Term
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Definition
| a hypothesis about evolutionary relationships |
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Definition
| represents the divergence of two species (or groups of species) |
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Definition
| a branch from which more than two groups emerge |
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Definition
| a group where more than two species arose (came into being) simultaneouslty |
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Definition
| there is insufficient data to resolve relationships |
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Definition
a group of species that includes a common ancestor and all of its descendants
WHAT YOU WANT |
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Definition
a group of species that includes an ancestral species and only some of its ancestors
some feel this is ok, others don't |
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Definition
a group that includes species with many different ancestors
this is NOT a good way to classify
often occurs due to incomplete info |
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Term
| evolutionary species concept |
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Definition
| a species is a single lineage (an ancestor-descendant lineage) populations of organisms that MAINTAINS AN IDENTITY separate from other such lineages which HAS ITS OWN EVOLUTIONARY FATE |
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Term
| phylogenetic species concept |
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Definition
a phylogenetic species is an irreducible (basal) cluster of organisms that is diagnosably distinct from other such clusters, and within which there is a parental pattern of ancestry and descent OR
a species is the smallest monophyletic group of common ancestry |
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Term
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Definition
| reproductively isolated species that are difficult to distinguish by morphological characteristics |
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| phylogenetic species concept |
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Definition
FOCUSES ON THE OUTCOME OF HISTORICAL EVOLUTIONARY PROCESSES
useful for sexual and asexual lineages (mostly)
results from fixation of genetic differences |
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Term
| biological species concept |
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Definition
| species are groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups |
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Term
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Definition
a region were closely related species overlap and hybridize
LIMITATION OF THE BSC |
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Term
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Definition
| prevent the formation of a zygote |
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Term
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Definition
| prevent (or reduce the likelihood of) mating from occurring thereby preventing the transfer of inter-specific gametes. |
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Term
| postmating, prezygotic barriers |
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Definition
| gametes are transferred but fertilization/zygote transformation does not occur |
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Definition
| hybrid zygotes are formed but have reduced fitness |
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Definition
| accounts for more than 95% of isolation in most species; most important |
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Term
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Definition
| prezygotic barrier; a plant that flowers in spring can't pollinate a plant that flowers in the fall |
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Term
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Definition
| prezygotic barrier; a plant that lives in one habitat won't be close enough to plants that live in a different habitat |
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Definition
| prezygotic barrier; animals do alot of strange things to attract a suitable mate of the proper species; plants manipulate the behavior of animals |
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Term
| prevention of pollen germination |
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Definition
| postmating/prezygotic barrier; pollen deposited on stigma, but prevented from germinating (no pollen tube, no mitosis of generative cell) |
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Term
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Definition
| postmating/prezygotic barrier; prevents pollen from other species from reaching the eggs; it allows only the most fit sperm to fertilize the egg |
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Term
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Definition
| postmating/prezygotic barrier; failure of egg and sperm to unite |
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Term
| intrinsic hybrid inviability |
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Definition
| postzygotic barrier; failure to develop (embryo/seed aborts); viable crosses often will work one way but no the other |
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Term
| extrinsic hybrid inviability |
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Definition
| postzygotic barrier; can't compete in parental populations; may be viable in intermediate, disturbed, or extreme habitat |
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Term
| reciprocal translocations |
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Definition
| exchange between non homologous chromosomes |
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Term
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Definition
| theory that: genetic drift reults (ultimtely) in the loss of all gene copies except one; how quick depends on population size |
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Definition
| the process of sorting of gene lineages into species; closely related species may share ancestral polymorphisms |
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Definition
| populations occupying separate geographical areas |
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Definition
| populations occupying adjacent geographic areas, meeting at the border |
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Definition
| populations occupying the same geographic area and capable of encountering one another |
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Definition
| members of the same species |
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Term
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Definition
| means that any of the several biological differences between populations greatly reduces gene exchange between them, even they aren't geographically separated |
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