Classification of Living Things

Classification of Living Things Taxonomy: Branch of biology that names organisms according to their characteristics. Putting things into orderly groups based on similar characteristics. Why do scientists classify? Biologists classify living organisms to answer questions such as: How many known species are there? What are the defining characteristics of each species? What are the relationships between these species?

Aristotle Aristotle Greek philosopher and teacher more than 2000 years ago The first person to group or classify organisms (300 B.C.)

Aristotle PLANTS: Based on size of stem Based on where they lived ANIMALS: Based on size of stem Based on where they lived

Limitations of Early Classification 1. Not all organisms fit into Aristotle’s 2 groups (plants or animals) Ex: Bacteria Fungi Images from: http://www.leighday.co.uk/upload/public/docImages/6/Listeria%20bacteria.jpg http://danny.oz.au/travel/iceland/p/3571-fungi.jpg

Limitations of Early Classification 2. Common names can be misleading Ex: A jelly fish isn’t a fish, but a seahorse is! Sea cucumber sounds like a plant but… it’s an animal! Image from: http://www.alaska.net/~scubaguy/images/seacucumber.jpg

Limitations of Early Classification 3. Common names vary from place to place Ex: puma, catamount, mountain lion, cougar are all names for same animal Image from: http://www4.d25.k12.id.us/ihil/images/Cougar.jpg

Limitations of Early Classification 4. Same organisms have different names in different countries. Chipmunk Streifenhornchen (German) Tamia (Italian) Ardilla listada (Spanish) Image from: http://www.entm.purdue.edu/wildlife/chipmunk_pictures.htm

Limitations of Early Classification Early Solution: Description of Organism Using Latin Names RED OAK Quercus foliis obtuse-sinuatis setaceo-mucronatis “oak with leaves with deep blunt lobes bearing hairlike bristles”

Limitations of Early Classification Problem with Latin Name descriptions? Names too long and difficult to remember Names don’t illustrate evolutionary relationships

“Father” of taxonomy and binomial nomenclature Carolus Linneaus Devised a new classification system based on morphology (Organism’s form and structure) (1707-1778) “Father” of taxonomy and binomial nomenclature

Carolus Linnaeus Linnaeus’s Classification System Organisms grouped in a hierarchy of seven different levels Each organism has a two part scientific name Binomial Nomenclature

Kingdom Phylum Class Order Family Genus Species Kids Prefer Cheese Over Fried Green Spinach

Kingdom Phylum Class Order Family Genus Species Animalia Chordata Mammalia Carnivora Felidae Panthera leo http://www.vetmed.wisc.edu/dms/fapm/personnel/tom_b/2004-lion.jpg

Binomial Nomenclature Binomial Nomenclature: Two name naming system Italicized or Underlined 1st Name = Genus Capitalized 2nd Name = Species Identifier Lower case

Binomial Nomenclature Vampire bat Desmodus rotundus Image from: http://212.84.179.117/i/Vampire%20Bat.jpg Eastern chipmunk Tamias striatus Image from: http://www.entm.purdue.edu/wildlife/chipmunk_pictures.htm

Binomial Nomenclature Humans Homo sapiens Homo sapiens Image from: http://www.earlylearning.ubc.ca/images/photo_baby.jpg

Modern Taxonomy Modern taxonomy involves the use of Linnaeus’s naming/classification system, but with additional kingdoms.

Organizes living things in the context of evolution Modern Taxonomy Organizes living things in the context of evolution

Modern Taxonomy Scientists use a variety of information in order to classify organisms: Fossil Record Morphology Embryology Chromosomes Macromolecules (DNA and Proteins)

We can trace some changes over time through the fossil record. Evolutionary history = PHYLOGENY

2. MORPHOLOGY Shape and Function   Image from: http://www.angelfire.com/ab7/evolution12/evolutionclues.html

Homologous characteristics suggest a recent common ancestor Morphology Homologous Characteristics: Same embryological origin (may have similar structure and function) Example: Bat Wing and Human Arm Homologous characteristics suggest a recent common ancestor

develop from same embryonic structures Morphology Bat wing and human arm develop from same embryonic structures HOMOLOGOUS STRUCTURES

Morphology Analogous Characteristics: May have similar structure and function, but different embryological origin Example: Bird Wing and Butterfly Wing Analogous characteristics evolved separately. Organisms not necessarily closely related.

have evolved with similar function ANALOGOUS STRUCTURES Bird wing and butterfly wing have evolved with similar function BUT different structure inside. http://uk.dk.com/static/cs/uk/11/clipart/bird/image_bird003.html Insects and birds NOT closely related! http://www.naturenorth.com/butterfly/images/05a%20tiger%20wing.jpg

I don’t get it! Analogous characters  the same function but different underlying construction. Homologous characters  different functions, but show an anatomical similarity inherited from a common ancestor. **Important for cladograms!**

3. Embryology Animals whose embryos develop in a similar pattern may be related Image from: http://calspace.ucsd.edu/virtualmuseum/litu/03_3.shtml

Even differences show relatedness amnion /am·ni·on/ (am´ne-on) bag of waters; the extraembryonic membrane of birds, reptiles, and mammals, which lines the chorion and contains the fetus and the amniotic fluid http://www.southtexascollege.edu/nilsson/4_gb_lecturenotes_f/4_gb_24_cla_ani_ve_spr2003.html

4. Chromosomes Similar karyotypes suggest closer relationships. Human: http://www.nationmaster.com/wikimir/images/upload.wikimedia.org/wikipedia/en/thumb/1/18/300px-Human_karyogram.png Chimpanzee: Middle School Life Science , published by Kendall/Hunt.

