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BIOL212.CH27
CH27 Phylogenies and the History of Life
| Question | Answer |
|---|---|
| define phylogeny. | The evolutionary history of a group of organisms. |
| the purpose of a phylogenetic tree is: _____ | a phylogenetic tree shows ancestor–descendant relationships among populations or species. |
| a monophyletic group is defined as ___ and is also called a ___ or ____. | a monophyletic group is an ancestor and all its descendants. AKA clade or lineage |
| these parts of a phylogenetic tree represent the tree's endpoints and represent living groups or a group’s end in extinction. | tips |
| these parts of a phylogenetic tree represent populations through time. | branches |
| these parts of a phylogenetic tree represent taxonomic group/s that diverged before the rest of the taxa being studied. | outgroup/s |
| a node in a phylogenetic tree where more than two descendant groups branch off is a ______. | polytomy |
| these parts of a phylogenetic tree represent any named group of organisms. | taxon |
| the most ancient node of the tree is shown at the bottom in this type of phylogeny. | rooted phylogenies |
| these parts of a phylogenetic tree represent poulations through time. | branches. |
| what are sister taxa in a phylogenetic tree? | adjacent branches. |
| these parts of a phylogenetic tree represent where an ancestral group split into two or more descendant groups. | Nodes |
| How are phylogenetic relationships among species estimated? | using Morphological and/or genetic characteristics. |
| What are synapomorphies? | synapomorphoses are the shared derived characters of the species under study; trait/s that certain populations or species have that no others have. The cladistic approach to inferring trees focuses on synapomorphies. |
| The phenetic approach to estimating Phylogenies is based on ____? | the overall similarity among populations. |
| This problem with both cladistic and phenetic analysis occurs when traits are similar for reasons other than common ancestry. (ex: dolfin-like dinosaurs) | Homoplasy |
| This problem with both cladistic and phenetic analysis occurs when traits are similar due to shared ancestry | Homology |
| Explain Convergent evolution, which is a common cause of homoplasy: | convergent evolution occurs when natural selection favors similar solutions to the problems posed by a similar way of making a living. |
| This principle of logic states that the most likely explanation or pattern is the one that implies the fewest overall evolutionary changes. | Parsimony |
| What are SINES? | short interspersed nuclear elements that can be shared derived traits (synapomorphies), ex: supporting the hypothesis that whales and hippos are indeed closely related. |
| List some limitations of the fossil record: | habitat bias, taxonomic bias, temporal bias, and abundance bias. |
| In this era, almost all life was unicellular and hardly any oxygen was present. | Precambrian |
| Many animal groups—including fungi, land plants, and land animals—appeared in this era. | Paleozoic era. |
| This era is aka the Age of Reptiles, and ended with the extinction of the dinosaurs. | Mesozoic era |
| This era is known as the Age of Mammals. | The Cenozoic era |
| This era encompasses the Hadean, Archaean, and Proterozoic eons. | Precambrian era |
| The 4 eras are: | the Precambrian, the Paleozoic, the Mesozoic, and the Cenozoic |
| List Four types of fossils. | intact fossils, compression fossils, cast fossils, and premineralized fossils. |
| Limitations of the Fossil Record: define Habitat bias. | 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. |
| Limitations of the Fossil Record: define Taxonomic bias. | Taxonomic bias is due to the fact that some organisms (e.g., those with bones) are more likely to decay slowly and leave fossil evidence. |
| Limitations of the Fossil Record: define Temporal bias. | Temporal bias occurs because more recent fossils are more common than ancient fossils. |
| Limitations of the Fossil Record: define Abundance bias. | Abundance bias occurs because organisms that are abundant, widespread, and present on Earth for a long time leave evidence much more often than do species that are rare, local, or ephemeral. |
| Paleontologists' (scientists who study fossils) limitations: | they are limited to asking questions about tiny and scattered segments on the tree of life, but analyzing fossils is the only way scientists have of examining the physical appearance of extinct forms and inferring how they lived. |
| The Doushantuo Microfossils were: | sponges, cyanobacteria, early animal embroys and multicellular algae in samples dated 570–580 Mya. |
| The Edicaran Faunas were: | Sponges, jellyfish, comb jellies, and traces of other animals dated 544–565 Mya are found in fossils from the Ediacara Hills of Australia. |
| The Burgess Shale Faunas included: | fossils datin 525–515 Mya indicated a tremendous increase in the size and morphological complexity of animals, accompanied by diversification in how they made a living. |
| What is a gene duplication event? | Duplication of Hox genes has been important in making the elaboration of animal body plans possible. However, changes in expression and function of existing genes have been equally or even more important. |
| Explain Hox genes in animal lineage | an strong association between the order in which animal lineages appeared during evolutionary history, the number of Hox genes present in each lineage, and each lineage's morphological complexity and body size. |
| What do star phylogenies/adaptive radiation represent? | major diversification over a relatively short period of time. The Cambrian explosion can be considered an extremely large–scale adaptive radiation. |
| What triggers are there for adaptive radiation? | ecological opportunity and morphological innovation |
Created by:
boborii