Classification of Living Things Chapter 18

Why Classify Classification is used to name organisms and group them in a logical manner – Biologists have classified and named over 1.5 million species – Estimate that 2 million- 100 million have yet to be discovered

Taxonomy A branch of biology where scientists classify organisms and assign each a universally accepted name

Taxonomy A good classification system puts organisms in groups with other organisms that are similar – Originally based on physical characteristics Physical traits are shared amongst unrelated organisms – Convergent evolution Shark vs. dolphin Bird vs. bat

Common Names Organism were originally referred to by common names – Names that are unique to a small group of people With out discussion; draw what comes to mind when you hear the word: cat

Use of common names Common names can be misleading – Given based on physical characteristics and what the organism reminds us of jellyFISH seaHORSE Sea CUCUMBER

Use of common names Common names vary among languages and even regions in the same country – Mountain lion – Puma – Cougar – Panther

Use of common names Different species sometimes share a common name – What is a buzzard??? United States- Vulture United Kingdom (England)- Hawk

Removing Confusion First Naming system – scientists used detailed physical descriptions Names were long and hard to remember Carolus Linnaeus (mid 18 th century) – Developed a two word naming system called Binomial nomenclature shows ancestral relation

Binomial Nomenclature scientific names are used to avoid confusion – Universally accepted Cathartes aura Buteo jamaicensis

Taxonomic Nomenclature Kingdom Phylum Class Order Family Genus Species Kids Prefer Candy Over Fried Green Spinach Hierarchical system (consists of levels) Each level is a taxon

Kingdom-Animalia Phylum-Chordata Class-Mammalia Order-Carnivora Family-Felidae Genus-Panthera Species-leo

Binomial Nomenclature Rules to follow 1.Always written in italics (or underlined) 2.First word is capitalized (genus name) 3.Second word is lowercased (species name)

Binomial Nomenclature Genus  a group of closely related species Ursus

Binomial Nomenclature Species  a group of similar organisms that can breed and produce fertile offspring Ursus Ursus Ursus arctosmaritimusamericanis

Modern Evolutionary Classification 18.2

Modern Evolutionary classification Taxonomic groups are invented by scientist to group organisms with similar characteristics

Which Similarities are most important Taxonomists try to group organisms according to biologically important characteristics – Linnaeus grouped species based on visible similarities (Dolphin example: Fish vs. Mammal) Barnaclecrablimpet

Evolutionary Classification Limpet and barnacle larvae are very different. Barnacles have jointed limbs, Limpets DON’T ! Barnacles have a segmented body, Limpets DON’T ! Barnacles have an exoskeleton that molts, Limpets DON’T !

Crab and barnacle larvae are very similar Barnacles have jointed limbs, So do CRABS ! Barnacles have a segmented body, So do CRABS ! Barnacles have an exoskeleton that molts, So do CRABS ! Evolutionary Classification

Organisms are grouped together based on evolutionary decent not just physical traits (WHY??) The higher the level of the taxon, the further back in time is the common ancestor

Lion Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Carnivora Family: Felidae Genus: Panthera Species: leo Tiger Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Carnivora Family: Felidae Genus: Panthera Species: tigris

Lion Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Carnivora Family: Felidae Genus: Panthera Species: leo Grey Wolf Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Carnivora Family: Canidae Genus: Canis Species: C. lupus

Cladistic analysis Cladogram: a diagram used to show evolutionary relationships A way of classifying organisms using only new evolutionary characteristics Derived characteristics- These characteristics appear in later organisms but not earlier ones

Molecular Clock Used to compare DNA of organisms – The more similar the DNA the more recently the organisms branched off from one another Neutral Mutations- are not affected by natural selection – Accumulate in the DNA over time (at the same rate in all species)

Cladogram Help us to understand how one lineage branched from another in the course of evolution. (family tree)

1. ______ Wings 2. ______ 6 Legs 3. ______ Segmented Body 4. ______ Double set of wings 5. ______ Jumping Legs 6. ______ Crushing mouthparts 7. ______ Legs 8. ______ Curly Antennae

Answer 1. ___F___ Wings 2. ___C___ 6 Legs 3. ___A___ Segmented Body 4. ___G___ Double set of wings 5. ___E___ Jumping Legs 6. ___D___ Crushing mouthparts 7. ___B___ Legs 8. ___H___ Curly Antennae

Kingdoms and Domains The tree of Live “Evolves”

Changes in the classification system New biological understanding lead to a more accurate classification system Genes show important similarities at the molecular level – Linnaeu’s didn’t know about DNA DNA from organisms can be sequenced and compared to show evolutionary relationships.

Molecular Clocks DNA comparisons can be used to estimate how long 2 species have been evolving independently. Mutations in the genes accumulate at different rates – The more similar mutations 2 species have the closer related they are

Effect on Classification Scientist used to believe there were just 2 groups of living things: plants and animals 2 kingdom system doesn’t adequately represent diversity of life 6 kingdom system: – Eubacteria – Archaebacteria – Protista – Fungi – Plantae – Animalia

Eubacteria Prokaryote Unicellular Autotroph or Heterotroph Cell wall with peptidoglycan (extra outer layer) Ecologically diverse (Common Bacteria) – Free-living soil organisms – Parasites – Photosynthetic – Anaerobic – aerobic

Archaebacteria Prokaryote Unicellular Autotroph or Heterotroph Cell wall without peptidoglycan layer Live in the most extreme environments (first living organisms) – Volcanic hot springs – Brine pools – Black organic mud (NO oxygen)

Protista Eukaryote Most are unicellular Autotroph or Heterotroph Cell walls of cellulose Some have chloroplasts Made up of organisms that cannot be classified elsewhere

Fungi Eukaryote Most are Multicellular (some unicellular) Heterotrophs – Feed on dead or decaying matter – Secrete digestive enzymes to break down food Cell wall of chitin

Plantae Eukaryote Multicellular Autotroph – Carry out photosynthesis Chloroplasts Cell wall of cellulose Non-motile (cannot move from place to place)

Animalia Eukaryote Multicellular Heterotroph No cell wall Most can move (at least at some point in there life cycle) Very diverse group – Species that exist in almost every part of the planet

3 Domain System Molecular clock analysis allows scientists to group organisms according to how long they have been evolving independently The domain is a more inclusive category than any other 3 Domains: Bacteria, Archaea, and Eukarya

Domain/ Kingdom Relationship