1. Finding Order in Diversity
Biology is divided into different fields because of the wide diversity of organisms.
There are about 1.5 million species that have been identified and named so far; scientists estimate there are between 2 and 100 million additional species that have not yet been discovered.
You’ve probably heard of different branches of biology – botany, zoology, herpetology, entomology, etc. Biology is divided into different fields because there is wide diversity of organisms. There are about 1.5 million species that have been identified and named so far. Scientists estimate there are between 2 million and 100 million additional species that have not yet been discovered! That’s a lot of different organisms!
Unit 2 Notes

2. Finding Order in Diversity
Because there are so many organisms, biologists use a classification system to name organisms and group them in a logical manner.
Why isn’t it good enough to use common names of organisms?
With so many organisms out there, you can imagine how hard it would be to keep up with all of them. Biologists us a classification system to name organisms and group them in a logical manner. Why can’t we just use common names of organisms? (Pause) Well, common names vary from place to place. Sometimes there are even several different kinds of organisms that share the same common name in different parts of the country or the world. For instance, salamanders are small amphibians that sort of look like slimy lizards. However, when I was a little girl, my dad said he was going to trap the salamanders that were messing up our yard. What he was really trapping were gophers – small mammals that dig around under the ground and leave tunnels and holes. You can see how confusing it would be to use only common names!
Unit 2 Notes

3. Finding Order in Diversity
Taxonomy – discipline of classifying organisms and giving each a universally accepted name
We currently use a system of binomial nomenclature - introduced by Carolus Linnaeus, an 18th-century Swedish botanist.
There’s a special branch of biology that deals only with naming and classifying organisms. It’s taxonomy – the discipline of classifying organisms and giving each a universally accepted name. Currently, we use a system called binomial nomenclature. Bi means 2, nomen is the Latin word for name, clature refers to a system or process. So, binomial nomenclature means a two name naming system. Our system was introduced by Carolous Linnaeus, an 18th century Swedish botanist.
Unit 2 Notes

4. Binomial Nomenclature
Each species is assigned a two-part scientific name, always written in italics, first name capitalized, second in lower case. Linnaeus’s system is hierarchical (made up of levels).
In our system of binomial nomenclature, each species is assigned a two part scientific name. The name is always written in italics, or underlined if you’re writing it. The first name (the genus name) is always capitalized, the second name is in lower case. There are several more levels in the naming system. After all, we need both small, specific categories and large, general categories. Linnaeus’s system is what we call hierarchical, or made up of multiple levels.
Unit 2 Notes

5. Linnaeus’s System
Kingdom – Linnaeus’s largest & most inclusive category
Phylum – several different classes that share important characteristics (like a backbone)
Class – group of similar orders
Order – group of similar families
Family – genera that share many characteristics
Genus – group of closely related species
Species – group of similar organisms that can breed and produce offspring
There are seven levels in the Linnaean naming system. The smallest category is the species – a group of similar organisms that can breed and produce offspring. For instance, all dogs belong to the same species. That’s why we have so many mutts! A group of closely related species make up a genus. Coyotes and dogs are similar, but not the same. They belong to the same genus, Canis. A family is a group of genuses, or genera, that share many characteristics. Coyotes and dogs belong to the family Canidae, along with foxes and jackals. An order is a group of similar families. Dogs belong to Order Carnivora, the meat eaters, along with cats, bears, etc. A class is a group of similar orders. Order Carnivora is a division of Class Mammalia, the mammals, along with rabbits, bats, and humans. The next largest group is a phylum – a group of several classes that share important characteristics, like a backbone. We’re in phylum Chordata, along with fish, birds, amphibians, and reptiles. Finally, the largest and most inclusive category in Linnaeus’s system is the kingdom. Linnaeus recognized only 2 kingdoms – plants and animals. With new discoveries and understandings, scientists have revised Linnaeus’s system. There are now 6 kingdoms, including 2 bacterial kingdoms, protists (single celled organisms), fungi, plants, and animals. Whew!
Unit 2 Notes

