Opportunities in Biology (1989) / Chapter Skim
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9. Ecology and Ecosystems
9. Ecology and Ecosystems
Pages 287-322
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From page 287... ...
The earliest ecological studies were those by naturalists interested in organisms and their relations to their environments, and this kind of work remains the core of basic research in ecology. Ecologists must be concerned with all levels of biological organization: cells, organisms, populations, communities, ecosystems, landscapes, and the biosphere.
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From page 288... ...
Nevertheless, several important principles exist. Central among these is evolutionary theory, which describes the ways natural selection, stochastic factors, and historical constraints have interacted to determine the patterns we see in nature.
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From page 289... ...
Such knowledge can then be applied directly to evaluate potential new crops as well as to develop kinds of plants and related agricultural practices that are efficient at using limited water and nutrient resources. As discussed in more detail in a later section, anthropogenic environmental changes also produce stresses and provide opportunities for study, as do natural catastrophes.
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From page 290... ...
In the 1920s, spot became so numerous that they clogged the cooling-water intakes of New York City's power plants. In a few cases it is possible to identify environmental changes responsible (for tilefish, a
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From page 291... ...
Causal and contributing factors in population ecology are either biological or nonbiological, and their study involves many disciplines. Understanding biological factors requires understanding individual life-history patterns and predator-prey, host-parasite, community, or evolutionary relations; sometimes all need to be understood at the same time.
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From page 292... ...
These :incur Lesions ~:usually result ~ :in the irreve~rsibie destruction: of :~ natural communities : ~ : ~ followed by the short-term: ~ag:ricu~ltural:exploitation of the la:nd~ that supports :: them.::~Bydesign:ingcommu~nitie~s~:pafterned~:diternatural:ecosyste:ms, it may : Possible to devise land-use: schemes that are more sustainable and : subsidy free while still maintaining an acceptable level of productivity. Such ~ ~ , agroecosystems should improve :human welfare and rsd~:uce the pressure on natural commundiesthat harbor the earthts legacy of evolution.: : ~: ~: ~::: : Hi: ~: : Chemical Ecology Many Ecological Interactions Are Mediated Through Chemistry All organisms are chemosensitive, and each is the source of substances to which other organisms respond.- In the course of evolution, this potential for interactions has been thoroughly exploited, and organisms of the most diverse kinds have entered into chemical interdependencies, both mutualistic and antagonistic, that are central to the fabric of life itself.
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From page 293... ...
Progress in chemical ecology is being accelerated by recent technical innovations in analytical chemistry. Vastly improved procedures have been developed for separating complex mixtures into their individual components, as well as for quantitating and chemically characterizing naturally occurring compounds.
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From page 294... ...
A vast array of natural products has been isolated from marine
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From page 295... ...
studies of communication, with an increasing emphasis on chemical communication; (2) foraging behavior, focusing on habitat selection, movement patterns, and prey choices in a patchy resource environment; (3)
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From page 296... ...
The Adaptive Basis of Behavior in Habitat Selection by Animals Is a Growing Area of Research Life history and population growth vary with habitat, so the behavioral basis of habitat selection can have a profound effect on population processes. At one level, for example, behavioral physiologists have known for years that animals prefer particular temperatures and will seek out these temperatures on thermal gradients in the laboratory.
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From page 297... ...
The application of foraging theory to a diverse set of organisms has made possible the emergence of a general theory of foraging, which applies to organisms as different as bumblebees and moose and to processes as diverse as growth patterns in plants "foraging" for light and the sexual behavior of males "foraging" for mates. Recent work on parental house wrens foraging for food for their nestlings under risk of predation illustrates the promise of behavioral hierarchy studies in the context of habitat selection and life-history research.
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From page 298... ...
Studies of this sort in behavioral ecology and evolutionary genetics can have an important practical benefit because they reveal how pests have evolved adaptatively to feed on crops-knowledge that can be used to help defeat their attack. Molecular genetics is also likely to play an increasing role in answering questions in evolutionary ecology in the next decade.
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From page 299... ...
The Union of Behavioral, Population, and Genetic Ecology Ecology in the Next Decade Will Forge New Links with Evolution and Behavior The synthesis of ecology, behavior, and evolution will contribute to the solution of some of society's most important problems-problems that are both complex and diverse. The problems range from understanding the biological basis of human aggressive behavior to the evolutionary ecology of disease, and to the ecological causes and consequences of species extinction.
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From page 300... ...
