How Do You Think The Domestication Of Wild Animals And Plants Is Tied To The Development

CARLOS A. DRISCOLL,^* ^† DAVID W. MACDONALD,^* and STEPHEN J. O'BRIEN^†

Bogus option is the pick of advantageous natural variation for human ends and is the mechanism by which near domestic species evolved. Most domesticates have their origin in ane of a few historic centers of domestication as farm animals. Two notable exceptions are cats and dogs. Wolf domestication was initiated late in the Mesolithic when humans were nomadic hunter-gatherers. Those wolves less afraid of humans scavenged nomadic hunting camps and over fourth dimension developed utility, initially as guards warning of approaching animals or other nomadic bands and before long thereafter as hunters, an attribute tuned past artificial selection. The first domestic cats had express utility and initiated their domestication amongst the earliest agricultural Neolithic settlements in the Near East. Wildcat domestication occurred through a self-selective process in which behavioral reproductive isolation evolved as a correlated character of assortative mating coupled to habitat option for urban environments. Eurasian wildcats initiated domestication and their evolution to companion animals was initially a process of natural, rather than artificial, pick over time driven during their sympatry with forbear wildcats.

Darwin famously first described natural selection in 1859 with his classic monograph On the Origin of Species. Sexual pick was addressed in Descent of Man, and Choice Related to Sex in 1871. In between those two, in 1868, Darwin published a 2-volume work, The Variation of Animals and Plants Under Domestication, in which he expands upon a third distinct stream of evolutionary machinery—bogus pick—that he offset had outlined in Origin.

NATURAL VS. Bogus SELECTION

Bogus choice is unique in that, as the proper noun suggests, it is wholly unnatural. That insight seems at get-go little, simply reflection reveals but how boggling and fundamental artificial selection (manifest every bit domestication) has been to human success equally a species. Information technology was no more than 12,000 years agone that humankind began to consciously harness the 4-billion-year evolutionary patrimony of life on Earth. Exploiting the genetic diversity of living plants and animals for our own do good gave humans a leading role in the evolutionary process for the get-go time. Agronomical food production (sensu lato, including animal husbandry) has allowed the human population to grow from an estimated 10 million in the Neolithic to 6.nine billion today, and still expanding (Groube, 1996). Today, 4.93 billion hectares are used for agronomical practices, which also business relationship for 70% of all freshwater consumed (World Resource Institute, 2000). The world's species are going extinct at a rate 100–i,000 times faster than the historic "groundwork" charge per unit, primarily as a result of habitat loss, which is itself overwhelmingly driven by conversion of natural habitats to agriculture. Even so, to engagement no domestic animal has gone extinct (Zeder, 2008). The consequences for the planet (equally well as for humanity and its domesticates) have been profound, and have included the consummate transformation of nigh every natural ecosystem on Earth.

Domesticating animals and plants brought surpluses of calories and nutrients and ushered in the Neolithic Revolution. However, the Neolithic Revolution involved more than unproblematic food production; information technology was also the growth of an agricultural economy encompassing a packet of plant and animal utilization that allowed for the development of urban life and a suite of innovations encompassing nearly of what we today think of as culture (Bar-Yosef, 1998; Peters et al., 2005). Much of modernity is an indirect consequence of artificial selection. The plow has come to symbolize the Neolithic Revolution, only viewing history in the light of evolution we run across that information technology was intelligently designed changes to the genetic composition of natural biota that made the real tools. In some sense, Neolithic farmers were the first geneticists and domestic agronomics was the lever with which they moved the world.

VARIATION OF ANIMALS AND PLANTS UNDER DOMESTICATION

Modern summaries (and this colloquium) arrange the drivers of "descent with modification" into natural, sexual, and bogus selection, but Darwin's conceptual arrangement was somewhat different from our own. He saw sexual selection as a part of natural selection, and bogus selection as a money with two sides, 1 he called Methodical and the other Unconscious (Darwin, 1890). Unconscious selection supposes no witting wish or expectation to permanently change a breed, whereas Methodical selection is guided by some predetermined standard every bit to what is best; intention therefore is the substantial difference (Darwin, 1890). This distinction has largely lapsed in today'southward debate, although Darwin idea it worth discussing.

