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