Part I Introduction

PA R T I Introduction COPYRIGHTED MATERIAL CHAPTER 1 Introduction One - horned rhinoceros, Section 5.3 We are at a critical juncture for the conservation and study of biological diversity: such an opportunity will never occur again. Understanding and maintaining that diversity is the key to humanity ’ s continued prosperous and stable existence on Earth. US National Science Board Committee on Global Biodiversity (1989) The extinction of species, each one a pilgrim of four billion years of evolution, is an irreversible loss. The ending of the lines of so many creatures with whom we have traveled this far is an occasion of profound sorrow and grief. Death can be accepted and to some degree transformed. But the loss of lineages and all their future young is not something to accept. It must be rigorously and intelligently resisted. Gary Snyder (1990) Chapter Contents 1.1 Genetics and civilization, 4 1.2 What should we conserve? 5 1.3 How should we conserve biodiversity? 9 1.4 Applications of genetics to conservation, 10 1.5 The future, 12 Guest Box 1 The role of genetics in conservation, 13 Conservation and the Genetics of Populations‚ Second Edition. Fred W. Allendorf, Gordon Luikart, and Sally N. Aitken. © 2013 Fred W. Allendorf, Gordon Luikart and Sally N. Aitken. Published 2013 by Blackwell Publishing Ltd. 4 Introduction We are living in a time of unprecedented extinctions tion of plants is thought to have been perhaps the key (Myers and Knoll 2001 , Stuart et al . 2010 , Barnosky step in the development of civilization (Diamond et al . 2011 ). Current extinction rates have been esti- 1997 ). Early peoples directed genetic change in domes- mated to be 50 – 500 times background rates and are tic and agricultural species to suit their needs. It has increasing; an estimated 3000 – 30,000 species go been estimated that the dog was domesticated over extinct annually (Woodruff 2001 ). Projected extinc- 15,000 years ago, followed by goats and sheep around tion rates vary from 5 – 25% of the world ’ s species by 10,000 years ago (Darlington 1969 , Zeder and Hess 2015 or 2020. Approximately 23% of mammals, 12% 2000 ). Wheat and barley were the fi rst crops to be of birds, 42% of turtles and tortoises, 32% of amphib- domesticated in the Old World approximately 10,000 ians, 34% of fi sh, and 9 – 34% of major plant taxa are years ago; beans, squash, and maize were domesticated threatened with extinction over the next few decades in the New World at about the same time (Darlington (IUCN 2001 , Baillie et al . 2004 ). Over 50% of animal 1969 , Kingsbury 2009 ). species are considered to be critically endangered, The initial genetic changes brought about by culti- endangered, or vulnerable to extinction (Baillie et al . vation and domestication were not due to intentional 2004 ). A recent assessment of the status of the world ’ s selection but apparently were inadvertent and inher- vertebrates, based on the International Union for the ent in cultivation itself. Genetic change under domes- Conservation of Nature (IUCN) Red List, concluded tication was later accelerated by thousands of years of that approximately 20% are classifi ed as Threatened. purposeful selection as animals and crops were selected This fi gure is increasing primarily because of agricul- to be more productive or to be used for new purposes. tural expansion, logging, overexploitation, and inva- This process became formalized in the discipline of sive introduced species (Hoffmann et al . 2010 ). agricultural genetics after the rediscovery of Mendel ’ s The true picture is much worse than this because the principles at the beginning of the 20th century. conservation status of most of the world ’ s species The ‘ success ’ of these efforts can be seen every- remains poorly known. Recent estimates indicate that where. Humans have transformed much of the land- less than 30% of the world ’ s arthropod species have scape of our planet into croplands and pasture to been described (Hamilton et al . 2010 ). Less than 5% of support the over 7 billion humans alive today. It has the world ’ s described animal species have been evalu- been estimated that 35% of the Earth ’ s ice - free land ated for the IUCN Red List. Few invertebrate groups surface is now occupied by crops and pasture (Foley have been evaluated, and the evaluations that have et al . 2007 ), and that 24% of the primary terrestrial been done have tended to focus on molluscs and crus- productivity is used by humans (Haberl et al . 