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Classification

Why do we need scientific names?

Ever hear of the  cougar? Mountain lion? Puma? American panther? Florida panther? They’re all the same animal.

Guinea pigs? They’re not from Guinea – and they are not pigs.

Jellyfish and starfish are not even closely related to fish.

Despite their name, strawberries, bayberries, raspberries, and blackberries are not true botanical berries. (A berry is a fleshy fruit produced from a single flower, and containing one ovary.
The plant’s entire ovary wall ripens into an edible outer layer.
Actual berries include: Bananas (!), Blueberries, Cranberries, Coffee berries, Elderberry, Grapes.)

What about the pineapple?
What should we name a pineapple

Obviously, then, sometimes “normal” names for animals and plants are misleading.

Animals with Misleading names

Binomial nomenclature (2-name naming)

Species names are two words: a capitalized genus name and an uncapitalized specific.

The second word has no meaning by itself, and is never capitalized, not even if a proper noun is used as the source of the term.

Species names (and Genus names) are also treated as foreign words in English, meaning that they are italicized or underlined when printed or written.

Species names are abbreviated by making an initial of the first word and spelling out the second – you may be familiar with E. coli, the abbreviated name of Escherichia coli, a common intestinal bacterium that can make you sick.

Binomial examples: Felines
{ Excerpted from http://en.wikipedia.org/wiki/Felidae }

Binomial examples: Canines

{ Excerpted from http://en.wikipedia.org/wiki/Canidae }

Subfamily Caninae[edit]

}

The 2 kingdom model – Animal and Plant

Carl von Linne, a Swedish botanist (plant scientist) created the first modern classification system for biology.

Aka Carolus Linnaeus (Latin was the common language for European science, and names were Latinized)

Parts of his system are still used today.

His system’s structure was similar to how human organizations of the time worked: groups-contained-within-groups, be they feudal power structures or military structures.

Each particular type of living thing is designated a species.

* Species are collected within a larger grouping, a genus.

* Genera are grouped into a family.

* Families into an order

* Orders into a class

* Classes into a phylum.

* Phyla into a Kingdom.

KPCOFGS Kingdom Phylum Class order Family examples Linnaean

Levels of classification

Examples: carnivores

Carnivore Feline Felis Mustelidae Canine Canis Classification

In Linnaeus time, there were just the Animal Kingdom and the Plant Kingdom.

Seaweed was thought to be a plant; it’s really in a protist, a kingdom that wouldn’t be understood and named until later.

Cardigan Bay Marine Wildlife Centre http://www.cbmwc.org/education/species-id-keys/

Cardigan Bay Marine Wildlife Centre
http://www.cbmwc.org/education/species-id-keys/

Mushrooms were thought to be plants – but they are really fungi, a kingdom that wouldn’t be understood and named until later.

Bacteria, Archaea and many single-celled protozoans were totally unknown at the time, so they too didn’t have a place in the Linnaeus plan.

What is a species?

It first meant a distinctly-describable type.

Then, a distinct type that could not interbreed;

Then, a distinct types that could breed and produce fertile offspring.

Today, a species is defined as: A group that, in natural surroundings, breeds exclusively within the group.

Like any definition, it has exceptions, such as coyotes, dogs, and wolves, which can interbreed, yet are considered separate species. But this definition works fairly well.

– Adapted from “An Online Introduction to the Biology of Animals and Plants” by Michael McDarby – Associate Professor, Fulton-Montgomery Community College.
http://faculty.fmcc.suny.edu/mcdarby/animals&plantsbook/History/02-Explaining-Life-Classification.htm

Example of salamanders evolving into different species, in the San Joaquin Valley, central California.

 

…a rare but fascinating phenomenon [is] known as “ring species.” This occurs when a single species becomes geographically distributed in a circular pattern over a large area. Immediately adjacent or neighboring populations of the species vary slightly but can interbreed. But at the extremes of the distribution — the opposite ends of the pattern that link to form a circle — natural variation has produced so much difference between the populations that they function as though they were two separate, non-interbreeding species.

this can be likened to a spiral-shaped parking garage. A driver notices only a gentle rise as he ascends the spiral, but after making one complete circle, he finds himself an entire floor above where he started.

A well-studied example of a ring species is the salamander Ensatina escholtzii of the Pacific Coast region of the United States. In Southern California, naturalists have found what look like two distinct species scrabbling across the ground. One is marked with strong, dark blotches in a cryptic pattern that camouflages it well. The other is more uniform and brighter, with bright yellow eyes, apparently in mimicry of the deadly poisonous western newt. These two populations coexist in some areas but do not interbreed — and evidently cannot do so.