We perceive today, as did Darwin, that natural selection is the environmentally driven mechanistic procedure by which more than advantageous traits are, on the whole, passed on to succeeding generations more often than less advantageous traits because of differential reproduction of the individuals possessing them. Sexual option is a natural procedure of intraspecific competition for mating rights. Artificial selection, generally the motive forcefulness backside domestication, is often equated with selective breeding. This often amounts to prezygotic selection (where mates are chosen by humans) versus postzygotic selection (where the nigh fit progeny reproduce differentially) as in natural selection. Although natural choice plays a considerable role in the evolution of many traits (due east.g., disease resistance) during the animal domestication procedure, sexual choice is finer trumped past the human-imposed arrangements of matings and often past the human desire for particular secondary sexual characters. Bogus selection is a conscious, if unintentional, process, and therefore is generally considered to be effected only by humans [simply see Schultz et al. (2005)].

We suggest that bogus selection has both a "weak" and a "strong" form. In weak artificial selection, selection force per unit area is applied postzygotically (selectively alternative a herd of deer, for instance) and natural selection proceeds from this modified genetic baseline. In potent bogus selection, selection is prezygotic, as well every bit postzygotic (due east.g., mating male offspring of high-yielding dairy cows to high-yielding cows). This will upshot in a dramatic acceleration of evolutionary processes and entail a much greater level of control over the selected organism.

Darwin's The Variation of Animals and Plants Nether Domestication (Darwin, 1890) offers a litany of facts and examples of artificial choice in activity at the easily of constitute and animal breeders. Darwin felt that an understanding and appreciation of the depth of bogus option was fundamental to the acceptance of natural selection. In Variation, Darwin wanted to expand on this artificial mechanism of evolution beyond examples in Origin, where he describes familiar and tangible results of husbandmen in his argument that pick by the coordinating natural ways—survival of the fittest—was non just plausible or possible, merely likely. Darwin considered any multifariousness, brood, or subspecies, no affair how it was derived, as an incipient species, irrespective of the detail selective mechanism driving the group's evolution (Darwin, 1890). He sought to illustrate that tremendous changes can exist wrought through the "gradual and accumulative force of selection," simply he also emphasized that evolution past selection of any blazon tin can just work where variation is present; "[t]he ability of selection … absolutely depends on the variability of organic beings" (Darwin, 1890). Thus, genetic differences between domesticates and their wild counterparts substantially reflect the native genetic variation (i.east., standing variation) present in the wild population before any selection (natural or artificial) for tameness, and the secondary effects of isolation (Darwin, 1890).

Through the plethora of examples laid out in Variation, Darwin was making a example that the consequences of artificial pick are similar in spirit to those of natural selection, merely, moreover, that bogus pick (whether methodical or unconscious) was skilful a very long time agone. Darwin farther suggested that there had been little need for humans to understand the mechanism of artificial pick, so long equally the procedure operated effectively and produced tangible results.

DOMESTICATION More often than not

Are domesticated strains separate species (either from one another, or from their wild ancestors)? The answer generally is "no," under the conceptual framework of the Biological Species Concept (Dobzhansky, 1937; Mayr, 1942; O'Brien and Mayr, 1991a,b; Avise, 2004). Breeds typically are interfertile and intercross if given the opportunity. When domesticates are sympatric with populations of the parent wild species (if the latter notwithstanding persist), factor catamenia generally can occur. When is an fauna truly domesticated? Hard definitions are elusive because domestication is a continuous transition, attributes differ by species, and genes and environment interact to produce selectable characters that may vary with circumstance (Price, 1984). However, an interconnected and characteristic suite of modifiable traits involving physiology, morphology, and behavior are often associated with domestication (Coppinger and Smith, 1983; Price, 1984; Hemmer, 1990; Morey, 1994). Critically, all domesticates manifest a remarkable tolerance of proximity to (or outright lack of fear of) people. Reproductive cycle changes such every bit polyestrousness and adaptations to a new (and often poorer) diet are typical (Hemmer, 1990). Common concrete and physiological recurrences among domesticated mammals include: dwarfs and giants, piebald glaze color, wavy or curly hair, fewer vertebrae, shorter tails, rolled tails, and floppy ears or other manifestations of neoteny (the retention of juvenile features into sexual maturity) (Clutton-Brock, 1999). Behaviorally also, domestication is not a single trait simply a suite of traits, comprising elements affecting mood, emotion, doubter and affiliative behavior, and social communication that all accept been modified in some way.

