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Chpt. 15.2- Evidence of Change
Pgs. 423-429
Pgs. 393-395
There are many ways scientists demonstrate how evolution might happen. This includes
1. Comparative anatomy
2. Comparative embryology
3. Fossils
Comparative Anatomy
Homologous Structures- Similar bone structures but adapted for different uses.
Ex: Wings on a bird, legs on a reptileUsed as evidence that traits were
inherited from a common ancestor.
Vestigial Structures
Vestigial Structures- Structures that are the reduced forms of functional structures in other organisms.
Analogous Structures
Analogous Structures- Different bone structures but has the same use.
Ex: Wings on a bird vs. Wings on a beetle
Comparative Embryology
Comparative Embryology- Vertebrate embryos shows homologous structures during certain phases of development but become totally different structures in adulthood.
Ex: Bird
and Mammal
Embryos
FossilsFossil- any preserved
evidence of an organism.
6 Categories of Fossil Types
Trace Fossils
Molds & Casts
Replacement
Petrified
Amber
Original material
Table 14.1-Pg. 393
Fossil Formation
A. Organism dies and is quickly buried by sediment (this protects the organism)
B. Minerals replace all or part of organisms original structure
C. Sediment hardens and turns into rock
Dating FossilsThere are 2 ways of
dating fossils.
1. Relative Dating- the age of a fossil is determined by its placement in layers of rock.
Younger layers are deposited on top. Gives an estimation of age.
2. Radioactive Dating- Using the half-life of an isotope to determine the age of a rock.
A half-life is the length of time required for half of the radioactive atoms in a sample to decay
Adaptations
Adaptation- a trait shaped by natural selection to increase the survival or reproductive success of an organism.
There are two types of adaptations.
1. Camouflage
2. Mimicry
Camouflage
Camouflage- adaptation that allows an organism to blend in with their environment.
-Allows to become almost invisible to predators.
-Results= more individuals survive and reproduce.
Camouflage Examples
MimicryMimicry- when one species looks like
another species.
Ex: California Kingsnake Vs. Western Coral Snake
Usually used by harmless organisms to warn predators.
Mimicry Example
Monarch Butterfly Viceroy Butterfly
Taste Bad to Predators Taste Good to Predators