Classification of OrganismsClassification of Organisms

Classifying Organisms Classifying Organisms

One important branch of biology investigates biodiversity, the variety of organisms considered at all levels from populations to ecosystems.

Since the early 1980’s Terry Erwin & others have been working to catalog insect species in plots of tropical rain forest

They fog the treetops with insecticide & catch the falling insects in a net

Classification is…Classification is… A way of grouping objects

together based on similarities In the beginning---plants were

grouped based on people who ate them—

Edible Non-edible

The history of the Tomato-1820 Colonel Robert Gibbon Johnson announced that at noon on September 26, he would eat a basket of tomatoes in front of the Salem NY courthouse—aka “love apple”

Scientists Who Developed ClassificationScientists Who Developed Classification

Aristotle: Greek PhilosopherAristotle: Greek Philosopher

Developed 1st method of classification

Classified into 2 major groups

1. Plants: herbs, shrubs or trees

2. Animals: According to where they lived: land, water or air

Carolus LinnaeusCarolus Linnaeus Swedish naturalist Methods still used today Selected physical

characteristics based on close relationships of organisms

Each category represents a level of grouping from larger, more general to smaller, more specific categories

Plants: based on reproductive structures

Animals: based on evolutionary traits

Carolus LinnaeusCarolus Linnaeus Invented the 2-word

naming system to identify species

called BINOMIAL NOMENCLATURE:

Bi (2) Nomial (name)

Scientific Name:1. Genus: 1st word: consist

of closely related species

2. Species: 2nd word: consist of description of the species.

RULES OF BINOMAL MONEMCLATURERULES OF BINOMAL MONEMCLATURE

1. Genus is ALWAYS capitalized & is 1st

2. Species is ALWAYS lowercase & is 2nd

3. BOTH ARE ITALICIZED OR UNDERLINED!!!

Homo sapiens

Felix tigerus

F. leo

F. domestica

SPECIESPECIE

Species names come from Latin roots and are needed to be the same for all countries and in every language

The name of a species is often descriptive

Subspecies Subspecies Biologists refer to variations of a species that live

in different geographic areas as subspecies A subspecies name follows the species identifier

Subspecies: Alabama Beach MouseSubspecies: Alabama Beach Mouse

This mouse is one of several subspecies of old field mice which live only in coastal sand dune areas. Living isolated from other beach mice for thousands of years has allowed each subspecies to develop its own slightly unique characteristics suited to its particular beach environment.

Peromyscus polionotus ammobates

Other Subspecies: Perdido Key beach mouse, Choctawhatchee beach mouse, Santa Rosa beach mouse, and St. Andrews beach mouse. They differ from the ABM and each other in coloration and body size

Also, it is confusing when a species has more than one common name.

Scientific & Common NamesScientific & Common Names

Many organisms have common names that can be misleading. Example: a sea horse is a fish, not a horse.

Common Names

Common Names

Do not tell you how organisms are related or classified

Can be misleading Confusion can occur

when organisms have more than one name

All newly discovered species are given Latin names because it is no longer used

Taxonomy is…Taxonomy is… Taxonomy (tak SAH nuh mee) is the branch of biology

that groups and names organisms based on studies of their different characteristics

Biologists who study taxonomy are called taxonomists

TaxonomistsTaxonomists

Is a useful tool – if a child has eaten a mushroom & You do not know whether it is poisonous…

Important to the economy- often discover new sources of lumber, medicines & energy…

Dichotomous KeyDichotomous Key Organisms can be identified

easily by using a dichotomous key

Animals around the world use the same identification system

A key is made up of sets of numbered statements. Each set deals with a single characteristic of an organism, such as leaf shape or arrangement

Using a dichotomous key to identify money!

SystematicSystematic

More than 200 years ago, Linnaeus grouped organisms according to similarities that he could readily see.

Modern biologists consider not only visible similarities, but also similarities in embryos, chromosomes, proteins, and DNA

Systematics is the classifying of organisms in terms of their natural relationships

CladisticsCladistics

In 1966, Willi Hennig developed cladistics, a system of phylogenetic analysis that uses shared or derived characteristics as the only criteria for grouping taxa

• Evolutionary relationships are determined on the basis of similarities in structure, breeding behavior, geographical distribution, chromosomes, and biochemistry.

The presence of many shared physical structures implies that species are closely

related and may have evolved from a common ancestor.

How are evolutionary relationships determined?How are evolutionary relationships determined?

• For example, plant taxonomists use structural evidence to classify dandelions and sunflowers in the same family, Asteraceae, because they have similar flower and fruit structures.

1. Structural similarities1. Structural similarities

• Taxonomists observe and compare features among members of different taxa and use this information to infer their evolutionary history.

• Sometimes, breeding behavior provides important clues to relationships among species.

• For example, two species of frogs, Hyla versicolor and Hyla chrysoscelis, live in the same area and look similar. During the breeding season, however, there is an obvious difference in their mating behavior.

•Scientists concluded that the frogs were two separate species.

2. Breeding Behavior2. Breeding Behavior

Gray Treefrog

Gray Treefrog

Crushing Bills

Probing Bills

Grasping Bills

Ancestral Species

Parrot Bills

SeedFeedersC

actu

s

Fee

ders

Insect

Feeders

Fruit

Feeders

3. Geographical Distribution3. Geographical Distribution

• These finches probably spread into different niches on the volcanic islands and evolved over time into many distinct species. The fact that they share a common ancestry is supported by their geographical distribution in addition to their genetic similarities.

