Classification of Living Organisms Unit 7 Part 1

Classification of Living Organisms Unit 7, Part 1

Classification Of Organisms • Classification (grouping) of organisms is done in a general to specific method, which results in a unique classification for each different type of creature. • From most general to most specific, organisms are grouped by kingdom, phylum, class, order, family, genus, species.

A Little Help • • Kings (kingdom) Play (phylum) Cards (class) On (order) Fat (family) Green (genus) Stools (species)

An Example • • Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Primates Family: Hominidae Genus: Homo Species: sapiens

Binomial Nomenclature • Binomial nomenclature is a method of naming an organism using the last two words of its scientific classification, always Latin words. • For example, the scientific name of a human is Homo sapiens. • In binomial nomenclature, the name is always underlined or italicized and the genus name is capitalized while the species name is lower-case.

• Biologists classify organisms into taxa in a process called taxonomy. Taxa are defined by their common traits. For example, animals belonging to the class Mammalia tend to have body hair, produce milk, and have live birth.

Why Classify? • Classification is used to bring order to the great diversity of species present on Earth. • It also serves as a basis for identifying newly discovered and unfamiliar organisms. • What is the importance of having the same naming system all over the world? • What is the difference between a panther, a jaguar, and a puma? Nothing, except for their common names - they all have the same scientific name.

Kingdoms • Scientists currently use a 5 - or 6 - kingdom system. • We will use the 5 -kingdom system, which includes kingdoms Animalia, Plantae, Fungi, Protista, and Monera. • Every organism fits into one of these categories, which are the broadest and largest of the taxa.

Kingdom Monera • Examples of organisms from this kingdom include most bacteria and some unicellular organisms. Bacteria like coccus, spirilium, and bacillus fall into this category.

Kingdom Protista • Organisms from this kindgom include amoeba, some types of algae (like red algae), and Euglena.

Kingdom Fungi • Organisms from this kingdom include: mushrooms, yeast, and penicillium.

Kindgom Plantae • Organisms in this kingdom include: trees (like oak and pine), succulent plants (like cactus and aloe), flowering plants (like roses and tulips), vegetable- and fruit-producing plants (like carrots and bananas) and grasses (like wheat and bamboo).

Kingdom Animalia • Organisms in this kingdom include: all types of fish, all types of birds, all types of reptiles, all types of mammals, and all types of insects.

Phylum • The second part of the scientific classification narrows down the groups considerably. • For humans, we fit into phylum Chordata. This includes all animals that have, or at one time during their life cycle, had, a tail bone.

Class • The third part of the classification is called Class. This step further narrows down the groups. As we progress down the ladder, we get more specific and there are more categories than the step before. • Again, for humans, we belong to class to Mammalia. This includes all animals that have body hair, give birth to their young rather than lay eggs, and produce milk.

Order • This is the next most specific branch. • Humans belong to order Primates. This includes all animals that have a certain size brain, facial structure, and specific organs.

Family • This step on the classification ladder breaks down the groups a little more. • We belong to family Hominidae. This group includes animals that stand up straight, walking on only two legs.

Genus • This group is included in the scientific name of an organism. • Humans belong to genus Homo. This is not the Greek form of the word meaning “same”, but the Latin form of the word meaning “man”.

Species • This is the most specific part of an organism’s classification. Each type of organism fits into its own special niche. • For humans, it’s Sapiens. • Sapiens means “thinking”, therefore describing humans as “thinking men”. • Remember, the last two parts of the classification make up the scientific name.

Test Your Knowledge • Do you what the common names of these organisms are? • Canis familiaris • Felis catus • Ursus arctos • Latrodectus mactans • Gorilla gorilla

The Answers • • • Domesticated dog House cat Brown bear Black widow spider Gorilla

Natural and Artificial Selection Unit 7, Part 2

Natural v. Artificial Selection • Natural selection is often referred to as “survival of the fittest. ” This simply means that those organisms that are most able to survive under given conditions are the ones who will reproduce and pass on their genes. • An example of this would be a smaller or slower animal being eaten by a predator while its faster and larger family members escape. • Natural selection happens without human influence. It means that an organism with unsuitable characteristics will be wiped out naturally.

• Artificial selection is when an organism is allowed to live based on its traits. This means that humans choose the traits that are most favorable to them. • An example of this is when people breed dogs for certain traits. • Another example is dating and marriage. You pick the person with traits that are desirable and ultimately, you pick which genes are passed on to the next generation.

The Theory of Natural Selection • Point #1 • In nature, there is a tendency toward overproduction. • For example, mice, watermelons, ants, fish, dandelions, and mosquitoes are well-known overproducers.

• Point # 2 • Not all offspring that are produced survive. • For example, many bacteria treated with antibiotics will die. Not all seeds from a watermelon will grow and thrive. Not all babies will make it through birth, or will die within the first year of life due to many factors.

• Point # 3 • Variations exist in any population. • For example, some spadefoot toads mature faster than others. Some dogs have longer noses than others. Some kids have freckles or pale skin while others don’t.

• Point # 4 • Variations are inherited. • For example, the long fur of a cat will be passed on to the cat’s offspring. The color pattern of many insects are the same from generation to generation. A cleft chin will show up in many generations.

• Point # 5 • Those individuals with variations that are suitable for their environment will live longer and leave more offspring on average than will individuals not having the variations. Thus, suitable variations will tend to be passed on and unsuitable ones lost. • For example, penicillin-resistant bacteria will survive and reproduce after treatment with this antibiotic.

• Point #6 • The resulting population as a whole will change as it becomes better adapted to its environment. • For example, mosquitoes can become resistant to certain pesticides or leopards with darker spots will become more numerous as they produce offspring that look like them.

Adaptations v. Variations • In many cases, adaptations and variations can lead to changes in the classification process. • This is why sometimes, an organisms’ scientific name will change.

• Variation and adaptation do not mean the same thing. Variations lead to adaptation. • This means that a single organism may have a variation, but over time, the entire population adapts because of that variation.

• Generally speaking, only variations that aid survival will be preserved by natural selection. • For example, a hunting cat that is born with an albino mutation has a variation. If he is unable to capture prey because he does not blend in, he will likely starve and not pass on that gene. Therefore, it does not become an adaptation for the future population.

• However, if a hunting cat is born with a variation of long claws, he may be more successful at his job and will survive to produce more offspring with long claws. That is an adaptation. • The adaptation that comes from a beneficial variation will be a general characteristic of the entire population.

Keep In Mind • Adaptations do not arise all at once. They are the result of adaptive changes being passed down by many generations. • Natural selection does not invent new organisms. It only modifies what already exists for posterity.

Evolution: Macro v. Micro • Macroevolution is a term used to describe evolution occurring on a large scale (like one species changing to another). • Microevolution refers to changes happening on a molecular (genetic) level, such as those changes that occur during natural or artificial selection, including mutations.

Something to think about… • Why would it be a bad thing if all organisms of a certain species in a given region had no variations?

Advantages of Biodiversity • Aside from aesthetic reasons, diversity is important for preservation. All organisms interact with and rely on one another in some form. • Without the vast diversity of living organisms we have, we could not carry out our normal processes, nor could any other organism.