Binomial Nomenclature Diversity of Living Things Binomial Nomenclature

Classification How is every organism classified? Using Dichotomous Keys How does every species get a unique name? Binomial Nomenclature First’ let’s review.

Classification Seven Levels of taxonomic classification for the grizzly bear.

Classification This plant example shows how the number of species decreases with each taxa level.

How Do Scientists Determine Species? A biologist thinks they have discovered a new species. How can they be sure? There are three different species concepts used to classify organisms in taxonomy.

Species Concepts 1) Biological species concept – organisms can successfully breed and produce fertile offspring. This widely used concept only works for living, sexually reproducing organisms.

Species Concepts 2) Morphological species concept – comparing the measurements and physical descriptions. Often used for plants or asexually reproducing organisms.

Species Concepts 3) Phylogenetic species concept – looks for evolutionary relationships between organisms. Usually based on DNA studies or fossil evidence.

Dichotomous Keys Dichotomous means to divide in two. Scientists use a dichotomous key and ask yes or no questions to classify a newly discovered organism compared to existing organisms.

Dichotomous Keys

Dichotomous Keys The questions biologists ask in a dichotomous key are based on known species characteristics or organisms. The choice of one alternatives or no answer determines the next step in the dichotomous key.

Dichotomous Keys For example: 1) Does it have feathers? No. 2) Does it have legs? Yes.

Dichotomous Keys Identify the animals on the right:

Dichotomous Keys A dichotomous key can be shown as a branching tree diagram with characteristics on each branch. The questions start with: 1) Is it multicellular? 2) Does it have tissues? 3) Radial symmetry? 4) Bilateral symmetry? These characteristics classify animals.

Dichotomous Keys Using a morphological species concept can give a different classification than phylogenetic species concept. So it can be difficult to classify a newly discovered organism. What is different here?

Similar

Different

Binomial Nomenclature Your newly discovered organism now needs a name. Carolus Linnaeus developed the binomial naming system so every species have a unique two part scientific name. The rules are:

Binomial Nomenclature 1) The scientific name consists of the genus and species. 2) Both words are italicized or underlined. 3) Genus is always capitalized. 4) Species is always lower-case. 5) Both names are in Latin. 6) The species name must be unique in the same genus. Ex. Ursus arctos or Homo sapiens

Binomial Nomenclature

Binomial Nomenclature What is the honey bees’ scientific name? Apis mellifera And the large milkweed bug? Oncopeltus fasciatus

Why use Scientific Names? Common names of an organism are different in every language. Ex. Durian’s scientific name is Durio zibethimus

Why use Scientific Names? Look at p. 395 in your text. Imagine how hard it must be for someone learning English to understand the meaning of “fish” in all those common names.

Carcharodon carcharias