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A landrace is a domesticated, regional ecotype; a locally adapted, traditional variety of a domesticated species of animal or plant that has developed over time, through adaptation to its natural and cultural environment of agriculture and pastoralism, and due to isolation from other populations of the species. Landraces are generally distinguished from cultivars, and from breeds in the standardized sense, although the term landrace breed is sometimes used synonymously instead, as distinguished from the term standardized breed in contexts in which the word breed is used expansively.
Specimens of a landrace tend to be relatively genetically uniform, but are more diverse than members of a standardized or formal breed. Some standardized animal breeds originate from attempts to make landraces more consistent through selective breeding and a landrace may become a more formal breed with the creation of a breed registry and/or publication of a breed standard. In such a case, the landrace may be thought of as a "stage" in breed development. However, in other cases, formalizing a landrace may result in the genetic resource of a landrace being lost through crossbreeding. Landraces are distinct from ancestral wild species of modern stock, and from separate species or subspecies derived from the same ancestor as modern domestic stock. Landraces are not all derived from ancient stock largely unmodified by human breeding interests. In a number of cases, most commonly dogs and horses, domestic animals have escaped in sufficient numbers in an area to breed feral populations that, through evolutionary pressure, can form new landraces in only a few centuries. In other cases, simple failure to maintain breeding regimens can do the same. For example, selectively bred cultivars can become new landraces when loosely selective reproduction is applied.
Increasing adoption of and reliance upon modern, purposefully selected plant strains, considered improved – "scientifically bred to be uniform and stable" – has led to a reduction in biodiversity. The majority of the genetic diversity of domesticated species lies in landraces and other traditionally used varieties, a "reservoir of genetic resources".
General features that characterize a landrace may include:
- It is morphologically distinctive and identifiable (i.e., has particular and recognizable characteristics or properties), yet remains "dynamic".
- It is genetically adapted to, and has a reputation for being able to withstand, the conditions of the local environment, including climate, disease and pests, even cultural practices.
- It is not the product of formal (governmental, organizational, or private) breeding programs, and may lack systematic selection, development and improvement by breeders.
- It is maintained and fostered less deliberately than a standardized breed, with its genetic isolation principally a matter of geography acting upon whatever animals that happened to be brought by humans to a given area.
- It has a historical origin in a specific geographic area, usually it will have its own local name(s), and will often be classified according to intended purpose.
- Where yield (e.g. of a grain or fruit crop) can be measured, a landrace will show high stability of yield, even under adverse conditions, but a moderate yield level, even under carefully managed conditions.
- At the level of genetic testing, its heredity will show a degree of integrity, but still some genetic heterogeneity (i.e. genetic diversity)
Not every source on the topic enumerates each of these criteria, and they may be weighted differently depending on a given source's focus (e.g., governmental regulation, biological sciences, agribusiness, anthropology and culture, environmental conservation, pet keeping and breeding, etc.). Additionally, not all cultivars agreed to be landraces exhibit all possible landrace characteristics. Plant landraces have been the subject of more intensive study, and the majority of the academic literature about landraces is focused on agricultural botany, not animal husbandry. Most plant landraces are associated with traditional agricultural systems.
While many landrace animals are associated with farming, other domestic animals have been put to use as modes of transportation, as companion animals, for sporting purposes, and for other non-farming uses, so their geographic distribution may differ. For example, horse landraces are less common because human use of them for transport has meant that they have moved with people more commonly and constantly than most other domestic animals, reducing the incidence of populations locally genetically isolated for extensive periods of time.
The word landrace (literally 'country-breed', German: Landrasse) and close cognates of it are found in various Germanic languages. The term was first defined (in German) by Kurt von Rümker in 1908, and more clearly described (in Dutch) in 1909 by U. J. Mansholt, who wrote that landraces have better "stability of their characteristics" and "resistance capacity to tolerate adverse influences" but lower production capacity than cultivars, and are apt to change genetically when moved to another environment. H. Kiessling added in 1912 that a landrace is a mixture of phenotypic forms despite relative outward uniformity, and a great adaptability to its natural and human environment. The word in entered non-academic English in the early 1930s, by way of the Danish Landrace pig, a particular breed of lop-eared swine.
