The Tree of Life Chapter 17 Notes
Rose Early scientists named new found organisms however they wanted and it was usually named after the founder.
Taxonomy is Born In the 1750’s, Carolus Linnaeus derived a standard way to organize and name organisms: Taxonomy is the science of naming and classifying organisms. Linnaeus, at the time, based all groupings on physical and structural similarities. Organisms are placed in different Taxons, which are categories of classification.
The Scientific Name Linnaeus also gave each organism a Scientific Name. The scientific name was a two-part name. This idea is called Binomial Nomenclature. Scientific names are made up of the Genus and Species that the organism belongs to. The first part of the name is the Genus and the second part is the Species. ie.) Quercus alba = White Oak ie.) Homosapien sapiens = Human The Genus part of the name is always CAPITALIZED, and the species is always lowercase. The name is always in italics or underlined.
Why Scientific Names? Mostly to avoid confusion between scientists. For example, the Puma, Mountain Lion, and Cougar are all the same cat, but are called different names in different regions. However, if they use Puma concolor, Every scientist knows what cat is being talked about. Puma concolor ›
The System of Classification Linnaeus’s Classification System had 7 levels or Taxons: Kingdom -> Phylum -> Class -> Order - > Family -> Genus -> Species(most specific) Each section or taxon is “nested” with the taxon right before it. ie.) Kingdoms contain many Phyla, Phyla contain many classes, etc. Pleases Refer to Figure 1.3 in your book…
The System of Classification (con’t) Linnaeus’s Classification system does have limitations. His system obviously focused only on physical structures. As we know now, physical similarity (Analogous Structures) don’t always mean a close relationship. Today’s technology allows us to compare at a molecular level!
17.2- Classification Based on Evolutionary Relationships Similar traits often mean similar ancestors; however, scientists have learned that similar traits can be because organisms are trying to fit in the same environment. This makes organisms look more and more alike even though they are not related. This is called Convergent Evolutions: Therefore, modern classification is based more on evolutionary relationships and less on physical similarities.
Classification Based on Evolutionary Relationships (con’t) Many types of diagrams can show these relationships between organisms. One of the most common is a Cladogram. This is an evolutionary tree that proposes how species may be related to each other through common ancestors. Motor Walking Bike Bike Car Plane Wheels Motor Enclosed Passengers Wings
Classification Based on Evolutionary Relationships (con’t) As you can see, the diagram shows the relationship between all the types of locomotives, but also shows how one evolved into another.
Interpreting a Cladogram: Derived Characters – Traits that have come about over time: These are shown as hashmarks between the branches. Nodes – Each place where a branch splits. Clades – Are groups of organisms that share common ancestors
17.4- Domains and Kingdoms Classification is an ever-changing science. New discoveries lead to changes in the classification system. Changes have included: Two kingdom (plant and animal) until 1866 when kingdom Protista was found Prokaryotes (bacteria) got their own kingdom because they are only organisms with no nucleus 1959 – Fungi got own kingdom based on how they feed 1977 – Bacteria split into 2 different kingdoms based on different genes
Domains and Kingdoms From all these findings, scientists proposed a new taxon bigger and more general than kingdom. It is called a Domain. There are 3 domains: 1. Domain Bacteria – Single celled prokaryotes in Kingdom Bacteria (Kingdom Bacteria) 2. Domain Archaea – Single celled prokaryotes in Kingdom Archaea (Kingdom Archaea) 3. Domain Eukarya – All organisms that have nuclei in their cells. Includes all other kingdoms and organisms except bacteria. (Kingdoms Protista, Fungi, Plantae, Animalia)