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Chapter 3The Diversity of Life

Part Two: Classification and Diversity

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Taxonomic Groups

• Six kingdoms– Prokaryotes

1. Archaeobacteria

2. Eubacteria

– Eukaryotes3. Plantae

– producer

4. Fungi– consumer

5. Animalia– consumer

6. Protistahttp://www.ucmp.berkeley.edu/

http://tolweb.org/tree/phylogeny.html

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SystematicsUnderstanding the history of life

Systematics is based on our understanding the life diversified from a single origin. Diversity is a product of descent with modification.

• Taxonomy– Naming and classification of life– System of organizing the

relationships between organisms

• Taxonomic groups– The six kingdoms and their

subordinate groups

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Taxonomic Groups

• Taxa range from broad (phylum) to narrow (species)Kingdom AnimaliaPhylum ChordataClass MammaliaOrder PrimatesFamily HominidaeGenus HomoSpecies Homo sapiens

– Species• Group of individuals that can

interbreed• Name includes genus• Italicized

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Taxonomic Groups

• Primitive traits– Appear early in

evolutionary history– Hagfish group traits

• Derived traits– Evolved later– Present only in some

subgroups– Jaws, lungs, claws or nails,

feather, fur, and mammary glands

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Prokaryotes- Eubacteria

Prokaryotes: Unicellular (mostly) organisms without a nucleus

Bacteria may be aerobic or anaerobicClassified as 1. heterotrophs

fermentation and respiration2. autotrophs

photoautotrophic or chemoautotrophs• Critical to Earth System as a mechanism for recycling nutrients

like carbon, nitrogen and sulfur• Carbon is removed from the atmosphere by plants. Bacteria

oxidize this carbon after plants death, which recycles it back to the atmosphere as CO2. No CO2= No plants= No life

• Oldest known fossils are 3.5 billion years old: bacteria like organisms

• Most common in rock record are stromatolites: Layered mats of cyanobacteria

Photo: http://www.sharkbay.org/terrestial_enviroment/page_15.htm

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Prokaryotes- Archaeans

• Discovered in the 1970’s• Inhabit extreme environments

– Temperatures >100 degrees Centigrade• Hot springs

– Low or no oxygen– Alkaline or Acidic conditions

• They are methanogens: they produce methane

• Have probably not changed much through time: recognized as far back as 3.8 bya

http://www.ucmp.berkeley.edu/archaea/archaeasy.html

- No driving mechanism for evolution. No competition.

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Eukaryotes: Protista

• Eukaryotes: organisms with complex cells with nuclei.

• Protozoans (single celled, nuclei)– Animal-like protists divided on

the basis of locomotion and morphology

• Amoebas– Change shape

• Flagelleates– Flagellum for locomotion

• Ciliate– Cilia for locomotion

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Protista

• Unicellular algae– Plant-like protists

• Dinoflagellates

• Diatoms: chert

• Calcareous nannoplankton: chalk

• Originated in the Mesozoic Era– Important marine producers

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Protista

Protozoans with skeletons

• ForaminiferaChambered skeleton of

calcium carbonate

Very abundant

Useful for dating rocks and sediments

Why?

They are good index fossils.

Planktonic, over 250,000 species, distinct ranges

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Protista

• Protozoa with skeletons

• Radiolarians– Skeleton made out of

opal (SiO2): chert

– Related to foraminifera

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Eukaryotes: Fungi

• Decomposers– Obtain nutrients from

dead organisms using digestive enzymes (heterotrophs)

– Spore producers

• Diverse– Yeast– Mushroom

• Poor fossil record

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Plants

• First land plants in the Ordovician (490-443my)

• Vascular versus Non-vascular– Vessels for transport of

water, dissolved nutrients, food

– Transportation of materials by diffusion

• Example: Mosses

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• Ferns– Devonian (417-354my)– Adapted to life on land with

roots and leaves– Spores

• One set of chromosomes• Fertilized by sperm• Sperm migration requires

moisture

– Vast Late Paleozoic swamps led to coal formation

– Origin of name “Pennsylvanian Period” after coal mines in Pennsylvania

Spore Plants

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Seed Plants• Seeds enabled plants to exploit drier, non

coastal habitats

• Gymnosperms– Greek word meaning “Naked seed” plants– Conifers

• Cone-bearing plants

• Eggs are fertilized in cone by pollen– Pollen bears sperm; carried by wind

• Dominant in the Mesozoic

• Angiosperms– Flowering plants

• Pollen carried by pollenators (animals)