Aside from some standardized breeds having "Landrace" in their names, actual landraces and standardized breeds are sometimes further confused when the word "breed" is used very broadly. As one example, a glossary in a Food and Agriculture Organization of the United Nations (FAO) guideline defines landrace or landrace breed (treated synonymously) as "a breed that has largely developed through adaptation to the natural environment and traditional production system in which it has been raised". It also defines breed expansively and in multiple ways, with a focus on treating differing senses, landrace breed and standardized breed, as equivalent for "genetic management" purposes, the focus of the FAO guideline. It does clearly distinguish between the two concepts, however, both with a distinct definition of "standardized breed" and in the main body of the guideline, referring to the "interaction between landraces and standardized breeds"), and that FAO document uses "breed" to mean "the unit of conservation, i.e. the specific population of animals that is to be conserved". Similarly, the Oxford English Dictionary defines landrace as a "local cultivar or animal breed that has been improved by traditional agricultural methods", without specifying which definition of breed is cross-referenced. might be intended. (The definition is also at odds with some peer-reviewed material, in which lack of formal, scientific breeding for genetic improvement (e.g. uniformity and stability) is characteristic of landraces; such sources clearly distinguish landraces from cultivars.)
A landrace native to, or produced for a long time (e.g. 100 years or longer) within the agricultural system in which it is found is referred to as an autochthonous landrace, while an introduced one is termed an allochthonous landrace. "Within academic agronomy, the term autochthonous landrace is sometimes used with a more specific, productivity-related definition, synthesized by A. C. Zeven from previous definitions beginning with Mansholt's; it is not often encountered outside that field.[a] These terms are most often applied to plants, with animals more often being referred to as indigenous or native.[b]
Many languages do not use separate terms, like landrace and breed in English, but instead rely on extended description to convey such distinctions.[c] The FAO notes: "The distinction between breeds and ecotypes within breeds is not very objective, and generally involves cultural rather than genetic factors."
The term landrace breed is sometimes encountered. In various domestic species (including pigs, goats, sheep and geese) some standardized breeds include "Landrace" in their names, and "Landrace breeds" (with capital "L") is sometimes used to refer to them collectively.[d] but may be used more ambiguously to include actual landraces.[e]
Similar ambiguity may be encountered in the use of terms such as ancient breed, native breed (not to be confused with native species), old breed, and indigenous breed. Farmers' variety, usually applied to local cultivars, or seen as intermediate between a landrace and a cultivar, may also include landraces when referring to plant varieties not subjected to formal breeding programs.
The term breed itself has multiple definitions and uses,[f] some of which may encompass the concept of landraces. For example, the FAO Commission on Genetic Resources for Food and Agriculture (CGRFA) guideline provides a definition of "breed", for "genetic management" purposes, that overlaps with many definitions of landrace, and defines "landrace (or landrace breed)" as a type of "breed".
Biodiversity and conservation
Due to their adaptation to the local environment, some farmers using scientifically "improved" domesticates also continue to raise landraces, because the latter often exhibit benefits, ranging from lower cost, and cultural (e.g. culinary) preference, to superior hardiness in a less-than-ideal climate, and better disease resistance. There may be more variety-specific pluses; a plant landrace may have, e.g., lower fertilizer requirements, or something about a plant or animal product's texture, color or ease of use might be a major factor.