Even differences show relatedness Human- 46 chromosomes Chimpanzee- 48 chromosomes Even differences show relatedness Chimpanzees have 2 smaller chromosome pairs we don’t have Humans have 1 larger chromosome pair (#2) they don’t have. Human: http://www.nationmaster.com/wikimir/images/upload.wikimedia.org/wikipedia/en/thumb/1/18/300px-Human_karyogram.png Chimpanzee: Middle School Life Science , published by Kendall/Hunt.

5. Macromolecules Comparison of macromolecules such as Proteins and DNA Organisms with similar sequences are (thought to be) more closely related.

Macromolecules

Evolutionary Relationships Determined through the use of: Morphology Fossil Record Embryology Chromosomes Macromolecules Evolutionary relationships can be illustrated on a phylogenetic tree

Cladistics Shows evolutionary relationships based on “shared derived characteristics” Cladistic relationships illustrated through the use of a Cladogram Phylogeny: Evolutionary History

Cladogram The greater the number of derived characters shared by groups, the more recently the groups share a common ancestor.

Domains Three Domains: 1. Archaea 2. Bacteria 3. Eukarya Domains are taxonomic groups that are even bigger than kingdoms. Each of the six kingdoms belongs to a single domain. Three Domains: 1. Archaea 2. Bacteria 3. Eukarya Do Kids Prefer Cheese Over Fried Green Spinach?

Domain Bacteria Eubacteria are prokaryotes whose cell walls contain peptidoglycan. “True bacteria”

Domain Archaea Archaea are thought to be more ancient than bacteria and yet more closely related to our eukaryote ancestors. Cell walls without peptidoglycan They are called extremophiles because they can live in extreme environments.

Domain Eukarya All eukaryotes are classified in Domain Eukarya. Domain Eukarya contains Kingdom Protista, Kingdom Fungi, Kingdom Plantae, and Kingdom Animalia.

Kingdom Archaebacteria Some archaebacteria are heterotrophs, but some are autotrophs. Most archaebacteria are unable to move, but a few can move. Archaebacteria are the old known life forms. Why are archaebacteria not classified with “modern bacteria”? Archaebacteria and eubacteria are chemically different!

Kingdom Archaebacteria Cool archaebacteria info: Three divisions of archaebacteria: Methanogens: methane producing organisms Thermophiles: These can live in extremely hot, acidic environments like sulfur springs. Halophiles: Can only live in bodies of concentrated salt water, like the Dead Sea.

Kingdom Eubacteria Traditional prokaryotic bacteria Unicellular. Some are autotrophic, some are heterotrophic. Found in soil, water, human body, etc. Esterichia coli (E. coli) is found in large numbers in human intestines, where it produces vitamin K.

Kingdom Eubacteria Unlike archaebacteria, eubacteria require oxygen. Some bacteria contain cilia or flagella which allows them to move. 47

Kingdom Protista Eukaryotic organisms. This is why they are not considered bacteria! Most protists are single-celled but some are simple, multicellular organisms “Junk Drawer Kingdom” or “Odds and Ends Kingdom” Some protists are autotrophic, some protists are heterotrophic. Animal-like protists, plant-like protists 48

Most protists are able to move, but some cannot Kingdom Protista Most protists are able to move, but some cannot

Kingdom Fungi Molds and mushrooms are examples of fungi. Fungal cell walls contain chitin. (cell walls of plants contain cellulose). The study of fungi is known as mycology. Fungi are more closely related to animals than to plants! Usually, the only fungi that we see are reproductive structures. Tasty!!

Kingdom Plantae Plants are eukaryotic, multicellular organisms. They are autotrophs- they make their food through photosynthesis. Plants can be found on land and in shallow water (where there is light)

Kingdom Plantae Plant cells have cell walls Made up of cellulose, to provide them with a rigid structure Some plants reproduce through both asexual and sexual reproduction.

Kingdom Animalia This kingdom contains many complex, multicellular organisms. All animals are heterotrophic. All animals are able to move, even if it is only during some stages of the life cycle.

Kingdom animalia All animals are eukaryotic organisms, but animal cells do not have a cell wall. Most animals reproduce through sexual reproduction, but some are able to reproduce asexually (or both!). The most simple organism in the kingdom animalia is a sponge.