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Questions and Answers
Which term describes a distinctive feature that is unique to a given taxon?
Which term describes a distinctive feature that is unique to a given taxon?
What distinguishes a crown group from a stem group?
What distinguishes a crown group from a stem group?
Which type of character state is described as an ancestral character shared by a group?
Which type of character state is described as an ancestral character shared by a group?
What concept suggests that the simplest explanation with the least number of character changes is preferred?
What concept suggests that the simplest explanation with the least number of character changes is preferred?
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Which statement about homologous and analogous structures is true?
Which statement about homologous and analogous structures is true?
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What is the term used for the gradual changes in living organisms over time?
What is the term used for the gradual changes in living organisms over time?
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Which process leads to the increase in frequency of advantageous traits in a population?
Which process leads to the increase in frequency of advantageous traits in a population?
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What do we call it when genetic features are passed from parents to offspring?
What do we call it when genetic features are passed from parents to offspring?
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What is a cladogram used for in phylogenetic systematics?
What is a cladogram used for in phylogenetic systematics?
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Which of the following best defines a species in biological terms?
Which of the following best defines a species in biological terms?
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What is one characteristic that differentiates evolution from non-genetic changes observed during an organism's life span?
What is one characteristic that differentiates evolution from non-genetic changes observed during an organism's life span?
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What is the difference between genotypic evolution and phenotypic evolution?
What is the difference between genotypic evolution and phenotypic evolution?
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Which statement about natural selection is true?
Which statement about natural selection is true?
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What distinguishes a phylogram from a chronogram?
What distinguishes a phylogram from a chronogram?
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According to the concept of parsimony, which cladogram is preferred?
According to the concept of parsimony, which cladogram is preferred?
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What type of group is formed by the human and gorilla based on shared diagnostic characters?
What type of group is formed by the human and gorilla based on shared diagnostic characters?
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What defines a primitive character in a phylogenetic context?
What defines a primitive character in a phylogenetic context?
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Which of the following is NOT a characteristic of a cladogram?
Which of the following is NOT a characteristic of a cladogram?
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Which statement is true regarding advanced (derived) characters?
Which statement is true regarding advanced (derived) characters?
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Which of the following best illustrates the concept of parsimony in phylogenetics?
Which of the following best illustrates the concept of parsimony in phylogenetics?
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What are characters in the context of phylogenetic analysis?
What are characters in the context of phylogenetic analysis?
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Which cladogram would be considered less parsimonious?
Which cladogram would be considered less parsimonious?
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Which characteristic does NOT define a polyphyletic group?
Which characteristic does NOT define a polyphyletic group?
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What type of group includes a single ancestor and all of its descendants?
What type of group includes a single ancestor and all of its descendants?
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Which statement accurately describes a polyphyletic group?
Which statement accurately describes a polyphyletic group?
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What distinguishes a crown group from a stem group?
What distinguishes a crown group from a stem group?
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What is a characteristic of a paraphyletic group?
What is a characteristic of a paraphyletic group?
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Which of the following best describes a cladogram?
Which of the following best describes a cladogram?
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Which type of taxonomic group includes both extinct species and their living descendants?
Which type of taxonomic group includes both extinct species and their living descendants?
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Which statement is true regarding the selection of characters in systematics?
Which statement is true regarding the selection of characters in systematics?
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Which statement about phylogenetic datasets is correct?
Which statement about phylogenetic datasets is correct?
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What does a nested monophyletic clade represent in a phylogenetic context?
What does a nested monophyletic clade represent in a phylogenetic context?
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The process by which systematists analyze relationships among species is primarily based on:
The process by which systematists analyze relationships among species is primarily based on:
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What defines a species in the phylogenetic sense?
What defines a species in the phylogenetic sense?
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Which of the following best describes the Linnaean system of classification?
Which of the following best describes the Linnaean system of classification?
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What is a cladogram used for in phylogenetic systematics?
What is a cladogram used for in phylogenetic systematics?
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How are diagnostic characters significant in phylogenetic studies?