Landraces are often free from many intellectual property and other regulatory encumbrances. However, in some jurisdictions, a focus on their production may result in missing out on some benefits afforded to producers of genetically selected and homogenous organisms, including breeders' rights legislation, easier availability of loans and other business services, even the right to share seed or stock with others, depending on how favorable the laws in the area are to high-yield agribusiness interests. As Regine Andersen of the Fridtjof Nansen Institute (Norway) and the Farmers' Rights Project puts it, "Agricultural biodiversity is being eroded. This trend is putting at risk the ability of future generations to feed themselves. In order to reverse the trend, new policies must be implemented worldwide. The irony of the matter is that the poorest farmers are the stewards of genetic diversity." Protecting farmer interests and protecting biodiversity is at the heart of the International Treaty on Plant Genetic Resources for Food and Agriculture (the "Plant Treaty" for short), under the Food and Agriculture Organization of the United Nations (FAO), though its concerns are not exclusively limited to landraces.
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In 2005, a "working definition" of plant landraces was proposed: "a dynamic population(s) of a cultivated plant that has historical origin, distinct identity and lacks formal crop improvement, as well as often being genetically diverse, locally adapted and associated with traditional farming systems."Another definition, dating to 1975, of the term landrace as used in botany (and by extension in agriculture, horticulture, anthropology, etc.) was provided by J. R. Harlan:
"Landrace populations are often highly variable in appearance, but they are each identifiable morphologically and have a certain genetic integrity. Farmers usually give them local names. A landrace has particular properties or characteristics. Some are considered early maturing and some late. Each has a reputation for adaptation to particular soil types according to the traditional peasant soil classifications, e.g. heavy or light, warm or cold, dry or wet, strong or weak. They also may be classified according to expected usage; among cereals, different landraces are used for flour, for porridge, for 'bulgur', and for malt to make beer, etc. All components of the [plant] population are adapted to local climatic conditions, cultural practices, and disease and pests."
Landrace plants are grown from seeds which have not been systematically selected and marketed by seed companies, nor developed by plant breeders. The label Landraces includes all those regional cultigens that are highly heterogeneous, but with enough characteristics in common to permit their recognition as a group.
This includes all cultigens cultivated without any specific nomenclature and value. A landrace identified with a unique feature, and selected for uniformity over a period of time for maintenance of the characteristic features of the population, can evolve into a "farmers' variety", or even a modern cultivar as in many crops (for example, Cajanus cajan 'Maruti' in the case of pigeon peas).
A "significant proportion" of farmers around the world continue to grow landrace crops. However, as industrialized agriculture spreads, cultivars, which are selectively bred for high yield, rapid growth, disease and drought resistance, and other commercial production values, are supplanting many landraces, putting more and more of them at risk of extinction.
Using Europe as an example, data collected for an agricultural study published in 2008, showed that landrace cereal crops began to decline in Europe in the 19th century with selective seed improvements, and continued with varietal improvement in the 20th century, such that cereal landraces "have largely fallen out of use" in Europe. Landrace cultivation in central and northwest Europe was almost eradicated by the early 20th century, due to economic pressure to grown improved, modern cultivars. While many in the region are already extinct, some have survived in commercial European farming by being passed from generation to generation of farmers, and have also been revived by enthusiasts outside Europe to preserve European "agricultural and food heritage" elsewhere. These survivals are usually for specific uses, such as thatch, and traditional European cuisine and craft beer brewing. Systematic preservation efforts for these cereal strains are ongoing, in situ and in online-searchable germplasm collections (seed banks), coordinated by Biodiversity International and the National Institute of Agricultural Botany (UK). However, more may need to be done, because plant genetic variety, the source of crop health and seed quality, depends on a diversity of landraces and other traditionally used varieties. Efforts (as of 2008[update]) were mostly focused on Iberia, the Balkans, and European Russia, and dominated by species from mountainous areas. Despite their incompleteness, these efforts have been described as "crucial in preventing the extinction of many of these local ecotypes".
