Presentation on theme: "Classification A work in progress."— Presentation transcript:

1 Classification A work in progress

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2 Vocabulary Classification - grouping of items according to similar characteristics Taxonomy - The science of classifying living things - also the task of naming things Dichotomous Key - A tool used in the identification of organisms. Prokaryote - No cell nucleus (before nucleus) - primitive cells Eukaryote - Nucleus present (true nucleus) - most cells

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3 Grouping according to similar CharacteristicsAll the different organisms in the world need to be grouped or classified according to similar characteristics. Grouped according to structure Grouped according to evolutionary relation Grouped according to genetic relation. (This will one day be the only way that we classify organisms. According to there genetic code)

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4 Early example of Classification - Only 3 kingdoms

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5 Cladistics Cladistics - is a branch of biology that determines the evolutionary relationships between organisms based on derived similarities Cladistics is a particular method of hypothesizing relationships among organisms. Like other methods, it has its own set of assumptions, procedures, and limitations. Cladistics is now accepted as the best method available for phylogenetic analysis, for it provides an explicit and testable hypothesis of organismal relationships.

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6 Example Cladistics

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7 Modern Classification SystemModern classification systems are based on the assumption that all present forms of life developed or evolved from earlier forms of life and therefore have common ancestors.

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8 Domains Or Super KingdomsThe three-domain system was first invented in 1990, but not generally accepted until later. Now, the majority of biologists accept the domain system, but a large minority use the five-kingdom method. Three-domains of Life: - Archaea – no nuclear membrane (Live in very harsh conditions) - Bacteria (Monera) – no nuclear membrane - Eucarya – Nuclear membrane

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9 Example of ClassificationIt"s like classifying an address: - The World is classified into Countries - The Countries are classified into States - The States are classified into Counties - The Counties are classified into Towns - The Towns are classified into Streets - The Streets are classified into Numbers, which results in an address.

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10 Classification of Organisms- organisms are first classified into Kingdom - a kingdom is separated into separate Phyla - each phyla is separated into separate Classes - each class is separated into separate Orders - each order is separated into separate Families - each family is separated into separate Genera (Genus plural) - each Genus is separate Species.

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11 Order of Classification (General to Specific)Kingdom Phylum Class Order Family Genus Species

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12 Binomial Nomenclature “two name system”Binomial Nomenclature- "two-name" naming system that scientists use to name organisms, also known as the scientific name Scientific Name - Genus capitalized followed by species in lowercase. **The scientific name uses only the last two categories of the Modern Classification system, Genus and species. Genus is always capitalized; species is always in lowercase.

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13 Binominal Nomenclature (Humans)Example: Our scientific name or binomial name is Homo sapiens. The Genus, Homo, is capitalized, and the species, sapiens, is in lowercase.

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14 Binominal Nomenclature (Felis)Other animals with the same Genus but different species: Felis domestica(the housecat) Felis leo(the lion) Felis tigris(the tiger) Only organisms of the same species can produce offspring that are fertile. (Fertile means they, too, can reproduce.)

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15 Close but not quite The donkey and the horse can get together and make a mule, but the mule is always sterile. The donkey and horse are of the same Genus but of different species.

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16 Again, Close but Not FertileThe Lion and Tiger can reproduce to make a Liger, but the Liger is always infertile.

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17 The Test What question do you ask to find out if organisms are the same species? - Can they reproduce with each other? - If they can, are there offspring fertile? If both of those questions are a yes then they belong to the same species.

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18 The Five Kingdoms 5 Kingdoms: Monera Protists Animal Plantae Fungi

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19 Advantage of the 5 Kingdom SystemThe major advantage of using the 5 kingdom system of classification is that the evolutionary relationships between organisms become evident

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20 KINGDOM MONERA (monerans) -1 cell no true nucleus - prokaryote (genetic material scattered and not enclosed by a membrane) some move (flagellum); others don"t some make their own food (autotrophic); others can"t make their own food (heterotrophic) examples - bacteria, blue-green bacteria (cyanobacteria)

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21 MONERA Continued primitive cell structure with no nuclear membranes (prokaryotic) No mitochondria No endoplasmic reticulum have cell wall some are photosynthetic most are heterotrophic

