Chapter 5.2: Speciation, Phylogenetics, Taxonomy

Systematics

• Construction of family trees

• determine evolutionary relationships among species, etc.

Taxonomy

Using Family Tree to Name & Classify Organisms.

Phylogeny

Evolutionary Relationships among species, basically family tree.

Importance of Phylogeny

• Basis for Identification & classification

• Explains why species evolved certain adaptations and others not

Traditional Methods Constructing Trees

• Looked at similarities

• Includes Ancestral & derived traits

Modern Methods Constructing Trees

• Shared derived characteristics

Cladistics

• Members share common evolutionary history, closely related, recognized by sharing features not in distant ancestors

Cladistics Steps

1. Choose similar traits trhoguh common ancestor

2. Determine if primative or derived

• Primative More Common

• Look at fossil ancestor. If there, primative

• trait occurs early in development means primative

• Use distinct related species. If there, primative

3. Repeat with many traits

4. Choose Most Parsimonious Tree

• Tree with Fewer Evolutionary steps

• 4 Species: A,B,C,D

• A,B,C = trait 1

• B,C = Trait 2

• C = Trait 3

Cladistic Taxonomy

Cladist insist decent is only thing that counts for taxonomy. Basically, sister groups classified together.

Evolutionary Taxonomy

Evolutionary Systematists argue decent and overall similarity important. basically Grouped based on common ancestry and how different they’ve become over time.