One definition of a landrace applied to both plants and animals is "which has developed over a long period of time and as a result has adapted to the local natural environment in which it lives." Geneticist D. Phillip Sponenberg described animal breeds as "consistent and predictable genetic entities" falling into several "classes": the landrace, the standardized breed, modern "type" breeds, industrial strains and feral populations. He describes landraces as an early stage of breed development, created by a combination of founder effect, isolation and environmental pressures. Human selection plays a role, but for end goals, not as a result of careful selection.
One definition of a landrace, as applied to animals, is a biological race of [domestic] animal adapted to thrive in a specific land or locality.[unreliable source?] Another, applied to both plants and animals, is a variety "which has developed over a long period of time and as a result has adapted to the local natural environment in which it lives."
There are various distinctive landraces of domestic cat around the world, including the Aegean, Cyprus, Domestic Long-Haired, Domestic Short-Haired, Kellas and Sokoke, among others. The Van cat of modern-day Turkey is a landrace of symbolic (and disputatious) cultural value to Turks, Armenians and Kurds.
Many standardized breeds have rather recently (within a century or less) been derived from landraces. Examples, often called natural breeds, include Egyptian Mau, Korat, Kurilian Bobtail, Maine Coon, Manx, Norwegian Forest Cat, and Siberian, among many others.
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Dog landraces and selectively bred, standardized dog breeds vary widely depending on their origins and purpose. Landraces in dogs are defined as "dog or any livestock animal has been bred without a formal registry, although their breeders may have kept written or informal pedigrees of their animals." These are distinguished from "standardized breeds" that have breed clubs and registries. From a biological point of view, all dog types are classified as Canis lupus familiaris, a subspecies of the gray wolf Canis lupus. The process of how dogs were domesticated was paralled by the experiments undertaken by Dmitri Belyaev in the old Soviet Union with the silver fox, which eventually created the domesticated silver fox or by the genome-wide association studies of Elaine Ostrander at the NIH.
Landrace dogs breeds have more variety in their appearance than do standardized dog breeds. An example of a dog landrace with a related standardized breed with a similar name is the collie. The Scotch Collie is a landrace, while the Rough Collie and the Border Collie are standardized breeds. They can be very different in appearance, though the rough collie in particular was developed from the Scotch Collie by inbreeding to fix certain highly desired traits. In contrast to the landrace, in the various standardized Collie breeds, purebred individuals closely match a breed-standard appearance but might have lost other useful characteristics and have developed undesirable traits linked to inbreeding. Similarly, the ancient landrace of the Middle East that led to the Saluki breed excels in running down game across open tracts of hot desert, but conformation-bred individuals of the breed might not be able to chase and catch desert hares.
The now extinct St. John's water dog, a landrace native to the island of Newfoundland, Canada, was the foundational stock for a number of purpose-bred dogs, such as the Labrador Retriever, Chesapeake Bay Retriever, Cape Shore Water Dog, and the Newfoundland dog. Another example of a North American landrace, the Carolina dog or yellow dog, was developed from dogs originally from Asia; it also been established now as a standardized breed).
The mountain dog is more of a complex of superficially similar but not always related breeds and landraces, and is the common working dog type of mountain environs of central Eurasia. An actual surviving Old World canine landrace is the Armenian Gampr dog.
Goats and sheep
- Shetland sheep
- Spanish goat, the native landrace of Spain that survives in larger numbers in the American South as the "brush goat" or "scrub goat", among other names
- Spælsau sheep, which dates to the Iron Age
- Welsh mountain sheep
Some standardized, selective breeds that are derived from landraces include the Dutch Landrace, Swedish Landrace and Finnish Landrace goats. The confusingly named Danish Landrace is a modern mix of three different breeds, one of which was a "Landrace"-named breed.
Horses, ponies and donkeys
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Horse landraces are "local types which have become uniform through a combination of founder effect, long isolation from other populations and selection within a local environment." He further refines the definition, noting, "[t]he relative genetic uniformity of landraces results from both moderate inbreeding and from selection...a combination of natural factors and human factors, all acting in an agricultural or pastoral setting." It is rare for landraces among domestic horses to remain isolated, due to human use of horses for transportation, thus causing horses to move from one local population to another. Example of horse landraces include isolated island populations such as the Shetland pony and Icelandic horse, insular landraces in Greece and Indonesia, and, on a broader scale, New World populations derived from the founder stock of Colonial Spanish horse.
