The evolutionary mechanism of migration involves the contribution of the genetic inheritance of migrating individuals

a
to only the genetic makeup of an existing population of the same species.
b
to only the genetic makeup of an existing population of a new species.
c
to the genetic makeup of only one generation of an existing population of the same species.
d
to the genetic makeup of an existing population of the same species and a new, different species.

a. to only the genetic makeup of an existing population of the same species.