Classification Chapter 17-Pg. 502-523 Finding Order in Diversity Why Classify Organisms??...

Classification

Chapter 17-Pg. 502-523

Finding Order in Diversity

• Why Classify Organisms??– Biologists use classification systems to name

organisms and group them in a logical order

• Taxonomy: Scientists classify organisms and assign each organism a universally accepted name

The History of Organization

Aristotle 384-322 BCInterested in biological classification.

Patterns in nature.

Carl Linnaeus1707-1778 ACE

Father ofBiological

Classification!

Aristotle

• Developed the first system of classification.

• He classified all living things into plants and animals.

• Animals were grouped depending on where they lived. (On land, in air or in water)

• Later scientist became convinced that his system did not work because of organisms living in multiple habitats.

Carolus Linnaeus• Developed the system of

classification that is still used today.

• He selected physical characteristics that led to classification based on close relationships of organisms.

• He used characteristics such as bats having hair and feeding their young milk to classify the organisms.

• The system devised by Linnaeus gives each organism two names called Binomial Nomenclature.

WHY DO WE CLASSIFY ORGANISMS?

• We classify organisms in order to study the diversity of life.

• Biologist use a classification system to name the organism and group them into a logical manner.

In order to make their job easier, scientists classify living things into groups, based on how they are the same, and how they are different.

What is Classification?

Classification arranges objects, ideas, or information

into groups by finding common

traits or characteristics.

Assigning Scientific Names

• For many species, there are often regional differences in their common names– EX: Buzzard in the UK refers to a hawk,

Buzzard in the US refers to a vulture

• To eliminate such confusion, scientists agreed to use a single name for each species

• Binomial Nomenclature: Scientists assign each kind of organism a universally accepted name in the system– Two word system using the Genus and Species– Words are always written in italics– First word (Genus) is capitalized and second word

(Species) is lowercase– Second word is a Latinized description of a

particular trait– Developed by an 18th C. Swedish botanist named

Carolus Linnaeus• EX: Grizzly Bear = Ursus arctos

• Differences in Binomial Nomenclature:– 1st part of scientific name is genus to which the

organism belongs– A genus is composed of a number of closely

related species– 2nd part of scientific name is unique to the

species within the genus• EX: Ursus arctos= Grizzly Bear, Ursus maritimus= Polar

Bear• EX: Papio annubis and Papio cynocephalus do NOT

belong to the same species since the species part of the name is different. However, they do belong to the same genus

Common name: Robin

• Erithacus rubicula

• Turdus migratorus

Common name: Black and Polar Bear

Ursus americanus

Ursus maritimus

There are six basic characteristics of life. All living things have the following traits.

1. Show an orderly structure, or organization, of tiny units called cells.

2. Reproduce to make more living things. 3. Change during their lives through growth and

development.4. Adjust to their surroundings.5. Obtain and use energy to run the processes of

life.6. Pass on traits to their offspring.

2 types of Reproduction

1. ASEXUAL (binary fission) a single parent passes exact copies of it’s DNA to it’s offspring. Occurs in bacteria and single celled organisms such as the amoeba.

The single-celled amoeba demonstratesa simple method of asexual reproduction; it divides in half by a process called fission, producing two smaller daughter cells. Aftera period of feeding and growth, these two daughter cells will themselves divide in half.

2 types of Reproduction

2. SEXUAL - organisms having genetic characteristics derived from two parents are produced.

Male and female reproductive cells (gametes) unite to form a single cell, known as a zygote, which later undergoes successive divisions to form a new organism.

Adjust = HOMEOSTASIS

• Organisms respond to their external environment and then process the internal demands accordingly.

• The maintenance of stable internal conditions in spite of changes in the external environment.

Example: temperature of a human is always around 98.6 regardless of the temperature outside.

Groups are also arranged in hierarchical order.

• Linnaeus’s System of Classification:– Based on Taxonomy naming system

• Taxonomy: is the branch of biology concerned with the grouping and naming of organisms.

• a group at any level of an organization is referred to as a taxon.

