
Adaptation
Adaptive Radiation
Taxonomy:
Organisms can be classified based on physical
similarities.
Taxonomy
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= the science of naming and classifying organisms.
White oak:
Quercus alba
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A taxon is a group of organisms in a classification system.
Binomial nomenclature
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= two-part scientific naming system.
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uses Latin words
scientific names always written in italics
two parts are the genus name and species descriptor
A genus includes one or more physically similar species
– Species in the same genus are thought to be closely
related.
– Genus name is always capitalized.
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A species descriptor is the second part of a scientific
name.
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always lowercase
always follows genus
name; never written alone
Tyto alba
Scientific names help scientists to communicate.
– Some species have very similar common names.
– Some species have many common names.
Linnaeus’ classification system
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Each level is
included in the level
above it.
Levels get
increasingly specific
from kingdom to
species
The Linnaean classification system
has limitations.
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Linnaeus taxonomy doesn’t account for molecular
evidence.
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technology didn’t exist during Linneaus’ time.
 Linnaean system based only on physical similarities.
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Physical similarities are not
always the result of close
relationships.
Genetic similarities more
accurately show
evolutionary relationships.
KEY CONCEPT
Modern classification is based on evolutionary relationships.
Cladistics
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= classification based on common ancestry
Phylogeny is the evolutionary history for a group of
species.
 evidence
from living species, fossil record, and molecular
data
 shown with branching tree diagrams
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Cladistics is a common method to make evolutionary
trees.
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classification based on common ancestry
species placed in order that they descended from
common ancestor
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A cladogram is an evolutionary tree made using cladistics.
– A clade is a group of species that shares a common ancestor.
– Each species in a
clade shares some
traits with the
ancestor.
– Each species in a
clade has traits that
have changed.
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Derived characters are traits shared in different degrees by clade members.
basis of arranging
species in
cladogram
more closely related
species share more
derived characters
represented on
cladogram as hash
marks
1 Tetrapoda clade
2 Amniota clade
3 Reptilia clade
4 Diapsida clade
5 Archosauria clade
FEATHERS &
TOOTHLESS
BEAKS.
SKULL OPENINGS IN
FRONT OF THE EYE &
IN THE JAW
OPENING IN THE SIDE OF
THE SKULL
SKULL OPENINGS BEHIND THE EYE
EMBRYO PROTECTED BY AMNIOTIC FLUID
FOUR LIMBS WITH DIGITS
DERIVED CHARACTER
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Nodes represent the most
recent common ancestor
of a clade.
CLADE
1 Tetrapoda clade
2 Amniota clade
3 Reptilia clade
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4 Diapsida clade
Clades can be identified
by snipping a branch
under a node.
5 Archosauria clade
FEATHERS AND
TOOTHLESS
BEAKS.
SKULL OPENINGS IN
FRONT OF THE EYE AND
IN THE JAW
OPENING IN THE SIDE OF
THE SKULL
SKULL OPENINGS BEHIND THE EYE
EMBRYO PROTECTED BY AMNIOTIC FLUID
NODE
FOUR LIMBS WITH DIGITS
DERIVED CHARACTER
Molecular evidence reveals species’
relatedness.
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Molecular data may confirm classification based on
physical similarities.
Molecular data may lead scientists to propose a
new classification.
DNA is usually given the last word by scientists.
Peppered Moths
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An example of evolution of a species over the past
200 years
Before the Industrial Revolution in England the trees
were a mottled white color.
Coal burning factories began producing soot that
covered the forests, making the trees black in color.
The peppered moth population responded to this
change, by adapting to their environment
Moth Activity