Transcript Evolution - MarsicanoBiology

Evolution
Chapters 15/16
Intro Video
• https://youtu.be/FpfAZaVhx3k?list
=PLISBHwlJXpn2bmLjfiShKcIHpBP
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Evolution
• A change over time
• A process by which modern organisms
have descended from ancient organisms
• Theory- a broad, well tested
explanation that unifies a broad range
of observations
Earth’s History
• More than 4 Billion years old
• Fossils- preserved remains of
ancient organisms
• Many modern life forms appear to
be modifications of fossil forms
Theories of Evolution
• Three Scientists
• Lamarck
• Malthus
• Darwin
Lamarck
• French Scientist
• Proposed that
acquired traits
were passed on to
offspring
• Acquired Trait- one that is not
determined by genes, instead
arises over time by experience or
behavior
– Example- developing large muscles
• Disproved by current knowledge of
genetics
Malthus
• Stated that if the
human population
continued to grow
unchecked,
sooner or later
there would be
insufficient living
space and food
for everyone
Charles Darwin
• British Scientist
• Sailed on ship HMS
Beagle on trip to
explore S. America
• Was the Naturalist
on board, collecting
plant and animal
samples
Darwin’s Work
• While on the Beagle, Darwin
collected and recorded information
about all types of living species
• Back in Britain he analyzed his
observation and published The
Origin of Species
Darwin’s Theories
• Descent with Modification- newer
forms of life are modified
descendents of older species
• Modification by Natural Selectionstates how evolution is occurring
Theory Part 2 Concepts
• Natural Selection- organisms best
suited to their environment will
reproduce more successfully
• Adapt- a change in a population in
response to the environment
• Fitness- an individual’s genetic
contribution to the next generation
– High fitness= more offspring
• Survival of the fittest- competition
for food and living space will only
allow for those best suited to
environment to reproduce
Evidence of Evolution
• Homologous Features
• Analogous Features
• Vestigial Structures
• Conserved Genes
• Similarities in Embryos
• Macromolecules
Homologous Features
• Similar features
that have slightly
different mature
forms but
originated from a
common ancestor
– Example- forearm
of mammals
Analogous Feature
• Have same
function, but have
different
development
– Example: Wings
on bird and insect
Vestigial Structures
• Organ that serves
no current
purpose in
organism, but is
believed to have
one in ancestor
– Examples:
• Tailbone in
humans
• Appendix in
humans
• Pelvic bones in
Conserved Genes
• A gene that
remains
unchanged within
DNA, but is
turned off and not
used
– Example: hind
legs in whales
Similar Embryos
• During early fetal
development,
vertebrates all
appear the same
Macromolecules
• All have DNA as
basis
• Similar amino
acid sequence
that make up
proteins
– More similarities
the closer related
the two organisms
are
Patterns of Evolution
• Co-evolution
• Convergent
• Divergent
Coevolution
• Changes in two or
more species in
close association
with each other
– Example- plant
and animal
pollinators
Convergent
• Occurs when the
environment
selects for similar
phenotype, even
though ancestry
is very different
– Example- body
shape of dolphins
and sharks
Divergent
• Two related
species becoming
different from one
another
• Two Types
– Adaptive
– Artificial
• Divergent
Adaptive- change
is in response to
habitat
– Example:
Galapagos finches
• Divergent
Artificial- other
interference
speeds up
differences
(breeding)
– Example: Dog
breeding
Genetic Equilibrium
• Population Genetics- looking at
evolution from a genetic point of
view
• Population- members of a species
that live in the same area and
make up a breeding group
• In normal
circumstances the
percentages of a
particular trait
remain constant
– Equilibrium
Disruption of Equilibrium
• Mutation
• Genetic Drift
• Migration
• Non-random Mating
• Natural Selection
• Mutation- any
change to DNA
– Can affect the
protein made
which can affect
the individual and
their offspring
• Genetic Driftallele frequencies
(%) change due
to chance or
random events
– Example- Natural
disasters
• Migration- net
movement in or out
of a population
– Immigration- moving
into a population
– Emigrationmovement out of a
population
• Migration creates
gene flow
• Gene Flowmovement of
genes from one
population to
another
• Non-random
Mating- mating in
small populations
– Leads to higher
occurrences of
disorders
– Example- Amish
Natural Selection
• Traits being selected for or against
• Three Types
– Stabilization
– Directional
– Disruptive
Stabilization Selection
• Type of natural
selection in which
the average form
is being selected
for
Directional Selection
• Type of natural
selection in which
one extreme is
being selected
for, creating
movement in one
direction
Disruptive Selection
• Type of natural
selection in which
the average is
being selected
against and both
extremes are
being selected for
Formation of Species
• Speciation- process of forming new
species
• Morphology- internal and external
structure and appearance
– Scientists use this as basis for
classifying species
• Biological Species
Concept- A
species is a
population that
can interbreed,
but not breed
with other groups
Isolating Mechanisms
• Mechanisms that
can cause new
species to form
• Two Types
– Geographic
– Reproductive
• Geographic
Isolation- having
a physical barrier
between groups
– Example: river,
canyon, mountain
• Reproductive
Isolation- barrier
to successful
breeding
• Examples:
different mating
calls, different
mating seasons
Rates of Speciation
• Gradual- slow change over time
– Lots of intermediates in fossil record
• Punctuated- sudden shift in fossil
record
– Could be caused by natural disaster
or other sudden change to
environment