Classification/Taxonomy

Why Classify? To study the diversity of life, biologists use a classification system to name organisms, group them in a logical manner, and study evolutionary relationships.

In other words, naming things. Taxonomy Defined: Discipline of classifying organisms and assigning each organism a universally accepted name. In other words, naming things.

Why common names don’t work 1. Common names vary among different languages. Cat Arabic: quttah Czech: kocka French: chat German: katze Japanese: neko Russian: kotchka Spanish: gato

Why common names don’t work 2. Common names vary among different countries. Example: United Kingdom – Buzzard refers to a hawk United States – Buzzard refers to a vulture Red-tailed Hawk Honey Buzzard Turkey Vulture

Why common names don’t work 3. Many species have several common names. Sand tiger shark Sand shark Gray nurse shark

Why common names don’t work 4. Same common name used for different species Dolphin Dolphin Mahi mahi Turciops truncatus

First Attempt to Classify Aristotle (Greek Philosopher) * About 300 BC * Classified based on method of reproduction * Used the words like “genera” and “species” * Grouped animals between those with blood and those without blood * He had many errors in his classification system, but it was used until the 1700s

Carolus Linnaeus (1707 – 1778) Created the system of naming we use today. In taxonomy, a group or level of organization is called a taxonomic category or taxon.

Binomial Nomenclature “Bi” means 2 “nomial” means naming Nomenclature means “the system of” Defined: In Binomial Nomenclature, each species is assigned a two-part scientific name. (genus & species)

What do these mean?...lets see Here We Go… Polar Bear *Do NOT have to write* Species: maritimus Genus: Ursus Family: Ursidae Order: Carnivora Class: Mammalia Phylum: Chordata Kingdom: Animilia What do these mean?...lets see

What they mean *Do NOT have to write* Species: maritimus (lives in marine environment) Genus: Ursus (kind of bear) Family: Ursidae (larger category of bears) Order: Carnivora (meat-eating animals) Class: Mammalia (warm-blooded, hair, & milk) Phylum: Chordata (vertebrates) Kingdom: Animilia (there are 6 kingdoms)

Da King Phillip Came Over For Green Salad How to remember: Da King Phillip Came Over For Green Salad Domain Kingdom Phylum Class Order Family Genus Species

Phylum Chordata Class Mammalia Order Carnivora Family Ursidae Genus Ursus Species maritimus

Uniqueness: Every SCIENTIFIC NAME has to be unique. Rules of the Game Uniqueness: Every SCIENTIFIC NAME has to be unique. Universality: Zoologists have adopted, by International Code of Zoological Nomenclature, a set of rules for naming animals. All animals are given a generic name (common name) and specific name in Latin &/or Greek (scientific name). These names are in italics when TYPED or are underlined when HAND WRITTEN. Human: Homo sapiens Lion: Panthera leo

Felis Genus species domestica margarita negripes If these three species belong to the same genus, they are descended from a common ancestor. Felis domestica domestica Domestic Cat Felis Felis negripes negripes Black Footed Cat Felis margarita margarita Sand cat`

First Used ONLY Morphology Animal Systematics First Used ONLY Morphology Morphology is dealing with the study of the form and structure of organisms and their specific structural features.

Classification Using Cladograms Cladogram: A diagram that shows the evolutionary relationships among a group of organisms.

A Problem with Traditional Classification Traditional classification systems relied on body structure comparisons only (not DNA) Due to convergent evolution, organisms that are quite different from each other evolve similar body structures. Convergent Evolution: Process by which unrelated organisms independently evolve similarities when adapting to similar environments. Sugar Glider… Live in Australia Look similar, but totally unrelated! Flying Squirrel… Live in the US (GA)

Another Problem with Traditional Classification Example: The Crab, The barnacle, & The limpet The barnacle and the limpet have similarly shaped shells & look alike The crab has a very different body form Based on anatomy, the barnacle & limpet could be classified together and the crab in a different group.

This incorrect because crabs and barnacles are actually related

Modern Principles of Classification The key mechanism to evolution is Natural Selection. Speciation is the evolutionary process by which new biological species arise.  Modern classification has been revised to reflect Darwinian Principle of common descent

Modern Principles of Classification Divergent Evolution: Occurs when species evolve in several directions away from a common ancestor. This happens usually to fill a vacant ecological niche. This is also known as adaptive radiation.

Evidence of Natural Selection Vestigial Structure: A structure in an organism that has lost all or most of its original function in the course of evolution. Reduced legs in snakes Appendix in humans Pelvis in whales Tail bone in humans

Evolutionary Classification/Systematics Biologists now group organisms into categories that represent lines of evolutionary descent, not just physical similarities Evolution Classification (Systematics): Is the strategy of grouping organisms together based on their evolutionary history.