6. Linnaeus’s System Unit 2 Notes Grizzly bear Black bear Giant panda
Red fox
Abert squirrel
Coral snake
Sea star
KINGDOM Animalia
PHYLUM Chordata
CLASS Mammalia
ORDER Carnivora
FAMILY Ursidae
GENUS Ursus
SPECIES Ursus arctos
Here’s the Linnaean classification of the grizzly bear. This time we’ll start from the top down. Notice all the different animals shown are members of kingdom animalia. There are others we could include, like insects. When you move to the phylum level, the sea star is eliminated, because sea stars don’t have a backbone. Class mammalia includes all the animals shown except the coral snake. Can you imagine a snake with hair? Order carnivora leaves out the squirrels, which are plant eaters. Family ursidae includes only the bears – so long, Mr. Fox! The genus ursus includes the grizzly and the black bear, but not the panda. And, finally, species Ursus arctos includes only the grizzly bear. The most important thing to remember here is that the more categories 2 organisms share, the more closely related they are. The most closely related ones are members of the same genus – like the dog and the coyote!
Unit 2 Notes

7. Memory Device
It helps to have a memory device to remember the order of Linnaeus’s categories. Here’s one that’s widely used to remember the groups from largest to smallest:
King Philip Came Over For Good Soup
[Kingdom-Phylum-Class-Order-Family-Genus-Species]
Now, sometimes all these lists are difficult to remember, but it’s important to know the categories, and which is larger than the next. Very often in biology we use memory devices, or mnemonics, to help remember things. Here’s a sentence to help you remember the order of Linnaeus’s groups from largest to smallest: King Philip came over for great steak. Notice that the initials of each word match up with the levels – kingdom, phylum, class, order, family, genus, and species.
Unit 2 Notes

8. Memory Device
Can you think of another sentence that would work better for you? Use the space on your notes page to come up with your own memory device.
Can you think of another sentence that would work better for you? I learned a different sentence when I was in high school – keep putting cookies out for girl scouts. It doesn’t matter how you remember it, as long as you do. See if you can come up with your own memory device.
Unit 2 Notes

9. Panthera leo? There’s a ws to go with this make sure you have it.
Unit 2 Notes

10. Kingdoms and Domains
Linnaeus divided organisms into 2 kingdoms – Animalia and Plantae.
Scientists now consider these to be inadequate to represent the full diversity of life.
Now We have six Kingdoms
First, scientists agreed that microorganisms needed their own kingdom (Protista).
As we said earlier, Linnaeus recognized only 2 kingdoms – plants and animals. As other organisms were discovered and identified, it became difficult to classify them into only these 2 groups. They are inadequate to represent the full diversity of life. First, scientists agreed that microorganisms needed their own kingdom, Protista. After all, some of these organisms undergo photosynthesis like plants, others seem more animal-like, but all of them have more in common with each other than with either of these other groups.
Unit 2 Notes

11. Kingdoms and Domains
Then, mushrooms, yeasts, and molds were grouped into Kingdom Fungi, while bacteria were placed into Kingdom Monera.
Recently, scientists have recognized that bacteria were composed of two distinct groups, now called Kingdoms Eubacteria and Archaebacteria.
Then, mushrooms, yeasts, and molds were grouped into kingdom fungi. Although they sort of look like plants, they don’t have chlorophyll, don’t undergo photosynthesis, and their cell walls are made of different substances. Then bacteria were placed in a kingdom of their own called Monera. In recent years, scientists have recognized that bacteria were composed of 2 very distinct groups that are now called kingdoms Eubacteria and Archaebacteria. This brings the total number of kingdoms to 6 – what would Linnaeus have thought?
Unit 2 Notes

12. This makes the total number of kingdoms 6.
1.Animalia
2. Plantae
3. Fungi
4. Protista
5. Eubacteria
6. Archaebacteria

13. Kingdoms and Domains
By analyzing molecules of various organisms, a new taxonomic category has arisen – the domain. This is a more inclusive category than kingdom.
If Linnaeus had known about all the different organisms we now recognize and had access to our technology, he probably would have done what modern scientists have done – come up with a new category. Scientists now recognize an even larger category than kingdom – the domain.
Unit 2 Notes

14. Three Domains There are 3 domains:
Eukarya – protists, fungi, plants, and animals
Bacteria – corresponds to kingdom Eubacteria
Archaea – corresponds to kingdom Archaebacteria
There are 3 domains. Eukarya includes all organisms with a true nucleus in their cells. This includes everything except bacteria. Domain Bacteria corresponds to Kingdom Eubacteria and includes most of the bacteria you’ve heard of – strep, staph, E. coli., etc. Domain Archae corresponds to Kingdom Archaebaceria, which includes bacteria that live in very extreme conditions, like hot sulfur springs, deep ocean vents, and extremely salty water.
Unit 2 Notes

