Post on 08-Jun-2018
EQ:
What evidence supports the
theory of evolution?
SB5.c Explain how fossil evidence and biochemical evidence
support the theory.
KEY CONCEPT 10.4
Evidence of common ancestry among species comes
from many sources.
SOURCE #1: Fossils• Fossils in older/lower layers are more primitive/simple than
those in the newer/upper layers.
• Provided strongest evidence for the theory (before DNA
analysis)
Remember the Tortoises and Finches: similar but distinctly different from one another on Galapagos.
Also different from species on mainland of South America
Darwin decided they were descendents from a common mainland ancestor
Pinta IslandIntermediate shell
Pinta
Isabela IslandDome-shaped shell
Hood IslandSaddle-backed shellHoodFloreana
Santa Fe
Santa Cruz
James
Marchena
Fernandina
Isabela
Tower
The study of geography provides evidence of evolution.
– island species most closely resemble nearest
mainland species
– populations can show variation from one island to
another
SOURCE #3 - Embryology.
Larva
Adult barnacleAdult crab
– identical larvae = different adult body forms
– similar embryos = diverse organisms
Look the same as larva
Early stages of embryos hard to tell different organisms apart
(vertebrates especially)
Groups of cells develop in same order forming the homologous structures
Homologous Body Structures: structures with different mature form but develop from same tissues
Some organisms (especially vertebrates) have limbs constructed from same basic bones even though vary in function
Wings, legs, and Flippers all similar in structure & vary in function
ALL = Evidence for a common ancestor
Human hand Bat wingMole foot
– Homologous structures are similar in
structure but different in function.
– Homologous structures are evidence of a
common ancestor.
Bat wingFly wing
Analogous structures are NOT evidence of a common ancestor.
– Analogous structures have a similar
function.
• Vestigial structures are remnants of organs or
structures that had a function in an early ancestor.
• Ostrich wings are examples of vestigial structures.
Vestigial Organs: structures that have reduced in size so no longer functioning.
Examples include tailbone at the end of the spine, appendix in humans, hip bones in whales, and wings on the Ostrich
Still there but do not affect organisms ability to survive & reproduce
The skeleton of a baleen whale, a representative of the
group of mammals that contains the largest living species,
contains pelvic bones. These bones resemble those of
other mammals, but are only weakly developed in the
whale and have no apparent function.
KEY CONCEPT 10.5
New technology is furthering our understanding of
evolution.
EQ:
What modern evidence supports
the theory of evolution?
#2 Pseudogenes are sequences providing evidence of evolution.
– no longer function
– carried along with functional DNA
– can be clues to a common ancestor
Disabled genes, molecular relics scattered
across the human landscape, have a story
of their own to tell. And it is still unfolding.
-Mark Gerstein and Deyou Zheng, (2006)
Scientific American
#3 Homeobox genes (Hox genes) indicate a very distant common ancestor.
– control the development of specific structures
– found in many organisms #4 Protein comparisons, or molecular fingerprinting reveals
similarities among cell types of different organisms. (lab tomorrow comparing protein sequences)
• Scientist from many fields contribute to the understanding
of evolution.
• The basic principles of evolution are used in many
scientific fields (such as medicine, agriculture, geology,
biochemistry, and ecology).
10.4 Evidence of Evolution
1. With your assigned partner, read the Scientific American (published Jan. 11, 2015).
2. On a separate sheet of notebook paper, list 8 tetrapod species and their adaptations that are described in the article.
3. Describe how these adaptations give these species an advantage in their environment.
4. List any scientific terms that you do not understand (excluding species names).
5. Write using complete sentences!