Assertion: cosmic ray's source | /r/HasProperty | migration
Facets:
Source sentences:
text: The primary sources of evolution are migration (as organisms move into/out of populations they bring with them alternative alleles of genes, and if these are more favorable they will be selected for), Genetic Drift (chance: if there is a tornado that wipes out part of a population, the genetic makeup of the survivors could be greatly different from the original population), and Natural Selection (defined as nonrandom differential reproduction of individuals, for example if the girls all want blue-eyed boys, then the boys with eyes of other colors won't get to reproduce and pass on their genes, and soon all boys will be blue-eyed).