Chapter 18 classification
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Chapter 18 Classification. 18.1 Finding Order in Diversity. Assigning Scientific Names Common names confusing=varies w/ lang & location Scientific name ( latin ) same worldwide. Puma. Cougar. Panther. Common names for a mountain l ion:. Dichotomous key : guide to ID unknown org

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Chapter 18 Classification

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Chapter 18 Classification

18.1 Finding Order in Diversity

  • Assigning Scientific Names

    • Common names confusing=varies w/lang & location

    • Scientific name (latin) same worldwide




Common names for a mountain lion:

  • Dichotomous key: guide to ID unknown org

    • Uses paired statements with alternate choices

  • Binomial Nomenclature:

    • Linneaus (Swedish botanist) developed

    • 2-word naming system

      • Genus speciesor Genus species

      • Genus=type or group; species=unique description

  • Classifying species into larger groups

    • Systematics: organizing life into meaningful groups

    • Taxa: biological groupings

The king vulture Sarcorhamphus papahas a scientific name that means "father or leader with a fleshy, curved beak."

This poison arrow frog's scientific name,

Dendrobatesazureus, means blue tree-walker!

Linnaean Classification System

  • Uses 7 hierarchical, ordered ranks-taxa

    • Largest to smallest: Kingdom, phylum, class, order, family, genus, species

Problems with Traditional Classification

Used visible similarities/differences (barnacles look like limpets but are more like crabs)

Today: use evolutionary relationships


gastropod mollusk

Barnacle: crustacea

Crab: Crustacea

18.2 Modern Evolutionary Classification

  • Evolutionary Classification

  • Phylogeny: species grouped by evolutionary descent

    • Common Ancestors: taxa groupings show relationships

      • Larger, more diverse taxa=more ancient common ancestor

    • Clades-a monophyletic group: single common ancestor and all descendants (living & extinct)


Cladistic analysis shows specific traits branch from comm ancestor

Links groups showing evolutionary relationships

Building Cladograms: branches (nodes) represent ancestral species splitting in 2

Each node=last point species above line shared com ancestor

Root of node=common ancestor of those more recent

Derived Characters: trait arising in most recent ancestor of lineage

Losing Traits: tetrapods (4 limbs) include reptiles; snake still reptile

Interpreting Cladogram: character positions reflects order they arose

Clade vs Traditional grps: evol. links more accurate=clades connects all species back to original ancestor (dinosaurs/ birds/reptile)

  • DNA in Classfication

    • Genes as Derived Characteristics

      • Gene homologies (similarities) determine evolutionryrelationshps

      • Mutations=derived characteristisc

      • More recent commn ancestors = ↓ diffs in genes (more mutations

        in common) =>closer related





Giant Panda

New Evolutionary Trees

DNA=more accurate evolutionary tree

American vulture looks like African vulture yet DNA & behavior more similar to stork (more recent comm ancestor)

Giant panda DNA more like bears; Red panda DNA more like racoons (Pandas now in different clades)

Raccoons Red pandas Giant pandas Bears




Common Ancestor

18.3 Kingdoms (6) & Domains(3)

  • Changing Ideas about Kingdoms

  • W/diversity of life: science moved from Linnaeus’s 2 kingdms to 5

  • Genetic data= bacteria Kingdom Monera divided into 2

  • Genome data=new taxonomic division: Domain (larger than kingdom); now have 3

    • “Protista”: so diverse, > than 1 commancestr=not true clade

The Tree of Life

Domain Bacteria

  • Kingdom Eubacteria

  • Characteristics:

    • Unicellular

    • Prokaryotic

    • Thick Cell Wall

      • Peptidoglycan

    • Diverse (majority)

Domain Archaea

  • Kingdom Archaebacteria

  • Characteristics:

    • Unicellular & anaerobic

    • Prokaryotic

    • Cell membranes contain unique lipids

    • Extreme Env’t

Domain Eukarya w/4 Kingdoms

  • Kingdom Protista

    • Paraphyletic group (more than 1 com ancestor)

    • Plant-like, fungus-like, animal-like members

    • Now at least 5 clades

    • Most single celled

  • Kingdom Fungi

    • Feed on dead/decaying org.

    • Cell walls contain chitin

    • Digest externally

    • Most multicellular

  • Kingdom Plantae

    • Autotrophic=Photosynthesis

    • Cell Wall (cellulose)

    • All plants are sister group to red algae (protist)

  • Kingdom Animalia

    • Multicellular/hetero

    • No Cell Wall/Motile

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