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8 Provisioning
A honeybee (Apis mellifera) colony contains thousands of foragers that collect large amounts of nectar, pollen, propolis, and water and deliver them to the hive. The colony’s activities and, ultimately, reproduction depend on these resources. Millions of years of honeybee evolution and thousands of years.
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9 Foraging in the Face of Danger
A juvenile coho salmon holds its position in the flow of a brook. To conserve energy, it positions itself in the lee of a small rock. Distinctive blotches of color on its sides, called parr marks, provide effective camouflage. As long as it holds its position, it is virtually impossible to see.
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10 Foraging with Others: Games Social Foragers Play
On a bone-chilling winter night in the far north, a lone wolf travels through the boreal forest looking for his next meal. The half-dozen pack members in the adjacent home range howl periodically throughout the night.
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11 Foraging and Population Dynamics
Every ecology textbook tells the story of snowshoe hare cycles. The vaguely sinusoidal plots of hare densities wiggle across the bloodless page. The hare population traces out a complete cycle every 8 to 11 years; the difference between low- and high-population years.
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12 Community Ecology
Two species of gerbils, the 24 g Allenby’s gerbil and the 40 g greater sand gerbil, live together on sand dunes in the Negev Desert. These species are very much alike. They eat mostly seeds (Bar et al. 1984), they are nocturnal, they live in burrows, they are caught by the same predators, and they compete intensively with each other.
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13 Foraging and the Ecology of Fear
The reintroduction of wolves in 1995 changed Yellowstone National Park. Riparian habitats have seen a marked increase in willows and aspen. The streams running through these willow thickets meander more. Wetlands have reappeared.
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14 On Foraging Theory, Humans, and the Conservation of Diversity: A Prospectus
The Tertiary is over. The world of our remote ancestors has nearly vanished. No nostalgia can save it; no yearning can restore it. We have entered the geological era of Homo sapiens. Like it or not, we are the boss.
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1
Molecular Genetics in Ecology
What is Molecular Ecology?
Over the past 20 years, molecular biology has revolutionized ecological research. During that time, methods for genetically characterizing individuals, populations and species have become almost routine, and have provided us with a wealth
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2
Molecular Markers in Ecology
Understanding Molecular Markers
In Chapter 1 we started to look at the extraordinary wealth of genetic information that is present in every individual, and to explore how some of this information can be accessed and used in ecological studies.
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3
Genetic Analysis of Single Populations
Why Study Single Populations?
Now that we know how molecular markers can provide us with an almost endless supply of genetic data, we need to know how these data can be used to address specific ecological questions.
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4
Genetic Analysis of Multiple Populations
Why Study Multiple Populations?
In Chapter 3 we learned that by quantifying the genetic diversity of single populations we can gain considerable insight into processes as varied as bottlenecks, reproduction and natural selection.
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5
Phylogeography
What is Phylogeography?
Current patterns of gene flow may bear little resemblance to the historical connections among populations, but both are relevant to the contemporary distributions of species and their genes.
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6
Molecular Approaches to Behavioural Ecology
Using Molecules to Study Behaviour
Behavioural ecology is a branch of biology that seeks to understand how an animal’s response to a particular situation or stimulus is influenced by its ecology and evolutionary history.
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7
Conservation Genetics
The Need for Conservation
Biodiversity quite simply refers to all of the different life forms on our planet, and includes both species diversity and genetic diversity. There are many reasons why we value biodiversity, the most pragmatic being that ecosystems.
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8
Molecular Ecology in a Wider Context
Applications of Molecular Ecology
By this stage in the book it should be evident that the acquisition and analysis of molecular data over the past two or three decades has provided us with considerable insight into the ecology of wild.
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Answers to Review Questions
Chapter 1
1.1 Nucleotide insertion. This is a frameshift mutation. Following this mutation, all but the first triplet encode different amino acids. The functionality is changed and therefore mutation is unlikely to be neutral.
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About Island Press
Island Press is the only nonprofit organization in the United States whose principal purpose is the publication of books on environmental issues and natural resource management. We provide solutions-oriented information to professionals, public officials, business and community leaders.
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Part One
HUMANS, NATURE, AND INTERACTIONS
All organisms live in ecological communities just as all people live in human communities. Often, however, we tend to forget that human communities also exist within an ecological context—that we cannot survive without the natural world around us.
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2
An Introduction to Ecology and Biodiversity
Southeastern Arizona is one of the most beautiful parts of North America, with stunning deserts interspersed among pine-covered mountain ranges. The watershed of the San Pedro River, undammed along its entire 140-mile.
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Introduction
We have chosen to start this book with chapters about organisms, then to consider the ways in which they interact with each other, and lastly to consider the properties of the communities that they form. One could call this a ‘constructive’ approach. We could though, quite sensibly
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Chapter 2
Conditions
2.1 Introduction
In order to understand the distribution and abundance of a species we need to know its history (Chapter 1), the resources it requires (Chapter 3), the individuals’ rates of birth, death and migration (Chapters 4 and 6), their interactions with their own and other species
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Chapter 3
Resources
3.1 Introduction
According to Tilman (1982), all things consumed by an organism are resources for it. But consumed does not simply mean ‘eaten’. Bees and squirrels do not eat holes, but a hole that is occupied is no longer available to another bee or squirrel
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Chapter 4
Life, Death and Life Histories
4.1 Introduction: an ecological fact of life
In this chapter we change the emphasis of our approach. We will not be concerned so much with the interaction between individuals and their environment, as with the numbers of individuals and the processes leading to changes in the number of individuals.
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Chapter 5
Intraspecific Competition
5.1 Introduction
Organisms grow, reproduce and die (Chapter 4). They are affected by the conditions in which they live (Chapter 2), and by the resources that they obtain (Chapter 3). But no organism lives in isolation.
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Chapter 6
Dispersal, Dormancy and Metapopulations
6.1 Introduction
All organisms in nature are where we find them because they have moved there. This is true for even the most apparently sedentary of organisms, such as oysters and redwood trees.
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Chapter 7
Ecological Applications at the Level of Organisms and Single-Species Populations: Restoration, Biosecurity and Conservation
7.1 Introduction
The expanding human population (Figure 7.1) has created a wide variety of environmental problems. Our species is not unique in depleting and contaminating the environment but we are certainly unique in using fire, fossil fuels and nuclear fission to provide the energy to do work.
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Part 2
Species Interactions
Introduction
The activity of any organism changes the environment in which it lives. It may alter conditions, as when the transpiration of a tree cools the atmosphere, or it may add or subtract resources from the environment that might have been available to other organisms
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Chapter 9
The Nature of Predation
9.1 Introduction: the types of predators
Consumers affect the distribution and abundance of the things they consume and vice versa, and these effects are of central importance in ecology. Yet, it is never an easy task to determine what the effects are, how they vary and why they vary.
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Chapter 10
The Population Dynamics of Predation
10.1 Introduction: patterns of abundance and the need for their explanation
We turn now to the effects of predation on the population dynamics of the predator and its prey, where even a limited survey of the data reveals a varied array of patterns.
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Chapter 11
Decomposers and Detritivores
11.1 Introduction
When plants and animals die, their bodies become resources for other organisms. Of course, in a sense, most consumers live on dead material – the carnivore catches and kills its prey, and the living leaf taken by a herbivore is dead by the time digestion starts.
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