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22 Blue-green Algae (Monera)cells larger than bacteria (still prokaryotic); all are photosynthetic (no chloroplasts though); chlorophyll not enclosed in chloroplasts, contain ribosomes, produce oxygen

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23 KINGDOM PROTISTA (protists) -1 cell have a true nucleus – (eukaryote) some have chloroplasts and can do photosynthesis some are autotrophic; others are heterotrophic Eukaryotes not classified as Plant, Animal, or Fungi fall into the Protista Kingdom

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24 KINGDOM FUNGI multicellular have nuclei (Eukaryotic)not photosynthetic mainly do not move from place to place heterotrophic (food is digested outside of fungus) examples - mushroom, mold, puffball, shelf/bracket fungus, yeast, etc.

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25 KINGDOM PLANTAE (plants)Multicellular have nuclei (Eukaryotic) do not move Autotrophic examples - multicellular algae, mosses, ferns, flowering plants (dandelions, roses, etc.), trees, etc

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26 KINGDOM ANIMALIA (animals)Multicellular have nuclei(Eukaryotic) do move heterotrophic examples - sponge, jellyfish, insect, fish, frog, bird, man

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27 Classification ContinuedStill A Work in Progress

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28 How many species are there?About 1 3/4 million have been given scientific names.  Nearly 2/3 of these are insects.  Estimates of the total number of living species generally range from 10 to 100 million.  It is likely the actual number is on the order of 13 to 14 million, with most being insects and microscopic life forms in tropical regions.  However, we may never know how many there are because many of them will become extinct before being counted and described.

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29 Human Like Life Rare The tremendous diversity in life today is not new to our planet. The noted paleontologist Stephen Jay Gould estimated that 99% of all plant and animal species that have existed have already become extinct with most leaving no fossils. It is also humbling to realize that humans and other large animals are freakishly rare life forms, since 99% of all known animal species are smaller than bumble bees.

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30 History of ClassificationCarolus Linnaeus - One of the most important 18th century naturalists was a Swedish botanist and medical doctor He wrote 180 books mainly describing plant species in extreme detail.

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31 Linnaeus In 1735, Linnaeus published Systema Naturae in which he outlined his scheme for classifying all known and yet to be discovered organisms according to the greater or lesser extent of their similarities.  This Linnaean system of classification was widely accepted by the early 19th century and is still the basic framework for all taxonomy in the biological sciences today.

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32 Why do we classify living things today?Biological classification has come to be understood as reflecting evolutionary distances and relationships between organisms.  The creatures of our time have had common ancestors in the past. In a very real sense, they are members of the same family tree.

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33 The great diversity of life is largely a result of branching evolution or adaptive radiation. This is the diversification of a species into different lines as they adapt to new ecological niches and ultimately evolves into distinct species.  Natural selection is the principal mechanism driving adaptive radiation.

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34 Methods used to help Classify organismsHomologies Parallelism Convergence Analogies

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35 Homologies Homologies (Homologous Structures) are anatomical features, of different organisms, that have a similar appearance or function because they were inherited from a common ancestor that also had them.  Example, the forelimb of a bear, the wing of a bird, and your arm have the same functional types of bones as did our shared reptilian ancestor. 

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36 Parallelism Parallelism, or parallel evolution, is a similar evolutionary development in different species lines after divergence from a common ancestor that had the initial anatomical feature that led to it.  Example, some South American and African monkeys evolved relatively large body sizes independently of each other. Their common ancestor was a much smaller monkey but was otherwise reminiscent of the later descendant species. Apparently, nature selected for larger monkey bodies on both continents during the last 30 million years.

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37 Convergence Convergence, or convergent evolution, is the development of a similar anatomical feature in distinct species lines after divergence from a common ancestor that did not have the initial trait that led to it.  The common ancestor is more distant in time than is the case with parallelism.  The similar appearance and predatory behavior of North American wolves and Tasmanian wolves is an example. 

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38 Analogies Analogies (analogous structures) are anatomical features that have the same form or function in different species that have no known common ancestor.  For example, the wings of a bird and a butterfly are analogous structures because they are superficially similar in shape and function.  Both of these very distinct species lines solved the problem of getting off of the ground in essentially the same way.  However, their wings are quite different on the inside.


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Bird wings have an internal framework consisting of bones, while butterfly wings do not have any bones at all and are kept rigid mostly through fluid pressure.

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