Phylogeny and the Tree of Life Quiz
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Questions and Answers

What does a branch point in a phylogenetic tree represent?

  • The extinction of a species
  • The division of a lineage into two evolutionary lineages (correct)
  • The appearance of a new species
  • The increase in genetic similarity among species

Which taxa diverged after the shared lineage split from taxon A?

  • Taxa B and C (correct)
  • Only taxon A
  • All taxa A, B, and C
  • Taxa A and B

What could cause an organism to be reclassified in a phylogenetic context?

  • Alterations in the organism's physical appearance
  • New evidence indicating a mistake in the evolutionary relationships (correct)
  • Changes in the organism's habitat
  • The organism's geographic location

In the described diagram, what does branch point 3 represent?

<p>The common ancestor of taxa A, B, and C (B)</p> Signup and view all the answers

Which genus is mentioned in the context?

<p>Panthera (C)</p> Signup and view all the answers

What does PhyloCode change about taxa classification?

<p>Taxa will be classified without any hierarchical ranks. (C)</p> Signup and view all the answers

What is a phylogenetic tree used to represent?

<p>The evolutionary history of organisms. (D)</p> Signup and view all the answers

Which group would Aves be classified under based on evolutionary history?

<p>Aves would be considered a subgroup of Reptilia. (D)</p> Signup and view all the answers

What is one reason for misclassification of species by taxonomists?

<p>The species lost a key feature shared with its relatives. (B)</p> Signup and view all the answers

How are taxa currently classified according to traditional methods?

<p>In a nested hierarchy within inclusive groups. (A)</p> Signup and view all the answers

What is a common misconception about the relationship between taxonomy and evolutionary history?

<p>Taxonomies can reflect evolutionary history even if based on old classifications. (B)</p> Signup and view all the answers

What approach are many systematists adopting due to PhyloCode?

<p>A phylogenetic approach based on evolutionary relationships. (A)</p> Signup and view all the answers

Which of the following statements about evolutionary relationships is true?

<p>They are hypotheses formed based on data. (A)</p> Signup and view all the answers

Which tree was identified as the most parsimonious among the three possible phylogenies?

<p>Tree I (A)</p> Signup and view all the answers

How many additional base-change events do the trees at sites 2, 3, and 4 collectively require?

<p>5 events (D)</p> Signup and view all the answers

What is the total number of base-change events for Tree II?

<p>7 events (C)</p> Signup and view all the answers

What color were the hatchmarks indicating base-change events?

<p>Purple (D)</p> Signup and view all the answers

What identifies a phylogeny as most parsimonious?

<p>Least number of base-change events (D)</p> Signup and view all the answers

How many events does Tree I require?

<p>6 events (D)</p> Signup and view all the answers

Which of the following is NOT a tree mentioned in the study?

<p>Tree IV (A)</p> Signup and view all the answers

What aspect is primarily considered when identifying the most parsimonious tree?

<p>Base-change events (A)</p> Signup and view all the answers

What does a phylogenetic tree illustrate regarding leopard, badger, and wolf?

<p>Their evolutionary relationships (D)</p> Signup and view all the answers

What term describes evolution due to similar environmental pressures rather than shared ancestry?

<p>Convergent evolution (A)</p> Signup and view all the answers

In constructing a phylogenetic tree, what is a potential error caused by confusion between analogy and homology?

<p>Misinterpreting similar traits (D)</p> Signup and view all the answers

If taxon E is the sister taxon to taxa D and F, what does this imply?

<p>E shares a recent common ancestor with D and F (B)</p> Signup and view all the answers

Which statement best describes analogy in the context of evolutionary biology?

<p>Traits arising from convergent evolution (A)</p> Signup and view all the answers

What should scientists consider when estimating divergence times in phylogenetic trees?

<p>Molecular data (B)</p> Signup and view all the answers

What is the significance of convergent evolution in studying phylogenetic relationships?

<p>It may mislead interpretations of relationships (D)</p> Signup and view all the answers

Which evolutionary concept explains why two different species may display similar external traits?

<p>Analogous structures (B)</p> Signup and view all the answers

Why might hair not be a useful character for distinguishing a particular clade of mammals?

<p>Hair is found in all mammals regardless of clade. (A), Hair can evolve independently in different lineages. (D)</p> Signup and view all the answers

What can gene duplication contribute to in the evolutionary process?

<p>Enhanced adaptability through increased gene count. (D)</p> Signup and view all the answers

What is the primary concern with using the most parsimonious tree of evolutionary relationships?

<p>It may not accurately represent all possible relationships. (C)</p> Signup and view all the answers

Which type of gene is described as having divergence traced back to speciation events?