You can also see that ALL have a free swimming larva stage Crustaceans Gastropods Molted Exoskeleton You can also see that ALL have a free swimming larva stage Segmentation Free swimming Larva

The Three-Domain System In 1990, a new taxonomic level called Domain was introduced and changed how bacteria were classified. Domain Archaea Domain Bacteria Domain Eukarya There are 6 Kingdoms total: 1. Eubacteria 2. Archaebacteria 3. Protista 4. Fungi 5. Plantae 6. Animalia Both are Bacteria Everything else (Except viruses)

3 Modern Methods to Classify Animals

Systematics First Used Morphology… Now also use other methods too! 1. Molecular Evidence - is the analysis of hereditary molecular differences, mainly in DNA sequences, to gain information on an organism's evolutionary relationships.

Systematics First Used Morphology… Now use other methods too! 2. Biochemical Evidence – is the analysis of similar chemical makeups of organisms to compare evolutionary relationships.

Systematics First Used Morphology… Now use other methods too Systematics First Used Morphology… Now use other methods too! Click HERE for video 3. Embryonic Evidence – is the analysis of the early development of embryos an comparing them to other animals.

Layers of Tissue Tissues derived from three embryonic layers Ectoderm – Outer layer Mesoderm – Middle layer. Gives rise to supportive, contractile, and blood cells. Endoderm – Inner layer

Other Patterns of Organization Unicellular Level of Organization Protista- one-celled organisms Diploblastic Organization Body parts organized into layers derived from two tissue layers Ectoderm – gives rise to epidermis (outer layer) Endoderm – gives rise to gastrodermis , the tissue that lines the gut cavity Examples: Jellyfish & Hydra Amoeba Hydra

Other Patterns of Organization Triploblastic Animals Contains ALL three embryonic layers Ectoderm Mesoderm Endoderm

Other Patterns of Organization Triploblastic Animals (continued) Organized based on the presence or absence of body cavity Body Cavity – fluid-filled space containing the digestive tract and other organs. A true body cavity is known as a coelom (si lem).

Types of Coeloms Coelomate – “True coelom” - The complete mesoderm lining allows organs to be attached to each other so that they can be suspended in a particular order while still being able to move freely within the cavity. Examples: Most bilateral animals & all the vertebrates Psuedocoelomate – “False cavity” -  Tissue derived from mesoderm only partly lines the fluid filled body cavity of these animals. Thus, although organs are held in place loosely, they are not as well organized as in a coelomate. Example: Roundworms Acoelomate - have no body cavity at all. Semi-solid mesodermal tissues between the gut and body wall hold their organs in place. Example: Tapeworms and Flukes

Advantages of a Body Cavity Provide more room for organ development Provide an area for storage Provide a vehicle for eliminating wastes & reproductive products from the body Facilitate increased body size

With Life, Comes Death: 5 Mass Extinctions Name of Extinction When What happened Ordovician-Silurian mass extinction 443 Million years ago  During the Ordovician, most life was in the sea, so it was sea creatures such as trilobites, brachiopods and graptolites that were drastically reduced in number. In all, some 85% of sea life was wiped out. Caused by climate change (Ice Age). Late Devonian mass extinction 359 Million years ago Three quarters of all species on Earth died out in the Late Devonian mass extinction, though it may have been a series of extinctions over several million years, rather than a single event. Caused by climate change & low oxygen levels. Permian mass extinction 248 Million years ago The Permian mass extinction has been nicknamed The Great Dying, since a staggering 96% of species died out. All life on Earth today is descended from the 4% of species that survived. Caused by climate change, methane released, drop in oxygen levels, & changing sea levels.

With Life, Comes Death: 5 Mass Extinctions Name of Extinction When What happened Triassic-Jurassic mass extinction 200 Million years ago During the final 18 million years of the Triassic period, there were two or three phases of extinction whose combined effects created the Triassic-Jurassic mass extinction event. Many non-dinosaur animals died, leaving many niches available for dinosaurs to fill. Climate change, flood basalt eruptions and an asteroid impact have all been blamed. Cretaceous-Tertiary mass extinction “K/T Extinction” 65 Million years ago Is famed for the death of the dinosaurs. However, many other organisms perished. The decline was due to flood basalt eruptions affecting the world's climate, combined with drastic falls in sea level. Then a huge asteroid or comet struck the seabed near the Yucatan Peninsula in Mexico and was the straw that broke the camel's back.

The End.