Introduction

Population growth is the result of a balance between biotic potential and environmental resistance. What do these terms mean, and what are the basic patterns of growth of natural populations?

Density-dependent mechanisms help to regulate natural populations. Explain density-dependence and density-independence, and apply the concept of critical number.

Predators, parasites, and grazers are important in controlling populations. Explain how they can operate in a density-dependent manner.

The introduction of a foreign species frequently has disruptive ecological results. Explain why this is the case. Give examples.

Competition between species can be an important check on populations. How is competition between plant species minimized by different plant adaptations and a balanced herbivory?

In nature, we find that each species is remarkably adapted to the factors of the ecosystem in which it exists. What does this imply about the "moldability" of species?

Natural selection can lead to the development of new species. How does this occur? What are the prerequisites and limitations?

In the face of environmental changes, some species will survive, whereas others will become extinct. What attributes influence the survival of a species?

Loss of biodiversity undercuts the ability of species, ecosystems, and agriculture to adapt to changing conditions. Why is this the case?

Natural ecosystems may undergo gradual succession until they reach a climax, or a more stable state of ongoing adaptation. What is meant by succession, and what factors are responsible?

Fire is a major form of disturbance to terrestrial ecosystems. Of what significance are disturbances, and what role can they play in maintaining high levels of biodiversity?

Replenishment of nutrients, regrowth of plant cover, and succession to a forest can all be thought of as resilience mechanisms. Explain the concept of resilience in ecosystems. Give examples.

The major ecological imbalance on Earth is between the human species and the rest of Earth's biota. What will be the probable consequences of not achieving a balance? What directions can be taken toward achieving a balance?