The Hierarchy of Ecology
The Hierarchy
of Ecology
Ecology is studied as a hierarchy of biological systems in interaction with their environments. At the base of the ecological hierarchy is an organism. To understand why animals are distributed as they are, ecologists must examine the varied physiological and behavioral mechanisms that animals use to survive, grow, and reproduce. A near-perfect physiological balance between production and loss of heat is required for the success of certain endothermic species (such as birds and mammals) under extreme temperatures as found in the Arctic or a desert. Other species succeed in these situations by escaping the most extreme conditions by migration, hibernation, or torpidity. Insects, fishes, and other ectotherms (animals whose body temperature depends on heat in the environment) compensate for fluctuating temperatures by altering biochemical and cellular processes involving enzymes, lipid organization, and the neuroendocrine system. Thus an animal’s physiological capacities permit it to live under changing and often adverse environmental conditions. Behavioral responses are important also for obtaining food, finding shelter, escaping enemies and unfavorable environments, finding a mate, courting, and caring for the young. Physiological mechanisms and behaviors that improve adaptability to the environment assist survival of species. Ecologists who focus their studies at the organismal level are called physiological ecologists or behavioral ecologists.
Animals in nature coexist with others of the same species; these groups are known as populations. Populations have properties that cannot be discovered from studying individual animals alone, including genetic variability among individuals (polymorphism), growth in numbers over time, and factors that limit the density of individuals in a given area. Ecological studies at the population level help us to predict the future success of endangered species and to discover controls for pest species.
Just as individuals do not exist alone in nature, populations of different species co-occur in more complex associations known as communities. The variety of a community is measured as species diversity. The populations of species in a community interact with each other in many ways, the most prevalent of which are predation, parasitism, and competition. Predators obtain energy and nutrients by killing and eating prey. Parasites derive similar benefits from their hosts, but usually do not kill the hosts. Competition occurs when food or space are in limited supply and members of different species interfere with each other’s use of their shared resources. Communities are complex because all of these interactions occur simultaneously, and their individual effects on the whole structure often cannot be isolated.
Ecological communities are biological components of the even larger, more complex entities called ecosystems. An ecosystem consists of all of the populations in a community together with their physical environment. The study of ecosystems helps us to understand two key processes in nature, the flow of energy and the cycling of materials through biological channels. The largest ecosystem is the biosphere, the thin veneer of land, water, and atmosphere that envelopes the great mass of the planet, and that supports all life on earth (see The Biosphere and Animal Distribution).
Ecology is studied as a hierarchy of biological systems in interaction with their environments. At the base of the ecological hierarchy is an organism. To understand why animals are distributed as they are, ecologists must examine the varied physiological and behavioral mechanisms that animals use to survive, grow, and reproduce. A near-perfect physiological balance between production and loss of heat is required for the success of certain endothermic species (such as birds and mammals) under extreme temperatures as found in the Arctic or a desert. Other species succeed in these situations by escaping the most extreme conditions by migration, hibernation, or torpidity. Insects, fishes, and other ectotherms (animals whose body temperature depends on heat in the environment) compensate for fluctuating temperatures by altering biochemical and cellular processes involving enzymes, lipid organization, and the neuroendocrine system. Thus an animal’s physiological capacities permit it to live under changing and often adverse environmental conditions. Behavioral responses are important also for obtaining food, finding shelter, escaping enemies and unfavorable environments, finding a mate, courting, and caring for the young. Physiological mechanisms and behaviors that improve adaptability to the environment assist survival of species. Ecologists who focus their studies at the organismal level are called physiological ecologists or behavioral ecologists.
Animals in nature coexist with others of the same species; these groups are known as populations. Populations have properties that cannot be discovered from studying individual animals alone, including genetic variability among individuals (polymorphism), growth in numbers over time, and factors that limit the density of individuals in a given area. Ecological studies at the population level help us to predict the future success of endangered species and to discover controls for pest species.
Just as individuals do not exist alone in nature, populations of different species co-occur in more complex associations known as communities. The variety of a community is measured as species diversity. The populations of species in a community interact with each other in many ways, the most prevalent of which are predation, parasitism, and competition. Predators obtain energy and nutrients by killing and eating prey. Parasites derive similar benefits from their hosts, but usually do not kill the hosts. Competition occurs when food or space are in limited supply and members of different species interfere with each other’s use of their shared resources. Communities are complex because all of these interactions occur simultaneously, and their individual effects on the whole structure often cannot be isolated.
Ecological communities are biological components of the even larger, more complex entities called ecosystems. An ecosystem consists of all of the populations in a community together with their physical environment. The study of ecosystems helps us to understand two key processes in nature, the flow of energy and the cycling of materials through biological channels. The largest ecosystem is the biosphere, the thin veneer of land, water, and atmosphere that envelopes the great mass of the planet, and that supports all life on earth (see The Biosphere and Animal Distribution).
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