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TAXONOMY
AND
CLADOGRAMS Chapter 19
• Perhaps no one in history has contributed more hours of work to science than Carolus Linnaeus
• Linnaeus is the father of taxonomy, or the science of classifying organisms.
• Linnaeus developed the binomial standard for naming organisms (genus and species, Homo sapiens)
• He also organized and classified ALL known plants at the time according to a system of rules and a hierarchy of important features
CAROLUS LINNAEUS
• Why is there a need for organization? – Common names change from country to country, and even within
a country. Its important for scientists to all speak the same language
– Its just too hard to not have a system of organization. There are too many species and organisms on the planet to try and just “wing it.”
– Its not always obvious whether two species are related, or how so. We need agreement, which means we need a system • Water buffalo vs a bison
• Salamander vs gecko
• Clydesdale horse vs mustang horse
– Latin is a universal language and, at the time of Linnaeus, most scholars spoke (it was a high school class at one point). No one’s feelings would be hurt by using this language.
CAROLUS LINNAEUS
• Since Aristotle, organisms were first organized based on one question: Do they move (animals) or not move (plants)?
• In the 1880’s German scientist Ernst Haeckel added a 3rd kingdom to describe single-celled organisms, the protists.
• In 1969, scientists began to create the 5-kingdom system based on prokaryotic or eukaryotic cells, single-celled or multi-cellular, and how they obtain energy. The groups were plants, animals, fungus, protists and monera.
• By 1980, Carl Woese of the University of Illinois argued that the number of single-celled monera was more than the other four groups combined and showed tremendous variety by themselves.
• He proposed combining the other four groups into the category called “Domain: Eukarya” and separate monera into two other forms: “Domain: Bacteria” and “Domain: Archaea”
THREE-DOMAIN SYSTEM
• Bacteria are prokaryotic organisms.
• They can live in colonies and typically form symbiotic relationships with other organisms, but they are unicellular.
• Although some contain pigments for photosynthesis (cyanobacteria for example), most consume organic material for chemosynthesis or glycolysis.
• They cause a number of minor and major diseases for eukaryotes, but are essential to nearly every nutrient cycle in ecosystems due to their ability to remove waste from the environment
– 90% of the cells in your body are bacteria
DOMAIN BACTERIA
• Archaea are also prokaryotic and unicellular organisms.
• The defining characteristic of archaea is their ability to live in extreme environmental conditions (high/low pH, salinity, temperature, pressure, light conditions, etc).
• This may be due to their plasma membranes and cell walls, which are made not of separate phospholipids as the other domains but instead have strong, branching designs.
• Archaea are able to obtain nutrients from chemicals that would be considered toxic by all other species, such as sulfur, methane, benzenes, and phenols
DOMAIN ARCHAEA
• Eukarya are the eukaryotic, multicellular organisms on the planet (or single-celled, eukaryotic organisms).
• The four kingdoms within eukaryotes are animalia, plantae, fungi, and protists
• Other common traits of eukaryotes include sexual reproduction, although the life cycles are incredibly different
• Due to their complexity, eukaryotes are believed to have arisen due to multiple mutations and combinations of prokaryotic cells
• As such, these organisms are much younger than the prokaryotic organisms
• The multicellular, eukaryotic conditions of these organisms allow them to have thousands of more functions than prokaryotes, but also thousands of more requirements to remain alive
DOMAIN EUKARYA
• Protists are defined by being a eukaryotic cell that primarily lives in colonies of single-celled organisms
• Protists contain six separate phyla within their kingdom
– Green algae and Red algae
– Brown algae, diatoms, water molds
– Euglenas
– Amoebas, slime molds
– Foraminifrins and radiolarians
– Choanoflagellates
• *Be able to name these organisms as protists, not by their different phyla.*
DOMAIN EUKARYA: PROTISTS
• Fungi are eukaryotic cells, form spores for reproduction, lack flagella for motility, and have chitinous cell walls (not cellulose)
• Although the fossil record for fungi is weak, fungi appear to be more closely related to animals than plants
• Fungi obtain nutrients through saprotrophic mechanisms (they release digestive enzymes to break down organic matter, then absorb nutrients through their cells)
• Fungi have five recognized phyla
– Club fungi (mostly edible mushrooms)
– Sac fungi (cup fungus)
– AM fungi (Glomerales)
– Chytrid fungi (Aquatic fungus)
– Zygomycota (Black mold)
DOMAIN EUKARYA: FUNGI
• Plants are defined as eukaryotic, photosynthetic, multicellular organisms with cellulose-based cell walls. They are also one of two groups with clearly defined separate tissues that build their bodies
– They also have a crazy reproductive system called the alternation of generations—more on that later.
• Plants have four recognized phyla (more on these in our plant unit later)
– Bryophytes (moss, liverworts, hornworts)
– Tracheophytes (ferns, horse tails, club mosses)
– Gymnosperms (conifers, cycads, ginkgos, gnetals)
– Angiosperms (flowering plants)
DOMAIN EUKARYA: PLANTAE
• Animals are known for their extreme adaptations for motility (movement), relying primarily on respiration for energy, and an enormous catalog of organs and tissues that create different features and functions for animals.
• Animals are branched first into vertebrates or invertebrates (based on the presence of a backbone)
– Human bias: we’ve named an entire category of animals based on what they DON’T have, even though invertebrate species outnumber vertebrate species 11:1
• America and Non-America
• Land and Non-Land
DOMAIN EUKARYA: ANIMALIA
• Eleven phyla make up the invertebrate groups
– Echinoderms (starfish, urchins, sand dollars)
– Arthropods (insects, arachnids, crustaceans)
– Nematoda (roundworms)
– Annelids (worms and leeches)
– Mollusca (squids, slugs, snails)
– Platyhelminthes (flatworms)
– Rotifers (ascomores)
– Lophoporans (brachiopods)
– Ctenophores (comb jellies)
– Cnidarians (jellyfish, anemones, corals)
– Sponges
DOMAIN EUKARYA: ANIMALIA INVERTEBRATES
• The vertebrate branch contains five major classes
– Fish* (although the types and numbers of species in this group are more than the other three groups combined)
• Contain jaws, bones, and lungs
– Amphibians
• Development of four limbs
– Reptiles and birds (simultaneously appear in the fossil record)
• Development of external eggs with protective shells
• Birds have feathers, hollow bones, and are warm-blooded
• Reptiles have scales, flexible bones, and are cold-blooded
– Mammals
• Internal eggs, production of milk in mammary glands, fur
DOMAIN EUKARYA: ANIMALIA VERTEBRATES
• This question is worth an extra 5% on your essay exam
• You may check your answers with me ahead of time for a yes or no response as many times as you like.
• Which common group of organisms do not fit into any accepted kingdom or domain discussed in this lecture?
EXTRA CREDIT QUESTION