lesson 17.1: the linnean system of...

Classification Unit

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KEY CONCEPT: Organisms can be classified based on physical similarities.

taxonomy- is the science of naming and classifying organisms.

Linnaean taxonomy classifies organisms based on their physical and structural similarities.

A group of organisms in a classification system is called a taxon.

Classifying systems give scientists a framework of logic and order. Relationships among living things

can be seen easily.

White oak:Quercus alba

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Binomial nomenclature - is a system that gives each species a two part scientific name using Latin words. First part of the name is the genus.

Genus- one or more species closely related

Always CAPITALIZED and either italicized or underlined

Second part of the name is the species descriptor Can refer to a trait of the species, the scientists who first

discovered it, or its native location.

Always lowercase and either italicized or underlined

Ex: Grey Wolf = Canis lupis Canis = genus

lupis= species descriptor

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Scientific names help scientists to communicate.

– Some species have similar common names.

– Some species have many common names.

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1. by their physical characteristics

2. embryological similarities

3. biochemical similarities in DNA and genetics

Evolutionary and genetic relationships are the basis of classification today!

Linnaeus’ Classification system Each level is included in the level above it.

Levels get increasingly specific from kingdom to species.

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Kingdom

Phylum

Class

Order

Family

Genus

Species

Domain

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Kingdoms are divided into groups called phyla

Phyla are subdivided into classes

Classes are subdivided into orders

Orders are subdivided into families

Families are divided into genera

Genera contain closely related species

Species is unique

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Did

Ken

Pour

Coffee

On

Fred’s

Good

Shirt?

Can you think of one?

Easier for your brain to remember one sentence that 8 individual words

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The Linnaean classification system has limitations: Is based on physical similarities

When this was devised there was not enough technology to use molecular evidence (DNA).

Physical similarities are not always the result of close relationships.

Genetic similarities more accurately show evolutionary relationships. Ex: The red panda

(Ailurus fulgens) is more closely related to raccoons than to giant pandas.

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Classification Unit

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KEY CONCEPT: Modern classification is based on evolutionary relationships.

phylogeny – The evolutionary history for a group of species. Uses the fossil record and molecular data (DNA) to group

organisms.

cladistics- classification based on common ancestry Goal of cladistics: place species in the order in which they

descended from a common ancestor.

Armadillo Glyptodon

Ex: The glyptodon (Glyptotherium arizonae) illustrated above was the size of a small car and lived more than 10,000 years ago. It is the common ancestor to about 20 modern armadillo species,

including the nine-banded armadillo (Dasypus novemcinctus)14

cladogram / phylogenetic tree- evolutionary tree that proposes how species may be related to each other through common ancestors.

Cladograms (also known as phylogenetic trees) show evidence from living species, the fossil record, and

molecular data

shown with branching tree diagrams

Derived characters

Node

Clade

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nodes - represent the most recent common ancestor shared by a clade. each place where a branch splits is called a node.

clade is a group of species that shares a common ancestor.– each species in a clade shares some traits with the ancestor.– can be identified by snipping a branch under a node.– A clade looks like the letter V, including all the branches that extend from

the right end of the V.

FOUR LIMBS WITH DIGITS

Tetrapoda clade1

Amniota clade2

Reptilia clade3

Diapsida clade4Archosauria clade5

EMBRYO PROTECTED BY AMNIOTIC FLUID

OPENING IN THE SIDE OF THE

SKULL

SKULL OPENINGS IN FRONT

OF THE EYE AND IN THE

JAW

FEATHERS AND

TOOTHLESS

BEAKS.

SKULL OPENINGS BEHIND THE EYE

NODE DERIVED CHARACTER

CLADE

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derived characteristics: trait that differs in structure or function from that found in the ancestral line for a group of species; used in constructing cladograms

more closely related species share more derived characters

represented on cladogram as hash marks

FOUR LIMBS WITH DIGITS

Tetrapoda clade1

Amniota clade2

Reptilia clade3Diapsida clade4

Archosauria clade5

EMBRYO PROTECTED BY AMNIOTIC FLUID

OPENING IN THE SIDE OF THE

SKULL

SKULL OPENINGS IN FRONT

OF THE EYE &

IN THE JAW

FEATHERS &

TOOTHLESS

BEAKS.

SKULL OPENINGS BEHIND THE EYE

DERIVED CHARACTER17

Classification Unit

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KEY CONCEPT: The current tree of life has three domains.

Classification is always a work in progress.

The tree of life shows our most current understanding.

NOTE: You are a eukaryote in the domain Eukarya

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The three domains in the tree of life are Bacteria, Archaea, and Eukarya.

Domains are above the kingdom level. proposed by Carl Woese based on rRNA studies of

prokaryotes

domain model more clearly shows prokaryotic diversity

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kingdom Animaliakingdom Fungi

kingdom Plantae

kingdom Protista

Domain Eukarya includes all eukaryotes.4 Kingdoms of Eukarya include:

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Domain Bacteria includes prokaryotes in the kingdom Bacteria.

– one of largest groups on Earth

– classified by shape, need for oxygen, and diseases caused

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Domain Archaea includes prokaryotes in the kingdom Archaea.

• cell walls chemically different from bacteria

• differences discovered by studying RNA

• known for living in extreme environments

Initially given the name Archaea due to the extreme environments it lives it. Environments are similar to how the Earth was billions of years ago. Was thought to be before bacteria

Molecular evidence shows that it ACTUALLY has some similarities to prokaryotes as well as other similarities to eukaryotes.

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Bacteria and archaea can be difficult to classify.

• transfer genes among themselves outside of reproduction

• blurs the linebetween “species”

• more researchneeded tounderstand prokaryotes

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