domestica) with a suggestion for complex song evolution. The cephalic neural crest exerts a critical effect on forebrain and midbrain development. Epigenetics and the biological basis of gene x environment interactions. Our contention that the effects of any single gene mutation on neural crest derivatives depend on its interactions with a host of other genes is clearly supported by the variable clinical picture associated with Waardenburg syndrome. Specifically, haploinsufficiency of TCOF1 leads to lowered levels of Treacle, which in turn leads to depletion of the NCC precursors of the first and second visceral arches (Dixon et al. A third, poorly understood, neurobiological aspect of domestication involves changes in the central nervous system. The Xenopus homolog of this gene, XSIP1, has been well studied and is strongly expressed early in prospective neuroectoderm, then in the neural plate, and later in the neural tube and neural crest. Sign up to receive alert notifications of new articles. La domestication étant un phénomène où les individus étaient originairement sélectionnés par leurs aptitudes comportementales, la méthylation de certains gènes aurait persisté dans leur progéniture aboutissant à des phénotypes avantageux pour l'exploitation humaine. NOTE: We request your email address only to inform the recipient that it was you who recommended this article, and that it is not junk mail. For example, one trait, curly tails, though not a universal consequence of domestication, presently defies a direct explanation in our terms. Of course, the small external ears of humans and rodents provide imperfect models for the elongated, erect ears of most carnivores and artiodactyls, and thus the biomechanical aspect of our explanation remains somewhat speculative. Conventional point mutations, however, are not necessarily the sole genetic source of the condition. Most importantly, however, the precise genetic—and epigenetic—bases of the domestication syndrome require further elucidation. In plants, … W.T.F. It was first described in animals (although not named as such) by Charles Darwin [ 1 ]. 2009). Langer, L., K. Sulik, and L. Penny, 2013 Cleft palate in a mouse model of Sox2 haploinsufficiency. 2009), we trace the mechanistic basis of tameness to reduced size and function of the adrenal glands, which play a central role in the physiology of both fear and stress responses. The available evidence on these genes fits these predictions and this material is summarized in Table 2. also thanks Brian Hare and Tory Wobber for a decade of discussions about domestication. Another recently identified human neurocristopathy of interest is Mowat-Wilson syndrome, a rare syndrome featuring microcephaly, specific narrowing of the jaw, and a host of other neural-crest-related symptoms (e.g., changes in ear morphology, heart disease, and as for Waardenburg’s, variable presence of Hirschsprung’s disease) along with mental retardation and epilepsy. Plant domestication can be thought of as a two-step process. en 2013[29] traite justement de l’avantage sélectif dont bénéficient les chiens par leurs expressions faciales pédomorphiques. Most of the modified traits, both morphological and physiological, can be readily explained as direct consequences of such deficiencies, while other traits are explicable as indirect consequences. Developmental schematic of the “domestication syndrome” in relation to the neural crest. a domestication syndrome: Distinctive fruit and seed characteristics that are typically associated with domestication relative to wild phenotypes growing in the same region. Les résultats obtenus confirment donc que la domestication aurait permis l’expression de mouvements et le développement de certains muscles chez les chiens domestiques en comparaison aux loups sauvages par des pressions de sélection visant à faciliter la communication. Without the signal, neural crest cells fail to delaminate from the neural tube. Most explanations focus on particular traits, while neglecting others, or on the possible selective factors involved in domestication rather than the underlying developmental and genetic causes of these traits. In the head specifically, cranial neural crest cells (CNCCs) are crucial precursors of bony, cartilaginous, and nervous components of the craniofacial region, including the jaws, hyoid, larynx, and external and middle ears. Une seconde et plus probable hypothèse serait que le mouvement AU101 ressemble à l’expression faciale produite par les humains quand ils sont tristes et entraîne l’expression de caractéristiques pédomorphiques telles que des yeux plus gros donnant une apparence plus juvénile engendrant ainsi une réponse de soins et présentant un avantage sélectif. L’autre différence est la