Final answer:
A group of taxa with multiple different ancestors does not have a specific term like a clade, which includes an ancestor and all its descendants. Complex relationships, such as the web of life, represent these kinds of taxonomic anomalies.
Step-by-step explanation:
A group of taxa derived from two or more different ancestors is not known by a standardized term like clade or sister taxa; instead, it reflects a complex evolutionary history. For example, when two lineages emerge from the same branch point, they are called sister taxa, such as the two species of orangutans. If a linage branches off earlier and does not share a more recent common ancestor with the sister taxa, it may be considered a basal taxon. Phylogenetic relationships can become even more intricate when considering events like horizontal gene transfer, which can create a network of evolutionary histories rather than a straightforward tree, sometimes referred to as a web of life. In systematics, the complexity of these relationships is acknowledged, and organisms are classified into hierarchy of groupings called taxa (singular, taxon), which include levels from kingdom to species.
A group of taxa derived from 2 or more different ancestors is known as a clade. A clade is a group of organisms that includes an ancestor and all of its descendants. It is a phylogenetic classification based on evolutionary relationships.
For example, if we consider the mammal clade, it includes all mammals and their common ancestor. This means that any mammal, such as humans, dogs, or bats, can be classified within the mammal clade.
Clades are represented by cladograms, which are diagrams showing branching patterns that indicate evolutionary relationships among different taxa.