| A | B |
|---|
| the Genus and specific epithet | are always together, and italicized (or underlined). |
| genus example | Homo sapiens or Homo sapiens |
| Taxonomic classification | is hierarchical |
| A group of related genera make up | a Family |
| Related families make up | an Order |
| Related orders are grouped into | a Class |
| Related classes are grouped into | a Phylum or Division |
| Related phyla or divisions are grouped into | a Kingdom |
| Related kingdoms are grouped into | a Domain, the highest level of classification in the modern system |
| The gold standard for “related” is based | DNA sequence similarities, but other criteria are used as well (we don’t have the complete DNA sequence of all known species) |
| Species | : “Kind of living thing” |
| Word “species” | is both plural and singular |
| Species, relatively easy to define for sexual organisms | hard for asexual organisms and extinct species |
| biological species concept (for sexual organisms) | one or more populations whose members are capable of interbreeding and producing fertile offspring, and whose members are reproductively isolated from other such groups |
| biological species concept not always clear-cut | because some can interbreed under “artificial” conditions but don’t appear to do so in nature |
| biological species concept sometimes, “race” and “subspecies” designations are used, | but often different specific epithets are used when there are clear morphological differences involved |
| asexual species – definition based on | biochemical (think DNA sequence) and morphological differences; no solid rules |
| asexual species also includes use of “race,” “subspecies,” | and “strain” designations |
| in asexual species, microevolution over time | leads to macroevolution (speciation) |
| evolutionary species concept | a single line of descent (lineage) that maintains its distinctive identity from other lineages; works for all species, but it can be hard to clearly define “distinctive identity” |