The appreciable metabolic and morphological changes that oftentimes accompany behavioral adaptation to the human environs usually lead to a significant dependence on humans for food and shelter. All the same, domestication should not exist conflated with taming. Taming is conditioned behavioral modification of an individual; domestication is permanent genetic modification of a bred lineage that leads to, among other things, a heritable predisposition toward human clan. And domestic animals need not exist "tame" in the behavioral sense (consider a Spanish fighting bull) and, conversely, wild animals can be quite tame (consider a handraised cheetah or tiger). A domestic animal is ane whose mate option is influenced by humans and whose tameness and tolerance of humans is genetically adamant. Controlled convenance amounts to prezygotic selection, a critical element to domestication (because captive convenance allows for the strongest, most direct artificial selection). However, an creature merely bred in captivity is not necessarily domesticated. Tigers, gorillas, and polar bears breed readily in captivity only are nevertheless not "domesticated." Likewise, Asian elephants are wild fauna that with taming manifest outward signs of domestication, still their breeding is not human controlled and thus they are not true domesticates (Lair, 1997).

NEOLITHIC Earth OF THE FERTILE CRESCENT

Most of today'south domesticates began every bit nutrient, merely all domesticates, including dogs and cats, have ane thing in common: They are all tolerant of people. Where, how, and why did this tolerance develop? To understand this phenomenon, nosotros take to step back to a fourth dimension when humans began living in settled groups.

Accumulated archaeological, cultural, and genetic evidence points to the Concluding Pleistocene (≈12,000 years ago) in the Fertile Crescent (Fig. v.i) as the principal locus of domestication for many western domesticates (Zeuner, 1963; Smith, 1995; Clutton-Brock, 1999; Peters et al., 2005; Zeder et al., 2006a; Bellwood, 2007; Zeder, 2008). Estimated dates for these events range from 15,000 years B.P. for the domestic dog to 8,000 B.P. for cattle (Table 5.ane). The term Fertile Crescent was coined by James Henry Breasted who characterized the region by both ecological and cultural features pres ent at the time of earliest civilisation (Breasted, 1916). In his conception, the Fertile Crescent extends from the Mesopotamian plains, through the Taurus mountains and forth the Mediterranean declension to the Levant, and does non include Egypt (Fig. 5.1). Here, hunter-gatherers first became sedentary, domesticated plants and animals, developed agronomics, and built urban villages—the suite of cultural innovations and consequences known as the Neolithic Revolution. The Fertile Crescent during the final Pleistocene was much different from the thorny, overgrazed scrub that is nowadays today. Gazelle and deer, wild cattle, boar, horses, and goats and sheep flourished through an oak/pistachio parkland (Bar-Yosef, 1998; Clutton-Brock, 1999). Among the hundred or and so species of edible seeds, leaves, fruits, and tubers, there were thick natural stands of cereals (barley, einkorn, and emmer wheat) and pulses (pea, chickpea, lentil), which provide a rich source of calories and a balance of nutrients. Together with flax (used for fiber) and biting vetch, these plants would later form a parcel that became our viii founder crops (Bellwood, 2007). For >100,000 years, humans had been nomadic hunter-gatherers. Notwithstanding, because the Fertile Crescent was then bountiful, the inhabitants of the Levant at this fourth dimension (known archaeologically every bit Natufians) were able to hunt and gather all they needed with just brusk forays from base camps; they became a "hunter-gatherer elite" (Bar-Yosef, 1998). Over fourth dimension, movable camps evolved into permanent semisubterranean pit-houses where (nosotros suppose) the Natufians stored wild grains for use throughout the year (Bar-Yosef, 1998).

Effigy five.1

Map of the Near East indicating the Fertile Crescent [according to Breasted (1916)]. Shaded areas betoken the approximate areas of domestication of pig, cattle, sheep, and goats with dates of initial domestication in calibrated years b.p. [later Zeder (more...)

Table 5.1

Common Western Domestic Animals and Their Context.

