Term
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Definition
| the evolutionary history of a group of organisms |
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Term
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Definition
| a graphical summary of a phylogeny, showing the ancestor-descendent relationships among populations, species, or higher taxa, and clarifying who is related to whom |
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Term
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Definition
| the most universal of all phylogenetic trees, depicting the evolutionary relationships among all living organisms on Earth |
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Term
| branches on the left of a phylogenetic tree are more _____, while the ones on the right are more _____ |
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Definition
| ancient/ancestral; recent/derived |
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Term
| what do nodes represent on a phylogenetic tree? |
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Definition
| hypothetical common ancestors |
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Term
| where are taxa located on a phylogenetic tree? |
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Definition
| on the branch tips, never within the tree |
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Term
| node/fork on a phylogenetic tree |
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Definition
| a point within the tree where a branch splits into two or more branches |
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Term
| outgroup on a phylogenetic tree |
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Definition
| a taxon that diverged prior to the taxa that are the focus of the study; closely related to the group being studied, but not part of it |
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Term
| root on a phylogenetic tree |
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Definition
| the most ancestral branch in the tree |
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Term
| polytomy on a phylogenetic tree |
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Definition
| a node that depicts an ancestral branch dividing into three or more descendent branches |
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Term
| tip/terminal node on a phylogenetic tree |
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Definition
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Term
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Definition
| any genetic, morphological, physiological, or behavioral characteristic to be studied |
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Term
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Definition
| a characteristic that existed in an ancestor |
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Term
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Definition
| a characteristic that is a modified form of the ancestral trait, found in a descendent |
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Term
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Definition
| based on the principle that relationships among species can be reconstructed by identifying shared derived characters |
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Term
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Definition
| a trait found in two or more taxa that is present in their most recent common ancestor but is missing in more distant ancestors; a shared, derived trait |
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Term
| monophyletic group/clade/lineage |
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Definition
| an evolutionary unit that includes an ancestral population & all of its descendants, but no others |
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Term
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Definition
| similarity in organisms due to common ancestry |
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Term
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Definition
| similarity in organisms due to reasons other than common ancestry |
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Term
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Definition
| natural selection favors similar solutions to the problems posed by a similar way of making a living in different species |
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Term
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Definition
| a piece of physical evidence from an organism that lived in the past |
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Term
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Definition
| the total collection of fossils that have been found throughout the world |
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Term
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Definition
| scientists who study fossils |
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Term
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Definition
| the interval between the formation of Earth about 4.6 billion years ago & the appearance of most animal groups about 542 million years ago |
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Term
| 2 main points about Precambrian |
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Definition
1. life was exclusively unicellular for most of Earth's history
2. oxygen was virtually absent from the oceans & atmosphere for almost 2 billion years after the origin of life |
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Term
| 3 eras of the Phanerozoic |
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Definition
1. Paleozoic era: begins with the appearance of most major animal lineages & ends with the obliteration of almost all multicellular life-forms at the end of the Permian period
2. Mesozoic era: begins with the end-Permian extinction events & ends with the extinction of the dinosaurs & other groups at the boundary between the Cretaceous period & the Paleogene period
3. Cenozoic era: the Paleogene, Neogene, & Quaternary periods |
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Term
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Definition
| when a single lineage rapidly produces many descendant species with a wide range of adaptive forms |
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Term
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Definition
| collection of animal species |
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Term
| 4 hypotheses for reason behind the Cambrian explosion |
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Definition
1. higher oxygen levels
2. the evolution of predation
3. new niches beget more new niches
4. new genes, new bodies |
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Term
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Definition
| the rapid extinction of a large number of lineages scattered throughout the tree of life |
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Term
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Definition
| the lower, average rate of extinction observed when a mass extinction is not occurring |
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Term
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Definition
| an asteroid struck Earth & snuffed out an estimated 60-80% of the multicellular species alive |
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