Classification of Organisms

Taxonomy The science of naming and classifying organisms. Think of how the mail man sorts mail: Zip code Street name House number How do you organize your closet?

Genus means “group” Greek Philosopher and naturalist Aristotle grouped plants and animals according to their structure. These phrases sometimes consisted of 12 or more Latin words. This multiple words were called polynomials. Poly = many nomen = name Figure 1 on Page 100

A simpler system… Carl Linnaeus created a simpler system which gave species each a two-word Latin name. Binomial nomenclature: two-word system for naming organisms. “Bi” meaning two Now is known as its scientific name. European Honey Bee = Apis mellifera

What is a genus? A taxonomic category containing similar species. Organisms in a genus share important characteristics. Example: The genus Quercus is composed of oak trees Red Oak – Quercus rubra Willow Oak – Quercus phellos

Humans– Homo Sapiens The first letter of the genus name is ALWAYS capitalized. The first letter of the second word is lowercase. Both words are italicized OR underlined. Once you state the full 1 one time, you can write it abbreviated as = H. sapiens

System of Classification Domain Kingdom Phylum Class Order Family Genus Species Dazzling King Philip Came Over For Good Soup

Biological species = A group of natural populations that are interbreeding or that could interbreed. Different species interbreed and reproduce offspring called hybrids. (think of a hybrid car) Ex: wolves and dogs in same genus , different species When reproductive barriers between 2 species are not complete, the 2 species are closely related

Biological Species Concept In the Kingdom Animalia, barriers to hybridize usually exist. Ex: Asian and African elephants do not interbreed Within many groups however, there are no barriers to interbreeding between species such as fish and plants.

Evolutionary History Organisms have different degrees of similarity Ex: A tiger resembles a gorilla more than a fish

Organisms that are more similar to one another have descended from a more recent common ancestor. Phylogeny = An organisms evolutionary history IMPORTANT: Not all features or characters are inherited from a common ancestor Certain structures in different organisms can make them related. Ex: A bird and insect both have wings for flight

Convergent evolution – similarities evolve in organisms not closely related to one another, often since they live in similar habitats Similarities that arise through convergent evolution are called analogous characters.

Ex: birds and mammals both have a backbone Cladistics = a method of analysis that reconstructs phylogenies by inferring relationships based on shared characters. Used to hypothesize the sequence in which different groups of organisms evolve. Ancestral character = if it evolved in a common ancestor of both groups Ex: birds and mammals both have a backbone

Ancestral character = if it evolved in a common ancestor of both groups Ex: birds and mammals both have a backbone Derived character =evolved in an ancestor of one group but not of the other. Ex: birds have feathers and mammals do not

Vestigial Structures refers to an organ or part (for example, the human appendix) which is greatly reduced from the original ancestral form and is no longer functional or is of reduced or altered function. Vestigial structures provide a clue to the evolutionary history of a species because they are remnants of structures found in the ancestral species.

A biology using cladistics constructs a branching diagram called cladogram.

Pros and Cons to a cladistics

Evolutionary Systematics and Phylogenetic trees Taxonomists analyze evolutionary relationships by looking at different characters.