The wild progenitor of the domestic horse is now extinct. The Przewalski's horse, Equus ferus przewalskii, is a wholly separate subspecies with a different number of chromosomes than domesticated horses (E. f. caballus), and has never been successfully domesticated.
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The Mulefoot pig breed originated as a landrace, but has been a standardized breed since the early 1900s. The standardized swine breeds named "Landrace" are not actually landraces, and often not even derived from one, but from other breeds with "Landrace" in their names. The Danish Landrace pig breed, pedigreed in 1896 from the actual local landrace, is the principal ancestor of the American Landrace (1930s). The Swedish Landrace is derived from the Danish and from other Scandinavian breeds, as was the British Landrace breed, which was established as late as 1950.
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Landrace chicken breeds include:
The Swedish Blue duck, a modern breed, is derived from a landrace of the same name. The Pilgrim goose is a North American landrace, thought to descend from western European stock dating back to the 17th century. The variety is associated with the Mayflower Pilgrims of Plymouth Colony, and has also been standardised as a formal breed since 1939. The standardized breeds named "Landrace", e.g. the Twente Landrace duck, are not actually landraces, though may be derived from them.
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- Gotland rabbit, a rare landrace of Sweden (not entirely limited to Gotland), and now a standardized breed with a pedigree studbook and two color varieties
- Mellerud rabbit, a very rare landrace of Sweden, subject to conservation but not development efforts by breeders
- Zeven (1998) provides the following agronomic definition: "an autochthonous landrace is a variety with a high capacity to tolerate biotic and abiotic stress, resulting in a high yield stability and an intermediate yield level under a low input agricultural system."
- Examples of references in sources to long-term local landraces of livestock include constructions such as "indigenous landraces of sheep", and "Leicester Longwool sheep were bred to the native landraces of the region". Some usage of "autochthonous" does occur in reference to livestock, e.g. "autochthonous races of cattle such as the Asturian mountain cattle – Ratina and Casina – and Tudanca cattle."
- As an example of lack of distinction at the nomenclature level between breeds and landraces in other languages, the Spanish word raza ('race') covers the concepts of both breed and landrace, as well as biological race, and race as a human classification.
- The British Pig Association uses "Landrace breed", in reference to standardized breeds, e.g. "new lines ... making the British Landrace pig unique amongst other Landrace breeds throughout the world". For example, the British Landrace pig is a standardized breed, derived from earlier breeds with "Landrace" names. BPA's breed-specific usage is commonly found in various other publications.
- One example of general and specific use in the same document, is an article in a UN FAO journal that refers to "landrace breeds" in its title, but distinguishes between formal breeds like Nguni cattle, the Boer goat and "indigenous pig breeds" on the one hand, and "indigenous sheep landraces" on the other.
- E.g. "a relatively homogenous group of animals within a species, developed and maintained by humans."; "a group of organisms within a species, esp a group of domestic animals, originated and maintained by man and having a clearly defined set of characteristics"; "A stock of animals or plants within a species having a distinctive appearance and typically having been developed by deliberate selection."; "a group of animals or plants presumably related by descent from common ancestors and visibly similar in most characters; especially : such a group differentiated from the wild type under domestication
- Jones, Huw; Lister, Diane L.; Bower, Mim A.; Leigh, Fiona J.; Smith, Lydia M.; Jones, Martin K. (August 2008). "Approaches and Constraints of Using Existing Landrace Material to Understand Agricultural Spread in Prehistory". Plant Genetic Resources (6). Cambridge University Press. pp. 98–112. doi:10.1017/S1479262108993138. Archived from the original on May 14, 2008. Retrieved August 6, 2014. The copy at this URL is missing the author information but provides full text otherwise; that information is available in this official online abstract.
