Population Ecology in Practice

Dennis L. Murray, Brett K. Sandercock, Dennis L. Murray, Brett K. Sandercock

• Publisher: Wiley-Blackwell
• Year: 2019
• Print ISBN: 9780470674147
• eBook ISBN: 9781119574620
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Ecology
• Index: Biological Sciences

A synthesis of contemporary analytical and modeling approaches in population ecology

The book provides an overview of the key analytical approaches that are currently used in demographic, genetic, and spatial analyses in population ecology. The chapters present current problems, introduce advances in analytical methods and models, and demonstrate the applications of quantitative methods to ecological data. The book covers new tools for designing robust field studies; estimation of abundance and demographic rates; matrix population models and analyses of population dynamics; and current approaches for genetic and spatial analysis. Each chapter is illustrated by empirical examples based on real datasets, with a companion website that offers online exercises and examples of computer code in the R statistical software platform. 

• Fills a niche for a book that emphasizes applied aspects of population analysis
• Covers many of the current methods being used to analyse population dynamics and structure
• Illustrates the application of specific analytical methods through worked examples based on real datasets
• Offers readers the opportunity to work through examples or adapt the routines to their own datasets using computer code in the R statistical platform

Population Ecology in Practice is an excellent book for upper-level undergraduate and graduate students taking courses in population ecology or ecological statistics, as well as established researchers needing a desktop reference for contemporary methods used to develop robust population assessments.

Part I
Tools for Population Biology

1
How to Ask Meaningful Ecological Questions

Charles J. Krebs

Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada

Summary

I present and discuss four rules for asking good ecological questions:

• Rule No. 1. Understand the successes and failures from ecological history but do not let this knowledge become a straitjacket.
• Rule No. 2. Develop and define a series of multiple alternative hypotheses and explicitly state what each hypothesis predicts and what it forbids.
• Rule No. 3. Seek generality from your hypotheses and experiments but distrust it.
• Rule No. 4. If your research has policy implications, read the social science literature about how scientific information and policy decisions interface.

Meaningful questions in population ecology address theoretical issues or management questions that demand a solution. The solution should be looked for among a set of multiple working hypotheses. If you have only one hypothesis with no alternatives, there is nothing to do. The classical null hypothesis in a statistical sense is not an alternative hypothesis in which population ecology is interested. Given a question, the possible outcomes of the study should be noted before any field work is carried out, and an interpretation given of what each possible result means in terms of basic theory or applied management. The most useful questions often have multiple dimensions and apply to more than one taxonomic group. Once you have an important question formulated with alternative hypotheses, you must discuss the critical aspects of the experimental design – replication, randomization, treatments, and controls. How many replicates are needed over what landscape units? How long a study is required? How often do you need to sample? Will the confidence limits of any estimates be narrow or wide? If the proposed steps are not followed, it is possible to get lost in the mechanical details of a study without knowing clearly how the outcome will reflect back on the original questions. Serendipity may rescue poorly conceived studies, but the probability of this event may be less than P < 0.01. Management and conservation problems demand both good data and effective policy development. Ecologists need to become more proactive in providing solutions to politicians and business leaders who develop policy options with ecological consequences.

1.1 What Problems Do Population Ecologists Try to Solve?

Every ecological question comes down to a question of population ecology, and hence it is useful to start by asking how one goes about asking meaningful ecological questions in population ecology. Implicitly the starting point must involve answering the flip question of: How does one avoid questions that yield information that do not help in solving an ecological problem? The first and simplest guide is to look at the historical literature in population ecology, which is littered with questions that have led nowhere in terms of increased understanding of ecological dynamics or improving sustainable land management (Hartway and Mills 2012; Walsh et al. 2012). The second guide must be that a historical search is not sufficient, because it will not tell you about future research questions. Thus, it is possible to make a mistake and to spend time exploring alleys that are dead ends. But it is useful to realize that setbacks are not a scientific defeat because these explorations will show the next generation of ecologists what to avoid. So this advice might be coded as the first rule of asking meaningful questions:

1. Rule No. 1. Understand the successes and failures from ecological history but do not let this knowledge become a straitjacket.

A simple example will illustrate this point. The management of Northern Bobwhites (Colinus virginianus) in the USA involved a controversial issue of whether quail populations could be limited by the lack of water and thus would benefit from managers providing free water, such as a pond, in their habitat. Guthery (1999) examined the competing hypotheses about water limitation and showed that even in southern Texas quail did not need free water to survive and thus that water sources were not required as a management tool. Whether this conclusion will hold under climate change is an important issue for managers in the future.

At a general level, philosophers of science provide a set of guidelines on how to develop general theory. Ask general questions rather than particular ones. General questions will apply to a variety of species and habitats, particular questions will involve only one or a few species in a restricted environmental space. Formulate your research questions as testable hypotheses, and if possible develop ...

Table of contents

• Cover
• Table of Contents
• Contributors
• Preface
• About the Companion Website
• Part I: Tools for Population Biology
• Part II: Population Demography
• Part III: Population Models
• Part IV: Population Genetics and Spatial Ecology
• Part V: Software Tools
• Index
• End User License Agreement