“I can” explain the different ways in which organisms are classified. Classification “I can” explain the different ways in which organisms are classified.

Essential and Guiding Questions Why is it important to classify organisms? Guiding What is the hierarchy of the classification system we use today? Who is Carolus Linnaeus? What is the difference between Homologous and Analogous Structures ? What does a Dichotomous Key tell us about an organism?

Classification the grouping of information or objects based on Taxonomy is the science of grouping and naming organisms. Classification the grouping of information or objects based on similarities.

Devil Cat

Ghost Cat

Mountain Lion

Screaming Cat

Puma

Florida Panther

Cougar

There are at least 50 common names for the animal shown on the previous 7 slides. Common names vary according to region. Soooo……why use a scientific name?

Modern System:Hierarchy Seven Levels of Organization Carolus Linnaeus (mid-1700’)s was a Swedish biologist who established a simple system for classifying and naming organisms. He developed a Hierarchy (a ranking system) for classifying organisms that is the Basis for Modern Taxonomy. For this reason, he is considered to be “father” of modern taxonomy.

Modern System a Nested Hierarchy-Seven Levels of Organization Linnaeus used an organism’s morphology (form and structure), to categorize it. His system is still being used today. His system allowed organisms to be grouped with similar organisms. He first divided all organisms into two Kingdoms, Plantae (Plants) AND Animalia (animals). This was the same as Aristotle’s main categories.

Modern System a Nested Hierarchy-Seven Levels of Organization Each kingdom (plant and animal) was divided into a phylum* (division for plants) Each phylum was divided into smaller groups called class. Each class was divided into an order. Each order was divided into family (families). Each family was divided into a genus (plural-genera) Each genus was divided into a species. (scientific name) *Note: Phyla and family were not in Linnaeus’s classification system but were added by modern scientists.

Six-Kingdom System

Levels of Classification Remember: King Philip Came Over For Grandma’s Soup. Kingdom Phylum Class Order Family Genus Species

Classification Hierarchy of Organisms

Classification of Modern Humans

Classification of cheetah

Binomial Nomenclature Names were based on Latin or Ancient Greek words - scientist everywhere understood these languages. The FIRST word of the Scientific Name is the name of the genus to which the organism belongs. The Genus name refers to the relatively small group of organisms to which a particular type of organism belongs. The SECOND word of the name is the species. (Species identifier) The Species name is usually a Latin description of some important characteristic of the organism.

The Fossil Record The fossil record often provides clues to evolutionary relationships It can not be read like a story book because some fossil records are incomplete Systematic taxonomists consider other evidence to confirm information contained within the fossil record with other lines of evidence, like…

Morphology Taxonomists study an organism’s morphology and compare it to other living organisms. Homologous features are important but it is important to separate features that are truly homologous with those that seem homologous but are actually analogous. The more homologous features two organisms share, the more closely related they are thought to be.

Homologous Structures

modifies homologous structures

Convergent Evolution These animals have evolved similar adaptations for obtaining food because they occupy similar niches. What can you infer about their evolution from their geographic locations?

Analogous Structures - Convergent evolution leads to………. Analogous Structures  -  Traits that are morphologically and functionally similar even though there is no common ancestor.

Comparative Embryology All vertebrate embryos follow a common developmental path due to their common ancestry. All have a set of very similar genes (the homeobox genes) that define their basic body plan. As they grow, the differences that will distinguish the embryos as adults become more and more apparent. The study of this development can yield insights into the process of evolution.

Embryology

The Dichotomous Key A key for easily and quickly identifying an unknown organism. The dichotomous key is the most widely used type in biological sciences. The user is presented with a sequence of choices between two statements, couplets, based on characteristics of the organism. By always making the correct choice, the name of the organism will be revealed.

copyright cmassengale Dichotomous Keying Used to identify organisms Characteristics given in pairs Read both characteristics and either go to another set of characteristics OR identify the organism copyright cmassengale

Example of Dichotomous Key 1a Tentacles present – Go to 2 1b Tentacles absent – Go to 3 2a Eight Tentacles – Octopus 2b More than 8 tentacles – 3 3a Tentacles hang down – go to 4 3b Tentacles upright–Sea Anemone 4a Balloon-shaped body–Jellyfish 4b Body NOT balloon-shaped - 5 copyright cmassengale