Phylogenetic trees and cladograms Knowledge-Based Practice

Questions

1. 1.

   In phylogenetic systematics, what is the primary purpose of including an outgroup when constructing a cladogram?

   • A) To identify which ingroup branch has undergone the fastest rate of genetic mutation
   • B) To calculate the absolute chronological divergence dates among ingroup species
   • C) To determine character polarity by distinguishing ancestral traits from derived traits
   • D) To ensure that analogous structures are grouped together rather than homologous structures
2. 2.

   In phylogenetic systematics, which statement correctly describes sister taxa on a cladogram or phylogenetic tree?

   • A) They are two lineages that share an immediate common ancestor not shared by any other taxon.
   • B) They are two taxa that share similar morphological traits caused by convergent evolution rather than descent.
   • C) They are taxa positioned next to each other at the terminal tips regardless of their common node.
   • D) They are an ancestral species and a subset of its descendant lineages excluding living relatives.
3. 3.

   In phylogenetic systematics, which statement correctly defines a monophyletic group, or clade?

   • A) It consists of a common ancestral species and all of its evolutionary descendants.
   • B) It includes an ancestral species and only some, but not all, of its evolutionary descendants.
   • C) It unites distantly related organisms derived from multiple distinct evolutionary ancestors.
   • D) It consists solely of extant species that share analogous structures without a recent common ancestor.
4. 4.

   How does a standard cladogram differ from a phylogram in phylogenetic systematics?

   • A) A cladogram incorporates absolute geological time on its branch lengths, whereas a phylogram indicates only relative branching sequences without a time scale.
   • B) A cladogram is constructed exclusively using morphological data, whereas a phylogram is derived entirely from molecular sequence alignments.
   • C) A cladogram illustrates only the branching order and relationships among taxa, whereas branch lengths in a phylogram represent the amount of evolutionary divergence.
   • D) A cladogram permits the inclusion of polyphyletic groupings, whereas a phylogram is restricted strictly to monophyletic clades.
5. 5.

   In phylogenetic systematics, what does an internal node (branch point) on a phylogenetic tree or cladogram represent?

   • A) The geographic region where an ancestral lineage first underwent adaptive radiation
   • B) The complete extinction of a primitive lineage without producing surviving descendants
   • C) An evolutionary event where two separate taxa fused through extensive hybridization
   • D) The most recent common ancestor shared by the descendant lineages that diverge from it

Answers and step-by-step solutions appear after you finish the test.