Chapter 50 An Introduction to Ecology and the Biosphere Overview The Scope of Ecology Ecology is the scientific study of the interactions between organisms and their environment Concept 50 1 Ecology is the study of interactions between organisms and the environment Ecologists ask questions about factors affecting the distribution and abundance of organisms Ecologists might study how interactions between organisms and the environment affect the number of species living in an area the cycling of nutrients or the growth of populations Natural history remains a fundamental part of the science of ecology Ecology and evolutionary biology Ecology has a long history as a descriptive science Modern ecology is also a rigorous experimental science decades to millennia Ecology and evolutionary biology are closely related sciences Events that occur over ecological time minutes to years translate into effects over evolutionary time For example hawks feeding on field mice kill certain individuals over ecological time reducing population size an ecological effect altering the gene pool an evolutionary effect and selecting for mice with fur color that camouflages them in their environment over evolutionary time The environment of any organism includes the following components Organisms and the Environment Abiotic components nonliving chem and physical factors such as temperature light water and Biotic components all living organisms in the individual s environment nutrients Biota all of the organisms Subfields of Ecology Includes disciplines of physiological ecology evolutionary ecology and behavior ecology Population ecology concentrates mainly on factors that affect how many individuals of a particular species Organismal ecology is concerned with the behavioral physiological and morphological ways individuals interact with the environment A population is a group of individuals of the same species living in a particular geographic area live in an area A community consists of all the organisms of all the species that inhabit a particular area it is an assemblage of populations of many different species Community ecology examines the interactions between species in a community and considers how factors such as predation competition disease and disturbance affect community structure and organization An ecosystem consists of all the abiotic factors in addition to the entire community of species that exist in a certain area components Ecosystem ecology studies energy flow and cycling of chemicals among the various abiotic and biotic Landscape ecology deals with arrays of ecosystems and their arrangement in a geographic region Each landscape or seascape consists of a mosaic of different types of patches an environmental characteristic ecologists refer to as patchiness The biosphere is the global ecosystem the sum of all of the planet s ecosystems The biosphere includes the entire portion of Earth inhabited by life ranging from the atmosphere to a height of several kilometers to the oceans and water bearing rocks to a depth of several kilometers Ecology and Environmental Issues It is important to clarify the difference between ecology the scientific study of the distribution and abundance of organisms and environmentalism advocacy for the protection or preservation of the natural environment environment population declines in many nontarget organisms or extinct species are just a few of the problems that threaten the Earth To address environmental problems we need to understand the interactions of organisms and the In 1962 Rachel Carson s book Silent Spring warned that the use of pesticides such as DDT was causing Today acid precipitation land misuse toxic wastes habitat destruction and the growing list of endangered The science of ecology provides that understanding 1 are introduced purpose It is important to communicate the scientific complexity of environmental issues Many influential ecologists feel a responsibility to educate legislators and the general public about decisions that affect the environment Our ecological information is always incomplete decision making on environmental issues Concept 50 2 Interactions between organisms and the environment limit the distribution of species Biogeography is the study of past and pres distrib of individual species in the context of evolutionary The precautionary principle essentially an ounce of prevention is worth a pound of cure can guide Ecologists have long recognized distinct global and regional patterns in the distribution of organisms Ecologists ask a series of questions to determine what limits the geographical distribution of any species Biogeography provides a starting point for understanding what limits the geographic distribution of a theory species The movement of individuals away from centers of high population density or from their area of origin The dispersal of organisms is crucial to understanding geographic isolation in evolution and the broad Dispersal and Distribution called dispersal contributes to the global distribution of organisms patterns of geographic distribution of species Species Transplants One way to determine if dispersal is a key factor limiting distribution is to observe the results when humans have accidentally or intentionally transplanted a species to areas where it was previously absent For the transplant to be considered successful the organisms must not only survive in the new area but also reproduce there If the transplant is successful then the potential range of the species is larger than its actual range Species introduced to new geographic locations may disrupt the communities and ecosystems to which they Consequently ecologists rarely conduct transplant experiments today Instead they study the outcome when a species has been transplanted accidentally or for another Behavior and Habitat Selection Sometimes organisms do not occupy all of their potential range but select particular habitats Does behavior play a role in limiting distribution in such cases Habitat selection is one of the least understood ecological processes but it appears to play an important role in limiting the distribution of many species Biotic Factors Do biotic factors limit the distribution of species Negative interactions with other organisms in the form of predation parasitism disease or competition may limit the ability of organisms to survive and reproduce Predator removal experiments can provide information about how predators