Chapter 17 Classification of Organisms

Until more recent times, scientists named 17-1 Finding Order In Diversity Until more recent times, scientists named Things with crazy long names that Just described the organism. Apis pubescens, thorace subgriseo, abdomine fusco, pedibus posticis glabis, untrique margine cilatus.

The science of naming and classifying organisms is called taxonomy. Until the mid-1700s, biologists named a particular type of organism by adding descriptive phrases to the name of the genus

A Simpler System A simpler system for naming organisms was developed by the Swedish biologist Carl Linnaeus

Linnaeus’s two-word system for naming organisms is called binomial nomenclature Over the past 250 years since Linnaeus first used two-part binomial species names, his approach has been universally adopted

Scientific Name The unique two-part name for a species is now referred to as its scientific name The first word is the genus to which the organism belongs. A genus is a taxonomic category containing similar species

With Linnaeus’ system, the honey bee Is now called Apis mellifera. The second word in a scientific name identifies one particular kind of organism within the genus, called a species. A species is the basic biological unit in the Linnaean system of classification With Linnaeus’ system, the honey bee Is now called Apis mellifera.

Similar genera are grouped into a family Similar families are combined into an order Orders with common properties are united in a class

Classes with similar characteristics are assigned to a phylum Similar phyla are collected into a kingdom Similar kingdoms are grouped into domains

17-2 The 6 Kingdoms What Is a Species? In 1942, the biologist Ernst Mayr of Harvard University proposed a biologically based definition of species, which is called the biological species concept

Only about 1.5 million species have been described to date Number of Species The number of species in the world is much greater than the number described Only about 1.5 million species have been described to date Scientists estimate that 5 million to 10 million more species may live in the tropics alone

Evolutionary History Classification based on similarities should reflect an organism’s phylogeny, that is, its evolutionary history Through the process called convergent evolution, similarities evolve in organisms not closely related to one another, often because the organisms live in similar habitats

Phylogenic Diagram of Mammals Similarities that arise through convergent evolution are called analogous characters Phylogenic Diagram of Mammals

Cladistics Cladistics is a method of analysis that reconstructs phylogenies by inferring relationships based on shared characters

A biologist using cladistics constructs a branching diagram called a cladogram, which shows the evolutionary relationships among groups of organisms Organisms that share derived characters, are grouped together on the cladogram

Cladogram: Mammals, Reptiles, and Birds

Cladogram: Major Groups of Plants

Evolutionary Systematics and Cladistic Taxonomy

Bacteria, Archaea, Eukarya There are 3 domains…. Bacteria, Archaea, Eukarya Eukarya has 4 kingdoms… Protista, Fungi, Plantae and Animalia

Kingdoms are the 2nd largest Taxonomic group of organisms. Biologists groups organisms in the Different kingdoms based on Their similarities.

Most biologists use the 6 Kingdom system… Eubacteria Archaebacteria Protista Fungi Plantae Animalia

Characteristics of Eubacteria Eubacteria have strong cell walls Made of peptidoglycan. The entire gene is circular and is Transcribed as a single mRNA.

Eubacteria include species that Normally live in/on your body. Kinds of Eubacteria Eubacteria include species that Normally live in/on your body. Eubacteria are grouped based On their shape.

Characteristics of Archaebacteria Archaebacteria are distinguished From eubacteria based on their Metabolic differences. The cell wall of archaebacteria do not Contain peptidoglycan, instead they Use lipids. The genes are very similar to those Of the eubacteria.

Kinds of Archaebacteria There are at least 3 major groups Of extremophiles. Methanogens obtain their energy By making methane gas. Thermophiles live in very hot water, Usually around 170°F! Halophiles live in very salty places.

One of the 6 kingdoms, Protista, Is the most diverse. Protists are defined on the basis Of a single characteristic: They are eukaryotes that are Not fungi, plants, or animals. Most are unicellular.

Fungi are mostly multicellular. Fungi exist mainly in the form of Slender filaments barely visible with The naked eye called hyphae. Fungus cells have an exterior wall Made of Chitin, the same stuff As crab shells.

Unlike many other organisms, plants Cannot move, it is the seeds that Allow for the dispersal of plants. Since plants are autotrophs, they Are primary producers. (photosynthesis) Plants vary in size from the 1mm duckweed, to the 80m tall Great sequoia.

Nonvascular plants developed without A system of transport. Mosses. 4 kinds of plants Nonvascular plants developed without A system of transport. Mosses. Vascular plant have a large system Of vascular tissues that allow for The transport of water and nutrients From their roots to the tops.

Seedless vascular plants have Roots, stems, and leaves, but No seed, only spores. (ferns) Nonflowering plants are called Gymnosperms. They reproduce by Making seeds, but have no flowers. (pine trees)

Flowering seed plants produce Flowers and seed and are called Angiosperms. (roses, grasses, fruit trees)

Almost all animals are invertebrates, Which means that they Do not have a backbone. Of the more than 1 million living Species, only 42500 have a backbone And are referred to as vertebrates.

The animal kingdom includes about 35 phyla, most live in the sea. Animals are very diverse in form and Size. There are 0.5mm dust Mites and blue whales that are 30 m long and weigh 220 tons!

THE END