CHAPTER 18 CLASSIFICATION - Akron Elementary School
CHAPTER 18 CLASSIFICATION SECTION 1 FINDING ORDER IN DIVERSITY KEY CONCEPT QUESTIONS: How are living things organized for study? What is binomial nomenclature?
What is Linnaeuss system of classification? How are living things organized for study? To study the diversity of life, biologists use a classification system to name organisms and group them in a logical manner TAXONOMY discipline of classifying organisms
and assigning each organism a universally accepted name Classification System to organize all living creatures plants animals microbes etc.
Why do you classify anything? to be certain everyone is talking about the same thing Using common names can be confusing In the United Kingdom, the word buzzard refers to a hawk, whereas in many parts of the United States, buzzard refers to a vulture. Woodchuck and ground hog are the
same animal Why not use common names? Misleading starfish dragonfly Confusing blue jay, blue coat, corn thief dog, perro, chien
I swim, but Im still a bird! Why not use common names? But they all have only
one scientific name! Pyrrhosoma nymphula Cyanocitta cristata Pisaster ochraceus A more universal way of scientifically classifying came about BINOMIAL NOMENCLATURE
classification system in which each species is assigned a two-part scientific name Carolus Linnaeus The Linnean system proposed in 1700s each species has a 2 part name genus species
Homo sapiens Latin binomial 2 part scientific name Genus larger group to which organism belongs always capitalized species specific name for that organism always lowercase
example: Linnaeus named humans Homo sapiens means wise man perhaps in a show of hope & optimism The grizzly bear is called Ursus arctos. The first part of the scientific name in this case, Ursusis the genus
to which the organism belongs The second part of a scientific name in this case, arctosis unique to each species within the genus (this is usually a Latin name) GENUS a group of closely related species Linnaeuss System of Classification TAXON a group or level of organization;
aka: taxonomic category Genus groupings Classify organisms into broader groups Species that are closely related are grouped into the same genus Leopard
Panthera pardus African lion Panthera leo Tiger Panthera tigris Classification Kingdom Phylum Class
Order Family Genus species Orders & families KEY CONCEPT QUESTIONS: How are living things organized for study?
Taxonomic categories What is binomial nomenclature? 2-part universal naming system What is Linnaeuss system of classification? each species has a 2 part name genus species SECTION 2 MODERN EVOLUTIONARY
CLASSIFICATION KEY CONCEPT QUESTIONS: How are evolutionary relationships important in classification? How can DNA and RNA help scientists determine evolutionary relationships? Darwin's ideas about descent with
modification have given rise to the study of PHYLOGENY, or evolutionary relationships among organisms. evolutionary history of a species based on common ancestries inferred from fossil record morphological & biochemical resemblances molecular evidence
With the help of newer technology scientists have found more accurate ways of classifying organisms Biologists now group organisms into categories that represent lines of evolutionary descent, not just physical similarities. In other words, species placed within the
same genus should be more closely related to one another than to species of any other genus EVOLUTIONARY CLASSIFICATION method of grouping organisms together according to their evolutionary history To refine the process of evolutionary classification, many biologists now prefer a method
called cladistic analysis Cladistic analysis identifies and considers only those characteristics of organisms that are evolutionary innovationsnew characteristics that arise as lineages evolve over time. Characteristics that appear in recent parts of a lineage but not in its older members are called DERIVED
CHARACTERS. Illustrating phylogeny Cladograms patterns of shared characteristics diagram that shows the evolutionary relationships among a group of organisms Classify organisms according to the order
in time at which branches arise along a phylogenetic tree How is a cladogram constructed? Procedure : pg. 453 in textbook Identify the organism in the table that is least closely related to the others.
Use the information in the table to construct a cladogram of these animals. Analyze and Conclude: What trait separates the least closely related organism from the other animals? Lack of backbone List the animals in your cladogram in order of distance from the least closely related organism.
Trout, lizard, and human Does your cladogram indicate that lizards and humans share a more recent common ancestor than either does with an earthworm? Explain. Yes, lizards and humans shared an ancestor that had legs and a backbone and that evolved after the earthworms lineage branched off on another
evolutionary pathway Where would you insert a frog if you added it to the cladogram? Explain your answer A frog would occupy a branch between the trout and the lizard, because it has the derived characteristic of legs. Another derived characteristic, such as dry skin, would then have to be added for the lizard. How are genes used to help scientists
classify organisms? The genes of many organisms show important similarities at the molecular level. The similarities can be used to help determine classification Scientists compare the DNA of different organisms to establish similarities between them and reconstruct possible evolutionary relationships
Of Mice and Men Evolving genomes now that we can compare the entire genomes of different organisms, we find humans & mice have 99% of their genes in common 50% of human genes have a close match with those of yeast! the simplest eukaryote
The more similar the DNA sequences of two species, the more recently they shared a common ancestor, and the more closely they are related in evolutionary terms Comparisons of DNA can also be used to mark the passage of evolutionary time. A model known as a MOLECULAR CLOCK
uses DNA comparisons to estimate the length of time that two species have been evolving independently. To understand molecular clocks, think about a pendulum clock. It marks time with a periodically swinging pendulum. A molecular clock also relies on a repeating process to mark timemutation. Molecular clocks Trace variations
in genomes to date evolutionary changes Rate of change is calculated and then extrapolate back HIV-1M samples were collected from patients between early 1980s & late 1990s. The gene evolved at a relatively
constant rate. Concluded that HIV-1M strain first infected humans in 1930s. Simple mutations occur all the time, causing slight changes in the structure of DNA Some mutations have a major positive or negative effect on an organism's phenotype. These mutations are under powerful pressure from natural selection.
Other mutations have no effects on phenotype. These neutral mutations accumulate in the DNA of different species at about the same rate. A comparison of such DNA sequences in two species can reveal how dissimilar the genes are. The degree of dissimilarity is, in
turn, an indication of how long ago the two species shared a common ancestor. Evaluating molecular homologies Aligning DNA sequences more bases in common =
more closely related analyzed by software beware of molecular homologies Modern Systematics Shaking up some trees!
Crocodiles are now thought to be closer to birds than other reptiles KEY CONCEPT QUESTIONS: How are evolutionary relationships important in classification? evolutionary history of a species based on
common ancestries inferred from fossil record morphological & biochemical resemblances molecular evidence How can DNA and RNA help scientists determine evolutionary relationships? The more similar the DNA sequences of two species, the more recently they shared a common ancestor, and the more closely they are related in evolutionary terms
SECTION 3 KINGDOMS AND DOMAINS KEY CONCEPT QUESTIONS: What are the six kingdoms of life as they are now identified? What is the three-domain system of classification? Since Linnaeuss time kingdom
classification has changed. he had two kingdoms plantae and animalia now there are six eubacteria, archaebacteria, protista, fungi, plantae, and animalia There is also a level higher than kingdom called
Domains The three domains are: Bacteria kingdom Eubacteria Archaea kingdom Archaebacteria Eukarya Kingdom protists, fungi, plants, and animals. Universal Tree of Life
3 Domains Bacteria Eukarya Archaea KEY CONCEPT QUESTIONS: What are the six kingdoms of life as they are now identified?
eubacteria, archaebacteria, protista, fungi, plantae, and animalia What is the three-domain system of classification? Bacteria Archea Eukarya
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