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BIOL - chapter 23
Systematics & Phylogeny
| Question | Answer |
|---|---|
| Which of the following best describes the fossil record? | It is an incomplete record of species that have existed on Earth. |
| ____ is the study of the evolutionary relationships among organisms. | Systematics |
| A phylogeny is a diagram that represents _____ | the hypothesized evolutionary relationships among species |
| On a branching diagram, where should existing species be placed? | On twigs |
| On a phylogenetic tree, one can determine how closely related two species are by | looking at how recently they share a common ancestor |
| because the ____ record is incomplete, scientists must use other types of analysis to infer evolutionary relationships among organisms. | fossil |
| What is systematics? | The study of evolutionary relationships among organisms |
| The hypothesized evolutionary relationships among species are represented by a diagram known as a(n) | phylogeny |
| On a branching diagram, what does the joining of twigs and branches represent? | The pattern of common ancestry |
| The process of descent with modification from common ancestry can be depicted by diagrams with a ______ | branching pattern |
| Similarity between species may not accurately predict evolutionary relationships due to _______ | convergent evolution, the variable rate of evolution, evolutionary reversal |
| Why does convergent evolution sometimes cause unrelated species to have similar adaptations? | Because similar habitats may favor similar adaptations |
| Over time, a species of salamander loses an established characteristic and instead evolves a characteristic of its ancestral species. This is an example of ______ | evolutionary reversal |
| A similarity that arose prior to the most recent common ancestor of a group is called a(n) | ancestral character |
| Phenotypic similarity in organisms | can mean very little about their evolutionary relationship |
| Two species may independently evolve similar characters when adapting to similar environments rather than through inheritance from a common ancestor. This process is known as | convergent evolution |
| Only shared derived characters are instructive in determining evolutionary relationships among taxa because | they indicate recent evolutionary changes and are therefore exhibited in closely related taxa |
| An evolutionary ____ occurs when a species re-evolves the characteristics of an ancestral species. | reversal |
| Derived characters are only shared with the most recent common ancestor of a clade, whereas _____ characters are shared with the most recent common ancestor as well as earlier ancestors. | ancestral |
| What term describes the re-construction of evolutionary relationships between species, as determined by shared derived characters? | Cladistics |
| When examining species, we can look at multiple aspects of the makeup of those organisms, from DNA to behavior. Any such feature that we examine is called a(n) | character |
| Because they indicate recent evolutionary changes and therefore close relationships among taxa, only shared _____ characters are instructive in developing phylogenies. | derived |
| One type of diagram that represents hypothesized evolutionary relationships among taxa is called a | cladogram |
| Evolutionary relationships among species are evaluated through the identification of shared derived characters in an approach called | cladistics |
| In cladistics, a(n) _____ is any aspect of the phenotype, including morphology, physiology, behavior, and DNA. | character |
| What does a cladogram depict? | A hypothesis of evolutionary relationships |
| A clade consists of a common _____ species and all of its _____ species | ancestral and descendant |
| A _____ is a shared character state that was not inherited from a common ancestor. These characters can make two species seem related when they are actually not. | homoplasy |
| Which of the following most accurately describes the evolution of different characters? | Some characters evolve more rapidly than others. |
| In a cladogram, what word describes an ancestral species and all of its descendants? | clade |
| How does homoplasy affect cladistic analysis? | It causes organisms to seem closely related when they are not. |
| The field of ____ involves the reconstruction and study of evolutionary relationships among organisms, whereas _____ uses that information to place organisms into species and higher order groups | systematics and classification |
| The pace of evolution is | variable |
| What term describes the re-construction of evolutionary relationships between species, as determined by shared derived characters? | Cladistics |
| Taxonomy is the science of | classifying living things |
| Because taxa at a lower level are grouped into smaller and smaller numbers of taxa at higher levels, the taxonomic system is said to be | hierarchical |
| The most recent common ancestor of the group and all of its descendants are included. | Monophyletic |
| The most recent common ancestor of the group is included, as well as some, but not all, of its descendants. | Paraphyletic |
| The most recent common ancestor of all the members of the group is not included. | Polyphyletic |
| The process of categorizing species and determining where they belong in the taxonomic hierarchy is known as | classification |
| What are traditional taxonomic hierarchies based on? | Shared traits |
| The science of classifying organisms is termed | taxonomy |
| Phylogenies provide information about | how evolution occurred and evolutionary relationships among species |
| ____ traits are derived from the same ancestral structure or source whereas ____ traits only appear similar, arising independently through convergent evolution. | homologous, analogous |
| Saber teeth in saber-toothed cats, marsupials, and nimravids are | homoplastic because they evolved independently in each group as a result of convergent evolution |
| Traditional taxonomic groups, which are based on shared traits, do not always reflect _____ relationships | evolutionary |
| Phylogenies can be used to determine ____ relationships between species. | evolutionary |
| How are homologous and homoplastic traits different? | Homologous traits are inherited from a common ancestor; homoplastic traits are not. |
| The first stage in the evolution of a complex character is often an adaptation to some environmental selective pressure that is | different from that for which the character is currently adapted |
| Theropods, the dinosaur ancestors of birds, possessed feather-like structures but were unable to fly. For that reason, scientists hypothesize that feathers may have originally evolved as an adaptation for _____ | insulation |
| Which of the following examples is likely a case of evolutionary reversal? | Re-evolution of the larval stage in limpets |
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