présence et le niveau de développement du retractor anguli oculi lateralis (RAOL), un muscle qui permet de tirer latéralement le coin de la paupière vers les oreilles. The self-domestication hypothesis: bonobos evolved due to selection against male aggression. Today, the full set of these characteristics is known to include: increased docility and tameness, coat color changes, reductions in tooth size, changes in craniofacial morphology, alterations in ear and tail form (e.g., floppy ears), more frequent and nonseasonal estrus cycles, alterations in adrenocorticotropic hormone levels, changed concentrations of several neurotransmitters, prolongations in juvenile behavior, and reductions in both total brain size and of particular brain regions. The pineal glands are smaller in domesticated than wild female foxes and produce lower melatonin levels (Kolesnikova 1991). Another possibility involves the role of the pineal gland, a neural plate derivative that has not been thought to be NCC derived. The enamel-based crowns are produced from ameloblasts, which are not traditionally thought to be CNCC derived, but recent data suggest a neural crest contribution here as well (Wang et al. However, a second important virtue is that it makes a number of predictions that can easily be tested using existing methods. Instead, the data above clearly support the co-occurrence of multiple components of the DS as combined effects of multiple NCC-affecting mutations and, when considered as a whole, all of the components are known to result from NCC-related genetic effects. Genetics and the development of social behavior in dogs. This is also consistent with our hypothesis because neural crest cells are directly involved in tooth development (Hall 1999; Le Douarin and Kalcheim 1999; Gilbert 2003). Un article de Wikipédia, l'encyclopédie libre. While this suggestion remains hypothetical, it is testable, as discussed below. The origin of Darwin's "domestication syndrome" has remained a conundrum for more than 140 years. Les résultats ont démontré que les principales distinctions anatomiques faciales entre les chiens domestiques et les loups sauvages se trouvent au niveau de la musculature entourant l'œil, soit la présence chez les chiens et l’absence chez les loups du levator anguli oculi medialis (LAOM), un muscle permettant de hausser le coin intérieur des sourcils indépendamment du plissement de relaxation des yeux. The behavioral endocrinology of domestication: a comparison between the domestic guinea pig (Cavia aperea f. porcellus) and its wild ancestor, the cavy (Cavia aperea). The analysis showed that, regarding cranial changes, Pax3 interacts with at least two other genes, agouti and an unidentified sex-linked locus. (Both Treacher Collins and Mowat-Wilson sydromes are characterized by absent, reduced, or malformed ears). Il remarque sans doute que la sélection humaine sur des traits qu'il considère avantageux pourrait expliquer cette diversité, mais en partie seulement. 2009). Encyclopedia Britannica–Helen Hemingway Benton Publishing. This reduction, which is particularly prominent in the forebrain, is very significant in some species; for example, domestic pig brains are 35% smaller than expected for the same size wild boar, their presumed wild ancestor (Kruska 2005). Beyond such correlations, however, there is a considerable body of clinical and experimental work that provides direct empirical support for the hypothesis. Ces cellules se déplacent durant l'ontogenèse, donnant naissance aux précurseurs cellulaires de nombreux tissus [15],[16],[17],[18]; mélanocytes, l'os et le cartilage formant le crâne et les odontoblastes entre autres [19]. The first and most general was that the gentler “conditions of living” under domestication, in particular the improved diets provided to domesticated animals, induced these traits in some manner. 2001), and basal cortisol levels are also reduced in domesticated Bengalese finches, relative to their (captive raised) wild-type ancestors (Suzuki et al. Certain animal species, and certain individuals within those species, make better candidates for domestication than others because they exhibit certain behavioral characteristics: (1) the size and organization of their social structure; (2) the availability and the degree of selectivity in their choice of mates; (3) the ease and speed with which the parents bond with their young, and the maturity and … Most of the explanations proposed, however, do not attempt to account for the full spectrum of the DS but instead concentrate on isolated elements, such as coat color changes or muzzle size, positing particular selective pressures imposed by humans that might have fostered those traits.

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