Taxonomy & Systematics Study Guide

What is binomial nomenclature?

the two-part format of the scientific name of an organism.

What are the two parts of a scientific name and how are they formatted?

the Genus (capitalized) and Species Epithet (not capitalized).

What is the Linnaean System?

a way to categorize organisms by their traits and appearances, organizing them from broad to more specific categories

What is the hierarchical order of taxonomic categories from broadest to most specific?

Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

What mnemonic device can help remember the taxonomic hierarchy?

Dynamite kindly professors cannot often fail good students

What is one definition of a species?

members of a species can produce viable offspring.

What were the five kingdoms in the 1969 classification system?

Kingdom Plantae, Kingdom Animalia, Kingdom Fungi, Protists, and Bacteria.

What is the current classification system and what are its divisions?

three domains: Bacteria, Archaea, and Eukarya.

What is phylogeny?

the evolutionary history of relationships among organisms or their genes.

How is phylogeny typically represented?

in a diagram called a phylogenetic tree

Why is the tree of life important in biology?

• The complete evolutionary history of life (as far as we have discovered)

• Essential for making comparisons in biology

• A way to organize the relationships among all living things on earth based on evolution

• Includes species that no longer exist

What are protists?

eukaryotic organisms that are not animals, plants, or fungi. They do not neatly fit into a group/taxon, but contain eukaryotic cells.

What is a taxon (plural: taxa)?

any species or group of species that we name (e.g., primates, invertebrates). We group species together based on common traits.

What is a clade?

(also called a monophyletic group) is a point on a tree where things can be related to each other in a certain group. It consists of one ancestor and all of its descendants (extinct or not). can be "snipped off" of the tree with one cut.

How does a phylogenetic tree begin?

with a common ancestor.

What occurs at nodes in a phylogenetic tree?

divergences, signifying a speciation event. When the lines completely split apart, it signifies that the organisms no longer mate with one another.

Root of a phylogenetic tree

represents the common ancestry of all the organisms in the tree

lines of a phylogenetic tree

lineage (follow the descendants of an organism over time)

nodes of a phylogenetic tree

branching point which represents divergence, a split into two lineages with each evolving separately

red dots / synapomorphies of a phylogenetic tree

new traits that arise

phylogenetic trees

representations of lineages that continue to split and evolve new traits

What does a time or divergence axis show in a phylogenetic tree?

the timing of splitting or speciation events, but line length is not always to scale.

What is an outgroup in phylogenetic analysis?

a species closely related to the group being studied but not a part of the group (e.g., orangutans in a study of great apes).

What is an ingroup?

the group of primary interest in a phylogenetic study

What questions should be considered when examining traits in phylogenetic studies?

• Which traits are common and which traits differ

• When did these traits evolve

• How was the trait influenced by environmental conditions or selection pressures

What are homologous structures?

characteristics that appear similar and result from common ancestry, they can be any heritable trait - DNA sequence, protein structure, anatomical structures, or behavior. They are inherited from a common ancestor, but the function does not have to be the same.

What are analogous structures?

characteristics that look and/or function similarly but do NOT result from common ancestry. They are not good for building phylogenetic trees

What is convergent evolution?

When similar traits evolve independently in different lineages, like butterfly wings and bird wings both used for flight but having different evolutionary origins. It is not good for building phylogenetic trees

what is another term for a clade?

monophyletic group