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Basal (phylogenetics)
 
 
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In phylogenetics
Phylogenetics

In biology, phylogenetics is the study of evolutionary relatedness among various groups of organisms , which is discovered through molecular sequencing data and morphological data matrices....
, a basal clade
Clade

A clade is a term used in modern alpha taxonomy, the scientific classification of living and fossil organisms, to describe a monophyletic group, defined as a group consisting of a single common ancestor and all its descendants.The term "monophyletic group" is used in this article in the conventional sense of "an a...
 is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.

A basal group form an outgroup
Outgroup

In cladistics, whenever three or more monophyletic groups of organisms are compared, and all but one of them are more closely related to each other than any single one of them is to the last, the latter group is known as the outgroup....
 to the rest of the clade, such as in the following example:

The word "basal" is preferred to the loaded term "primitive", which has false connotations of inferiority or simplicity.

The basal status of a clade is relative to what it is being compared to.






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In phylogenetics
Phylogenetics

In biology, phylogenetics is the study of evolutionary relatedness among various groups of organisms , which is discovered through molecular sequencing data and morphological data matrices....
, a basal clade
Clade

A clade is a term used in modern alpha taxonomy, the scientific classification of living and fossil organisms, to describe a monophyletic group, defined as a group consisting of a single common ancestor and all its descendants.The term "monophyletic group" is used in this article in the conventional sense of "an a...
 is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.

A basal group form an outgroup
Outgroup

In cladistics, whenever three or more monophyletic groups of organisms are compared, and all but one of them are more closely related to each other than any single one of them is to the last, the latter group is known as the outgroup....
 to the rest of the clade, such as in the following example:

The word "basal" is preferred to the loaded term "primitive", which has false connotations of inferiority or simplicity.

The basal status of a clade is relative to what it is being compared to. In the first example below, humans are the basal group, as they are the first to diverge from the lineages of plant. In the second example, plants are basal to the animals considered.

The term basal can only be correctly applied to clades, not to traits - although it is frequently misused in the literature. While the term "basal" applies to clades, characters or traits are usually considered derived
Derived

In phylogenetics, a trait is derived if it is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary loss....
 if they are absent in a basal group, but present in other groups. This assumption only holds true if the basal group is a good analogy for the last common ancestor of the group: in the example of plants and apes above, it would be likely to break down.