Questions and Answers
What is the goal of evolutionary classification?
The goal of evolutionary classification is to group species into larger categories that reflect lines of evolutionary descent, rather than overall similarities and differences.
The _____________ the ____________ is, the farther ______________ back in time all its ________________ shared a common ______________.
larger, taxon, back, members, ancestor
Why do some taxa fail the 'clade test'?
Certain taxa fail the 'clade test' because they include species descended from more than one different ancestor.
Looking at Figure 19-6, what is the closest related species to crocodiles?
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What derived characters do coyotes and lions share and what clades are they in? What derived character is not shared?
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Looking at Figure 19-8, for which clade is an amniotic egg a derived character? Is the duck-billed platypus a member of the clade Amniota? Explain.
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A true clade must contain and exclude?
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What is the difference between a clade and a class?
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How are DNA sequences used in classification?
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Why is DNA analysis useful for classification?
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Cladograms are ____________________ presentations of _____________________________ about ________________________________, and are not ____________________.
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What does the tree of life show?
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Looking at Figure 19-12, which of the six kingdoms contains organisms that are not all in the same clade?
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Why isn't the kingdom 'Protists' a valid clade?
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Why is the circular model of the diversity of life a better representation of the living world?
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The family Camillidae includes camels and llamas. Do all the living members of the family form a clade?
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Study Notes
Evolutionary Classification
- The purpose is to classify species into larger groups based on evolutionary history, instead of mere physical similarities.
- Groups reflect evolutionary descent, indicating common ancestry among species.
Taxon and Ancestor Relationship
- Larger taxon indicates a more distant common ancestor for its members.
- Each taxon represents a group of species sharing a specific lineage.
Clade Test
- Some taxa fail the "clade test" because they contain species that descend from multiple ancestors, making them non-monophyletic.
Closest Relatives to Crocodiles
- Birds are identified as the closest living relatives to crocodiles.
Shared Derived Characters and Clades
- Coyotes and lions share derived characters such as shearing teeth (carnivora), hair (mammalia), and four limbs (tetrapoda).
- Coyotes and lions do not share retractable claws, which are specific to the clade Felidae.
Amniotic Egg and Platypus
- An amniotic egg is a derived character for the clade Amniota.
- The duck-billed platypus is part of Amniota because it is a mammal, which falls under this clade.
Components of a True Clade
- A true clade includes an ancestral species along with all its descendants.
- It must exclude any species not descended from that original ancestor.
Clade vs. Class
- A clade is defined as an ancestral species and all its descendants.
- A class is a broader category encompassing several related orders of organisms.
DNA Sequences in Classification
- Similar derived genetic characters in two species suggest a recent common ancestor, highlighting close evolutionary relationships.
Importance of DNA Analysis
- DNA analysis enhances the accuracy of evolutionary trees by clarifying relationships that may not be evident through physical characteristics alone.
Cladograms
- Cladograms serve as visual representations of hypotheses regarding evolutionary relationships rather than definitive conclusions.
Tree of Life
- The tree of life conveys current hypotheses about evolutionary relationships among all taxa categorized into the three life domains.
Kingdom "Protista"
- The kingdom "Protista" comprises organisms that do not all belong to the same clade, indicating its lack of monophyly.
Validity of "Protista" as a Clade
- "Protista" is considered invalid as a clade due to the absence of a single, exclusive common ancestor for its members.
Circular Model of Life's Diversity
- The circular model accurately reflects the complex diversity of living organisms, representing their interconnections more effectively.
Family Camillidae and Clade Inclusion
- The family Camillidae, which includes camels and llamas, does not form a complete clade because their recent common ancestor is extinct and must be considered for clade designation.
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Description
Test your knowledge on evolutionary classification concepts, focusing on taxon relationships, shared derived characters, and the clade test. Understand how species are grouped based on their evolutionary history and lineage. Discover interesting facts about the closest relatives of crocodiles and more.
