$A$ trait in an organism is influenced by

There is an inbuilt tendency to variation during reproduction,both because of errors in $DNA$ copying,and as a result of sexual reproduction.

Study the following cross showing self-pollination in $F_1$ generation,fill in the blank,and answer the question that follows:
Parents: $RRYY \times rryy$
(Round,yellow) (Wrinkled,green)
$F_1$: $RrYy \times$ ?
(Round,yellow)

Which organism can change its sex?

New species may be formed if
$(i)$ $DNA$ undergoes significant changes in germ cells
$(ii)$ chromosome number changes in the gamete
$(iii)$ there is no change in the genetic material
$(iv)$ mating does not take place

All human races,such as Africans,Asians,Europeans,Americans,and others,might have evolved from a common ancestor. Provide a few pieces of evidence in support of this view.