Between 13,000 and 11,000 B.P. the Natufian hunter-gatherers developed tools such as the sickle and grinding stones to harvest and process wild grains (Bar-Yosef, 1998). Afterward (11,000 to 10,300 B.P.), a cold and dry period reduced the bachelor wild plant nutrient and increased the Natufian's dependence on cultivated grasses and legumes (the founder crops mentioned in a higher place). This climatic shift, chosen the Younger Dryas event, may have been the trigger for a change in accent abroad from hunting-gathering and toward true agriculture via improvised tillage. With a reliable nutrient source, human populations began to ascension, applied science for collecting grains further improved, and settlements initially encouraged by naturally abundant food led to larger settlements. Although hunter-gatherers throughout the earth had long manipulated plants and animals (for instance by using fire to encourage edible plants or animals that thrive on disturbed land), Neolithic agriculture moved well beyond the raising and harvesting of plants and animals and into an entrenched economic system enforced by labor demands and ecological transformations. Productive country, now the predominant venue for nutrient supply and valued at a premium, would be cultivated and defended twelvemonth circular. This commitment to an agricultural life entailed permanent buildings and facilities for storing surpluses of food, and it created the offset farm communities.

Domestication of today's barnyard animals proceeded as a result of pressure by these early hunter-gatherers as they intuitively sought to stabilize their nutrient resources (Clutton-Brock, 1999; Zeder, 2006; Zeder et al., 2006b). Amidst the successful domesticates, most were behaviorally preadapted to domestication. Behavioral characteristics considered favorable and unfavorable are presented in Table 5.2. Undiscriminating animals descend from herd-living herbivores whose ancestors followed a dominant individual through a territory shared with other herds. Neolithic peoples exploited this dominance hierarchy by, in effect, supplanting the alpha individual and thereby gaining control of the herd. Herd-living animals were predisposed to tolerate close living quarters, and their temperament immune them to adapt hands to solitude. They also had a flexible diet (enough to live on what early farmers might provide), grew fast (and thus did not unduly expend farmers' resources), and would freely breed in the presence of people (Zeuner, 1963; Hemmer, 1990; Clutton-Brock, 1999). A comparing of the occurrence of preadaptive characters among wild species of the Fertile Crescent is presented in Table 5.iii. The predecessors of today's farm animals were undoubtedly selectively managed in hunts in natural habitats (corresponding to our weak artificial selection) earlier individuals were taken into captivity and bred (Darwin, 1890; Clutton-Brock, 1999; Zeder, 2006; Zeder et al., 2006b). Animals that bred well could then be selected (either consciously or unconsciously) for favorable traits (corresponding to our potent bogus pick). Domestication in these cases is a mixture of artificial selection (both weak and strong) for favorable traits and natural selection for accommodation to captivity, with artificial selection beingness the prime mover.

TABLE five.two

Favorable and Unfavorable Ecological and Behavioral Pre-adaptations to Domestication.

DOMESTICATION OF DOGS

The domestication of dogs and cats (today's two most popular companion animals) was a chip different from the barnyard animals. And although Darwin began Variation with a discussion of the dog and the cat, the ii could hardly be more different from each other (or from contemporary undiscriminating domesticates) in temperament, utility, and evolutionary origin. Subcontract animals were food items ("walking larders") brought into the human being sphere at the transition bespeak from hunting-gathering to agriculture (Clutton-Brock, 1999). Dogs, the earliest domesticate, proved useful equally guards and as hunters for the hunting-gatherers, and maybe offered necessary lessons for subsequent domestication of other species (Muller, 2005). Past contrast, cat domesticates arose much later (≈x,000 B.P.), after humans built houses, farms, and settlements.

The preponderance of molecular evidence points to an origin of dogs from the wolf, Canis lupus (Vila et al., 1997; Leonard et al., 2002). The molecular findings are also supported by a large body of archaeological evidence that implicates the Near E as a likely locus of definitive domestication [although domestic dog domestication may have begun in Central Europe equally early as the Upper Late Paleolithic (Clutton-Brock, 1999; Muller, 2005)]. Wolf domestication is seen as the upshot of 2 interwoven processes originating >fourteen,000 years agone during our hunter-gatherer nomadic period (Clutton-Brock, 1995). First, a founder group of less-fearful wolves would have been pulled toward nomadic encampments to scavenge kills or peradventure salvage wounded escapees from the hunt. Thereafter, these wolves may have constitute utility as barking sentinels, warning of man and animal invaders approaching at dark (Lindsay, 2000). Gradually, natural choice and genetic migrate resulting from homo activities began to differentiate these wolves from the larger autonomous population. Once people had direct interaction with wolves, a subsequent, "cultural process" would have begun. Suitable "preselected" wolf pups taken as pets would take been socialized to humans and unconsciously and unin tentionally selected for decreased flight behavior and increased sociality (Muller, 2005), 2 trademarks of tameness. Eventually, people established control over proto-domestic dog mating. From this indicate forward the wolf in outcome became a canis familiaris, under constant observation and subject to strong artificial selection for desired traits. Selection for tameness entails morphological and physiological changes through polygenes governing developmental processes and patterns (Trut, 1999; Muller, 2005), and these provide grist for the manufactory of further iterations of pick. For wolf domestication, the phases of natural and artificial selection blend one into the other, eventuating in "man's best friend" with doting and obedient behaviors. Although dogs accept been prized every bit household companions for thousands of years, the wide phenotypic variation of modernistic dog breeds began more recently (3,000–4,000 B.P.), leading to the ≈400 breeds recognized today past the Domestic dog Breeders Associations (Fogle and Morgan, 2000).