15. Concept Map Living Things Unit 2 Notes are characterized by
such as a nucleus
and differing
which place them in
which coincides with
which is subdivided into
Living Things
Kingdom Eubacteria
Kingdom Archaebacteria
Nucleus:
Eukaryotic cells
No nucleus:
Prokaryotic cells
Important characteristics
Cell wall structures
Domain Eukarya
Domain Bacteria
Domain Archaea
Kingdom Plantae
Kingdom Protista
Kingdom Fungi
Kingdom Animalia
Here’s a concept map showing how organisms are divided into kingdoms. Notice the largest category is all living things, and what steps must be taken to classify organisms into the 3 domains and 6 kingdoms.
Unit 2 Notes

16. Modern Evolutionary Classification
Phylogeny – classification based on evolutionary relationships among organisms.
This study is based on Darwin’s ideas about descent with modification.
Biologists now group organisms into categories representing lines of evolutionary descent rather than physical similarities.
We do still use Linnaeus’s naming system, but as with all theories, as new discoveries are made, theories must be revised. With the acceptance of evolutionary theory, classification had to be revised as well. Nowadays, scientists use the term phylogeny – classification based on evolutionary relationships among organisms. This is based on Darwin’s ideas about descent with modification. Biologists now group organisms into categories representing lines of evolutionary descent rather than just physical similarities.
Unit 2 Notes

17. Modern Evolutionary Classification
Cladistic analysis – looks at derived characters (evolutionary innovations) - new characteristics that develop within a group over time
This involves analyzing genetic similarities
Cladogram – diagram based on derived characters to show evolutionary relationships among a group of organisms
The new method is called cladistic analysis – identifying organisms considering characteristics that are evolutionary innovations. These are new characteristics that arise as lineages evolve over time. These derived characters, or new characteristics, are shown on a diagram called a cladogram.
Unit 2 Notes

18. CLASSIFICATION BASED ON VISIBLE SIMILARITIES
Cladogram
Appendages
Conical Shells
Crab
Barnacle
Limpet
Crab
Barnacle
Limpet
Molted exoskeleton
Segmentation
Here’s a cladogram comparing 3 marine species – a crab, a barnacle and a limpet. In this picture, the classification is based on visible similarities. When you look at the pictures, it seems very obvious that the barnacle and limpet must be more closely related to each other than either is to the crab. Both barnacles and limpets are stationary, conical shelled organisms that filter their food from the seawater that washes over them. Crabs have 10 legs, claws, and walk sideways – how could they possibly seem similar to either barnacles or limpets?
CLASSIFICATION BASED ON VISIBLE SIMILARITIES
Unit 2 Notes

19. CLASSIFICATION BASED ON VISIBLE SIMILARITIES
Cladogram
CLASSIFICATION BASED ON VISIBLE SIMILARITIES
CLADOGRAM
Appendages
Conical Shells
Crab
Barnacle
Limpet
Crustaceans
Gastropod
Molted exoskeleton
Segmentation
Tiny free-swimming larva
When we look at evolutionary relationships, however, things look different. All 3 organisms have tiny free swimming larvae. But barnacles also have body segmentation like crabs do, and they also molt their exoskeleton when they need to grow. Looking at what’s inside the shell shows very remarkable differences between the limpet and the barnacle. Limpets are snail-like organisms called gastropods, whereas barnacles and crabs are crustaceans.
Unit 2 Notes

20. Genetic Similarity
Genetic similarity – can be used to determine evolutionary relationships using DNA sequence analysis.
Molecular clock – using DNA comparisons of mutations to estimate how long two species have been evolving independently of each other.
How in the world can you work out evolutionary relationships? Nowadays we can examine their genetic similarity – comparing the sequences of DNA of different organisms. The more similarities there are between their genes, the more recently they had a common ancestor, and the more closely related they are. Scientists have gotten so good at analyzing these DNA sequences that they now talk about a molecular clock – using DNA comparisons of mutations, or changes in the DNA, to estimate how long 2 species have been evolving independently of each other. Pretty remarkable!
Unit 2 Notes