Chapter 18

•How are living things classified?•What traits do biologists use to classify?•What schemes do scientists use to organize their knowledge of living things and evolutionary relationships?

http://nanopatentsandinnovations.blogspot.com/2011/12/top-10-new-species-for-2011.html

Inquiry LabWhat is your system?

Directions:1. Examine the assortment of objects provided.2. Sort objects into groups of related objects. Try to get

every object into a group with at least one other object.3. Choose a name for each group. 4. Choose one object from your collection and trade it

with another group.5. Try to fit the new object into one of your groups.

The Importance of ClassificationIn order to study and use living things, we need a name for each. This avoids confusion from scientists around the world.

Taxonomy: the practice of describing, naming, and classifying organisms.

Biologists group organisms into large categories as well as smaller more specificcategories= taxon.

-Provides consistence-Common names not always the best

- More than one common name, ex Robin/Robin in Great Britain

- Advantage is to provide scientific naming system that biologist can communicate regardless of native language.

Great Britain RobinNorth American Robin

Levels of Classification

• 7 different levels of organization, (from largest to smallest)– Kingdom– Phylum – Class– Order– Family– Genus – Species

King Philip Came Over For Graduation Speeches

Carl Linnaeus

• 1750’s• Swedish biologist• Cataloged all known species and added a

two word Latin name for each species=Binomial nomenclature or scientific name

• No two species have the same scientific name

Scientific NamesCan you predict the common name?

Carnegiea gigantea

Canis familiaris Felis catus

Viola tricolor

Scientific Name Rules1. All members of same genus share the genus

name as the first term.2. Second term is the species identifier and is

often descriptive.3. Capitalize genus name.4. Species name is lowercase.5. Both terms should be italicized.

EX: Homo sapiens, Felis domesticus

Danaus plexippusMonarch butterfly

Latrodectus variolus

Black widow

Rana pipensLeopard frog

Pseudacris crucifer

Spring peeper frog

Chrysemys picta

Painted Turtle

Terrapene carolina

Eastern Box Turtle

Thamnophis sauritus

Ribbon Snake

Lampropeltis triangulum

Milk Snake

Tamias striatus

Eastern chipmunk

Mephitis mephitis

Striped Skunk

Procyon lotor

Raccoon

Didelphis virginiana

Opossum

Perca flavescens

Perch

Micropterus salmides

Largemouth bass

http://

mnfi.anr.msu.edu/data/specialanimals.cfm

This list presents the Endangered (E), Threatened (T), and Probably Extirpated (X) animal species of Michigan, which are protected under the Endangered Species Act of the State of Michigan.

Other Michigan Organisms….

Homo sapiens

Human

Review

Why do biologists have a system for naming and grouping living things?

What are the rules for scientific names?

List the categories of the Linnaean system from largest to smallest.

Modern SystematicsIt shows an organisms relationship to other organisms and their evolutionary history.

Systematics: a field of expertise where scientists identify one species from another.

Extinct theropod dinosaurCassowary modern bird

Old thinking… (based on physical similarities)Dinosaurs were reptiles.Bird were NOT reptiles but in own group.

New thinking …(based on new technology: DNA, proteins, embryo

development, fossils)

Birds evolved from dinosaurs.

Dolphin Whale

Fish!

Systematics

Old thinking…Dolphins and whales different than fish.

New thinking…Whales related to early land mammals.

Phylogenetics Drawing a family tree that links ancestors from thousands to millions of generations.

• NOT just based on physical similarities, which can be misleading

• Based on fossil evidence, bone structure, DNA, proteins, embryo development

Bird Wing

Insect Wing

CladisticsAn objective way to sort out relatedness; look for characteristics that are shared between groups because of common ancestry.

Cladogram: a phylogenetic tree drawn in a specific way to show a comparison of characters among several groups

Flowers are a derived character shared only with flowering plants.

Seeds are a derived character shared between conifers and flowering plants.

Modern SystematicsA. Cladistics

1. Model used to represent evolutionary history among species

2. Used to determine the sequence in which different groups of

organisms evolved

Dichotomous Keys

• Dichotomous Keys are used to identify unknown species based on classification characteristics.

• Pairs of descriptions that lead to the identification of an object.

Key to Forest Trees1a  Leaf edge is smooth or barely curved.  go to 2

1b  Leaf edge has teeth, waves, or lobes.  go to 3

2a  Leaf has a sharp tip with very little curve.  shingle oak

2b  Leaf has sharp tip with lots of curve go to 4

3a  Leaf edge has small, shallow teeth.  Lombardy poplar

3b  Leaf edge has deep waves or lobes.  go to 5

4a  Leaf is heart shaped.  eastern redbud

4b  Leaf is not heart shaped.  live oak

5a  Leaf edge has less than 20 large lobes.  English oak

5b  Leaf edge has more than 20 waves.  chestnut oak

Lab:Using the fish key,

identify the following Michigan fish.

*=Numbers that are circled DO NOT *=Numbers that are circled DO NOT have a body covered with scales!have a body covered with scales!

(#’s 1,2,6, 8, 11, 14, & 17)(#’s 1,2,6, 8, 11, 14, & 17)

Dichotomous Key- Shoes• Need 10 students to each

volunteer a shoe to use for “shoe collection”

• Study the structure and organization of a dichotomous key as a model for this activity

• As a class, work to design a new dichotomous key for the “shoe collection”

• Be sure that each part of key leads to either a definite identification of a shoe’s owner or another set of possibilities. Be sure that every shoe is included.

• Test the key using each shoe in the collection

Review

What are some problems that arise when weonly group based of physical similarities?

How do you make a cladogram?

Identify kinds of evidence used to infer relatedness.

Kingdoms and DomainsClassification systems change when scientists learn new information.

1700’s: Linnaeus, Plant and Animal Kingdoms

1800’s: All one-celled life grouped together until biologists noticed prokaryotic (kingdom Monera) and eukaryotic cells (kingdom Protista).

Sponges used to be grouped with plants, butwith the invention of microscopes, they are grouped with animals due to cell structure.

Kingdom MoneraKingdom protista

1950’s: Kingdom Fungi added

1990’s: Split Kingdom Monera into Kingdom Eubacteria and Kingdom Archaebacteria based on genetics

Plant cell walls made of cellulose… fungi cell walls made of chitin

6 Kingdom System

3 Domain System…This is used along with 6 Kingdom System because scientists see differences among Prokaryotes AND similarities between all Eukaryotes.

Review

How have biologists changed the LinnaeanSystem over time?

What are the 6 Kingdoms that align with the3 Domains?

List major characteristics of each Kingdom.