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3 - Origins of the dog: Genetic insights into dog domestication
- from PART I - ORIGINS AND EVOLUTION
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- By Bridgett M. Vonholdt, Department of Ecology and Evolutionary Biology, Princeton University, NJ, USA, Carlos A. Driscoll, National Institute on Alcohol Abuse and Alcoholism; National Institutes of Health, MD, USA
- Edited by James Serpell, University of Pennsylvania
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- Book:
- The Domestic Dog
- Published online:
- 30 December 2016
- Print publication:
- 08 December 2016, pp 22-41
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Summary
Introduction
Dogs are the oldest domesticated animal and today are second only to cats as the most popular pet in western societies (Boyko, 2011; Leonard et al., 2006; Wayne and vonHoldt, 2012). The dog has taken on many significant roles in human society, ranging from companion, sentry, and hunting partner to its more recent function as a model for understanding human disease. By exploring the genetic and evolutionary history of our canine companions, we can better understand not only the natural history of dogs but also our own evolutionary history.
Inquiries into the dog's natural history are now enlightened by molecular and genetic data to an overwhelmingly greater degree then they were 20 years ago when the first edition of this book was published. This trend towards increasing molecular inference will certainly continue, though morphology and archaeology will remain vitally important in completing our understanding of the cultural context of the changes wrought by domestication.
The wolf, ancestor of the dog
The dog and its ancestor, the wolf (Canis lupus), belong to the family Canidae. The 34 living species of canids are grouped into four clades: a red fox-like clade, a South American clade, a wolf-like clade, and a clade comprising only the gray and island fox (Urocyon cinereoargenteus and U. littoralis, respectively) (Lindblad-Toh et al., 2005; Perini et al., 2009) (Figure 3.1). Canids are found in all terrestrial habitats and, with the human-assisted introduction of dogs and foxes to Australia and New Zealand, Antarctica is now the only continent without a resident population. Currently, seven species belong to the dog-like genus Canis (Figure 3.2), which arose nearly six million years ago (mya) in North America and, along with a number of other carnivore species, expanded into Eurasia (4 mya) via the Beringian land bridge, and subsequently into Africa (3 mya) (Wang & Tedford, 2008). The archaeological record indicates that the modern-day gray wolf (Canis lupus lupus) evolved in Eurasia around 3–4 mya, re-invading North America about 500 000 years ago (Wang & Tedford, 2008). Supremely adaptable, the wolf inhabits nearly every habitat and environmental condition (Mech & Boitani, 2003). Wolves vary greatly in size depending on their environmental distribution, from the gracile 13 kg wolves of the Middle Eastern deserts to the large robust individuals (over 78 kg) of the Arctic tundra.
11 - Genome-Wide Approaches for the Study of Dog Domestication
- Edited by Paul Gepts, University of California, Davis, Thomas R. Famula, University of California, Davis, Robert L. Bettinger, University of California, Davis, Stephen B. Brush, University of California, Davis, Ardeshir B. Damania, University of California, Davis, Patrick E. McGuire, University of California, Davis, Calvin O. Qualset, University of California, Davis
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- Book:
- Biodiversity in Agriculture
- Published online:
- 05 June 2012
- Print publication:
- 23 February 2012, pp 275-298
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Summary
Dogs display a remarkable amount of phenotypic diversity in coat color, texture, and cranial and skeletal proportions, yet as a species they are distinct from wild canids (Wayne 1986a,b). Similarly, considerable variation in behavior and physiology are evident among breeds and between dogs and wild species (Hart 1995, Hare et al. 2002, Spady and Ostrander 2008). Considering the great diversity of dogs, Darwin and others postulated that domestic dogs were founded from more than one canid species (Darwin 1859, Lorenz 1954, Coppinger and Schneider 1995). However, molecular data showed conclusively that dogs originated from the gray wolf (Canis lupus) (Morey 1994, Vilà et al. 1997, Savolainen et al. 2002, Pang et al. 2009). Nonetheless, because of the morphologic divergence between dogs and gray wolves, identifying a specific ancestral gray wolf population is difficult.
The earliest proto-dogs were likely similar to wolves but subsequent evolution has rendered all breeds and dog populations as morphologically distinct from wild progenitors (Zeuner 1963, Epstein and Mason 1972, Olsen 1985, Morey 2006). Archaeological evidence suggests that the earliest dogs are from central Russia (15,000 y bP, Sablin and Khlopachev 2002), Western Europe (31,000 y bP, Germonpre et al. 2009) or the Middle East (12,000 y Bp, Nobis 1979, Olsen 1985, Davis 1987, Dayan 1994, Clutton-Brock 1995, Morey 2006). A problem with the archaeological data is that putative ancient dogs may in reality be differentiated varieties of local wolves (e.g., Leonard and Wayne 2008) or already so derived that the origin may be elsewhere. By contrast, East Asia is supported as a center of origin for dogs based on higher mitochondrial DNA (mtDNA) sequence diversity in dogs that originated there (Savolainen et al. 2002). However, mtDNA sequence is information from essentially a single gene and thus may not represent the history of the genome or the actual species tree (Wayne et al. 2006). For example, high mtDNA sequence diversity may reflect a center of regional trade rather than the location of species origin (Wayne et al. 2006). Consequently, genome-wide approaches are needed to sample a wider variety of gene histories and to provide a better consensus of evolutionary history.