– Is hierarchical and consists of 7 taxonomic categories– From largest to smallest:

• Kingdom (King)= Made up of phylums• Phylum (Phillip) = Made up of several different classes• Class (Came) = Made up of several different orders• Order (Over) = Made up of several different families• Family (For) = Made up of several different genuses• Genus (Grape) = Made up of several different species• Species (Soda)

SPECIES

• A GROUP OF SIMILAR LOOKING ORGANISMS THAT SHARE SIMILAR CHARACTERISTICS AND CAN INTERBREED WITH ONE ANOTHER TO PRODUCE FERTILE OFFSPRING.

horse + donkey = mule (non-fertile offspring)

species + species = non-species

Examples of Taxonomic Levels:• The most general and largest of Linnaeus’s

system is the Kingdom– Linnaeus recognized the kingdoms of plants (Plantae)

and animals (Animalia)

• The class of Mammalia includes mammals which are organisms that have:– Are warm-blooded– Have body hair– Produce milk for their young

Modern Evolutionary Classification

• Traditional classifications like Linnaeus’s tended to take into account primarily general similarities in appearance– However, some organisms that ARE NOT closely

related look alike because of convergent evolution!• Evolutionary Classification: The procedure of

grouping organisms based on their evolutionary history– Species within one genus should be more closely

related to each other than a species in another genus

– All genera within a family share a common ancestor. Similar genes

• Derived Characters: An evolutionary innovation– EX: Free swimming larva, segmented body

• Cladistic Analysis: Analysis that focuses on the order in which derived characters appear in an organism– Looks only at derived characters, or those characteristics that

are evolutionary innovations (EX: body structures, adaptations)– New characteristics emerge as lineages evolve over time

• Cladogram: a table analyzing derived characters that shows the evolutionary relationship between organisms– Helps scientists understand how lineages branched from one

another in the course of evolution– Shows the order in which derived characters evolved

Similarities in RNA and DNA:• Similar genes are evidence of common ancestry• Similarities in DNA can help determine

classification and evolutionary relationships– EX: A cow and a yeast’s degree of relationship can be

determined from their genes– EX: Scientists have found that humans and yeast

have similar genes for the assembly of certain proteins (Myosin)

• All organisms use DNA and RNA to pass on information

Similarities in RNA and DNA Cont…:

• DNA evidence can help show the evolutionary relationship between organisms and how species have changed– EX: Presence of similar genes in very

dissimilar organisms implies that the organisms share a common ancestor like vultures and storks!

Kingdoms and Domains

In the 1800’s scientists used a 3 kingdom classification system:– Animals, Plants, Protista– Scientists grouped organisms according to how long they

have been evolving independently• Biologists knowledge of diversity of life continued to grow• We now know there are 6 Kingdoms:

– Archaebacteria (used to be grouped as the Monera category)

– Eubacteria (used to be grouped as the Monera category) – Protista (used to be grouped with Plants)– Fungi – Plantae– Animalia

Kingdoms and DomainsThe Three Domain System:• Modern analysis of evolutionary trees have given rise to

a new taxonomic category– Domain• A domain is more inclusive and larger than a kingdom• There are 3 Domains:

– Eukarya: includes kingdoms protist, fungi, plants, & animals

– Archaea: includes kingdom Archaebacteria– Bacteria: Includes kingdom Eubacteria

• The 3 domains are thought to have diverged from a common ancestor before the evolution of the main groups of eukaryotes

• Recognizes fundamental differences between 2 groups of prokaryotes- Bacteria & Archaea

• Domain Archaea:– Kingdom Archaebacteria –ancient bacteria– Unicellular; Prokaryotes (do not have a true

nucleus)– Found in extreme environments– salt lakes,

swamps and VERY deep within the ocean. Deep sea bacteria, make their own food (autotroph) using energy derived from minerals coming form; without oxygen. Also heterotrophs

– Cell wall do not contain unusual lipids (peptidoglycan)– Subdivided into 3 groups based on their habitat ---

methanogens, thermoacidophiles, & extreme halophiles

Halophiles (like salt) Thermophiles (like heat)

• Kingdoms and Domains

•Domain Bacteria:

