Mendel carried out dihybrid crosses by crossing two pea plants differing in contrasting traits of two characters.
For example he crossed a pea plant having yellow coloured and round seed with another pea plant bearing green coloured and wrinkled seed. In the F2 generation, he got the pea plants with two parental and two recombinant phenotypes as yellow round and green wrinkled (parental) and yellow wrinkled and green round (recombinant). This indicated that traits separated from their original parental combinations and got inherited independently.
Darwin's Theory of Evolution is the widely held notion that all life is related and has descended from a common ancestor. Darwin's general theory presumes the development of life from non-life and stresses a purely naturalistic (undirected) "descent with modification". That is, complex creatures evolve from more simplistic ancestors naturally over time. So as random genetic mutations occur within an organism's genetic code, the beneficial mutations are preserved because they aid survival -- a process known as "natural selection." These beneficial mutations are passed on to the next generation. Over time, beneficial mutations accumulate and the result is an entirely different organism.