Chapter 16

The Diversity of Life

Phylogeny

• The scientific study of evolutionary relationships among species

• Practical applications

– Allows predictions about the needs or weaknesses of one species on the basis of its known relationship to another

Binomial System

• Devised by Carl von Linne

• Each species has a two-part Latin name

• First part is generic

• Second part is specific name

How Are Organisms Named and Classified?

• Each Species Has a Unique, Two-Part Name: Genus + specific epithet

Classification Is Hierarchy of Categories:

Domain

Kingdom

Phylum

Class

Order

Genus

Species

Inclusive groupings meant to reflect relationships among species

May include Super groups and Sub groups as well

How Are Organisms Named and Classified?

• Classification of Organisms Reflects Their Degree of Relatedness

How Are Organisms Named and Classified?

• Anatomy Plays a Key Role in Classification

A Cladogram

How Are Organisms Named and Classified?

• Molecular Similarities Are Also Useful for Classification

What Are the Domains of Life?

• In the earliest days of modern classification, there were only plants or animals

But what are these?

What Are the Domains of Life?

• The Five-Kingdom System Improved Classification

• Proposed in 1969 by Robert Whittaker

Why?

Bacteria and Archaea

Similar

• Single celled

• Prokaryotes

• Normally extremely small

What Are the Domains of Life?

• Kingdom-Level Classification Remains Unsettled

Bacteria and Archaea

• Classification of prokaryotes within each domain is difficult compared to eukaryotes.

• Classification based on

– Shape

– Means of locomotion

– Pigments

– Nutrition requirements

– Colony appearance

– Staining properties

Bacteria and Archaea

– Many Bacteria Form Films on Surfaces

Bacteria and Archaea

Bacteria and Archaea

• Prokaryotes Exhibit Diverse Metabolisms

– Photosynthetic/Chemosynthetic/Heterotrophic

– Aerobic/Anaerobic

• Prokaryotes Perform Functions Important to Other Organisms

– Prokaryotes Capture the Nitrogen Needed by Plants

– Prokaryotes Are Nature’s Recyclers

Bacteria and Archaea

• Some Bacteria Pose a Threat to Human Health

– Some Anaerobic Bacteria Produce Dangerous Poisons Ex: Clostridium tetani

– Humans Battle Bacterial Diseases Old and New Ex: Vibrio cholerae, Mycobacterium tuberculosis

– Some Common Bacterial Species Can Be Harmful Ex: Escherichia coli

– Most Bacteria Are Harmless!

Protists

• NOT Animals, Plants or Fungi

Protists

• Most Protists are single celled

• Biologists haven’t settled on classification scheme yet

• Formerly divided into Algae (“plants”) and Protozoa (“animals”)

Protists: The chromists

• The Chromists have hair-like projections on their flagella

• Include Photosynthetic and Nonphotosynthetic Organisms

• Some are multicellular

• Examples:

– Diatoms: marine phytoplankton

– Brown Algae: kelp seaweed

Protists: the alveolates

• The Alveolates have small cavities beneath the surface of their cells

• Include Parasites, Predators, and Phytoplankton

• Examples:

– Dinoflagellates: flagellated, photosynthetic, bioluminescent, coral partner, red tides

– Apicomplexans: parasites, no means of locomotion, malaria from Plasmodium

– Ciliates: complex, have cilia

Protists: the slime molds

• Slime Molds Are Decomposers That Inhabit the Forest Floor

– Have mobile feeding stage and stationary reproductive stage

– Acellular Slime Molds Form a Multinucleate Mass of Cytoplasm

Protists with pseudopods

• Various Protists Move by Means of Pseudopods (“false feet”)

– Amoebas: predatory, parasitic ones cause dysentery

– Foraminiferans and radiolarians: Marine, shelled

Protists: the green algae

• Green Algae Live Mostly in Ponds and Lakes

• Closely related to plants

Fungi

Fungi

• Body is a mycelium composed of hyphae

• Can’t move, but grow fast

• Reproductive structures produce spores

• Cell walls have chitin

Fungi

• Fungi Obtain Their Nutrients from Other Organism

– Most are decomposers

• Digestion is external

– Some are parasitic

– A few are predatory

Fungi

• Most Fungi Can Reproduce Both Sexually and Asexually

– Asexually when conditions are stable

– Sexually when environment changes

• Always with spores

Fungi Attack!

