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1

Systematic biology

Uses traits to infer evolutionary relationships among organisms

2

Taxonomy

The branch of biology concerned with identifying, naming, and classifying organisms

Early taxonomists relied on physical characteristics to classify organisms

Today taxonomists classify organisms into natural groups based on their evolutionary history using DNA analysis

3

Linnean taxonomy

Carolus Linnaeus developed binomial system to name species

Binomial nomenclature names organisms using a 2 part Latin name: Genus, Specific Epithet

4

Seven categories of classification

Kingdom
phylum
class
order
family
genus
species

5

The three domain system

Prokaryotic organisms are placed in the domain bacteria and in the domain Archaea

Eukaryotic organisms are placed in the domain Eukarya

6

Domain bacteria

Prokaryotic unicellular organisms

Produce asexually

Cyanobacteria are large photosynthetic prokaryotes

Most bacteria are heterotrophic

Breaks down organic remains thereby keeping chemical cycling going

Some bacteria are parasitic and cause disease

7

Domain Archaea

Prokaryotic unicellular organisms

Reproduce asexually

Live in extreme environments:
Methanogens (anaerobic swamps)
Halophiles (salt lakes)
Thermoacidophiles (hot acidic environments)

The cell wall is diverse but not the same as the bacterial cell wall.

8

Domain Eukarya

Unicellular or multicellular organisms

always have a membrane-bound nucleus

Sexual reproduction is common

Protests, fungi, plants, and animals are eukaryotes

9

Phylogeny

Classification reflects phylogeny

One goal of systematics is to create follow genetic trees showing the evolutionary history of a group of organisms

10

Interpreting a Phylogeny

A phylogenetic tree indicates common ancestors in lines of descent or lineages

When a new character evolves a new evolutionary path diverges from the old and a new lineage is formed

Different lineages diverging from a common ancestor have ancestral traits

11

Ancestral traits

Characteristics shared by the ancestor in the species in its lines of descent

12

Derived trait

Present only in a specific line of descent

13

Cladistics

A cladogram is a diagram showing relationships among species based on shared derived traits

A clade is an evolutionary branch that includes a common ancestor and all its descendent species