Geographical distributionGeographical distribution

• Both the number and structure of chromosomes, as seen during mitosis and meiosis, provide evidence about relationships among species.

•For example, cauliflower, cabbage, kale, and broccoli look different but have chromosomes that are almost

identical in structure.

4. Chromosomal Comparison 4. Chromosomal Comparison

• Therefore, biologists propose that these plants are related.

• The evolutionary history of a species is called its phylogeny (fy LAH juh nee).

Phylogenetic Classification: ModelsPhylogenetic Classification: Models

• A classification system that shows the evolutionary history of species is a phylogenetic classification and reveals the evolutionary relationships of species.

• One biological system of classification that is based on phylogeny is cladistics (kla DIHS tiks).

• Scientists who use cladistics assume that as groups of organisms diverge and evolve from a common ancestral group, they retain some unique inherited characteristics that taxonomists call derived traits.

CladisticsCladistics

Shared characteristicsShared characteristics

Is a feature that all members of a group have in common

Example: hair in mammals or feathers in birds

Derived characteristicsDerived characteristics

Is a feature that evolved only within the group under consideration

Example: feathers are though to be a derived characteristic for birds b/c scientists hypothesize that feathers evolved only within the bird lineage and were not inherited from the ancestors that birds share with reptiles

CladisticsCladistics

Theropods

Allosaurus

Sinornis

Velociraptor

Archaeopteryx

Robin

Light bones

3-toed foot; wishbone Down

feathers

Feathers withshaft, veins,and barbs

Flight feathers;arms as long

as legs

How are living things Classified?How are living things Classified?

Felix tigerus

Order of TaxaOrder of Taxa A group of organisms is

called a taxon (plural, taxa The smallest taxon is

species. Organisms that look alike and successfully interbreed belong to the same species.

The next largest taxon is a genus—a group of similar species that have similar features and are closely related

Mountain lion

Order of TaxaOrder of Taxa

Kingdom, Phylum, Class, Order, Family, Genus, & Species

Can you remember it this way? King Phillip Came Over For Graduation

Saturday. Kings Play Chess On Fine Glass Surfaces.

Important FactsImportant Facts

Linnaeus version of hierarchy of organization was made of only 2 kingdoms-animals & plants

Modern biologists adopted his system, but added several other kingdoms, as well as domains (categories above kingdoms)

**there are 3 domains of life

Domain

Kingdom

Phylum

Class

Order

Family

Genus

Species

Eukarya

Animalia

Chordata

Mammalia

Carnivora

Felidae

Lynx

Lynx rufus

Lynx canadensis

Bobcat Lynx

Introduction to ClassificationIntroduction to Classification

3 Domains of Life3 Domains of Life The three domain names

are Bacteria, Archaea, and Eukarya

All living things seem to be related by ancestry to one of these

Domain BacteriaDomain Bacteria Is made of small, single-celled prokaryotic

organisms Usually have a cell wall & reproduce by cellular

reproduction Each bacteria has a cell wall, plasma

membrane, cytoplasm (that lacks organelles) Do not have a true nucleus Oldest known fossils appear as bacteria

Domain ArchaeaDomain Archaea Consist of prokaryotes named Archaea Have distinctive cell membranes, & genetic

properties Some are autotrophs Some produce methane (as waste) Many inhabit harsh environments (sulfur

springs, deep-sea thermal vents, salty lakes…) Thought to be the earliest organisms on Earth

Domain EukaryaDomain Eukarya

Most familiar group Consist of eukaryotic organisms Have true nucleus, complex cellular organelles Include Plants, Animals, Fungi, and a variety of

single-celled organisms

6 kingdoms of life6 kingdoms of life

Woese and the 6 KingdomsWoese and the 6 Kingdoms

Biologists Carl Woese proposed in 1977 a 6-kingdom system that divided the then 5 kingdom into two new kingdoms; Archaebactera and Eubacteria

In 1990, Woese introduced the 3 domain system that is still used today

6 Kingdoms of Life6 Kingdoms of Life

Kingdom EubacteriaKingdom Eubacteria

Aligns with the domain Bacteria Eubacteria means “true bacteria” because it

distinguishes this group from archaea which are no longer considered to be bacteria

Blue-Green Bacteria

Kingdom ArchaebacteriaKingdom Archaebacteria Aligns with the domain Archaea Archaebacteria means “ancient

Bacteria” Are found in extreme habitats

where there is usually no oxygen available

Dead Sea

Thermal Vents

Kingdom ProtistaKingdom Protista Eukaryote that are not

plants, animals or fungi.

Unicellular organisms Examples are

amoebas, paramecium, euglenas, Seaweed, Diatoms…

Kingdom FungiKingdom Fungi Unicellular or multi-cellular

eukaryote that absorbs nutrients from organic materials in the environment

There are around 70,000 species of fungi

Include puffballs, mushrooms, rusts, smuts, mildew, and molds.

Kingdom PlantaeKingdom Plantae Consist of eukaryotic,

autotroph, multicellular plants that contain chloroplasts, use photosynthesis and have cell walls

There are more than 250,000 known species of plants

Kingdom AnimaliaKingdom Animalia Animals are eukaryotic,

multicellular heterotrophs that develop from embryos

Most have symmetrical body organization & move around their environment to find food

Nearly all are able to move from place to place.

Animal cells do not have cell walls

Future taxonomic systemsFuture taxonomic systems

Because taxonomy systems are changing, modern biologists are suggesting changes for the now six-kingdom, three-domain system

Suggestions like subkingdoms…