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lecture 9
ch9
| Question | Answer |
|---|---|
| evolution | accumulated inherited changes in a population over time |
| population | group of individuals of the same species living in the same location (interbreed to produce offspring within same species) |
| microevolution | short term adaptations that result from changes in the environment (changes in allele frequency) |
| macroevolution | process of development of new species from common ancestors |
| phylogeny | the history of descent with branching and is much like the genealogy that records our own family histories |
| phylogenetic tree | process of speciation can be depicted where branches represent diverging populations, hypothesis of the evolutionary relationships amongs organisms |
| nodes | the points in which they branch off, last common ancestor |
| the branching order found in a phylogenetic tree | hypothesizes the evolutionary relationship within a group |
| taxons | two groups, considered to be each others closest relatives if they share a common ancestor not shared by any other group |
| sister groups | two groups that are each others closest relatives |
| a node can be | rotated without changing the evolutionary relationships of the groups |
| rotating nodes | does not hcnage the implied relationship |
| monophyletic group | common ancestor and all of it descendants |
| paraphyletic group | common ancestor and some, but not all, of its descendants |
| polyphyletic group | does not include the common ancestor |
| only monophyletic groups | reflect evolutionary relationships because includes all descendants of a common ancestor |
| order levels | kingdom, phylum, class, order, family, genus, species |
| characters | features such as anatomical, physiological, or molecular features that make up an organism are compared |
| common descent | from an ancestor that had the same character state |
| convergent evolution | character state evolved independently in two separate groups |
| character states | characters have several observed conditions |
| homologous | characters that are similar because of common descnet |
| homoplasy (or analogy) | similarities due to adaptations by different species |
| synapomorphies | only shared derived characters, shared by some but not all of the members of the group under consideration |
| synapomorphies are | useful in constructing phylogenetic tree |
| cladistics | phylogenetic reconstruction on the basis of synpomorphies |
| outgroup | a group that we know falls on an earlier branch in the tree, believed to be closely related and compared |
| principle of parsimony | best fit tree with fewest number of changes, minimizes the total number of independent origin of character state, basically a perfect tree |
| we can also determine phylogeny based on | distance rather than synapomorphies |
| using molecular data, | compare species to an outgroup and generate a phylogeny based on synapomorphies |
| low distance indicates the | recency of common ancestry |
| unequal rates of evolution | result in incorrect phylogenetic relationships |
| rate constance of evolution | less likely to be violated when using molecular (instead of morphological) data |
| fossils | calibrate phylogenies in terms of time, record ectinxtspeces, evolutionary events in history |
| molecular fossils of | DNA, proteins, and lipids |
| burgess shale | sedimentary rock formation in deep sea floor 505 mya, marine life is more completely sampled than land sampled creatures |
| messel shale | 50mya, in a lake, retained impressions of fur and color patterning. |
| half life | half of carbon-14 decay in 5730, useful dating material syounger than 50,000 to 60,000 |
| older samples rely on | the radioactive decay of uranium or lead |
| pangea | 290mya clustered in a supercontinent but distributed widely over the planet's surface |
| biogeography | the study of the distribution of species and ecosystems in geographic space and through geological time |
| phylogenies hypothesize | impressive morphological and physiological shifts through time |
| archaeopteryx | lived 150mya, shares many characteristics with dromaeosaurs, preserved evidence of feathers, a finding that suggest a close relationship between birds and dinosaurs |
| tiktaalik | fins, scales, and gills, like fish, wrist bones, fingers, an amphibian like skull, and a true neck, like tetrapods |
| mass extinction at the end of the Cretaceous Period | eliminated dinosaurs (except birds) and made way for the age of mammals |
| the disadvantage of using comparative biology is that | we lack evidence of extinct species, the time dimension, and environmental context |
| molecular clock | calibrated using fossils and the estimated timing of the formation of the isthmus of panama to reconstruct the evolutionary relationships of pteropods |
| australopithecus afarensis (Lucy) | a mix of ancestral and derived characters, provide strong suppport for our phylogenetic tree, shows that humans and chimpanzes are sister taxa |
Created by:
jcava141
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