Download EVOLUTION AND CLASSIFICATION

EVOLUTION AND
CLASSIFICATION
Biology EOC
Boot Camp
April, 2013
created by David Campbell
• SC.912.L.15.1 Explain how the
scientific theory of evolution is
supported by the fossil record,
comparative anatomy, comparative
embryology, biogeography, molecular
biology, and observed evolutionary
change.
• Evolution is defined as the change in a
population of organisms over time.
Evidence for evolution shows:
Change over time AND/OR
Descent from a common ancestor.
Fossils show how species have
evolved over time with many
examples of intermediate stages
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Fossils show:
the evolution of whales from land mammals
the evolution of land animals from fish
the evolution of mammals from reptiles
the evolution of humans from apelike
ancestors
• and the evolution of birds from dinosaurs
• The fossil record is incomplete but
there are thousands of fossils that
support the theory of evolution.
Comparative anatomy shows how species evolved from a
previous ancestor.
• Homologous structures are made of the
same basic parts but have evolved for
very different functions. The wing of a bird,
the front leg of a human, and the flipper of
a whale all have the same bones but
evolved from a common ancestor to do
different things.
Comparative anatomy shows how species evolved from a previous
ancestor.
• Vestigial structures are structures that had
a function in an ancestor but are now
reduced and have no function. Wisdom
teeth in humans are vestigial structures.
Whales and some snakes still have the
hind legs and hipbones used by their
ancestors but not needed or used by them.
Comparative embryology shows that the
early stages of embryos from very different
organisms are often very similar.
• Embryonic tissue goes through the same
stages of development in early stage
embryos. Early vertebrate embryos
(including humans) all have tails. Early
dolphin embryos have four legs.
Patterns in the distribution of living and
fossil organisms tell us how modern
organisms evolved from common
ancestors.
• Closely related organisms may look very
different from each other if they evolved
under different conditions like the finches
and tortoises in the Galapagos and the
honeycreepers in Hawaii.
The universal genetic code and homologous
molecules provide evidence of descent from
common ancestors.
• The genetic code is the same for all
organisms. The DNA codon TAC always
codes for the amino acid methionine.
• A gene taken from one organism (like a
spider) and inserted into a goat will make
the goat’s cells produce the spider protein.
The universal genetic code and homologous
molecules provide evidence of descent from
common ancestors.
• Many basic development genes including the
genes controlling production of legs and eyes in
embryos are the same in insects, fish, and
humans.
• Many proteins are found in all living cells.
Cytochrome c is a protein is a protein used in
cellular respiration and is found in all eukaryotic
cells.
• Rhodopsin is a light detecting protein and is
found in cells ranging from bacteria to the
human eye.
Direct Observation of Evolutionary
Change
• Evolutionary change has been observed
in:
• Wild populations of guppies, birds, insects,
and mammals.
• It has also been observed in the laboratory
in bacteria, fish, and insects.
SC.912.L.15.13 Describe the conditions required for
natural selection, including overproduction of offspring,
inherited variation, and the struggle to survive, which
result in differential reproductive success.
• All organisms produce more offspring than the
environment can support. Giant puffballs can
produce trillions of spores. A female sea
urchin produces millions of eggs. Female fruit
flies produce roughly 200 eggs.
• Environmental resources are limited. The
environment can’t support unlimited numbers
of offspring.
• This leads to competition for resources and a
struggle for survival.
• Genetic variation exists in organisms. Some
variations are better than others.
• Those organisms with the better combination of
favorable adaptations survive better and
produce more offspring. They pass their
favorable genes on to their offspring. Organisms
with less favorable traits do not survive and do
not pass on their genes to offspring so those
variations die out.
• This is called differential reproduction.
• Favorable variations spread throughout a
population, changing the population.
• This change is evolution by natural
selection.
SC.912.L.15.15 Describe how mutation
and genetic recombination increase
genetic variation.
• Mutations (changes in the DNA code) are
the source of some variation in living
organisms because they introduce new
alleles into the gene pool.
SC.912.L.15.15 Describe how mutation
and genetic recombination increase
genetic variation.
• Recombination is the production of new
combinations of alleles by mixing alleles in
new ways.
• In sexually reproducing organisms the
biggest source of variation is genetic
recombination through meiosis and
fertilization
SC.912.L.15.15 Describe how mutation
and genetic recombination increase
genetic variation.
• Recombination occurs by:
• Crossing over in Prophase I
• Independent assortment in Metaphase I
and Anaphase I
• Fertilization
Discuss mechanisms of evolutionary
change other than natural selection such
as genetic drift and gene flow.
• Genetic drift is the random change in the
frequency of alleles in a population. It
usually occurs in small populations.
• Example – 99% of all Maya in Mexico and
Inca in the Andes mountains have type O
blood because the small groups of
humans who migrated there had O blood
• Gene flow is immigration into or emigration
out of an area. Alleles will be lost when
individuals enter or leave.
• Example – The frequency of red hair and
freckles rose sharply in New York and
Boston in the 1850s due to the Irish
immigration.
SC.912.L.15.4 Discuss how and why
organisms are hierarchically classified and
based on evolutionary relationships.