• Dominant in the Cenozoic

http://en.wikipedia.org/wiki/Angiospermhttp://www.ucmp.berkeley.edu/seedplants/seedplants.html

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Animalia

• Two groups– Vertebrates

• Possess a backbone

– Invertebrates

• Coelomates– Body cavity housing

internal organs

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Animals- Sponges

– Simple invertebrates– Suspension feeds

• Strain particles from water

• Mostly eat bacteria• Flagella pump water

through internal canals

– Calcium carbonate or silica spicules support structure

• Cambrian - modern

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Cnidarians

• Jellyfish and corals• Polyp and Medusae

stage• Radial symmetry and

more complex body plan including mouth, tentacles and digestive cavity

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Arthropods

• Insects, crabs, spiders, lobsters, trilobites

• Trilobite– Three-lobed body

• Central, left-and right- lobed– External skeleton– Gill-like structure for respiration– Legs– Primitive eyes

• Common in Cambrian (560-490 mya)

• Illustrates that complex life formed early in Earth History and challenges traditional view of evolution as a move from primitive to advanced forms of life.

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Mollusks

• Bivalves (Clams)

• Gastropods (snails)

• Cephalopods (octopuses)

•Shell of aragonite, calcite, or both•All share a common body plan, though they evolved to fit different ecological niches: crawlers, filter feeders, swimmers

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Mollusks

• Cephalopods– Squids, octopuses, chambered nautilusses– Swim in the sea

• Jet propulsion• Eyes

– Carnivores• Catch with tentacles• Eat with strong beak

• Chambered nautilus– Bouyancy due to gas in shell– Pressure accomodated by increased surface area

• Common in Phanerozoic

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Lophophores

• Brachiopods– Shell divided into two

valves– Lampshells– Lophophores

• Pump water• Strain food

– Inarticular brachiopods• Lack hinge teeth• Lingula

– Articulate brachiopods

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Bryozoans

• Moss animals• Ressemble corals, but

more closely related to brachiopods– Lophophore extended

from skeleton to feed– Calcified skeleton

• Colonial• Ordovician

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Echinoderms

• Spiny-skinned form• Five-fold symmetry

– Starfishes• Predators• Lower Paleozoic

– Sea urchins• Regular sea urchins

– Radially symmetrical bodies

• Irregular sea urchins– Bilaterally symmetric– Burrowers

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Echinoderms

• Crinoids– Sea lillies

– Sieve food using arms• Pass food to mouth with

tube feet

– May swim

– May be attached by flexible stalk

– Disk-shaped plates from stalk

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ChordatesNotochord, Gills and Tail

Notochord– Flexible, rodlike structure that supports body for some part of

life cycle– Spinal cord

• Runs next to notochord

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Vertebrates

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Vertebrates• Fishes

– Devonian 417 to 354 mya: Age of Fishes

– Jawless Fishes “Class Agnatha”– Placoderms: Earliest jawed fishes.

Armored plates but no teeth- sharp jaws instead. Devonian

– Ray-finned fishes• Fins supported by thin bones radiating

from body– Lobe-finned fishes (sharks)

• Tetrapods: Amphibians– Amphi meaning both, Bios meaning

life– 3000 living species– Devonian: Ichthyostega climbs to

shore in Greenland

An Ichthyosaur

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Vertebrates: Tetrapods• Tetrapods: Reptiles

– Eggs with protective shells

– Ectothermic• Environment controls internal body

temperature

• Question: What might be an advantage of this quality?

– Dinosaurs• Primitive reptiles 225 to 65 mya

– Birds• Endothermic

• Evolved from Dinosaurs

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Vertebrates: Tetrapods

• Mammals– Endothermic; Hair

– Bear live young

– Monotremes• Mammals that lay eggs

– Marsupial• Offspring develop in

pouch

– Placental

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Answers to your questions…

• How often do geologists find new species?

• What kind of fossils are in N. Idaho?

• What is the most common type of fossil found today?

• Total named species on Earth: 1.5 million.

• Actual number may= 100 million (mostly insects), but probably around 13-14 million. (Society for Conservation Biology)

• Grad student here in department found new species of brachiopod, got to name it.

• Stephen J. Gould estimated that 99% of all plant and animal species are exinct.

• Hagerman Fossils (S. Idaho): Pliocene age (3.7-3.1my). 140 species including horses, saber tooth cats, ground sloths…

• Miocene (20my) Plant Fossils• Cambrian Trilobites at Lake Pend

Oreille (545-495my)

Fungal Spores from the Rhynie Chert, ScotlandDevonian age (417-354my)