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Phylogenies and Evolutionary Misconceptions (Common Evolutionary…
Phylogenies and Evolutionary Misconceptions
Phylogeny: The evolutionary history of relationships among organisms
Monophyletic group: All descendants and the common ancestor
Can be created with one single cut of a phylogenetic tree
Horizontal gene transfer: Chunks of a genome or a single gene moving between not closely related organisms
Can complicate phylogenies because they are made using genetic data
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Homologous trait: A trait shared between two organisms due to a common ancestor
e.g. Similar bone structure in appendages of mammals and birds
Common ancestor has these same bones
Convergent trait: A superficially similar trait (not inherited) that evolved separately due to similar selective pressures
The common ancestor looked nothing like the two organisms
Some traits have elements of both a homologous and convergent trait
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e.g. Bats and birds evolved wings for flight separately, but bones in them are homologous
Ancestral trait: Trait that was present in the common ancestor of the group
Always relative to a certain lineage (unlike homologous and convergent)
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Derived trait: Trait that differs from one common ancestor had and only present in a subset of the group
All lineages (and specific species) are a mix of derived and ancestral traits
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Common Evolutionary Misconceptions
Evolution does not rely entirely on chance and randomness
Mutation and genetic drift are random, but selection is not
Species do not have discrete boundaries
Gene flow between what we define as species may be able to occur for some time
Natural selection and evolution are not the same thing
Every other evolutionary force besides selection is non-adaptive
Not all evolved traits are adaptations
Trait could have been shaped by a non-adaptive force, or been favored in a past environment but is no longer favored