Comparative Vertebrate AnatomyHypothesizing Evolutionary Relationships

Kingdom Animalia

• Common Characteristics: Multicellular; eukaryotic; heterotrophs that ingest their food; lack

cell walls; reproduce sexually Phylum Chordata

• Common Characteristics: Notochord, Pharyngeal Gill Slits, Dorsal Nerve Cord

Subphylum Vertebrata

• Common Characteristics: Backbone (vertebral column), Endoskeleton, Brain and Skull

Classes:

• Chrondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, Mammalia

I. Vertebrate Classification (Review)

II. Evolutionary Relationships

A. Organisms are classified using 2 main assumptions:

1. The more similar the genes and physical traits of two species are, the more closely related they are.

2. The similarities were inherited from a common ancestor.

B. Predicting Evolutionary Relationships

1. Evolutionary relationships can be predicted using diagrams. Each diagram is a hypothesis of how groups of organisms are related to one another.

a. Phylogenetic Trees - Hypothesize evolutionary relationships among organisms and predicts when important traits evolved. b. Cladograms - Hypothesize evolutionary relationships among organisms based on significant physical traits.

Figure 36-2, Miller-Levine, Biology

Phylogenetic Tree

Cladograms

Family tree that branches systematically at points (nodes) representing specific trait possessed by some groups, but not others.

Evolution of Individuals in the Workplace (Matt Groening, 1985)

Node:

Specific trait or traits

Organisms branching to right HAVE this trait.

Organisms branching to left DO NOT have this trait.

Branch: Name or Type of Organism

III. How To Make a Cladogram

Less Complex

More Complex

Primitive Traits

Derived Traits

Example

SLEIGH

BIKE

CAR

AIRPLANESPACE

SHUTTLE

modes of transportation

wheels

engine

wings

travels at 17,500 mph

Brain Case and Backbone; Endoskeleton; Dorsal Nerve

Cord(primitive traits)

4 Limbs; Lungs; Double-Loop Circulatory System; Highly Complex

Digestive System

Amnion; Internal Fertilization

Mammary Glands; Hair

4-Chambered Heart; Endothermy; Up and Down

MovementFISH

AMPHIBIANS

REPTILES

BIRDS MAMMALS

Dinosaurs?

Dinosaurs?

Vertebrate Cladogram