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Questions and Answers
What is phylogeny?
What is the purpose of constructing phylogenetic trees?
What does a branch point in a phylogenetic tree represent?
What are homologous structures?
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What are analogous structures?
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Why is morphology no longer the sole basis for classification?
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What is a vestigial structure?
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What is the primary function of a molecular clock in evolutionary biology?
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What is the term for the study of the morphology of ancient species?
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What do scientists use to group organisms into categories that represent lines of evolutionary descent?
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What is an example of a vestigial structure in humans?
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What is the primary purpose of comparing the DNA sequences of two species?
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What is the term for the study of the development of embryos?
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What is the significance of the presence of an amnion in embryonic development?
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What is the primary purpose of comparing the proteins of two organisms?
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What is the term for the similarities in chemical compounds found within cells?
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Which of the following types of evidence is used to determine the evolutionary relationships between organisms?
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What is the significance of finding similar genes in two organisms that are anatomically very different?
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What is the purpose of comparing the DNA sequences of two species?
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What is the significance of finding similar embryological structures in two organisms?
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What is the primary reason modern taxonomists consider phylogeny when attempting to classify an organism?
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What is the main difference between homologous and analogous structures?
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What is the significance of the wing of a bird, the wing of a bat, the forearm of a human, and the flipper of a whale being homologous structures?
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Why is morphology no longer sufficient for classification?
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What is the primary advantage of using phylogenetic trees in classification?
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Study Notes
Modern Taxonomy
- Modern taxonomists consider phylogeny, the evolutionary history of an organism, when attempting to classify it.
- Phylogenetic trees show the evolutionary relationships between different groups of organisms.
- The common ancestor of all organisms on a phylogenetic tree is represented by a branch point.
Phylogenetic Trees
- The phylogenetic tree shows the evolutionary relationships between different groups of organisms.
- Example: The phylogenetic tree of the Animal Kingdom shows the relationships between phyla.
Traditional Taxonomy
- Morphology, or the structure of the organism, was the basis for classification.
- Linnaeus' system of classification was based on morphology.
Morphology
- Morphology is classification based on the structures possessed by the organism.
- Homologous structures are similar in different species due to common ancestry.
- Example: The bones found in the wing of a bird, the wing of a bat, the forearm of a human, and the flipper of a whale are homologous.
- Analogous structures are similar in function but not in structure and are not derived from a common ancestor.
- Example: The wing of a bird and the wing of a butterfly have the same function but different structures.
- Vestigial structures are reduced in size and seem to be "left over" from a previous ancestor.
- Example: The appendix.
Additional Lines of Evidence
- The fossil record provides clues about the morphology of ancient species but is an incomplete record.
- Other lines of evidence must be considered when classifying an organism.
Cellular Organization
- Similarity in cell structures provides evidence of relationships between organisms.
- Examples: Types of plastids present, presence of a nucleus, cell wall composition.
Evolutionary Relationships
- Scientists group organisms into categories that represent lines of evolutionary descent or phylogeny.
- Fossils show that organisms alive today are similar to extinct organisms.
- Example: 25 breeds of dogs came from a wolf-like ancestor.
Biochemical Similarities
- Similarities of chemical compounds found within cells can be used as evidence to show relationships between organisms.
- A comparison between the proteins of two organisms serves as a "molecular clock".
- Example: The number of differences in amino acid sequences in proteins can indicate how long ago two species diverged from a common ancestor.
Genetic Similarities
- Similarities in DNA sequences and chromosome number can indicate relationships between organisms.
- Example: Humans and yeasts have similar genes for building myosin protein.
- The more similar the DNA sequences of two species, the more recently they shared a common ancestor.
Embryological Similarities
- Similarities in embryological development provide evidence of phylogenetic relationships.
- Example: The presence of an amnion in the embryos of reptiles, birds, and mammals indicates a common ancestry.
- The more similar the embryological development of two species, the more closely they are related.
Modern Taxonomy
- Modern taxonomists consider phylogeny, the evolutionary history of an organism, when attempting to classify it.
- Phylogenetic trees show the evolutionary relationships between different groups of organisms.
- The common ancestor of all organisms on a phylogenetic tree is represented by a branch point.
Phylogenetic Trees
- The phylogenetic tree shows the evolutionary relationships between different groups of organisms.
- Example: The phylogenetic tree of the Animal Kingdom shows the relationships between phyla.
Traditional Taxonomy
- Morphology, or the structure of the organism, was the basis for classification.
- Linnaeus' system of classification was based on morphology.
Morphology
- Morphology is classification based on the structures possessed by the organism.
- Homologous structures are similar in different species due to common ancestry.
- Example: The bones found in the wing of a bird, the wing of a bat, the forearm of a human, and the flipper of a whale are homologous.
- Analogous structures are similar in function but not in structure and are not derived from a common ancestor.
- Example: The wing of a bird and the wing of a butterfly have the same function but different structures.
- Vestigial structures are reduced in size and seem to be "left over" from a previous ancestor.
- Example: The appendix.
Additional Lines of Evidence
- The fossil record provides clues about the morphology of ancient species but is an incomplete record.
- Other lines of evidence must be considered when classifying an organism.
Cellular Organization
- Similarity in cell structures provides evidence of relationships between organisms.
- Examples: Types of plastids present, presence of a nucleus, cell wall composition.
Evolutionary Relationships
- Scientists group organisms into categories that represent lines of evolutionary descent or phylogeny.
- Fossils show that organisms alive today are similar to extinct organisms.
- Example: 25 breeds of dogs came from a wolf-like ancestor.
Biochemical Similarities
- Similarities of chemical compounds found within cells can be used as evidence to show relationships between organisms.
- A comparison between the proteins of two organisms serves as a "molecular clock".
- Example: The number of differences in amino acid sequences in proteins can indicate how long ago two species diverged from a common ancestor.
Genetic Similarities
- Similarities in DNA sequences and chromosome number can indicate relationships between organisms.
- Example: Humans and yeasts have similar genes for building myosin protein.
- The more similar the DNA sequences of two species, the more recently they shared a common ancestor.
Embryological Similarities
- Similarities in embryological development provide evidence of phylogenetic relationships.
- Example: The presence of an amnion in the embryos of reptiles, birds, and mammals indicates a common ancestry.
- The more similar the embryological development of two species, the more closely they are related.
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Description
Learn about phylogeny, the evolutionary history of an organism, and how scientists construct phylogenetic trees to show evolutionary relationships between different groups of organisms.