How are diagnostic characters significant in phylogenetic studies?
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Which statement is true regarding the Linnaean system following Darwin's evolutionary formulation?
Which statement is true regarding the Linnaean system following Darwin's evolutionary formulation?
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What percentage of all species that have ever existed is estimated to be extinct?
What percentage of all species that have ever existed is estimated to be extinct?
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Which classification level comes directly above 'Hominidae' in the Linnaean hierarchy?
Which classification level comes directly above 'Hominidae' in the Linnaean hierarchy?
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What is the primary focus of systematics?
What is the primary focus of systematics?
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Identify the term that refers to features possessed by organisms in phylogenetic studies.
Identify the term that refers to features possessed by organisms in phylogenetic studies.
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What aspect of organisms does phylogenetic systematics primarily examine?
What aspect of organisms does phylogenetic systematics primarily examine?
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Study Notes
Evolution
- Biological evolution describes cumulative changes in a species over time, resulting from genetic mutations and recombination during reproduction.
- These genetic changes affect an organism's morphology, known as phenotypic evolution.
- Natural selection drives evolutionary change by favoring advantageous traits that increase survival and reproduction.
- Traits acquired during an organism's lifetime, such as increased muscle mass, are not inherited and therefore not examples of evolution.
- A species, biologically, is a group of organisms with similar characteristics that can interbreed and produce viable offspring.
- A species, phylogenetically, is the smallest group (clade) of organisms sharing a common ancestor and having a unique combination of derived (defining) traits.
- 99.9999% of all species that have ever existed are extinct, known to us through fossil records.
Phylogenetic Systematics
- Phylogenetic systematics is a scientific approach to reconstructing evolutionary relationships based on shared, derived characters.
- It contrasts with the Linnaean system, which groups organisms based on overall similarity.
- Cladograms are hierarchical diagrams displaying relationships between organisms based on shared diagnostic characters.
- Phylograms are cladograms where branch lengths are proportional to the amount of character change.
- Chronograms are cladograms that explicitly represent time through branch lengths.
- Parsimony, a guiding scientific principle, assumes that the explanation requiring the fewest evolutionary steps is most likely correct.
- Cladograms are scientific hypotheses that can be revised or overturned with new data.
Important Phylogenetic Terms
- Character: A morphological feature of an organism defined qualitatively or quantitatively, used for phylogenetic analysis.
- Primitive (ancestral) character: A character present in ancestral taxa.
- Advanced (derived) character: A character expressed in descendant taxa.
- Autoapomorphy: A unique, derived trait present in a single taxon.
- Synapomorphy: A trait shared exclusively by descendants of a common ancestor.
- Plesiomorphy: An ancestral character state.
- Symplesiomorphy: An ancestral trait shared by two or more taxa, highlighting common ancestry.
- Monophyletic group (clade): A group with a shared common ancestor that includes all of its descendants.
- Paraphyletic group: A group with a common ancestor but excluding some of its descendants.
- Polyphyletic group: A group that does not share a single common ancestor.
- Crown group: A group defined by living taxa, including their common ancestor and all descendants.
- Stem group: A paraphyletic group of extinct species at the base of a crown group.
- Homologous structures: Structures with a shared evolutionary origin.
- Analogous structures: Structures with similar function but different evolutionary origins.
- Common ancestor: Represents a population from which a species descended, not a single individual.
Other Key Concepts
- Phylogenetic systematics uses shared, derived characters to determine relationships, whereas Linnaean classification relies on morphological similarity.
- Character choice, definition, and taxa examined influence the resulting hypothesis of relationship.
- Computer programs help determine the most parsimonious tree for datasets of large size.
- Phylogenetic systematics provides a more robust and data-based approach to understanding evolutionary relationships compared to the Linnaean system.
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Description
This quiz explores the key concepts of biological evolution, including genetic changes, natural selection, and species definitions. You'll also learn about phylogenetic systematics and its role in understanding evolutionary relationships. Test your knowledge on how species evolve and the history of life on Earth.
