Fixed Species Tree
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FIXED SPECIES TREE. Quercus agrifolia, Coast live oak.
South side of Serra Street in front of Encina Hall.
In evolutionary models of gene lineages evolving in a set of species, it is useful to treat the tree of species relationships — the species tree — as a fixed parameter. The gene lineages are viewed as evolving randomly conditional on the fixed species tree, in a manner specified by the evolutionary model. As is the case for this "fixed" coast live oak, the fixed species tree constrains the evolutionary possibilities for the gene lineages.
Photo: Noah Rosenberg, June 20, 2018