Themes in the Study of Life

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Slide 60

Concept 1.2: The Core Theme: Evolution accounts for the unity and diversity of life

“Nothing in biology makes sense except in the light of evolution”—Theodosius Dobzhansky

Evolution unifies biology at different scales of size throughout the history of life on Earth

Slide 61

Organizing the Diversity of Life

Approximately 1.8 million species have been identified and named to date, and thousands more are identified each year

Estimates of the total number of species that actually exist range from 10 million to over 100 million

Slide 62

Grouping Species: The Basic Idea

Taxonomy is the branch of biology that names and classifies species into groups of increasing breadth

Domains, followed by kingdoms, are the broadest units of classification

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Fig. 1-14

Species

Genus

Family

Order

Class

Phylum

Kingdom

Domain

Ursus americanus

(American black bear)

Ursus

Ursidae

Carnivora

Mammalia

Chordata

Animalia

Eukarya

Slide 64

The Three Domains of Life

The three-domain system is currently used, and replaces the old five-kingdom system

Domain Bacteria and domain Archaea comprise the prokaryotes

Domain Eukarya includes all eukaryotic organisms

Slide 65

Fig. 1-15

(a) DOMAIN BACTERIA

(b) DOMAIN ARCHAEA

(c) DOMAIN EUKARYA

Protists

Kingdom Fungi

Kingdom

Plantae

Kingdom Animalia

Slide 66

Fig. 1-15a

(a) DOMAIN BACTERIA

Slide 67

Fig. 1-15b

(b) DOMAIN ARCHAEA

Slide 68

The domain Eukarya includes three multicellular kingdoms:

Plantae

Fungi

Animalia

Other eukaryotic organisms were formerly grouped into a kingdom called Protista, though these are now often grouped into many separate kingdoms

Slide 69

Fig. 1-15c

(c) DOMAIN EUKARYA

Protists

Kingdom Fungi

Kingdom Plantae

Kingdom Animalia

Slide 70