The interactions between human population dynamics and the environment have often been viewed mechanistically. This review elucidates the complexities and contextual specificities of population-environment relationships in a number of domains. It explores the ways in which demographers and other social scientists have sought to understand the relationships among a full range of population dynamics (e.g., population size, growth, density, age and sex composition, migration, urbanization, vital rates) and environmental changes. The chapter briefly reviews a number of the theories for understanding population and the environment and then proceeds to provide a state-of-the-art review of studies that have examined population dynamics and their relationship to five environmental issue areas. The review concludes by relating population-environment research to emerging work on human-environment systems.
Competition is an interaction between organisms or species in which both the organisms or species are harmed. Limited supply of at least one resource (such as food, water, and territory) used by both can be a factor.
A reflex arc is a neural pathway that controls a reflex action. In a simple spinal reflex, the pathway for an impulse is along a sensory neuron directly to a motor neuron through an interneuron because an interneuron enables communications (i.e a pathway for information passage) between a sensory neuron and motor neuron. They play vital roles in reflex actions, neuronal oscillations, neurogenesis in an adult mammalian vertebrate brain.
