Cladograms?

Question

When you observe a cladogram you can assume that you're observing a representation of...........?
A.) two or more monophyletic lineages
B.) a species timeline that establishes fixed dates
C.) clearly determined species relationships
D.) an outline of inferred species relationships

*please dont guess

Answer 1

ANS: D

Cladograms are graphic tree-like representations that show the evolutionary relationships of organisms.
This belongs in the general term Cladistics.

Cladistics or phylogenetic systematics,is an approach to the classification of living things in which organisms are defined and grouped by the possession of one or more shared characteristics (called characters) that are derived from a common ancestor and that were not present in any ancestral group (as envisioned by Charles Darwin's idea of “descent with modification”). Developed by Willi Hennig, a German entomologist, in the 1950s, it is a method of reconstructing evolutionary relationships that emphasizes the importance of descent and common ancestry rather than chronology.

Cladistics places species in a group, or clade, based on a shared character. Within a clade, species that share other characters unique to them are grouped together, and so on, until a cladogram (a branching diagram that resembles a family tree) is assembled. For example, all vertebrates make up a clade; all tetrapods (vertebrates that have four limbs with wrists, ankles, toes, and fingers) form their own clade within the vertebrate clade. In this example the vertebrate clade would be considered “primitive” and the tetrapod clade “derived” or “advanced.” In living creatures genetic characters or behaviors as well as more obvious anatomical features might be considered in assembling a cladogram. In paleontology the characters are necessarily skeletal.

Cladistics is especially significant in paleontology, as it points out gaps in the fossil evidence. It is also felt to be more objective than fossil study, which of necessity extrapolates from a limited number of finds that may or may not be representative of the whole.

Answer 2

D

It is a different way of showing a family tree than the traditional method. It "outlines" the current best thinking on species relationships.

It does not establish "fixed dates" and doesn't "determine" species relationships.

Answer 3

D, a cladogram is based on relationships between organisms.