The wing of a bird and the arm of a human are examples of ___________ structures.
The only source of new alleles in a species is ___________.
The word "theory" in theory of evolution is best replaced by ___________.
"Survival of the fittest," or the reproductive advantage in individual who inherit traits that help it
adapt to a changing environment was something Darwin called ___________.
Two populations of crickets have stopped interbreeding over time, although they reside in the
same geographic region. What is one possible explanation?
Allopatric speciation is to geography as ___________ speciation is to genetic change.
Genetic variation is accomplished by all but one of the following. Which one is it?