Download Modern Evolutionary Classification

Andrew Jones
Taxonomy/Classification Notes
Notes taken from p. 477-453 and in class
Finding Order in Diversity
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Life has been on Erath for >3.5 billion years
Biologist have identified and named about 1.5 million species so far
o Anywhere between 2-100 million have yet to have discovered
Why Classify?
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To study the diversity of life, biologists use a classification system to name organisms and group
them in a logical manner
Taxonomy: classifying organisms and assigning each organism a universally accepted name
o Helps prevent confusion caused by regional names
o Makes studying the organism(s) much easier
o Organisms are classified into groups according to their biological significance
 Ex. ‘bird’ means many diff. things, but only Cardinalis cardinalis means N. Cardinal
Science requires very general and very specific terms to describe different groups of animals
Assigning Scientific Names
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By 18th century, scientists thought common names = confusing
o Common names vary from region to region, even within the same country
o In UK, “buzzard” = hawk; in US, “buzzard” = vulture
European scientists used Latin and Greek roots for scientific names because it was convenient
Early Efforts at Naming Organisms
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Originally, scientific names are super specific and super long, sometimes 20 words (!!!)
Wasn’t consistent since different scientists described and saw different parts of organisms
Binomial Nomenclature
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Carolus Linnaeus, 18th century Swedish botanist
o Developed 2-word naming system called binomial nomenclature, still used to this day
In binomial nomenclature, each species is assigned a two-part scientific name
o Always either italicized or underlined, first word is always capitalized, second one is
lowercase
Made up of the genus (group of closely related species) and the species name
o Species name is unique to each species, usually a Latinized description of an important
trait of the species
o Ex. Ursus arctos, Ursus maritimus
Linnaeus’s System of Classification
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Classification system is hierarchical
Consists of 7 taxons (levels): kingdom, phylum, order, class, family, genus, species
o Genus and species are used in the scientific name to describe the organism
o The more taxonomic levels two organisms share, the more closely related they are
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Modern Evolutionary Classification
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Organisms determine who belongs to their species by choosing with whom they will mate
Taxonomic groups are simply made for scientists to group and organize animals; nature doesn’t
actually follow the taxonomy system when differentiating species
Which Similarities Are Most Important?
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Linnaeus groups organisms and species into taxons primarily from visual similarity
Creates lots of problems about similar species
o Ex. Are dolphins fish or mammals?
Evolutionary Classification
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Darwin’s ideas about descent with modification led to rise of the study of phylogeny
Phylogeny: the study of evolutionary relationships among organisms
Biologists now group organisms into categories that represent lines of evolutionary descent
(phylogeny), not just physical similarities
o Called evolutionary classification
Taxons are organized so that as you get more and more general, the less genetically similar one
species in to another
o Changes in a species over time can be caused by natural selection
Ex. crabs, barnacles, and limpets
o Barnacles and limpets look more similar to each other than they do to crabs, but crabs
and barnacles are actually more similar to each other than they are to limpets
Classification Using Cladograms
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Many biologists now prefer a method to process evolutionary classification called cladistic
analysis
o Analysis is based off cladograms (diagram that shows evolutionary relationships among
organisms)
Derived characters: Characteristics that appear in recent parts of a lineage but not in its older
members
Cladograms are similar to similar to family tress; they tell how things have changed over time
Things to Remember from the Six Kingdoms Lab
Kingdoms Bacteria and Archae
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3 types of bacteria shapes
o Bacillus often had a rod shape to them
o Coccus (plural: cocci) bacteria are generally round in shape
 Most common bacteria shape
o Sprilla bacteria are curly like Twizzlers and springs
Treponema and Gonorrhea cause the STDs syphilis and gonorrhea, respectively
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Botulinum causes botulism, a disease caused by contaminated and poorly preserved food
(probably don’t need to know)
o Fun fact: Botulinum creates the most poisonous natural substance known to man, and we
just casually examined it like it was no big deal
Kingdom Protista
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Spirogyra is a plant-like protist, meaning it has chloroplasts and chlorophyll and is autotrophic
Paramecium are more animal-like; they are heterotrophic, have no cell wall, and have cilia for
feeding and movement
o They have contractile vacuoles, which are vacuoles specially made to store water
Amoeba are similar to white blood cells in that they digest their prey by engulfing them whole by
phagocytosis
o They have pseudopods, which are pieces of cytoplasm basically temporarily projected
outwards to “crawl” their way for movement instead of using cilia or flagella
Euglena are most plant-like since they, like the Spirogyra, have chloroplasts and chlorophyll
o Euglena use flagella more or less like a tadpole tail to swim their way through water
o They also have a red eyespot for detecting light for photosynthesis
Kingdom Fungi
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Rhizopus stolonifer (Black bread mold) is made up of hyphae, which are one-cell thick filaments
that make up the fungi, and spores, which are reproductive cells that can grow into a new
organism by mitosis alone (aka asexually)
Budding Yeast are one of the very few species of unicellular fungi
Kingdoms Plantae and Animalia
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Well, I really hope that you already know about these, otherwise I’m really worried about you ):
Miscellaneous Things You Should Know
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Prokaryotic organisms don’t have a nucleus, very primitive and ancient, and have free-floating
DNA. They also have much smaller than eukaryotic cells, and are always unicellular.
Eukaryotic organisms DO have a nucleus, and relatively more modern, and have complex
membrane-bound organelles. Their cells are much larger than prokaryotic cells and can be, but
aren’t always, multicellular.
o They both are forms of life and have a cell membrane, cytoplasm, ribosomes, and DNA
Autotroph: an organism that requires organic compounds to create its main source of food
Heterotroph: an organism that consumes other organisms to gain energy
Asexual reproduction: an organism that produces offspring through copying its own DNA,
creating a genetically identical organism to itself
Sexual reproduction: an organism that produces offspring through the contribution of DNA
from two individuals of a species, creating a genetically different individual from its parents
Motile: able to move from one place to another on its own
Mobile: able to move from one place to another with the aide of another force (another
organism, the wind, ocean currents, etc.)