Phylogeny - AP Biology
- What is the difference between rooted and unrooted trees?
- Rooted trees have a designated root; unrooted trees do not. Rooted trees show directionality of evolutionary time.
- What is a molecular marker in phylogenetics?
- A specific DNA sequence used to study genetic relationships. Provides data points for comparing evolutionary divergence.
- Which type of data is commonly used to construct phylogenetic trees?
- Molecular data, such as DNA, RNA, or protein sequences. DNA sequences provide objective measures of evolutionary change.
- What is meant by 'tree topology'?
- The branching pattern of a phylogenetic tree. The arrangement of branches showing evolutionary relationships.
- What is the significance of a shared derived character?
- It indicates a common ancestry among the organisms sharing it. Synapomorphies define clades and evolutionary relationships.
- What is a shared ancestral character?
- A character that originated in an ancestor of the taxon. Plesiomorphies are inherited from earlier common ancestors.
- Define outgroup in phylogenetic analysis.
- A species or group of species closely related but not part of the group under study. Used to root trees and determine character polarity.
- Define clade.
- A clade is a group of organisms that includes an ancestor and all its descendants. Also called a monophyletic group in phylogenetics.
- What is a monophyletic group?
- A group of organisms that consists of an ancestor and all its descendants. Same as a clade; represents natural evolutionary groups.
- What is a paraphyletic group?
- A group that includes an ancestor but not all of its descendants. Creates artificial groups that exclude some descendants.
- What is a character matrix?
- A table showing the presence or absence of traits across taxa. Organizes trait data for phylogenetic analysis.
- What is a reticulate evolution?
- Evolution involving the merging of different lineages through hybridization. Creates network-like patterns rather than simple trees.
- What role does bioinformatics play in phylogenetics?
- It assists in analyzing genetic data to infer evolutionary relationships. Provides computational tools for large-scale phylogenetic studies.
- What is a cladogram?
- A type of diagram that shows relationships among species based on shared characteristics. Focuses on branching patterns without time or rate information.
- What is an ultrametric tree?
- A tree where all paths from the root to the leaves are of equal length. Assumes molecular clock with constant evolutionary rates.
- What are synapomorphies?
- Shared derived characters used to construct phylogenetic trees. Define clades by showing evolutionary novelties.
- What is a phylogenetic tree?
- A diagram that represents evolutionary relationships among organisms. Branch patterns show how species diverged from common ancestors.
- What are orthologs?
- Genes in different species that evolved from a common ancestral gene. Share common ancestry and similar functions across species.
- What is horizontal gene transfer?
- The movement of genes between unrelated species. Can complicate phylogenetic trees by mixing lineages.
- What is analogy in phylogeny?
- Similarity due to convergent evolution, not common ancestry. Can mislead phylogenetic analysis by suggesting false relationships.
- What is the principle of parsimony in phylogenetics?
- The simplest explanation or path with the least evolutionary changes is preferred. Minimizes assumptions about evolutionary change events.
- What is the distinction between taxonomy and phylogeny?
- Taxonomy classifies organisms; phylogeny studies their evolutionary relationships. Taxonomy groups organisms; phylogeny traces their evolution.
- What is the importance of genetic distance in phylogeny?
- It measures evolutionary divergence between species or sequences. Quantifies how much species have diverged evolutionarily.
- What is an evolutionary tree?
- A diagram that represents hypotheses about the history of species divergence. Shows branching patterns of species through time.
- What is a polyphyletic group?
- A group that does not include the most recent common ancestor of its members. Forms unnatural groups based on convergent evolution.
- How is molecular clock used in phylogenetics?
- It estimates time of evolutionary events based on mutation rates. Assumes constant mutation rates to calculate divergence times.
- Identify a technique used to infer phylogenetic trees.
- Maximum likelihood or Bayesian inference methods. Statistical methods that evaluate multiple possible trees.
- What is phylogeny?
- Phylogeny is the evolutionary history and relationship of an organism or group of organisms. Shows how species evolved and are related through time.
- What does a branch point in a phylogenetic tree represent?
- A branch point represents a common ancestor of the lineages that diverge from it. Also called a node; where lineages split in evolutionary time.
- What are paralogs?
- Genes related by duplication within a genome. Result from gene duplication within the same organism.
- How does convergent evolution affect phylogenies?
- It can lead to analogous traits that may mislead phylogenetic inference. Creates homoplasy that obscures true evolutionary relationships.
- What is a sister group in phylogeny?
- Two descendants that split from the same node in a phylogenetic tree. Share the most recent common ancestor with each other.
- What is a consensus tree?
- A tree that summarizes the common features of a set of trees. Shows areas of agreement among different phylogenetic analyses.
- What is the purpose of bootstrap analysis in phylogenetics?
- To assess the reliability of inferred phylogenetic trees. Statistical resampling method to test tree robustness.
- What is a basal taxon in a phylogenetic tree?
- A lineage that diverges early in the history of a group. Represents an early-branching evolutionary lineage.
- What is homology?
- Similarity in characteristics resulting from a shared ancestry. Indicates true evolutionary relationship from shared ancestry.
- What is a character state?
- A specific form or variation of a character (trait) in a species. Different expressions of the same trait across species.
- Identify the root of a phylogenetic tree.
- The root represents the most recent common ancestor of all taxa in the tree. The starting point showing the oldest common ancestor.
- Define 'node' in the context of a phylogenetic tree.
- A point on a tree where a lineage splits into two or more lineages. Branch points where evolutionary splitting occurs.
- Define the term 'phylogenetic signal'.
- The pattern of trait resemblance among species due to shared ancestry. Strong signal indicates reliable phylogenetic inference.