- Commission on Genetic Resources for Food and Agriculture. "Reviewing the Roles of Animal Genetic Resources and Options for Their Conservation". In Vivo Conservation of Animal Genetic Resources (PDF). FAO Animal Production and Health Guidelines (14). UN Food and Agriculture Organization. pp. 4–5. ISSN 1810-0708.
- Sponenberg, D. Phillip (May 18, 2000). "Genetic Resources and Their Conservation". In Bowling, Anatoly; Ruvinsky. The Genetics of the Horse. Wallingford, Oxfordshire, UK: CABI Publishing. pp. 392–393. ISBN 0-85199-429-6. Retrieved September 28, 2014.
- Camacho Villa, Taina Carolina; Maxted, Nigel; Scholten, Maria; Ford-Lloyd, Brian (December 2005). "Defining and Identifying Crop Landraces". Plant Genetic Resources 3 (3): 373–384. doi:10.1079/PGR200591.
- Commission on Genetic Resources for Food and Agriculture. "Glossary of Selected Terms". In Vivo Conservation of Animal Genetic Resources (PDF). FAO Animal Production and Health Guidelines (14). UN Food and Agriculture Organization. pp. xv–xx. ISSN 1810-0708.
- Friis-Hansen, Esbern; Sthapit, Bhuwon (eds.) (2000). Participatory Approaches to the Conservation and Use of Plant Genetic Resources. Rome, Italy: International Plant Genetic Resources Institute. p. 199. ISBN 92-9043-444-9.
- Breton Olson, Meryl; Morris, Katlyn S.; Méndez, V. Ernesto (2012). "Cultivation of Maize Landraces by Small-scale Shade Coffee Farmers in Western El Salvador" (PDF). Agricultural Systems (111): 63–74.
- Andersen, Regine (April 2010). "An Issue of Survival". Development & Cooperation 51 (04). Internationale Weiterbildung und Entwicklung. Archived from the original on April 19, 2010. Retrieved August 6, 2014.
- Harlan, J. R. (1975). Crops and Man. Madison, Wisconsin: American Society of Agronomy and Crop Science Society of America.[page needed]
- Zeven, A. C. (1998). "Landraces: A Review of Definitions and classifciations". Euphytica 104 (2): 127–139. doi:10.1023/A:1018683119237. Abstract and first two pages are available for free access.
- Harlan, Jack R. (1971). "Agricultural Origins: Centers and Noncenters: Agriculture May Originate in Discrete Centers or Evolve Over Vast Areas Without Definable Centers". Science 174 (4008): 468–474. doi:10.1126/science.174.4008.468.
- "Landrace". Dictionray.com Unabridged. Random House. 2014. Retrieved August 5, 2014. Based on the Random House Dictionary.
- "Definition of landrace in English". OxfordDictionaries.com. Oxford University Press. 2014. Retrieved August 5, 2014.
- "Definition of breed in English". OxfordDictionaries.com. 2014. Retrieved September 25, 2014.
- "Section B. Landraces: B.1. Introduction". Resource Book for the Preparation of National Plans for Conservation of Crop Wild Relatives and Landraces (PDF). Food and Agriculture Organization of the United Nations. 2014. Retrieved August 6, 2014.
- Ramsay, K.; Smuts, M.; Els, H. C. (2000). "Adding Value to South African Landrace Breeds Conservation through Utilisation" (PDF). Animal Genetic Resources Information (Food and Agriculture Organization of the United Nations) (27): 9–15.
- Simmons, Paula; Ekarius, Carol (2009) . ""Charollais"". Storey's Guide to Raising Sheep (New ed.). Storey Publishing.
- "Picos de Europa". UNESCO.org. United Nations Education, Scientific and Cultural Organization (UNESCO). April 2014.