Theoretical studies of the wasps, based on the idea that natural selection should lead the female to maximize the number of her grandchildren, make predictions that agree remarkably well with what the wasps actually do another example of the successful integration of behavior, lifehistory theory, and genetics. Another promising avenue of interdisciplinary research in population biology and behavior is represented by the strong new interest in how behaviors of individuals in interacting groups combine and shape group behavior.
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From page 301... ...
genetic detail have become increasingly sophisticated, realistic, and general in the past few years. Such approaches are essential for the study of many traits and may have such practical benefit as the understanding of the evolutionary ecology of disease.
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From page 302... ...
Studies of the regulation of ecosystem processes therefore depend on population, community, and physiological ecology, and such studies must integrate across levels of biological organization. The central principles of ecosystem ecology are relatively easily summanzed, although the details are complex.
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From page 303... ...
~ ~ ~ ~ ~ ~ . · ~ , ~ ~ ~ : ~ ~;~App l~ea:~:aspect:s of t 1ls~:'vor ~m~ay:inc: uc e using waste~ hyd~rogen~s:u tiae ~ :~:~:~i~m~m~ediately~;:~:add~ressing ~t~he~ :acid~rain~: problem~ ~:~::~and~reassessing ~:singl~e-ce:ll~:;:~:::~::: ~:~:~protein :p~du:~on~: from ~wast:e~:~:meth~ane:.~:~:;~:~Furthermore ~::m~:~rob~logical ~stud-;:~::~:~:: ::::::;~: ~ies;::~of ~su~bm~ari~n~s ~geothermal;~:vents~have:~:~d~is=~red~; new~ f6;rms: of ~bat$eria: :: ~:~ ~:~: ~;~th~at~ ~are~:::~abl~e:~;::to::::grow~ at;::te~m~perat~u:res ~between: 8~:~and ~:1~1~:0°G ~:~and~:~:~h~aYe :~ ;~ ~in~itiated: ;a~ :bioch~em~icalibiophysica~l:~:~search~ for ~th:e~:upper~:te~mperat~ure:~lim~t:~:of ~: ~:: rf~ ,, :: : energy could be measured and upon which experiments could be imposed; it also provided a context and set of constraints for studies of ecological processes within watersheds.
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From page 304... ...
This capability is essential to the development of a science of the biosphere; without it, our measurements will be carried out on a much finer scale than the conclusions that we wish to draw from them. Approaches Based on Understanding the Functioning of Natural Ecosystems Have Proved Most Useful in the Analysis of Renewable Resources, Such as Water, Forests, and Soils Declining production in temperate-zone agriculture has often been reversed by massive applications of fertilizer, by the use of genetically improved crops, and by chemical and physical measures that are sometime extraordinarily intense.
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From page 305... ...
The effects of natural disasters, such as hurricanes, earthquakes, and disease epidemics, would be better understood if ecologists had the resources to study them as experimental systems. HUMAN-CAUSED ENVIRONMENTAL CHANGES, THE PROBLEMS THEY CAUSE, AND SOME SOLUTIONS Humans Have Been Changing the Natural Environment Since Prehistoric Times As human populations and technological ability have increased, humancaused environmental changes have increased also, both in their variety and in their potential to threaten life on earth.
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From page 306... ...
The screw ~f~c fib lies were paren o Russ so ~ area e he 44,000-heciare Mount Saint Helens National V~cqnic: Uor~umprd in 1982 ~ ~ The mayor ecological tissue studied around Mount Saint Helens has been succession. Thief way communitiss~ of organisms succeed one another has been a subject ~ sturdy and dewed for 100 years or more ~ 121s~ually~ Stevens ~ an area~is~clear~d, succession is strongly Affects 1~ the seeding of ~: ~ .
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From page 307... ...
Both types of threat provide many research opportunities in ecology indeed, they mandate such research. They represent ecological experiments at Be grandest scale.
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From page 308... ...
A majority of the human population resides in the tropics and subtropics and has access to only about a tenth of the world's wealth and the commodities that support human life. Their relation to the environment is often highly destructive of that environment Throughout the world, pollution of various kinds, much of it associated with industry, likewise threatens biological diversity.
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From page 309... ...
Considerable effort will be required in the coming decades to determine whether widespread mortality or shifts in species composition of this fauna are likely. Study of community structure and its natural variation should proceed in conjunction with experiments that illuminate the population biology, feeding
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From page 310... ...
The full range of techniques, from the most advanced molecular techniques for studying microorganisms to the most sophisticated in situ instrumentation and large-scale survey systems, have already been applied to the study of vent biology. The interdisciplinary RIDGE initiative sponsored by the National Science Foundation should advance our understanding of ridge processes.
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From page 311... ...