DOMESTICATION OF CATS

The domestication of cats took a unlike trajectory. Wildcats are improbable candidates for domestication (see Table 5.3). Like all felids, wildcats are obligate carnivores, meaning they take a limited metabolic ability to assimilate annihilation except proteins (Bradshaw et al., 1996). Cats live a solitary being and defend exclusive territories (making them more attached to places than to people). Furthermore, cats do non perform directed tasks and their bodily utility is debatable, even as mousers (Elton, 1953). [In this latter role, terrier dogs and the ferret (a domesticated polecat) are more suitable.] Accordingly, there is niggling reason to believe an early on agricultural community would have actively sought out and selected the wildcat as a house pet. Rather, the best inference is that wildcats exploiting human environments were simply tolerated past people and, over time and infinite, they gradually diverged from their "wild" relatives (Wandeler et al., 2003; Driscoll et al., 2009). Thus, whereas adaptation in barnyard animals and dogs to human being dominion was largely driven past bogus option, the original domestic cat was a product of natural selection.

A comprehensive genetic exam of the Felis silvestris species complex by our grouping revealed the relationships between domestic cats and their indigenous wild congeners (Driscoll et al., 2007). We typed 36 curt tandem echo loci and sequenced 2.6 kb of the mitochondrial genes ND5 and ND6 in ≈one,000 cats from wild and domestic settings, including representatives of registered-brood and random-bred pet cats from both feral and household environments. Phylogenetic and clustering analyses identified 5 genetically distinctive F. silvestris wildcat subspecies (Fig. five.two) nowadays in: Europe (F. silvestris silvestris, clade I), Southern Africa (F. silvestris cafra, clade II), Fundamental Asia (F. silvestris ornata, clade 3), the Near East (F. silvestris lybica, clade IV), and the northern edge of the Tibetan plateau (F. silvestris bieti, clade V). Local wildcat populations retained genetic signatures that tied them to their respective regions (Fig. 5.2A). In contrast, the world's domestic cats carried genotypes that differentiated them from all local wildcats except those from the Almost East. Domestic cats show no reduction in genetic diversity compared with the wild subspecies (Driscoll et al., 2007), thus giving no indication for a founding genetic bottleneck. Multiple genetic analyses produced concordant results, in each case tracing the maternal origins of cat domestication to at least 5 mutiny lines (A through East, Fig. five.iiB) originating in the Most East. The domestic cat is referred to as a 6th subspecies, F. silvestris catus, although information technology is clear that domestic cats derive very recently from F. silvestris lybica (Driscoll et al., 2007).

FIGURE v.2

Distribution of F. silvestris microsatellite and mitochondrial geno-types with associated dendrograms. (A) Textured regions on map reverberate the distribution of different STR genotype clades (see fundamental at top). The mtDNA haplotype frequencies are indicated (more...)

TABLE 5.3

Pre-adaptive Features of Some Commonly Encountered Neolithic Brute.