- In Vivo Conservation, FAO glossary, pp. xv–xx
- "The British Landrace: Breed History". BritishPigs.org.uk. Trumpington, Cambridgeshire, UK: British Pig Association. 2014. Retrieved 30 September 2014.
- Ramanandan, P. (1997). "Pigeonpea: Genetic Resources". In Nene, Y.L. The Pigeonpea. Wallingford, Oxfordshire, UK: CAB International. pp. 89–116.
- Staff. "breed, def 13". Dictionary.Reference.com. Retrieved 2014-08-07.
- "breed, def 6". World English Dictionary. Retrieved 2014-08-07. (Republished by Reference.com.)
- "Breed noun". Oxford Dictionaries. "American English" listings. Retrieved 2014-08-07.
- "Breed def 2, noun". Merriam-Webster. Retrieved 2014-08-07.
- Bonjean, Alain P.; Angus, William J. (eds.) (2001). The World Wheat Book: A History of Wheat Breeding 1. Paris, France: Lavoisier/Intercept. ISBN 978-1898298724.[page needed]
- "Irish Landraces". Irish Landraces. Waterford, Ireland: National Biodiversity Data Centre. 2012. Retrieved August 7, 2014.
- Sponenberg, D. Phillip; Bixby, Donald E. (2007). Managing Breeds for a Secure Future: Strategies for Breeders and Breed Associations. Pittsboro, North Carolina: American Livestock Breeds Conservancy. pp. 8–10. ISBN 9781887316071.
- "Florida Cracker and Pineywoods Cattle". Hobby Farms. 2012. Retrieved May 25, 2012.
- Lord, Kathryn; Coppinger, Lorna; Coppinger, Raymond (2013). "Differences in the Behavior of Landraces and Breeds of Dogs". In Grandin, Temple; Deesing, Mark J. Genetics and the Behavior of Domestic Animals (2nd ed.) (Academic Press). pp. 195–235. ISBN 9780124055087 //Books.Google.com/books?id=4L3dMJ8-aWgC&. Retrieved August 13, 2014. Missing or empty
- Dohner, Jan (December 6, 2013). "Choosing a Livestock Guard Dog Breed, Part Two". Mother Earth News. Retrieved August 13, 2014.
- Wozencraft, W. C. (2005). "Order Carnivora". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. ISBN 978-0-8018-8221-0. OCLC 62265494.
- Goldman, Jason G. "Man’s new best friend? A forgotten Russian experiment in fox domestication | Guest Blog, Scientific American Blog Network". Blogs.scientificamerican.com. Retrieved 2012-05-25.
- Ostrander, Elaine (2011). "The NHGRI Dog Genome Project". Canine Genome Project. Washington, DC: National Institute of Health. Retrieved July 13, 2011.
- Ward, Andy. "Landrace vs. Purebred Scotch Collies". Old-Time Farm Shepherd: Dedicated to Bringing Back the Old Scotch Collie of Yesterday. Old-time Scotch Collie Association.
- Van Asch, Barbara; Zhang, Ai-bing; Oskarsson, Mattias; Klütsch, Cornelya; Amorim, António; Savolainen, Peter (May 10, 2012). "MtDNA Analysis Confirms Early Pre‐Columbian Origins of Native American Dogs". KTH Publication Database DiVA. Stockholm, Sweden: KTH Royal Institute of Technology. Retrieved July 10, 2013.
- Gaddy, L. L. (2005). Biodiversity: Przewalski's Horse, Edna's Trillium, the Giant Squid, and Over 1.5 Million Other Species. p. 6. Retrieved September 29, 2014.
- "Przewalski's Horse". National Zoo. Smithsonian Institution. 2014. Retrieved September 25, 2014.
- Nabhan, Gary Paul (April 2008). Renewing America's Food Traditions: Saving and Savoring the Continent's Most Endangered Foods. White River Junction, Vermont: Chelsea Green. Retrieved 7 August 2014.