Phylogenetic trees and cladograms Knowledge-Based Download PDF

Questions

1. 1.

   On a phylogenetic tree, what does a polytomy—a node from which three or more descendant lineages branch—typically signify?

   • A) An unresolved divergence order where the exact sequence of evolutionary branching is not yet determined
   • B) A verified evolutionary event where one ancestral lineage simultaneously divided into three or more species
   • C) A polyphyletic grouping formed by taxa that independently acquired analogous characteristics
   • D) An evolutionary lineage that has ceased mutating and accumulated no novel derived traits over time
2. 2.

   In cladistics, which type of trait is shared by two or more taxa and uniquely derived from their most recent common ancestor, serving as the basis for defining monophyletic clades?

   • A) Synapomorphy
   • B) Symplesiomorphy
   • C) Homoplasy
   • D) Autapomorphy
3. 3.

   Which term describes an evolutionary grouping on a phylogenetic tree that includes a common ancestral species and some, but not all, of its descendants?

   • A) Monophyletic
   • B) Polyphyletic
   • C) Polytomic
   • D) Paraphyletic
4. 4.

   In phylogenetic systematics, two lineages are classified as sister taxa because they share which evolutionary relationship?

   • A) They share an immediate common ancestor that is not shared by any other taxon.
   • B) They developed analogous morphological traits through convergent evolution in similar habitats.
   • C) They represent the earliest-diverging lineage directly connected to the root of the tree.
   • D) They retain identical ancestral characteristics that have remained unchanged over geological time.
5. 5.

   In evolutionary biology, how does a standard cladogram differ fundamentally from a time-calibrated phylogenetic tree?

   • A) Cladograms indicate the exact geological dates of speciation events, whereas time-calibrated trees show only character transitions.
   • B) Cladograms depict polyphyletic groupings exclusively, whereas time-calibrated trees are restricted to paraphyletic lineages.
   • C) Cladograms place ancestral species at the terminal tips, whereas time-calibrated trees place all ancestors at the root.
   • D) Cladograms show only the relative branching order and relationships, whereas time-calibrated trees display branch lengths proportional to elapsed time.