2015 TOPIC 5 EVOLUTION Things to cover Biogeography The fossil record Comparing molecules Comparing anatomy WHAT DO YOU KNOW WHAT DO YOU KNOW WHAT DO YOU KNOW WHAT DO YOU KNOW ID: 289108
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Slide1
EVIDENCE FOR EVOLUTION
2015 - TOPIC 5Slide2
EVOLUTION
Things to coverBiogeographyThe fossil recordComparing molecules
Comparing
anatomySlide3
WHAT DO YOU KNOW?Slide4
WHAT DO YOU KNOW?Slide5
WHAT DO YOU KNOW?Slide6
WHAT DO YOU KNOW?Slide7
WHAT DO YOU KNOW?Slide8
EVIDENCE FOR EVOLUTION
The evidence that supports Darwin’s theory includes:BiogeographyFossil recordComparing molecules
Comparing anatomySlide9
BIOGEOGRAPHY
EVIDENCE #1Slide10
BIOGEOGRAPHY
Refers to geographical distribution of speciesEvolution would suggest that similarities would exist between species and those living in that area in the past.
If
organisms arose by ‘special creation’,
we
would expect that similar habitats
in
different parts of the world would
contain
similar plant and animals
.
But they don’t….Slide11
BIOGEOGRAPHY
We find that unique organisms live in similar habitats in different parts of the world. In Australia, our deserts contain spinnifex grass and salt bush
. American deserts contain
cacti
.Slide12
FOSSIL RECORDS
EVIDENCE #2Slide13
FOSSIL RECORDS
Refers to the record kept of the evidence of life
in the
past
Fossils don’t have to be
bones
!
They can also be:
Teeth
Feathers
Scales
Branches
Leaves
Footprints,
etcSlide14
FOSSIL RECORDS
Steps:Organism diesCovered by dirt, mud, silt or lava before decomposition can occurThe material that lies
above the fossil
compress, forming rock
This preserves the fossil.
Even if the organism itself decays
at a later stage, the imprint will remain in the rock.Slide15
FOSSIL RECORDSSlide16
FOSSIL RECORDS
Fossilisation is rare!It has to be buried before it decomposes.It has to be buried in an
area
that favours fossilisation
.
ie
. no silt, no fossil
Whole organism may not be
fossilised due to an attack by
predators
before being buried.Slide17
FOSSIL RECORDS
Fossilization is a rare event. Different types of fossil form under different conditions and environments.
Fossilized remains only form in the
absence of microbes
, which need food, oxygen, water and warmth.
amber
mud
ash/mud
ice and frozen soilSlide18
FOSSIL RECORDSSlide19
FOSSIL RECORDS
Finding a fossil is also rare!You need to know where to look! And even then, its hard!May only find
pieces
; not enough to get the whole picture of that organism.
May only find
one organism
.
Good scientists never rely on one piece of evidence to draw a good conclusion.
May only find
one gender
.
Many species are sexually dimorphic – meaning that males and females differ.Slide20
FOSSIL RECORDS
If a new species evolves from an ancestral species, the fossil record should contain organisms that are intermediates with
some features of both
the modern and ancestral forms
.
Birds are believed to have
evolved from reptiles.
One fossil type found is
Archeopteryx
lithographica
. Slide21
FOSSIL RECORDS
Archeopteryx lithographica
REPTILE FEATURES
BIRD FEATURES
teeth
feathers
a long, bony tail
wings
claws on wings
a wishboneSlide22
FOSSIL RECORDSSlide23
COMPARING MOLECULES
EVIDENCE #3Slide24
COMPARING MOLECULES
Scientists can compare a variety of molecules in order to determine whether two species are closely or distantly
related.
eg
:
DNA
Amino acid sequences
& proteinsSlide25
COMPARING MOLECULES
DNA HYBRIDISATIONAll organisms contain DNA in their cells.Double stranded DNA can be heated
so that it
separates into single strands
.
A single strand from one organism can be placed next to a single strand from another organism and
cooled down
. Slide26
COMPARING MOLECULES
DNA HYBRIDISATIONThe two single strands will bond to each other (hybridise) where complementary bases are found.
If the strands are similar, a
high amount of pairing
will take place.
eg
. +
high degree of pairing
eg
. +
low degree of pairingSlide27
COMPARING MOLECULES
COMPARING PROTEINSAll organisms share a number of proteins. Cytochrome C is an enzyme needed for respiration.If we
compare the amino acid structure
of
Cytochrome C in
different organisms, we find that closely related organisms have very similar
Cytochrome C.Slide28
COMPARING MOLECULES
COMPARING PROTEINS
Organism
No. of changes in amino
acid sub units relative to humans
Human
0
Rhesus
monkey
1
Whale
7
Chicken
13
Tuna fish
22Slide29
COMPARING MOLECULES
COMPARING PROTEINSThe longer that two species diverged from a common ancestor
, the more time there has been for
changes
to occur in the amino acid sequence.
This shows that humans and monkeys are more closely related than humans and fish.Slide30
COMPARING ANATOMY
EVIDENCE #4Slide31
COMPARING ANATOMY
Scientists look for similarities in bone structure and embryos in order to investigate common ancestry.These similarities are called
homologies
.
Species that share
homologous structures
share similarities because they have a
common ancestor
.
eg
:
The forelimb of all mammals is very similar in the number and structure of the bones present.Slide32
COMPARING ANATOMYSlide33
COMPARING ANATOMY
Analogous structures also exist. These are similarities in structure that have evolved due to similar environmental selection
pressures
.
eg
:
The fin of a shark (cartilaginous fish) and a dolphin (mammal).Slide34
REVIEW – TOPIC 5
The fossil ________ provides evidence that supports Darwin’s
theory.
Fossils can show
________
structures. These are structures that have a similar structure due to
________ ________
, but have evolved to suit different
________
.
________
structures do not result from common ancestry. These structures share
________
similarities due to their use for shared functions, in shared
________
.
Similarities in DNA
________ ________
can also provide evidence that supports Darwin’s theory.
record
common ancestry
homologous
functions
functional
chemical bonding
environments
common history
analogous
structural
base sequence
double
helixSlide35
REVIEW – TOPIC 5
The fossil
record
provides evidence
that supports Darwin’s
theory.
Fossils can show
homologous
structures. These are structures that have a similar structure due to
common ancestry
, but have evolved to suit different
functions
.
Analogous
structures do not result from common ancestry. These structures share
structural
similarities due to their use for shared functions, in shared
environments
.
Similarities in DNA
base sequence
can also provide evidence that supports Darwin’s theory.