in your own words, how would you define evolution? can you think of an example of evolution? how do...
TRANSCRIPT
In your own words, how would you define
Evolution?
Can you think of an example of Evolution?
How do you know when something
has evolved?
EVOLUTION IS
GENETIC CHANGE IN A POPULATION THROUGH TIME.
GENETIC CHANGE IN A POPULATION THROUGH TIME.
EVIDENCES OF EVOLUTION
Charles DarwinOn his journey around the world, Darwin found evidence of gradual change (evolution).
Darwin cited evidences he found in fossil records, geographic distribution and homologous structures.
Evidences of EvolutionToday most evidences for evolution are grouped into five main categories:
Fossil RecordBiochemicalComparative
AnatomyBiogeographyObservable Events
FOSSIL RECORD Paleontology Fossil – remains or traces of an
organism that lived long ago
Remains: ex. bone, tooth, or shell
Traces: ex. burrow, footprint, or imprint
FOSSIL RECORD Most fossils are found in
layered sedimentary rock
Oldest fossils are in the lowest layers
Newest fossils are in the top layers
FOSSIL RECORD
Comparing fossils from different layers shows:
Life on Earth has changed
Increased number of life forms
BIOCHEMICALDNA & the genetic code One codon codes for one amino
acid – it works the same way in all species The codon
code for each amino acid is the same in almost all organisms.
BIOCHEMICAL
The similarity of the way DNA codes for amino acids shows:
A probable common ancestor for all life on Earth
BIOCHEMICAL
“Universal” GENETIC CODE Similar genes Over the ages, the genetic code
has passed unchanged (or nearly so) from parent to offspring.
BIOCHEMICAL AMINO ACID SEQUENCING
The amino acid sequence in a particular protein is compared between organisms. Number of differences
from human hemoglobin
45
167
8
27
125
BIOCHEMICAL Comparing amino acid sequence
shows: Closeness of
relationship A probable
common ancestor
Species DifferenceGorilla 1Rhesus Monkey
8
Mouse 27Chicken 45Frog 67Lamprey 125
Amino Acid Difference in Hemoglobin
Compared with Human
Human hemoglobin has 146 amino acids
Amino Acid Sequencing is probably the STRONGEST evidence for relationships among organisms.
What organism belongs at
each branch?
BIOCHEMICAL CLADOGRAM: diagram that
shows the evolutionary relationship among a group of organisms.
Species Difference
Gorilla 1Monkey 8Mouse 27Chicken 45Frog 67Lamprey
125
Amino Acid Difference in Hemoglobin
Compared with Human
Number of Amino Acid Differences150
10050
040 2030 10
G
FE
DCBA
Common ancestor
Where would the common ancestor be?
COMPARATIVE ANATOMY
HOMOLOGOUS STRUCTURES
structures with similar structure but different function
TurtleAlligator
BirdMammal
COMPARATIVE ANATOMY
Homologous structures show
Similar genes – similar proteins Descent from a common ancestor
TurtleAlligator
BirdMammal
Ancient lobe-finned fish
COMPARATIVE ANATOMYVESTIGIAL STRUCTURES organs so reduced in
size that they are nonfunctioning remnants of similar organs in other species
ex: human tailbone, appendix, gallbladder, whale pelvis
COMPARATIVE ANATOMY
Vestigial structures show:
an organism’s evolutionary past
a common ancestor with species that have similar structures that are still functioning
BIOGEOGRAPHY GEOGRAPHIC DISTRIBUTION
OF ORGANISMS
organisms living far apart may be similar because they share a common ancestor
OBSERVABLE EVENTS
Some changes in species have been observed and studied:
Peter & Rosemary Grant’s Study of Beak Size Shift in Darwin’s Finches
H. Kettlewell’s Study of Peppered Moth Color Shifts
OBSERVABLE EVENTS
Observable events show that evolution is an ongoing process
Peter & Rosemary Grant’s Study of Beak Size Shift in Darwin’s Finches
H. Kettlewell’s Study of Peppered Moth Color Shifts