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Phylogenetic Trees quiz #1 Flashcards

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Phylogenetic Trees quiz #1
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  • How can DNA be useful in determining phylogenetic relationships among organisms?
    DNA is useful in phylogeny because similarities in DNA sequences between different species indicate homology, meaning they share a common ancestor. By comparing DNA sequences, scientists can reconstruct evolutionary relationships and build phylogenetic trees that show how species have diverged over time.
  • What do terminal nodes represent in a phylogenetic tree?
    Terminal nodes represent present-day organisms for which we have data. They are located at the ends of the branches in the tree.
  • What is the significance of branch length in a phylogenetic tree?
    Branch length usually indicates the amount of time since divergence between organisms. Longer branches represent greater time intervals.
  • How does a rooted phylogenetic tree differ from an unrooted tree?
    A rooted tree includes a specific internal node that is the common ancestor to all other nodes. This node represents the origin point for all organisms in the tree.
  • What is a monophyletic group or clade in the context of phylogenetic trees?
    A monophyletic group, or clade, consists of species all descended from a single common ancestor. It includes all descendants of that ancestor.
  • How does the cladistics approach construct phylogenetic trees?
    Cladistics considers all possible evolutionary pathways for a group of organisms. It then applies the principle of parsimony to select the simplest tree.
  • What is the principle of parsimony in phylogenetic tree construction?
    The principle of parsimony states that the simplest evolutionary tree is most likely correct. It helps scientists choose among many possible tree configurations.
  • How can homologous bone structures provide evidence for common ancestry?
    Similar bone configurations in different species suggest they inherited these traits from a shared ancestor. These homologous structures help reconstruct evolutionary relationships.
  • Besides DNA, what other type of homology can be used to build phylogenetic trees?
    Phenotypic traits, such as bone structures, can also be used to identify homology. These traits reveal evolutionary connections between species.
  • Why might constructing a phylogenetic tree for six organisms be mathematically complex?
    There are 6 factorial (6!) possible ways the tree could be formed, resulting in a large number of potential evolutionary pathways. This complexity requires systematic approaches like cladistics.