•Kingdom Eubacteria- true bacteria•Unicellular •Heterotroph or autotroph•Can be aerobic (require oxygen) or anaerobic (don’t need oxygen) •Cell walls are thick & rigid & contain lipid (peptidoglycan)•Found in practically every environment on Earth.•Can be identified by Gram staining (gram positive or gram negative) •Come in 3 basic shapes --- cocci (spheres), bacilli (rod shaped), spirilla (corkscrew shape) Some need oxygen to survive & others do not

Eubacteria

• Staphylococcus aureus

• Bacillus anthracis

• E. coli

• Domain Eukarya:– Eukaryotes– Consists of the 4 kingdoms:

• Protista: – organisms that cannot be classified as plants,

animals, or fungi– Usually unicellular but some multicellular– Have chloroplasts (autotroph) or Heterotroph– Membrane-bound organelles– Cell wall of cellulose – Classified by the way they move- flagellum, cilia,

or pseudopods– EX: Algae, Ameobas, Parameciums and kelp

Amoeba

Euglena

Rotifer

Kingdoms and Domains• Kingdom Fungi: • Eudaryotes

– Heterotrophs that feed on dead or decaying matter (saprobes). Decomposers – obtain energy by breaking down organic material that they absorb from the environment.

– Do not contain chlorophyll– Store food energy as glycogen.– decomposers & recyclers– Can be single or multicelled– Cell walls contain chitin (tough outer covering)– Non-motile (cannot move) – Lack true roots, stems, & leaves – EX: Mushrooms & yeast

Ringworm

Mushrooms

Kingdoms and Domains• Kingdom Plantae:

-Eukaryotes• Photosynthetic autotrophs or producers• Non-motile• Multicellular• Contain chlorophyll inside of chloroplasts• Undergo photosynthesis• Cell walls contain cellulose• All plants that reproduce sexually • EX: mosses, ferns, flowering plants, cone-

bearing plants, etc…

• Animalia:• Eukaryotes

– Multicellular & heterotrophic– Cells contain a nucleus and membrane bound

organelles– Show levels of organization including cell, tissue,

organ, & system – Cells are specialized for particular functions – No cell walls or chloroplast– Motile- can move about– EX: animals

Animalia

• 99% of the organisms in Kingdom Animalia are invertebrates – meaning they lack a backbone.

• Organisms that have a backbone are called verterbrates.

1. Which Kingdom do I belong to?

1. Sponges and Cnidarians

- The only animals that

do not have tissues.

- Mostly marine.

- Ex. Jellyfish, corals

2. Mollusks

• Have something called a coulomb (sac-like structure) that encloses their internal organs.

• Most have a hard external skeleton (shell).

• Ex. Snails, oysters, clams, octopuses

2. Mollusks

3. Worms

• Cylinder shaped bodies.

• Live on both land and water.

4. Arthropods

• Most diverse of all animals.

• Have an external skeleton.

• Have jointed appendages, such as antennae and jaws.

• High rate of reproduction.

• 2/3 of all animals.

4. Arthropods

5. Echinoderms

• Ability to regenerate a lost limb.

• Ex. Sea stars, sea urchins

6. Verterbrates

• Internal skeleton made of bone.

• Includes mammals, fish, birds, reptiles and amphibians.

What are Dichotomous Keys?

• a method for determining the identity of something (like the name of a butterfly, a plant, a lichen, or a rock) by going through a series of contrasting choices that leads the user to the correct name of the item.

• Dichotomous means "divided in two parts".

Using a dichotomous keyAt each step of the process of using the key, the user is

given two choices; each alternative leads to another question until the item is identified.

1a. If the leaves are flat….go to question 4. 1b. If the leaves are needle-like….go to question 2.2a. Are the needles in a bunch? Go to question 52b. Are they spread along the branch?“…pine tree

Eventually, when enough questions have been answered, the identity of the tree is revealed.

1a Butterfly exhibits only one color. Boring butterfly

1b Butterfly has two or more colors. Go to 2.

2a. Butterfly has a red body.

2b Butterfly has a black body. Go to 3.

3a. Butterfly contains the color red. Inachis io

3b. Butterfly contains the color orange. Danaus plexippus

New Discoveries

Questions

How can you answer these questions?

Why is Taxonomy Important?

Unknown species discovered.

New fossil Uncovered.

Classification Chapter 17-Pg. 502-523 Finding Order in Diversity Why Classify Organisms??...

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