Term
| What are the major tools used by biologists to study the history of life? |
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Definition
| Phylogenies and the fossil record |
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Term
| What was the Cambrian Explosion? |
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Definition
| The Cambrian explosion was the rapid morphological and ecological diversification of animals that happened during the Cambrian period. |
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Term
| What are adaptive radiations? |
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Definition
| Adaptive radiations are instances of ra[id diversification associated with new ecological opportunities and new morphological innovations. They are a major pattern in the history of life. |
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Term
| What are mass extinctions? |
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Definition
| Mass extinctions rapidly eliminate most of the species alive in a more or less random manner. They happen repeatedly throughout the history of life. |
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Term
| What is the name for the evolutionary history of a group of organisms? |
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Definition
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Term
| What does a phylogenetic tree show? |
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Definition
| a phylogenetic tree shows ancestor-descendant relationships among populations or species |
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Term
| What do the branches of a phylogenetic tree represent? |
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Definition
| Branches represent populations through time |
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Term
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Definition
| A taxon is any named group of organisms |
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Term
| Where do nodes occur on a phylogenetic tree? |
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Definition
| Nodes occur where an ancestral group split off into two or more descendant groups |
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Term
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Definition
| A polytomy is a node where more than two descendant groups branch off |
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Term
| WHat do the tips on a phylogenetic tree represent? |
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Definition
| They represent the trees endpoints and represent living groups or a group's end in extinction. |
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Term
| What are two other terms for a monophyletic group? |
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Definition
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Term
| What are the two approaches used to estimate phylogenetic trees? |
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Definition
| The phenetic approach and cladistic approach |
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Term
| What is the phenetic approach to estimating phylogenetic trees? |
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Definition
| It is used to estimate trees based on the overall similarity among populations |
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Term
| What is the cladistic approach to estimating phylogenetic trees? |
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Definition
| The cladistic approach to inferring trees focuses on synapomorphies, the shared derived characters of the species under study. |
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Term
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Definition
| A synapomorphy is a trait that certain populations or species have that exists in no others. |
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Term
| What problems can arise with both cladistic and phenetic estimations of phylogenetic trees? |
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Definition
| Problems can arise with both types of analysis because similar traits can involve independently in two distant species rather than from a trait present in a common ancestor. |
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Term
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Definition
| Homoplasy occurs when traits are similar for reasons other than common ancestry. |
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Term
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Definition
| Homology occurs when traits are similar due to shared ancestry |
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Term
| What is convergent evolution? |
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Definition
| Convergent evolution occurs when a natural selection favors similar solutions to the problems posed by similar way of making a living |
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Term
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Definition
| Parsimony is a principle of logic stating that the most likely explanation or pattern is the one that implies the least amount of change |
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Term
| That is a common cause of homoplasy? |
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Definition
| Convergent evolution is a common cause of homoplasy |
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Term
| Which should be more common homology or homoplasy? and why? |
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Definition
| Convergent evolution and other causes of homoplasy should be rare compared homology. The tree that implies the fewest overall evolutionary changes should be the one that most accurately reflects what really happened during evolution. |
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Term
| What kind of information does the fossil record provide us with? |
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Definition
| The fossil record provides the only direct evidence about what organisms that lived in the past looked like, where they lived, and when they existed. |
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Term
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Definition
| A fossil is the physical trace left by an organism that lived in the past |
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Term
| What is the fossil record? |
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Definition
| The fossil record is the total collection of fossils that have been found that the world |
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Term
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Definition
| Most fossils are formed when an organism is buried in sediment before decomposition occurs. |
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Term
| What are the four types of fossils? |
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Definition
| The four types of fossils are: intact fossils, compression fossils, cast fossils, and premineralized fossils |
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Term
| What are the four types of biases in the fossil record? |
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Definition
Habitat bias
taxonomic bias
temporal bias
abundance bias |
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Term
| What is the explanation for habitat bias in the fossil record? |
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Definition
| Habitat bias occurs because organisms that live in areas where sediments are actively being deposited are more likely to form fossils than are organisms that live in other habitats |
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Term
| What is the explanation for taxonomic bias in the fossil record? |
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Definition
| Taxonomic bias is due to the fact that some organisms (for example those of bones) are more likely to decay slowly and leave fossil evidence |
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Term
| What is the explanation for temporal bias in the fossil record? |
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Definition
| Temporal bias occurs because recent fossils are more common than ancient fossils |
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Term
| What is the explanation for abundance bias in the fossil record? |
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Definition
| Abundance bias occurs because organisms that are abundant, widespread and present on Earth for a long time leave evidence much more often then do species that are rare, local for ephemeral |
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Term
| Which era is known as the age of reptiles? |
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Definition
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Term
| Which era is known as the age of mammals? |
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Definition
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Term
| When did animals first originate? |
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Definition
| Animals first originated around 565 million years ago |
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Term
| How do we know the Cambrian explosion occurred? |
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Definition
| We know the Cambrian explosion occurred because it is documented by three major fossil assemblages that occurred before, during and after the Cambrian explosion |
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Term
| What are the names of the three major or fossil assemblages that document the Cambrian explosion? |
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Definition
- The Doushantuo Microfossils
- The Edicaran Faunas
- The Burgess Shale Faunas |
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Term
| What does a higher number of Hox genes in an organism indicate in terms of evolutionary history? |
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Definition
| A higher number of Hox genes indicates that an organism is more derived than an organism with less Hox genes |
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Term
| How are adaptive radiations depicted on a phylogenetic tree? |
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Definition
| Adaptive radiations are depicted as dense groups of branches, scattered throughout the tree |
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Term
| What are two triggers of adaptive radiations? |
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Definition
| Ecological opportunity and morphological innovation |
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Term
| What organisms studied are a prime example of ecological opportunity as a trigger of adaptive radiation? |
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Definition
| The anolis lizards of the Caribbean islands. On the two islands that were studied, the same for ecological types eventually evolved, because the islands had similar varieties of habitats. |
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Term
| What is a mass extinction? |
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Definition
| A mass extinction is the rapid extinction of a large number of lineages scattered throughout the tree of life. |
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Term
| What causes mass extinctions? |
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Definition
| Mass extinctions are caused by extraordinary, sudden and temporary changes in the environment. |
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Term
| What is the difference between background and mass extinctions? |
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Definition
| Natural selection causes most background extinctions where is mass extinctions are caused by exposure to exceptionally harsh, short-term conditions |
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Term
| What are the qualifying criteria for a mass extinction? (% in what time frame?) |
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Definition
| In mass extinction occurs when at least 60% of the species present are wiped out within 1 million years |
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Term
| What is the main hypothesis for the extinction of dinosaurs? |
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Definition
| The impact hypothesis for the extinction of dinosaurs proposed that an asteroid struck Earth and snuffed out an estimated 60% to 80% of the multicellular species alive |
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Term
| What evidence supports the impact hypothesis for the extinction of dinosaurs? |
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Definition
| Conclusive evidence includes iridium, shocked quartz, and microtektites found in rock layers dated two 65 million years |
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