Transcript Evolution

Evolution
Natural Selection and
Evidence
Ch. 15.1
Definition
•Evolution =
the change in
populations
over time
Evidence
•How do we know that
evolution happened?
–Adaptations
–Fossils
–Anatomy
–Embryology
–Biochemistry
Evidence
•Fossils
–Show changes through time
–Not complete, but gives the
overall picture
Evidence
•Anatomy
•Homologous structures
–Similarity in form of major body
parts
–Indicates that the species had a
common ancestor
Evidence
• Homologous structures
See p. 409 in book
Evidence
•Vestigial structures
–Body structure that has no
function
–Probably was useful in an
ancestor
–Ex. Appendix in humans, wings
in ostrich, leg bones in snakes
Evidence
•Embryology
–Study of the earliest stages of
growth
–Can see similarities in embryos
that you don’t see in adult
forms
–Suggests they evolved from a
common ancestor
Evidence
•Embryology
Evidence
•Embryology
Evidence
•Embryology
Evidence
•Embryology
Evidence
•Biochemistry
–All living things share same
biochemistry
–Closely related organisms have
more similar DNA sequences
–Can use comparisons of DNA to
determine relationships
between species
Evidence
•Can see it happening in species
with short generation times
–Bacteria
–Insects
–Yeast