• Bad: Plants That Are Important to People Ex. Corn smut

• Good: Insects that eat our plants

Fungi Attack!

• Fungi Cause Human Diseases

– Ringworm, Valley fever, etc

• Fungi Can Produce Toxins

– Aflotoxins, Amanita

But at ease disease…

• Many Antibiotics Are Derived from Fungi

– Penicillin

• Fungi Make Important Contributions to Gastronomy

– On pizza!

– Cheese

– And of course the yeast:

• Wine and beer

• Bread

Fungi

• Fungi Play a Crucial Ecological Role: decomposer

• Releases nutrients to recycle ecosystems through again

Plants

Plants

• Multicellular

• Photosynthetic

• Cell walls

• Divided into groups by whether they have vascular (conducting) tissue, and by seed structures

Bryophytes Lack Conducting Structures

• They must be small

• The reproductive structures of bryophytes are protected

• Need water to reproduce

• Ex: Liverwort, moss

Plants

• The Vascular Plants Have Conducting Vessels That Also Provide Support

• Can grow taller

• Seedless or seed plants

• Seedless Vascular Plants:

– Club Mosses,

– Horsetails

– Ferns

Plants

• The Seed Plants Dominate the Land, Aided by Two Important Adaptations: Pollen and Seeds- adaptations to dryness

• Gymnosperms Are Nonflowering Seed Plants

• Angiosperms Are the Flowering Seed Plants

Plants

• Angiosperms are hugely successful

– Flowers Attract Pollinators

– Fruits Encourage Seed Dispersal

– Broad Leaves Capture More Sunlight

Animals

Animals

• Multicellular

• Consume food via ingestion

• Reproduce sexually

• No cell wall

• Motile at some life stage

• Have nerve cells and or muscle tissue

Animals

• Most Animals Lack Backbones

Animals

• Cnidarians Are Well-Armed Predators

• Stinging cells

• Radial symmetry

Animals

• Annelids Are Composed of Identical Segments

• 3 groups:

• Oligochaetes

• Polychaetes

• Leeches

Animals

• Arthropods Are the Dominant Animals on Earth

• Jointed Legs, Exoskeleton of Chitin

• Segments Grouped into Head, Thorax, and Abdomen

• 3 major groups

– Insects

– Crustaceans

– Arachnids

Animals

• Class Insecta

• Very diverse

• Six legs

• Only flying invertebrates

• Undergo metamorphosis

Animals

– Most Arachnids Are Predatory Meat Eaters

Animals

– Most Crustaceans Are Aquatic

– Class Crustacea

Animals

• Most Mollusks Have Shells

• Phylum Mollusca

• Three major classes

– Gastropods

– Bivalves

– Cephalopods

Animals

• Gastropods Are One-Footed Crawlers

• Feed with radula

Animals

– Bivalves Are Filter Feeders

– 2 shells connected by hinge

Animals

– Cephalopods Are Marine Predators

– Sharks, squid, etc

Animals

• The Chordates (Phylum Chordata) Include Both Invertebrates and Vertebrates

– The Invertebrate Chordates Live in the Seas

Chordate Characteristics

• Dorsal hollow nerve cord

• Notochord

• Pharyngeal gill slits

• Post anal tail

Animals

– Vertebrates Have a Backbone (Vertebral column)

– Also:

• Paired appendages

• Increased size and complexity of brain & sensory organs

– Several classes

• Bony fishes

• Amphibians (Class Amphibia)

• Reptiles (Class Reptila)

• Birds (Class Aves)

• Mammals (Class Mammalia)

Amphibians (Class Amphibia)

Reptiles (Class Reptila)

Birds

Biology Home

Dr. Latham's Home Page

Merced College Home