Cat domestication dates to at least 3,600 B.P., when what are clearly house cats are depicted in tomb paintings of the Egyptian New Kingdom (Clutton-Brock, 1993, 1999). All the same, the oldest archaeological evidence of cat taming dates to ≈9,500 B.P. in Crete (Vigne et al., 2004) and cat remains have also been dated to viii,700 B.P. from Jericho (Zeuner, 1963). Given that, a reasonable window for cat domestication is 9,500–3,600 B.P. However, we estimated a coalescence date of 131,000 years ago for the catus/lybica mtDNA clade (Driscoll et al., 2007). This date is greater by at least an order of magnitude than whatever plausible domestication issue only can in principle be explained by multiple maternal-lineage recruitments from the wild source population (Jones and Brown, 2000). Considering the broadest range of dates for domestication to be from xi,000 to 4,000 B.P., and applying an internally calibrated mutation rate for true cat mitochondrial DNA (mtDNA) (Lopez et al., 1997), we wait 0–3 mutations over the 2.6-kb mtDNA surveyed in modernistic domestic cats (Driscoll et al., 2007). We annotation that ≈xc% of domestic cats share haplotypes that are ane nucleotide diverged from each other, a finding that is consequent with these mutations having occurred very recently. Domestic true cat mtDNA is therefore expected to take few, if any, widely divergent domestic-specific haplotypes. Our sample, in effect, represents a sampling of the source wildcat population'southward mitochondrial genetic diversity. In sum, the genetic evidence appears to be most consistent with a single protracted domestication episode, one incorporating multiple wildcat matrilines over the wide Most Eastern human cultural area. We feel this development can best exist understood in the context of agricultural development patterns. The post-obit scenario for cat domestication seems likely.

SYMPATRIC Deviation AND PLURAL MITOCHONDRIAL ORIGINS

The bachelor archaeological show indicates that the process of mutiny domestication began in the Neolithic in the same place and time as the development of yr-round settlements and the onset of an agricultural economic system (Clutton-Brock, 1993; Vigne et al., 2004; Driscoll et al., 2007). Every bit far as the local animate being was concerned, these permanent human settlements adult ex nihilo. Opportunistic animals apparently ventured into this new urban environment, rich in nutrient year-round and complimentary of well-nigh predators, and found fertile new ecological niches to exploit (Zeuner, 1963; Coppinger and Smith, 1983). The ability to live around people therefore conferred important advantages to those animals that adjusted to it (Morey, 1994). Commensal species such equally mice, rats, and sparrows that adapted to human being village environment (and their trash) probably emerged outset. Although the primeval grain cache (of wild, not domestic, grains) in the Near Due east is dated to 21,000 B.P. (Tanno and Willcox, 2006), the origin of agriculture per se in the region is dated to between 12,500 and 11,250 B.P. (Hillman et al., 2001), and it is from approximately this period that house mice locally appeared (Auffray et al., 1988). Resident populations of peridomestic rodents sustained by trash dumps and stockpiles of grain provided a reliable food source for native wildcats, which and so became adjusted to an "urban" surroundings as peridomestic human commensals themselves (Serpell, 1990; Sunquist and Sunquist, 2002).

Cereal domestication in the Fertile Crescent is characterized by multiple independent domestication of multiple grain species in multiple centers from the southern Levant through Syrian arab republic to southern Anatolia (Willcox, 2005). If cat domestication is largely a sequela of the development of towns (enhanced by the domestication of grains), divergent mitochondrial lineages (A–E in Fig. v.2B) may not be unexpected, because recruitment of naturally occurring wildcat mitochondrial lineages would reflect the broad distribution of homo settlements. Bearing in heed that an mtDNA gene tree represents only a tiny subset of the species' genetic history (MacHugh and Bradley, 2001; Avise, 2004), and considering domestication as a polygenic trait affecting beliefs (Trut, 1999), the polygenic allelic serial behind domesticity and mtDNA need not take congruent histories. Over time and space, multiple wildcat matrilines would have been incorporated into the domestic true cat gene pool through the admixture of an initial domesticate with additional wild female conspecifics, thereby spreading genes for the domestic phenotype through the early on Fertile Crescent agronomical surface area. Thus, the relatively profound depth (131,000 years) of the catus/lybica clade may be all-time explained by a protracted wildcat domestication process that spanned thousands of years and extended over much of the Fertile Crescent (Fig. five.i). The alternative hypothesis—of multiple independent domestication events—seems unlikely for 2 reasons: First, the vast majority of sampled domestic cats fall into the same mtDNA clade, which also includes F. silvestris lybica; and 2d, the clade lacks biogeographic construction. Individual house cats from whatever i sampling area may fall into any lineage, and even the near genetically divergent lineages have domestic individuals from the same sampling area. An important validation of this hypothesis awaits the identification of the causal mutations mediating domestic behavior in cats. Finding dissimilar mutations for the tame phenotype would propose the multiple independent invention of domestication in cats, whereas finding the identical mutation(s) in all v domestic cat lineages would support a single origin for the gene complex spread by population improvidence.

