lesson 17.1: the linnean system of...
TRANSCRIPT
Classification Unit
1
2
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
3
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
4
Scientific names help scientists to communicate.
– Some species have similar common names.
– Some species have many common names.
5
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.
6
Kingdom
Phylum
Class
Order
Family
Genus
Species
Domain
7
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
8
9
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
10
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.
11
Classification Unit
12
13
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
15
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
16
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
18
19
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
20
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
21
kingdom Animaliakingdom Fungi
kingdom Plantae
kingdom Protista
Domain Eukarya includes all eukaryotes.4 Kingdoms of Eukarya include:
22
Domain Bacteria includes prokaryotes in the kingdom Bacteria.
– one of largest groups on Earth
– classified by shape, need for oxygen, and diseases caused
23
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.
24
Bacteria and archaea can be difficult to classify.
• transfer genes among themselves outside of reproduction
• blurs the linebetween “species”
• more researchneeded tounderstand prokaryotes
25