Conservation of Wildlife Populations: Demography, Genetics, and Management

Abstract

Population biology spans the wide and fascinating world of population ecology, demography, and population genetics. This book extracts from these fields the most relevant concepts and principles for solving real-world management problems in wildlife and conservation biology. It will build on your training in basic ecology and genetics, then move deeper into areas where ecological and genetic concepts and theory are applied. Because this is an applied book on population biology, it will not derive or prove theoretical premises, nor will it dwell on theory not directly applicable to management problems. There are already excellent books that cover basic ecology, theoretical and mathematical population biology, and conservation genetics. There are also excellent books describing case studies of wildlife management and conservation practice. With this book, I hope to fill in the space between these texts, providing a conceptual framework spanning from fieldwork to demographic models and genetic analysis as they inform applied decision-making. The book is organized into three sections. The first provides a background to the science of applied wildlife population biology. Here I cover the context of historical and current extinction rates, the dynamics of human population growth, an overview of study design and ethics, essential background on genetics necessary for understanding the interface between genetic and demographic approaches, and the estimation of within-population vital rates. The second section covers population processes that form the basis for applied management. Beginning with exponential and then density-dependent population growth, I will next cover stage-structured population dynamics, predation (a necessary background for understanding the impacts of harvest by humans), effects of genetic variation on population dynamics, and animal spacing within and among populations. The final section brings together concepts and principles from the first two sections. The emphasis here is less on introducing new conceptual material and more on synthesizing the previous chapters by applying the ideas to specific problems of declining, small, or harvestable populations. Chapters deal with deterministic factors leading to population decline, specific issues related to small and declining populations, the use of focal species to bridge population biology and ecosystem approaches, and harvest theory and practice. Although I do review fundamental concepts and relevant theory, I assume that readers will have taken the equivalent of a basic ecology class and (hopefully) a basic genetics course. Ideally, you will have also taken at least one semester of statistics and PREFACE calculus, although I will review the math and keep it honed to that which is critical to application. Throughout I will present rules of thumb. These guidelines represent simple answers to complex questions, always a dangerous undertaking. I hope they will be useful for distilling subtle and complicated topics into the bare essence that can inform management as a starting point. Of course there will always be complexities, and in many specific cases the rules of thumb will, ultimately, be wrong. I will explain the primary caveats that accompany the rules of thumb, and in all cases will give references that explore the intricacies in more detail. Finally, you’ll notice two major themes running throughout this book: in class, I call these bumper stickers. One of them is embrace uncertainty. Do not be intimidated by the fact that ecological processes are complex. Do not feel that wide variance in estimates of parameters come from weak science. Do not freeze up from a lack of knowledge about all the pieces that are necessary for understanding a problem. Rather, recognize and illuminate the complexity of ecological systems as you deal with applied questions. The lack of full scientific certainty should never be used as a reason for inaction in the face of a wildlife population problem. Embrace uncertainty. My other bumper sticker is that ecological processes are not democratic. All vital rates are not equal in their effect on population growth, all age classes are not equal in their importance to population dynamics, all individuals do not contribute equally to genetic composition of a population, all species are not equal in their effects on community structure and stability, and so on. Because ecological processes are not democratic, we can rank and act on both research priorities and threats to wildlife populations. L.S. Mills