<p>Orthologous genes. (C)</p> Signup and view all the answers

What is a significant aspect of molecular phylogenies concerning gene duplications?

<p>They account for repeated duplications that lead to gene families. (D)</p> Signup and view all the answers

How did traditional classifications view taxa besides birds and mammals?

<p>As part of the clade known as reptiles. (B)</p> Signup and view all the answers

In the context of genome evolution, what is a major role of molecular systematics?

<p>It traces the phylogenies of gene families. (D)</p> Signup and view all the answers

What relationship do cytochrome c genes in humans and dogs illustrate?

<p>They are orthologous genes linked to speciation. (C)</p> Signup and view all the answers

What type of genes are formed as a result of speciation?

<p>Orthologous genes (B)</p> Signup and view all the answers

Which genomic type is suggested to evolve relatively rapidly for tracking evolutionary relationships?

<p>mitochondrial DNA (C)</p> Signup and view all the answers

What percentage of genes are shared as orthologous between humans and mice?

<p>99% (D)</p> Signup and view all the answers

Which organisms share 50% of their genes as orthologous despite 1 billion years of divergence?

<p>Humans and yeast (B)</p> Signup and view all the answers

What does the comparison of rRNA sequences indicate about the evolutionary relationship of fungi?

<p>Fungi are more closely related to animals than to green plants (D)</p> Signup and view all the answers

What is one outcome of the divergence of lineages that occurred a long time ago?

<p>They can still share orthologous genes (B)</p> Signup and view all the answers

What role do biochemical and developmental pathways play in different organisms?

<p>They explain shared characteristics among disparate organisms. (C)</p> Signup and view all the answers

What does the presence of orthologous genes between vastly different species suggest?

<p>Common evolutionary ancestry (D)</p> Signup and view all the answers

Flashcards

Dichotomies in evolutionary relationships

Relationships often shown as branching points representing the divergence of lineages from a common ancestor.

Branch Point

A point on a phylogenetic tree where two evolutionary lineages split from a common ancestor.

Phylogenetic tree

A visual representation of evolutionary relationships among organisms.

Common Ancestor

An ancestral organism shared by two or more different lineages.

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Reclassification of Organisms

Re-evaluating and adjusting the classification of an organism based on emerging evidence (like new relationships).

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PhyloCode

A system for naming species that focuses on evolutionary relationships (phylogeny) rather than rank.

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Linnaean classification

Old classification system that uses ranks like family and class to group organisms. Does not always reflect evolutionary history.

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Evolutionary history

The sequence of events leading to the present form of a group of organisms.

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Taxa

Groups of organisms (species, genus, etc.)

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Misclassification

Placing a species within a group to which it is not closely related.

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Evolutionary Relationships

How different species are connected through shared ancestry.

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Phylogenetic approach

Classifying organisms based on their evolutionary relationships.

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Parsimonious tree

The phylogenetic tree requiring the fewest evolutionary changes to explain the data.

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Base-change events

Changes in the DNA sequence of an organism over time.

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Most parsimonious tree

The tree requiring the fewest evolutionary steps between different organisms to explain the traits of interest.

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Molecular data

Data related to the genetic material of organisms used to construct phylogenetic trees.

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Brooding behavior

When a parent animal warms eggs with its body.

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Base-change analysis

Method of determining the phylogenetic relationships by comparing base changes across multiple sites/sequences.

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Multiple sites analysis

Considering numerous genetic sequences to construct a phylogenetic tree.

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Homology vs. Analogy

Similarities in traits due to shared ancestry (homology) versus similar traits due to similar environments (analogy).

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Convergent evolution

The process of unrelated organisms evolving similar traits due to similar environments.

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Sister taxon

Two lineages that share a common ancestor that is not shared by any other lineages.

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Divergence times

The points in evolutionary history when two lineages split.

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Phylogeny

The evolutionary history of a species or group of species.

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Hair as a Clade Character

Hair is a shared derived character of mammals, making it a useful feature for classifying them within the larger clade of Mammalia.

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Parsimony Principle

The principle of parsimony suggests the most likely evolutionary tree is the one with the fewest evolutionary changes.

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Gene Duplication's Role

Gene duplication increases the number of genes in the genome, providing raw material for evolution and potential development of new functions.

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Tracing Gene Phylogeny

Molecular techniques allow us to reconstruct the evolutionary history of genes and trace their duplication events.

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Gene Family

A group of related genes within an organism's genome, often arising from repeated gene duplication events.

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Orthologous Genes

Genes found in different species that share a common ancestor and diverged due to speciation events.

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Paralogous Genes

Genes within the same organism that arose from gene duplication events and can have different functions.

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Cytochrome C Gene

An example of an orthologous gene, found in different species like humans and dogs, involved in electron transport chain.

