Transcript Indirect Evidence of Evolution

Living Organisms
 1.
Embryology
 2.Homologous and Analogous Features
 3. Vestigial Features and Anatomical Oddities
 4. Biochemical Evidence
 5. Artificial Selection
 The
study of organism in the early stages of
development
 Von Baer (a German Scientist ) said he could
not differentiate between the embryos of
lizards, birds and mammals.
 It was later suggested that similarities where
do to their evolution from a common
ancestor
 Embryology helps identify homologous
structures
~ 1-2 days
~ 41 days
~ 52 days
~ 120 days
 Homologous


Features
Features with similar structures but different
functions
Example – flippers of a seal, forelimbs of a dog,
wings of a bat, the human arm
 Homologous
structure are thought to have
followed a process of divergent evolution.
 Divergent Evolution – the process where to
species with the same ancestor have
developed different forms and functions as a
result of adaptations to different
environments
 Analogous


Features
Features that are similar in appearance and
function, but do not appear to have the same
evolutionary origin
Example: wings of a insect and wings of a bird
 Analogous
structures are thought to have
evolved through a process of convergent
evolution
 Convergent Evolution – independent
evolution of traits based on adaptation to
similar environments
 Divergent
Evolution
Homologous Structures
- same origin, different
appearance and function
Convergent Evolution
Analogous Structures
- different origin, similar
appearance and function
 Vestigial
Features are rudimentary structures
with no apparent useful function
 This suggests that they once served some
function in an ancient ancestor, but the
organism evolved to function without the
structure.
 Eg.
Whales and snakes have vestigial hip and
leg bones!
 Based
on the theory that all life came from
one original cell
 Genetic material (DNA) is similar in all
organisms
 This is “tested” by comparing the number of
differences in amino acid sequences. The
fewer differences, the closer related the
organisms are. The more differences, the
further apart the organisms are from a
common ancestor.
 Cow:
GAG GAAG G T T C G G T C

 Human:
G
AC GTAC GTAC GATC
 Monkey:
GAG G TAAG TAC C AT C

 Just
like biologists descovered vestigial
anatomical features, geneticists are
discovering vestigial genes!!!!
 Humans
have a set of (defective) genes that
would allow us to make our own Vitamin C!
Fortunately for Florida orange growers, we
have lost both the ability and the need to
make our own.
 The
process of humans selecting and
breeding individuals with specific desired
traits.
 Practice
 Lab

Questions page 145 # 1-2
Exercise 5.A on page 147
Do the evidence and analysis
 5.3
Questions page 149 # 1-3