Taken together, these results provide both phylogenetic and phylogeographic testify that the divergence of domestic cat from mutiny occurred sympatrically. First, with respect to phylogeny, the monophyly of distinct taxa from the aforementioned surroundings (domestic cat and wildcat from the Near East) (Fig. five.2B and C) is conspicuously consequent with sympatric deviation. Second, with respect to a phylogeography, sympatric divergence seems plausible because domestic cat and Near Eastern wildcat are phenotypically divergent (in terms of behavior) still are more than closely related to one another than Near Eastern wildcat are to more than phenotypically similar allopatric groups (such as Asiatic wildcat or Southern African mutiny) (Fig. five.2A). This scenario supposes a model of sympatric habitatrace formation in which habitat-specific beneficial mutations accumulated by assortative mating into a coherent allelic serial. Chiefly, this model avoids the "selection-recombination antagonism" described past Felsenstein (1981), whereby genes required for mating and genes required for assortative mating must exist linked, because the same genes that drive habitat choice also bulldoze assortative mating [encounter Via (2001) for review].

It seems likely that behavioral genes affecting domestication were initially selected by habitat choice of individual wildcats better fit for urban life, and that these genes were later on transferred to geographically disparate spots, promoted past a human preference for tameness and perhaps the translocation of these individuals. However, it is also possible that private component polygenes contributing to domestication derive from unlike population recruitments every bit well. Each adaptive locus/allele may accept been independently selected in a different Fertile Crescent population and through fourth dimension these combined, each allele contributing an increasingly additive effect, until their genomic consilience in an irrefutably domestic animal. Domestication in cats could thus be an allelic series of independently selected alleles from throughout the wildcat natural range, only assembled equally a composite. In an analogous fashion, modern hog and cattle breeds are routinely "improved" via the introduction of advantageous alleles through crossbreeding distant strains (descended from contained Oriental and European domestications in pigs, and from European and Southeastern Asia in cattle), rather than past independent pick of each trait within each lineage.

IS Wildcat DOMESTICATION Consummate?

At its most basic, domestication is a dependence on humans for food, shelter, and control of breeding (Price, 2002). Because 97% or more of the nearly one billion domestic cats living today are random-bred house cats, or are feral and intact, the overwhelming preponderance of domestic cats choose their own mates. Only a tiny fraction of cats (by and large those in registered breeds) accept mates chosen for them (prezygotic pick). Furthermore, the majority of feral cats obtain what they eat without human being assistance. Additionally, the domestic true cat varies little morphologically from the mutiny trunk program (Yamaguchi et al., 2004a,b), although, as Darwin noted, domestic cats have longer intestines than wildcats, a trait he attributed to a "less strictly carnivorous diet" as a event of feeding on kitchen scraps (Darwin, 1890). So an argument can be made that cat domestication is <200 years old and may yet exist incomplete (Serpell, 1990). Domestic cats have, however, become polyestrous, and their glaze colors frequently depart wildly from the mutiny's striped mackerel tabby. And domestication did socialize the wildcat (cats are the only domesticate that is social nether domestication yet lonely in the wild). Yet, the most noticeable adaptation is the true cat'southward overwhelming tolerance of people, a key aspect of any domesticated animal, but certainly the master characteristic that has made cats the delightful and flourishing profiteers in our homes that they are.

The mod domestic true cat is the product of 11 million years of natural choice in a world free of people (Johnson et al., 2006; O'Brien and Johnson, 2007), and 12,000 years of natural selection in a globe increasingly dominated by humanity (Johnson et al., 2006; O'Brien and Johnson, 2007). In 1868, Darwin commented that there are no breeds of cats native to England considering of a lack of selective breeding (Darwin, 1890, Vol. I, p. 50 and Vol. II, p. 222). The power of artificial pick to produce modernistic fancy cat breeds has only recently—inside the final 200 years—been brought to bear on the accumulated store of mutiny genetic variation (Fogle, 2001; Stephens and Yamazaki, 2001). Just already the pace of change is quickening, and the previously uniform wildcat is establish in varieties of hairless and longhair, dwarf and giant, which Darwin himself would have wondered at.

ACKNOWLEDGMENTS

We thank John Avise and 2 anonymous reviewers for helpful comments on an earlier typhoon of this manuscript.

*: Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, Tubney Business firm, Abingdon Road, Tubney, Oxon OX13 5QL, Great britain; and
†: Laboratory of Genomic Diversity, National Cancer Institute, Frederick, MD 21702.

Source: https://www.ncbi.nlm.nih.gov/books/NBK219727/

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