Organizing Life’s Diversity Chapter 17

EVERYONE classifies… Doesn’t have to be just for living things In your house, where would I find: cereal drinking glasses socks blue jeans bath towels extra bars of soap

Classification Classify – to group things together based on similarities Why Classify? To make organisms/items easier to identify To make organisms/items easier to compare How do we classify? Compare Traits – features or characteristics of an organism/item When dealing with living things, the science of Classification is called Taxonomy

2 Big Challenges of Classification 1. Many different kinds of living things -- diversity Today we have identified and named 1.5 million species Millions more are believed to be unclassified Organisms scattered all over the world, some in harsh, difficult to reach environments 2. Classifications are made by people Opinions may differ from scientist to scientist

Timeline of Classification 1. 384 – 322 B.C. Aristotle 2 Kingdom Broad Classification 2. 1735 - Carl Linnaeus 2 Kingdom Multi-divisional Classification (Kingdom, Phylum, Class, Order, Family Genus, Species) 3. Evolutionary Classification – (After Darwin) Group By lines of Evolutionary Descent 4. 5 Kingdom System – 1950s 5. 6 Kingdom System – early 1990s 6. 3 Domain System – late 1990s

Early Classification – Aristotle 384-322 B.C. Plant Animal Green Not green Does not move Does move Shrub Air Land Water Tree Herb Size Pattern of growth Where live

How would you classify these using the Plant/Animal system? Aristotle’s Grouping of life not specific enough

Carl Linnaeus Linnaeus (1735) Swedish Botanist Reworked Classification system *Based on Body structure -- morphology Called his classification Systema Naturae Used a hierarchy of categories to classify *Compared physical traits of Organisms *Used Comparative Morphology

Linnaeus Divisions Still Used in Modern Classification 1. Kingdom – largest group 2. Phylum 3. Class 4. Order 5. Family 6. Genus 7. Species (Most Closely Related)

Mnemonic Device – To help remember categories and order Kingdom - King Phylum - Phillip Class – Came Order – Over Family - For Genus - Ginger Species - Snaps

Taxons Within each category, a particular group is called a Taxon Many Taxons for each category Ex: Mammalia is the Taxon for the Class category in Humans Carnivora is the Taxon for the Order category in Lions

Similarities/Changes Linnaeus Made to Aristotle’s System *Both had 2 “Kingdom” Systems Plantae and Animalia Differences: 1. Plants and Animals were classified using more divisions - to account for diversity 2. Each division from Kingdom to species is based on specific traits Ex: Vertebrae, Mammary Glands, Diet 3. Taxons of each group are descriptive of trait being used in forming that group Ex: Class Mammalia – mammary glands are used to nurse young

Linnaeus Introduced Scientific Naming Binomial Nomenclature is the 2 word scientific name of an organism Uses Genus and Species Genus is capitalized, not species, all italicized In writing the name, can’t italicize, so underline Used Latin – Universal unifying, “dead” language *Latin can be understood by all scientists, regardless of native language *Uniform, unlike common name usage Ex: Cougar, Puma, Panther- all same organism name depends upon where you live, but Scientific name is the same WORLDWIDE Felis concolor

Example Classification Lion 1. Kingdom – Animalia (all Animals) 2. Phylum – Chordata (All vertebrate animals) 3. Class – Mammalia (All Mammals – mammary glands) 4. Order – Carnivora (Meat eaters) 5. Family – Felidae (includes all Cats) 6. Genus – Panthera (Includes all roaring Cats) 7. Species – leo (Lions)

From Kingdom to Species

Classification Key Also Known as: Dichotomous Key, Biological Key Useful in Identifying Organisms Based on Comparison of Morphological Traits Use physical features to compare, contrast Determine if Organism is in group or not, based on Key criteria At each level you only have a few contrasting characteristics to choose from (if have, if not have) Ex: Tennis shoe, non Tennis shoe Body shape plans, Characteristics such as fur Refer to your Shark lab handout

Tools Used to Classify Organisms Comparative Morphology (structural similarities) Breeding behavior (behavioral similarities) Geographical distribution (biogeography) Chromosome comparisons Biochemistry Evolutionary Relationships

Comparative Morphology Body structure Presence/absence of body parts Ex. Number of limbs Ex. Presence of feathers Ex. Presence of flowers *REMEMBER THOUGH-- This can be misleading – divergent and convergent evolution could play a part and appearance is NOT indictitive of true taxonomic relationships…..

Breeding Behavior Differs between species Ex. Mating calls of frogs Differences in breeding behavior allows for SPECIATION to occur, and can result in isolation

Biogeography Finches, tortoises in Galapagos Bears on different continents Sugar glider and flying squirrel

Chromosome comparisons and Biochemistry Number and structure of chromosomes are set from species to species!!! Similarities in chromosomes and the proteins that are made leads to idea that orgs are related. Ex. Cauliflower, cabbage, kale, broccoli

Molecular clocks Page 530

Two types of data for molecular clocks… Mitochondrial DNA –

Ribosomal RNA –

Evolutionary Relationships – Cladistics vs. Systematics Both are Phylogenetic Classification models – deal with evolutionary history Difference *Cladistics uses a “order of appearance” approach – cladogram this shows groups of organisms evolving from a common ancestor and utilizes “derived characters”, but not specific times

In cladistics, similar characteristics that come from a common ancestor are used to divide organisms into groups. A cladogram will begin by grouping organisms based on a characteristic displayed by all the members of the group. Subsequently, the larger group, or clade, will contain increasingly smaller groups (clades) that share the traits of the clades before them, but also exhibit distinct changes as the organism evolves. To make a cladogram, scientists first collect data on the features of all the organisms they hope to classify. This data is then analyzed to determine which characteristics were present in what could have been a common ancestor and which might have been developed in later times.

Page 525

Cladogram vs. Comparative (Traditional) Morphology p.452 Derived Characters Common Ancestor  <-- Common Ancestor  Common Ancestor  Common Ancestor 

Systematics uses a fan-like approach that communicates a timeline Instead of a few derived characters, systematics uses as many characteristics of orgs as possible and makes groupings based on overall degree of similarity

Timeline of Classification 1. 384 – 322 B.C. Aristotle 2 Kingdom Broad Classification 2. 1735 - Carl Linnaeus 2 Kingdom Multi-divisional Classification (Kingdom, Phylum, Class, Order, Family Genus, Species) 3. Evolutionary Classification – (After Darwin) Group By lines of Evolutionary Descent 4. 5 Kingdom System – 1950s 5. 6 Kingdom System – early 1990s 6. 3 Domain System – late 1990s

From 2 Kingdoms to 6 p. 458

6 Kingdom System moves to 3 Domains Animalia Plantae Fungi Protista Eubacteria Archaeabacteria

4. Three Domain System 1. Domain Bacteria Corresponds to Eubacteria Kingdom Unicellular Prokaryotic Organisms No Nucleus Ecologically Diverse – live everywhere! Metabolically Diverse Cell Walls contain substance called Peptidoglycan – special protein and sugar Trait used to distinguish between Bacteria and Archaea Target of many antibiotics

Three Domain System 2. Domain Archaea – “Ancient Bacteria” Corresponds to Kingdom Archaebacteria Unicellular, Prokaryotes Metabolically Diverse No nucleus Live in Extreme environments like those of early Earth Cell walls without Peptidoglycan a trait used to distinguish between Archaea and Bacteria domains

Three Domain System 3. Eukarya Contains Kingdoms: Protista, Fungi, Plantae, Animalia Eukaryotic, single or multi-cellular Organisms Nucleus Most visible life Humans are in Domain Eukarya