• The goal of any classification system is to
organize living things into groups that have
biological meaning.
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We classify organisms:
For easy reference and identification
To show relationships between organisms
To trace the origins of organisms
• Classification is based on phylogeny, the
evolutionary history of organisms.
The Linnaean System
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Kingdom
Phylum
Class
Order
Family
Genus
Species
King
Phillip
Came
Over
For
Great
Spaghetti
Animalia
Chordata
Mammalia
Primate
Hominida
Homo
sapiens
• The last two categories in the Linnaean system
form an organism’s binomial scientific name.
• The genus is capitalized and is a noun
• The species is lower case and is an adjective
• Scientific names are underlined or italicized.
• Gammaracanthuskytodermagammarus
loricatobaicalensis
• Gammaracanthuskytodermagammarus
loricatobaicalensis
• Linnaeus used physical characteristics to
classify.
• Modern scientists use evolutionary
relationships.
• All the organisms in one group are
descended from the same common
ancestor.
Cladistics
• All the organisms descended from a the same
common ancestor are a clade.
• Cladograms are diagrams that show how
evolutionary lines or lineages branched off from
a common ancestor.
• Branching points are called nodes. A node is
the last point at which two branches shared a
common ancestor.
• Nodes are defined by DERIVED
CHARACTERS, characteristics that arose in the
most recent shared common ancestor.
SC.912.L.15.6 Discuss distinguishing
characteristics of the domains and kingdoms
of organisms.
• DOMAIN ARCHAEA
– Single-celled
– Prokaryotic
– Live in extreme environmental conditions like
high temperature, very low pH or no Oxygen.
– Corresponds to Kingdom Archaebacteria
SC.912.L.15.6 Discuss distinguishing
characteristics of the domains and kingdoms
of organisms.
• Domain Bacteria
– Single-celled
– Prokaryotic
– Rigid cell walls
– Corresponds to the Kingdom Eubacteria
– Most of the bacteria you know and love fall
into this domain
SC.912.L.15.6 Discuss distinguishing
characteristics of the domains and kingdoms
of organisms.
• Domain Eukarya
– Cells contain a nucleus
– Consists of the other four kingdoms
– Kingdom Animalia
• Multicellular, heterotrophic, do NOT have cell walls and are
capable of movement
– Kingdom Plantae
• Multicelluar, autotrophic, cell walls made of cellulose
– Kingdom Fungi
• Heterotrophic, cell walls made of chitin. Secrete digestive
enzymes into their food and absorb digested nutrients
– Kingdom Protista
• Everything else
SC.912.L.15.8 Identify basic trends in hominid
evolution from early ancestors six million years
ago to modern humans, including brain size, jaw
size, language, and manufacture of tools.
• 6 Million years ago the lineage that led to
humans split from the lineage that led to
chimpanzees
• Supported by both fossil and DNA
evidence
• During that six million years
– Brain size quadrupled (grew 4X)
– Jaw size and tooth size decreased as diet changed.
Human jaws do not stick out like ape jaws do
– Humans evolved language, allowing greater range of
communications.
– Homo habilis is the earliest KNOWN tool maker (2
million years ago). As genus Homo evolved a larger
brain tools became more sophisticated.
– Language and culture allowed tool making skills to be
passed down.
SC.912.L.14.5 Explain the evidence
supporting the scientific theory of the origin
of eukaryotic cells (ENDOSYMBIOSIS).
• Endosymbiotic theory – Eukaryotic cells evolved
when a prokaryotic cell capable of aerobic
respiration was engulfed by a larger prokaryotic
cell and not digested
• The smaller cell became the mitochondrion and
the larger cell around it is the ancestor of all
modern eukaryotic cells.
• Chloroplasts are the result of one of the
eukaryotic cells engulfing a photosynthetic
bacteria and not digesting it.
• Mitochondria and chloroplasts:
– Contain DNA in a single, circular chromosome
just like bacteria cells
– Have “naked” DNA without attached proteins
just like bacteria cells
– Reproduce by binary fission just like bacteria
cells
SC.912.L.15.8 Describe the scientific
explanations of the origin of life on Earth.
• Early Earth’s atmosphere was very
different from the atmosphere today.
– Little or no molecular oxygen
– Made mostly of carbon dioxide, water vapor,
nitrogen and some hydrogen sulfide.
• Four step process from basic atmosphere
to primitive life
– Combine existing chemicals to form simple
organic molecules like amino acids, sugars,
and nitrogen bases. Miller-Urey experiment is
one proposed mechanism.
– Simple organic molecules combine under the
right conditions to form simple proteins and
nucleic acids. Conditions include smoker vent
environment and clay particles.
Steps 3 and 4
• Large organic chemicals combine to form
microspheres, round hollow membrane
enclosed spaces that perform some basic
functions of living cells.
• First genetic material was probably RNA
– Simpler than DNA
– RNA can self-replicate and act as a catalyst
– In lab, small RNA molecules self-replicate and
evolve in a changing environment
• Earliest known fossil bacteria are 3.5
billion years old.
• Photosynthesis evolves by 2.2 billion
years ago, producing oxygen and allowing
evolution of aerobic respiration.
The End!