78. The dynamics of any subpopulation within a metapopulation differs from-that of a normal
    population in that the
    (1) birth rates are lower than the death rates.
    (2) death rates are lower than the birth rates.
    (3) immigration and emigration rates are significantly higher.
    (4) immigration and emigration rates are negligible.

Introduction

In ecology, the concept of a metapopulation describes a group of spatially separated populations of the same species that interact through dispersal. Unlike isolated, normal populations, subpopulations within a metapopulation experience unique dynamics shaped by migration. Understanding these differences is critical for conservation biology, species persistence, and managing fragmented habitats.

What Is a Metapopulation?

A metapopulation consists of multiple local populations (subpopulations) occupying discrete habitat patches. Each subpopulation may fluctuate in size, go extinct, or be recolonized over time. The overall metapopulation persists through a balance of local extinctions and recolonizations, facilitated by movement of individuals between patches.

Key Difference: Immigration and Emigration Rates

The dynamics of subpopulations within a metapopulation differ from those of isolated populations primarily because:

• Immigration: Individuals move into a subpopulation from other patches.

• Emigration: Individuals leave a subpopulation to colonize or bolster others.

These movements are significantly higher in subpopulations compared to isolated populations, where immigration and emigration are negligible or absent.

Why Are Immigration and Emigration Important?

• Rescue Effect: Immigration can prevent local extinction by supplementing declining populations.

• Colonization: Emigration allows species to recolonize empty or newly suitable habitats.

• Genetic Diversity: Movement between subpopulations maintains genetic variation, reducing inbreeding risks.

• Population Stability: High connectivity through dispersal buffers against environmental fluctuations affecting individual patches.

Contrast with Normal Populations

In a normal, isolated population:

• Birth and death rates primarily drive population dynamics.

• Immigration and emigration are negligible or absent.

• The population is more vulnerable to extinction due to demographic and environmental stochasticity.

In contrast, subpopulations within a metapopulation rely heavily on dispersal to maintain persistence despite local extinctions.

Conclusion

The defining characteristic of subpopulations within a metapopulation is that immigration and emigration rates are significantly higher than in normal populations. This connectivity allows metapopulations to persist over time through a dynamic balance of extinction and recolonization, making them a vital concept in ecology and conservation.

Correct answer:
(3) Immigration and emigration rates are significantly higher.