Study guide 5

Systematics

• Purpose of Systematics:

  • To study organisms and their evolutionary relationships.

  • It classifies species into taxa and reconstructs phylogeny

Key Differences in Classification

• Phylogeny vs. Taxonomy:

  • Phylogeny: The evolutionary history and the relationships between species.

  • Taxonomy: The classification and naming of organisms.

Binomial Nomenclature

• are use for 2 part scientific name for a species in latin or greek

• less ambiguity compared to common names

Hierarchical Classification

• Taxa Levels:

  • Domain

  • Kingdom

  • Phylum

  • Class

  • Order

  • Family

  • Genus

  • Species

Phylogenetic Trees

• Description: Diagrams that represent evolutionary relationships among organisms.

• Information Displayed:

  • Common ancestors

  • Lineages

  • Branching patterns indicating speciation

• Components:

  • Branch: Lineages diverging from a common ancestor.

  • Node: Represents a common ancestor.

  • 

  • Polytomy: A node that branches into three or more groups.

  • Sister Taxa: Groups that share a common ancestor.

  • 

Analyzing Phylogenetic Trees

• Common Ancestor of Taxa A-C: Circle and label on phylogenetic tree.

• Alternate Tree Drawing: Concept of rearranging branches without changing relationships.

Types of Homologies

• Molecular Homologies:

  • similarities at molecular dna level between organisms due to shared ancestry

  • used to construct phylogeneces

• Morphological Homologies:

  • Structural similarities that closely related species have in common

  • used to construct phylogeneces

why do convergent evolution and the appearance of analogous structures have the potential to complicate tree building

1. natural selection produces similar adaptation in organism from different evolutionary. lineages can cause misleading construction

Clades

• Definition: A group of organisms with a common ancestor

Types of Groups in Cladistics

• Monophyletic Group:

  • the group that consists of an ancestor and all their decendants

  • 

• Paraphyletic Group:

  • Includes ancestral strucutre and some of its decendants

• Polyphyletic Group:

  • consists of distantly related species and not the most recent common ancestor

  • 

shared ancestral character

1. character that originated in an ancestor of the taxon

Shared derived characters

2. evolutionary novelty unique to a clade