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How do orthologous genes prove evolutionary relationships?

By comparing orthologous genes, scientists can identify similarities and differences between species that diverged millions of years ago, revealing how they are related.

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What is a Molecular Clock?

A technique that uses the rate of genetic change in a gene to estimate the time of divergence between two species.

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Why are rRNA and mtDNA useful for tracing evolution?

rRNA evolves slowly, useful for studying distant relationships. mtDNA evolves quickly, good for recent lineages.

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What are the two patterns observed in comparing genomes?

  1. Distant lineages can share orthologous genes. 2) 50% of human genes are orthologous with yeast despite 1 billion years of divergence.
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Study Notes

Phylogeny and the Tree of Life

  • Biologists use evolutionary relationships to categorize species
  • Comparing traits helps place species in the correct "container"
  • Shared traits suggest close evolutionary relationships
  • Legless condition evolved independently in different lizard groups
  • Snakes and lizards are part of the evolutionary continuum
  • Phylogeny traces the evolutionary history
  • Observing phylogeny is about understanding evolutionary patterns.

Phylogenies Show Evolutionary Relationships

  • Organisms share traits due to common ancestry
  • Knowing a species' evolutionary history gives insight into its characteristics
  • Shared genes, metabolic pathways, and structural proteins point to close relatives
  • Taxonomy is the scientific discipline that names and classifies organisms
  • Taxon is the named taxonomic unit at a specific hierarchical level.

Binomial Nomenclature

  • Common names can cause confusion, as one name can refer to multiple species
  • Scientific names (binomials) avoid such ambiguity.
  • Binomials consist of the genus name (capitalized) and the species epithet (not capitalized)
  • Scientific names are italicized
  • Use of binomial names helps avoid ambiguity across languages and contexts.

Hierarchical Classification

  • Species are grouped into increasingly inclusive categories.
  • Species grouped into genera, genera into families, families into orders, orders into classes, classes into phyla, phyla into kingdoms, and kingdoms into domains.
  • This resembles a postal address (e.g., individual apartment, to building, to street, to city).
  • This system is called the Linnaean system.
  • Taxa are the named taxonomic units at each level of the hierarchy.

Linking Classification and Phylogeny

  • Phylogenetic trees depict evolutionary history as a branching diagram
  • Branching patterns of phylogenetic trees often match how taxonomists classify organisms.
  • Sometimes, species might be classified in a way that contradicts its true evolutionary history
    • Loss of a key feature or other similar factors.

Shared Characters in Constructing Phylogenetic Trees

  • Homologous characters reflect shared ancestry.
  • Analogous characters result from convergent evolution.
  • Using homologous characters is key to establish evolutionary relationships
  • Phylogenetic trees are hypotheses about evolutionary relationships
  • Outgroup is a species or group of species that branched from the lineage before the group being studied.
  • Using outgroups can help establish evolutionary relationships among the species in the group.

Phylogenies Inferred from Morphological and Molecular Data

  • Systematists collect and analyze information about organism's morphology, genes, and biochemistry
    • to determine evolutionary relationships
  • Homologous traits reflect shared ancestry.
  • Distinguish homology from analogy (convergent evolution).

Molecular Homologies

  • Comparing DNA sequences helps analyze evolutionary relationships in the absence of a strong fossil record.
  • DNA sequences in closely related species differ in only one or a few sites.
  • DNA sequences in distantly related species differ at numerous locations.

Evaluating Molecular Homologies

  • Aligning comparable DNA sequences is the first step to comparing them.
  • A computer program can determine the best way to align comparable DNA sequences.

Molecular Clocks and Evolutionary Time

  • Molecular clocks measure average rates of change in genes or proteins.
  • Gene or protein sequences can serve as reliable molecular clocks.
  • Calculating the amount of difference in gene or protein sequences can help estimate the dates of events that cannot be determined from the fossil record

New Information Revises Understanding of the Tree of Life

  • The current tree of life is based on three domains: Bacteria, Archaea, and Eukarya.
  • Organisms are classified into domains based on ribosomal RNA gene sequences and other factors.
  • Horizontal gene transfer makes understanding the tree of life complex.
  • Gene transfer between organisms makes analyzing relationships more challenging.

Phylogenetic Trees as Hypotheses

  • Any phylogenetic tree represents a hypothesis about the relationship amongst the species in the tree.
  • The best hypothesis is the one that best fits all available data
  • These hypotheses can be modified as new evidence becomes available.
  • Can predict new characteristics based on phylogenetic bracketing.

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Description

Test your understanding of phylogeny and the tree of life. This quiz covers evolutionary relationships between species, shared traits, and the significance of taxonomy. Explore concepts like binomial nomenclature and how organisms are classified based on their evolutionary history.

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