$A$ system of classification in which a large number of traits are considered is

$Nicotiana \ sylvestris$ flowers only during long days and $N. \ tabacum$ flowers only during short days. If raised in the laboratory under different photoperiods,they can be induced to flower at the same time and can be cross-fertilized to produce self-fertile offspring. What is the best reason for considering $N. \ sylvestris$ and $N. \ tabacum$ to be separate species?

The scientific name of maize is .........

The scientific name of Mahua is ......... .

The biological species concept emphasizes on:

Which species concept was proposed by Ernst Mayr?