2007 ). taceans. Among the insects, only the swallowtail but- Recently, however, we have begun to understand the terfl ies, dragonfl ies, and damselfl ies have received cost at which this success has been achieved. The much attention. replacement of wilderness by human - exploited envi- Conservation biology poses perhaps the most diffi - ronments is causing the rapidly accelerating loss of cult and important questions ever faced by science species and ecosystems throughout the world. The (Pimm et al. 2001 ). The problems are diffi cult because continued growth of the human population and their they are so complex and cannot be approached by the direct and indirect effects on environments imperils a reductionist methods that have worked so well in other large proportion of the wild species that now remain. areas of science. Moreover, solutions to these problems Aldo Leopold inspired a generation of biologists to require a major readjustment of our social and politi- recognize that the actions of humans are embedded cal systems. There are no more important scientifi c into an ecological network that should not be ignored challenges because these problems threaten the con- (Meine 1998 ). The organized actions of humans are tinued existence of our species and the future of the controlled by sociopolitical systems that operate into biosphere itself. the future on a timescale of a few years at most. All too often our systems of conservation are based on the economic interests of humans in the immediate future. 1.1 GENETICS AND CIVILIZATION We tend to disregard, and often mistreat, elements that lack economic value but that are essential to the stabil- Genetics has a long history of application to human ity of the ecosystems upon which our lives and the concerns. The domestication of animals and cultiva- future of our children depend. Introduction 5 In 1974 , Otto Frankel published a landmark paper 1.2.1 Phylogenetic d iversity entitled ‘ Genetic conservation: our evolutionary responsibility ’ , which set out conservation priorities: The amount of genetic divergence based upon phylogenetic relationships is often considered when setting First, . we should get to know much more about the conservation priorities for different species (Mace et al . structure and dynamics of natural populations and com- 2003 , Avise 2008 ). For example, the United States Fish munities. Second, even now the geneticist can play a and Wildlife Service (USFWS) assigns priority for part in injecting genetic considerations into the planning listing under the Endangered Species Act (ESA) of the of reserves of any kind. Finally, reinforcing the United States on the basis of “ taxonomic distinctive- grounds for nature conservation with an evolutionary ness ” (USFWS 1983 ). Species of a monotypic genus perspective may help to give conservation a permanence receive the highest priority. The tuatara raises several which a utilitarian, and even an ecological grounding, fail important issues about assigning conservation value to provide in men ’ s minds. and allocating our conservation efforts based upon taxonomic distinctiveness (Example 1.1 ). Frankel, an agricultural plant geneticist, came to the Faith (2008) recommends integrating evolutionary same conclusions as Leopold, a wildlife biologist, by a processes into conservation decision - making by con- very different path. In Frankel ’ s view, we cannot antici- sidering phylogenetic diversity. Faith provides an pate the future world in which humans will live in a approach that goes beyond earlier recommendations century or two. Therefore, it is our responsibility to that species that are taxonomically distinct deserve “ keep evolutionary options open ” . It is time to apply greater conservation priority. He argues that the phylo- our understanding of genetics to conserving the genetic diversity approach provides two ways to natural ecosystems that are threatened by human consider maximizing biodiversity. First, considering civilization. phylogeny as a product of evolutionary process enables the interpretation of diversity patterns to maximize biodiversity for future evolutionary change. Second, phylogenetic diversity also provides a way to better 1.2 WHAT SHOULD WE CONSERVE? infer biodiversity patterns for poorly described taxa when used in conjunction with information about geo- Conservation can be viewed as an attempt to protect graphic distribution. the genetic diversity that has been produced by evolu- Vane - Wright et al . (1991) presented a method for tion over the previous 3.5 billion years on our planet assigning conservation value on the basis of phyloge- (Eisner et al . 1995 ). Genetic diversity is one of three netic relationships. This system is based upon the forms of biodiversity recognized by the IUCN as deserv- information content of the topology of a particular ing conservation, along with species and ecosystem phylogenetic hierarchy. Each extant species is assigned diversity ( www.cbd.int , McNeely et al . 1990 ). Unfortu- an index of taxonomic distinctness that is inversely

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