7.2: Taxonomy
Background Information
Humans are excellent classifiers. Scientists classify organisms based on features that are shared in common with other related organisms. The formal process of classifying organisms is referred to as taxonomy .
Traditional taxonomy relies primarily on physical traits so that organisms that look alike are placed in the same group. One traditional taxonomic system, called the Linnaean system of taxonomy, established the following categories:
| Critter 1 | Critter 2 | |
|---|---|---|
| Domain | Eukarya | Eukarya |
| Kingdom | Animalia | Animalia |
| Phylum (Division) | Chordata | Arthropoda |
| Class | Mammalia | Insecta |
| Order | Carnivora | Hymenoptera |
| Family | Felidae | Formicidiae |
| Genus | Felis | Solenopsis |
| Specific Epithet | domestica | invicta |
Can you tell what organisms are categorized here?
Classifying organisms based on shared evolutionary history attaches powerful information to a classification scheme. While traditional taxonomy relied primarily on classifying organisms by their shared physical characteristics (or morphology), technological advancements have allowed scientists to determine an organism’s evolutionary history more accurately. Taxonomy based on presumed evolutionary relationships is referred to as phylogeny . Phylogeny is similar to constructing a family tree in that shows how different species are related to each other the same way that you are related to your ancestors. The largest difference is that a phylogenetic tree shows the relationship between populations instead of individuals (as in a family tree). It helps us understand how different species have evolved over time and how they are related to one another. Just like a family tree, a phylogenetic tree has branches and roots, with the roots representing the earliest ancestors and the branches showing how species have evolved and changed over time. By studying phylogeny, we can learn about the history of life on Earth and the relationships between different species.
A phylogenetic tree of living things, based on RNA data and proposed by Carl Woese, showing the separation of bacteria, archaea, and eukaryotes. (SVG phylogenetic tree of life CC0)
Usually, traditional taxonomic systems agree with phylogenetic systems when determining where organisms should be classified. However, sometimes, striking conflicts can arise. For example, birds are traditionally placed in their own class Aves . However, a wealth of research indicates that birds are actually living dinosaurs, and are thus technically reptiles.
Check out some more information on this fascinating situation . More information can be found here: https://evolution.berkeley.edu/learn-evolution/