Moving up the state, the two populations are divided geographically, with the dark, cryptic form occupying the inland mountains and the conspicuous mimic living along the coast. Still farther to the north, in northern California and Oregon, the two populations merge, and only one form is found. In this area, it is clear that what looked like two separate species in the south are in fact a single species with several interbreeding subspecies, joined together in one continuous ring.”
– http://www.pbs.org/wgbh/evolution/library/05/2/l_052_05.html

Evolution in action

3 kingdom model – Animal, Plant and Protista

The term protista was first used by Ernst Haeckel in 1866.

Protists were originally used to describe small, single-celled organisms that lived in watery ecosystems (swamps, muddy areas, ponds, streams, and then later some protists were discovered in the oceans.)

Some were microscopic, “animal-like” protozoa – they could move and swim, but they were just single celled organisms.

Some were plant-like, single-celled creatures that peformed photosynthesis (like algae) – but sometimes they wove together to create giant organisms, tens of feet long.

Some were “fungus-like” slime molds – but they weren’t related to true fungi. Although each fungus-like protist was a single cell, they wove together to create giant slimy balls tissue

Family tree of protists

Today we know that there are far more than 3 basic types of protists – if we compare the DNA of all living organisms, we find a clade (family tree) of all life on Earth.
In the following diagram:
pink: all forms of fungi
blue: all forms of animals
green: all forms of plants
yellow: dozens of different kingdoms of life, collectively called “protista”.

* The last two yellow kingdoms, on the far right, are close relatives of the plant family, and only much more distantly related to the other protists.

So we can see that from a “family tree” point of view, there is really no such thing as the protista kingdom.  One type of protista is just as different from another, as a plant is from an animal!

*

5 Kingdom model

In 1969 Robert Whittaker proposed splitting life into five distinct kingdoms:
Animals
Fungus
Plants
Protista
Monera (single-celled organisms which we now call bacteria)

 

3 Domain model

In 1977 Carl Woese blew the roof off the world of biology. His RNA study of little known single-celled organisms showed that there was an entire form of life living on our planet that had never been recognized! Some scientists described it as such a stunning discovery, it was almost like discovering alien life on Earth.

The DNA of Archaea are more closely related to animals, than to bacteria!

By 1990 so much had been discovered about this strange new domain of life, that he proposed a new way of classifying life on Earth – and his argument was so compelling that biologists around the world accepted his new system.

http://www.igb.illinois.edu/about/archaea

http://www.fossilmuseum.net/Evolution/archaeaevolution.htm

 

______________________

Protists

Protists are organisms that are classified into the kingdom Protista. The protists form a group of organisms that really do not fit into any other kingdom. Although there is a lot of variety within the protists, they do share some common characteristics.
All protists are eukaryotic. That is, all protists have cells with nuclei. In addition, all protists live in moist environments.

Protists can be unicellular or multicellular. Protists can be microscopic or can be over 100 meters (300 feet) long. Some protists are heterotrophs, while others are autotrophs.

Since protists vary so much, we will group them into three subcategories:

Protists that are classified as animal-like are called protozoans and share some common traits with animals. All animal-like protists are heterotrophs. Likewise, all animal-like protists are able to move in their environment in order to find their food. Unlike, animals, however, animal-like protists are all unicellular.

Fungus-like protists are heterotrophswith cell walls. They also reproduce by forming spores. All fungus-like protists are able to move at some point in their lives. There are essentially three types of fungus-like protists: water molds, downy mildews, and slime molds.

Plant-like protists are autotrophic. They can live in soil, on the bark of trees, in fresh water, and in salt water. These protists are very important to the Earth because they produce a lot of oxygen, and most living things need oxygen to survive. Furthermore, these plant-like protists form the base of aquatic food chains.

http://www.lanesville.k12.in.us/lcsyellowpages/Tickit/Carl/protists.html

Learning Standards

Massachusetts Science and Technology/Engineering Curriculum FrameworkLife

Science (Biology), Grades 6–8.
Classify organisms into the currently recognized kingdoms according to characteristics that they share. Be familiar with organisms from each kingdom.

Biology, High School
5.2 Describe species as reproductively distinct groups of organisms. Recognize that species are further classified into a hierarchical taxonomic system (kingdom, phylum, class, order, family, genus, species) based on morphological, behavioral, and molecular similarities.

Benchmarks for Science Literacy, American Association for the Advancement of Science

Students should begin to extend their attention from external anatomy to internal structures and functions. Patterns of development may be brought in to further illustrate similarities and differences among organisms. Also, they should move from their invented classification systems to those used in modern biology… A classification system is a framework created by scientists for describing the vast diversity of organisms, indicating the degree of relatedness between organisms, and framing research questions.

SAT Biology Subject Area Test

Evolution and diversity: Origin of life, evidence of evolution, patterns of evolution, natural selection, speciation, classification and diversity of organisms.

Teaching About Evolution and the Nature of Science, National Academy Press (1998)

Biological classifications are based on how organisms are related. Organisms are classified into a hierarchy of groups and subgroups based on similarities which reflect their evolutionary relationships. Species is the most fundamental unit of classification.

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