Download Evidence of Evolution - David Brotherton CCCMC

Biology
Class Notes
Lesson 29: Evidence of Evolution
Objective: 3.4.1
Evolution: A change in gene frequency over time.
• It explains how species change over generations as genes are
passed from parent to offspring, or lost due to a lack of
reproductive success or extinction.
Evidence for Evolution
Homologous structures: Similar body parts that originated in different
species and suggest a shared ancestor.
Analogous Structures: Features that serve the same purpose in different
species, but evolved independently and suggest species do not share a
closely related ancestor.
Ex: Wings/Ability to fly
Vestigial structures: Structures that were probably useful to an
ancestor, but are not useful to the organism that currently has them.
Fossils: Provide evidence of changes between species that lived in the
past vs. those alive today.
Comparative morphology: Body parts of living things can be
compared to understand the development of differences among
species (i.e. different species have similar but different traits).
Embryology/Ontogeny: The study of the early stages of life before
birth reveals striking similarities between species and suggests
relatedness (i.e. “ontogeny reveals phylogeny”).
Gel Electrophoresis: Process that allows scientists to compare DNA
from different organisms.
DNA fingerprint: A pattern produced by gel electrophoresis.
 The more similar the pattern, the more related the organisms.
Steps:
1. DNA is cut into fragments of different sizes.
2. DNA is placed in the wells at the end of a gel
3. A ‘+’ charge is hooked to the far end of the gel, and a ‘-’ to the
other.
4. Because the phosphate group has a net negative charge, DNA
moves towards the ‘+’.
5. DNA fragments migrate to different extents/are separated
according to mass with larger fragments moving further.
Key Words:
Homologous structures
Analogous structures
Vestigial structures
Embryology
Embryo