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:
- They cannot interbreed in nature
- They are reproductively distinct
- They are physiologically distinct
- They are morphologically distinct
The Correct Option is A
Solution and Explanation
The primary reason for considering Nicotiana sylvestris and Nicotiana tabacum as separate species is indeed that they cannot interbreed in nature due to their different flowering responses to photoperiods.
So, the correct option is (A): They cannot interbreed in nature
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Concepts Used:
Photoperiodism
Photoperiodism, the functional or behavioral response of an organism to changes of duration in daily, seasonal, or yearly cycles of light and darkness. Photoperiodic reactions can be reasonably predicted, but temperature, nutrition, and other environmental factors also modify an organism’s response. In animals, the regular activities of migration, reproduction, and the changing of coats or plumage can be induced out of season by artificially altering daylight. Birds, for example, have migrated north in the winter after having been exposed to reversed seasonal lighting in laboratories.