The Loss of Genetic Diversity That Can Occur When Populations Become Too Small Is an Important Concern of Conservation Biology In zoo populations and domestic livestock, the effects of inbreeding depression on growth, development, survival, and reproduction are well known. However, we know little about the actual sizes of breeding populations of plants and animals in the wild and only a modest amount about genetic variation in natural populations.
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From page 312... ...
Research in Ecosystem Restoration and Regeneration Will Yield Many Observations Useful in the Development of Ecological Understanding Over the next several decades, conservation biology will focus increasing attention on the restoration of degraded or destroyed ecosystems. This effort is important for two reasons.
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From page 313... ...
The effects of these pollutants are cumulative and usually cross jurisdictional boundaries. The burning of fossil fuel in Ohio can affect lakes in Quebec; the building of dams in Idaho and in Egypt can affect fisheries in Oregon and in the Mediterranean; the use of fertilizers in Maryland and Virginia can affect fisheries as far distant as Nova Scotia The problems caused by pollutants released into water and air, or widely into the terrestrial environment, are political as well as scientific.
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From page 314... ...
TECHNOLOGICAL AND METHODOLOGICAL ADVANCES Remote Sensing Evaluation of Global Change Requires the Ability to Document It and to Study Patterns at Fine Scales by Remote Techniques Remote sensing is not a new technique in ecology interpretation of aerial photographs has been a valuable part of ecological studies for at least 50 years. The scope and quality of remote sensing has changed dramatically in the last 10 years, however, and we have every reason to believe that its ecological applications are far from reaching their potential.
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From page 315... ...
Laser fluorescence can be used to measure the photosynthetic potential of individual leaves. These and other laser-based technologies will be applied more widely to ecological studies in the future, with consequent gains in insight about natural phenomena Tools for Studying Paleoecology For systems at equilibrium, the time dimension is relatively unimportant; consequently ecologists sometimes ignore history in deciphering patterns that can be seen in contemporary biotic systems.
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From page 316... ...
In plant physiological ecology, the use of stable isotopes provides a reliable means of scaling up from instantaneous metabolic rates to longer term estimates of physiological activity. Thus carbon isotope ratios provide information on water-use efficiencies, hydrogen isotope ratios on water sources, and nitrogen isotope ratios on nitrogen-fixation rates.
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From page 317... ...
Many single and multiple mixtures of stable isotopes are used to study plant-herbivore interactions as well as relations between animals and other organisms further up the food chain. In a recent study, for example, stable isotopes of carbon, nitrogen, and sulfur were used to trace the flow of organic material within a salt marsh ecosystem and to identify the origins of the detrital substances that were accumulated by He mussels downstream.
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From page 318... ...
The roots of mathematical ecology can be traced to the demographic studies of Graunt and others as early as the seventeenth century. The well-known arguments of Malthus, which indicated that a 'population growing without bound would soon outstrip the capacity of the environment to support it, were based on detailed analyses of births and deaths in human populations.
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From page 319... ...
Current work uses mathematical models to help to understand the factors underlying disease outbreaks and to develop methods for control, such as vaccination strateg~es. Finally, the need for environmental protection in the face of threats from such competing stresses as toxic substances, acid precipitation, and the generation of power has led to the development of increasingly sophisticated models that address the stress-related responses of community and ecosystem characteristics; for example, succession, productivity, and nutrient cycling.
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From page 320... ...
320 OPPORTUNITI~ IN BIOLOGY ~ ~ ~ : :::NONEQI~JILIB~RIAL::~SYSTEMS~: IN~ ~ECOLOGY ~: ~ ~ ~ The ~tradition of ~:~co~nsider:i~n~g ~eq~uilibri:al ~ ~stem~s~ in: theo~retical~ ~ology::: i:s ~: E~ ~ ~ ~ ~ :: : ~ ~ ::changing.~:: :arly mathemat~cal :~models:~ of: ~:~:ecological:~:~systems ~:~dealt wit:h~ ~::~: ~: :~ ~ ~ ~ ~:~ ~ ~ : ~ : ~ ::: ~ ::~: ~ ~: : :~ ~ .
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From page 321... ...
The insights from any investigation are therefore contingent on the choice of scale, and there is no single correct scale of observation. In many efforts to model particular ecological situations, irrelevant details are introduced on the mistaken premise that somehow more detail assures greater truth.
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From page 322... ...
That the conservation of species cannot be separated from the preservation of their habitats has given birth to new approaches to ecosystem restoration and rehabilitation. Tropical forests are among the most severely affected, and they have deservedly received tremendous attention.
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