Final answer:
It is adaptive for seeds to remain dormant to ensure germination occurs under optimal conditions for survival. Dormancy allows seeds to tolerate harsh environmental conditions and to be dispersed over time, securing their enduring success and expansion into new habitats. The key role in inducing dormancy is played by the hormone abscisic acid, and the dormancy ends when favorable conditions return.
Step-by-step explanation:
Seed Dormancy and Its Adaptive Significance
It is adaptive for some seeds to remain dormant before they germinate to enhance the chances of survival and successful propagation. Seed dormancy helps seeds withstand unfavorable conditions, such as extreme temperatures, desiccation, or lack of sunlight, by maintaining a state of low metabolic activity. This dormancy can last months, years, or even decades, allowing seeds to germinate under the most favorable conditions for the seedling’s survival. For example, certain seeds may require vernalization (cold treatment) before they germinate, ensuring that they do not sprout during a warm spell in winter only to be killed by subsequent frosts. Similarly, seeds with a thick coat may undergo scarification for successful germination.
The hormone abscisic acid (ABA) promotes seed dormancy, and various environmental cues trigger the end of dormancy and the start of germination. As a result, seeds are highly adapted for dispersal through space and time, giving them an evolutionary advantage over their non-seed counterparts. With stored food for nourishment and a protective coat, seeds are primed to introduce the plant species into new ecological niches when conditions are right.