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42 Cards in this Set
- Front
- Back
taxonomy |
science of describing, naming, and classifying living organisms |
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systematics |
study of biological diversity and the evolutionary relationships among organisms |
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extant |
species still alive |
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extinct |
no species no longer alive |
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taxonomic group |
hypotheses regarding evolutionary relationships from systematics |
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taxon |
each group at any level |
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domain |
the three domains that ALL life fall under: bacteria, archaea, and eukarya |
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supergroup |
lies between a domain an kingdom |
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the seven supergroups |
excavata land plants and relatives alveoloata stramenopila rhizaria amoebozoa opisthokonta (fungi and animalia)
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the taxonomic hierarchy |
1. domain 2. supergroup 3. kingdom 4. phylum 5. class 6. order 7. family 8. genus 9. species
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binomial nomenclature |
how species are named
genus and species name used, genus is capitalized and species lowercase |
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phylogeny |
the evolutionary history of a species or a group of species, using systematics
based on morphological or genetic data
always a hypothesis |
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phylogenetic tree |
hypothesis of evolutionary relationships |
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cladogenesis |
a species that diverges into 2 or more species |
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clade |
all species that derive from a common ancestor |
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anagensis |
one species evolve into a different species |
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extinct and extant species on a phylogenetic tree |
extinct are at the bottom and middle while extant are always on top |
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monophyletic |
a group that contains a common ancestor and ALL of its descendants (a clade) |
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paraphyletic group |
a group that contains a common ancestor but doesn't have all of its descendants |
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polyphyletic group |
groups species with different common ancestors but may be classified together because they have a similar characteristic that developed convergently |
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what group to taxonomists usually recognize and classify? |
monophyletic groups |
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systematics based on homolgy |
similarities song species occur because they are derived from a common ancestor; can be morphological, developmental, or genetic |
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what did the first studies of systematics focus primarily on? |
morphological features; but this was troublesome because of convergent evolution due to some species not being related at all but having similar characters |
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molecular systematics |
studies genetic homologies and propose phylogenetic trees
looks at DNA and amino acid sequences |
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reversal |
when a DNA section is deleted in a species but them reinserted later on in an evolutionary descendent; the character state has been regained |
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cladistics |
compares homologous traits which exist in two or more states
based on evolutionary relationships
chooses the least complex explanation |
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cladogram |
a diagram based off cladistics, is the least complex of all the options based on evolutionary relationships
can also be constructed using gene sequences change in gene = modification in character |
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characters |
features of a species |
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branch point |
where two species will differ in shared derived characters |
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shared primitive character |
inherited from ancestors older than last common ancestor |
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shared derived character |
originated in most recent common ancestor |
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ingroup |
the group whose evolutionary relationships are being evaluated |
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outgroup |
a species or group that is assumed to have diverged before the species of the ingroup so they are not being analyzed |
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how to construct a cladogram |
1. determine polarity of character states between primitive and derived
2. group taxa by shared derived characters and they should only appear once unless convergent evolution occurred
3. choose the most likely, simplest option |
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principle of parsimony |
the preferred hypothesis of a cladogram is the one that is the simplest for all the characters and their states |
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molecular clocks |
nucleotide differences used to estimate time since divergence
more time since divergence = greater accumulation of mutations |
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linearity of a molecular clock |
not very linear, due to difference in generation times and variation in mutation rates |
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rapidly evolving genes |
are useful for studying closely related species |
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slowly evolving genes |
are useful for studying evolution over long periods |
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vertical evolution |
hanges in groups due to descent from common ancestor |
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neutral theory of evolution |
proposes that most genetic variation that exists in populations is due to the accumulation of neutral mutations that are not acted upon by natural selection |
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horizontal gene transfer |
an organism incorporates genetic material from another organism without begin the offspring of the organism
common in prokaryotes (bacteria and archaea gave rise to chloroplasts and mitochondria) |