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43-403: When a language is not shared with the village or hearing community as a whole, but is only used within a few families and their friends, it may be distinguished as a family sign language . In such cases, most of the hearing signers may be native speakers of the language, if they are members of one of these families, or acquired it at a young age. The nature of the village sign language depends on

86-546: A 1:2:1 genotype ratio with the first two classes showing the (A) phenotype, and the last showing the (a) phenotype, thereby producing the 3:1 phenotype ratio. Mendel did not use the terms gene, allele, phenotype, genotype, homozygote, and heterozygote, all of which were introduced later. He did introduce the notation of capital and lowercase letters for dominant and recessive alleles, respectively, still in use today. In 1928, British population geneticist Ronald Fisher proposed that dominance acted based on natural selection through

129-423: A consequence, grammatical and other linguistic structures may develop relatively slowly. There are exceptions, however. Kailge Sign Language is reported to use both concrete and metaphorical pointing, and to use sign space grammatically for verbal agreement. Because, at least in cases of genetically recessive deafness, village sign languages are used by large numbers of hearing people who also use spoken languages,

172-597: A decade, the deaf children of the village have attended a boarding school in Mampong-Akuapem , where the ASL based Ghanaian Sign Language is used. As a consequence, this language has become the first language of these children and their command of AdaSL is decreasing. This is likely to lead to a complete shift of the deaf community in Adamorobe to Ghanaian Sign Language. As such, AdaSL is an endangered sign language. ^b Denotes

215-416: A given gene of any function; one allele can be dominant over a second allele of the same gene, recessive to a third, and co-dominant with a fourth. Additionally, one allele may be dominant for one trait but not others. Dominance differs from epistasis , the phenomenon of an allele of one gene masking the effect of alleles of a different gene. Gregor Johann Mendel , "The Father of Genetics", promulgated

258-453: A membrane-bound H antigen. The I enzyme adds a galactose. The i allele produces no modification. Thus the I and I alleles are each dominant to i ( I I and I i individuals both have type A blood, and I I and I i individuals both have type B blood), but I I individuals have both modifications on their blood cells and thus have type AB blood, so the I and I alleles are said to be co-dominant. Another example occurs at

301-406: A pink snapdragon flower. The pink snapdragon is the result of incomplete dominance. A similar type of incomplete dominance is found in the four o'clock plant wherein pink color is produced when true-bred parents of white and red flowers are crossed. In quantitative genetics , where phenotypes are measured and treated numerically, if a heterozygote's phenotype is exactly between (numerically) that of

344-453: A shared signing community is the island Martha's Vineyard ( Martha's Vineyard Sign Language ). AdaSL shares signs and prosodic features with some other sign languages in the region, such as Bura Sign Language , but it has been suggested these similarities are due to culturally shared gestures rather than a genetic relationship. AdaSL has features that set it apart from the sign languages of large deaf communities studied so far, including

387-663: Is a key concept in Mendelian inheritance and classical genetics . Letters and Punnett squares are used to demonstrate the principles of dominance in teaching, and the upper-case letters are used to denote dominant alleles and lower-case letters are used for recessive alleles. An often quoted example of dominance is the inheritance of seed shape in peas . Peas may be round, associated with allele R , or wrinkled, associated with allele r . In this case, three combinations of alleles (genotypes) are possible: RR , Rr , and rr . The RR ( homozygous ) individuals have round peas, and

430-446: Is a shared sign language which differs from urban sign languages such as Ghanaian Sign Language because the majority of speakers of a shared sign language aren't actually deaf. National sign languages usually emerge for the purpose of use by deaf individuals such as those attending schools specifically for the deaf. This important feature of shared sign languages alters the way it is maintained, developed, and shared. A historical example of

473-782: Is the phenomenon of one variant ( allele ) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome . The first variant is termed dominant and the second is called recessive . This state of having two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new ( de novo ) or inherited . The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes ( autosomes ) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant , X-linked recessive or Y-linked ; these have an inheritance and presentation pattern that depends on

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516-417: The rr (homozygous) individuals have wrinkled peas. In Rr ( heterozygous ) individuals, the R allele masks the presence of the r allele, so these individuals also have round peas. Thus, allele R is dominant over allele r , and allele r is recessive to allele R . Dominance is not inherent to an allele or its traits ( phenotype ). It is a strictly relative effect between two alleles of

559-636: The F1 generation are self-pollinated, the phenotypic and genotypic ratio of the F2 generation will be 1:2:1 (Red:Spotted:White). These ratios are the same as those for incomplete dominance. Again, this classical terminology is inappropriate – in reality, such cases should not be said to exhibit dominance at all. Dominance can be influenced by various genetic interactions and it is essential to evaluate them when determining phenotypic outcomes. Multiple alleles , epistasis and pleiotropic genes are some factors that might influence

602-779: The Mardin family of Turkey and the family in which the Central Taurus Sign Language of Turkey emerged. Deaf people tend to have deaf children, and so pass the language on directly. With plenty of direct contact between deaf signers, the languages tend to be well developed. With fewer hearing people with deaf relatives, there are also generally fewer hearing people who sign, and less intermarriage; families tend to have their own vocabulary (and perhaps language), as on Amami Oshima in Japan. There are exceptions, however: In Ban Khor in Thailand

645-468: The absence of the type of classifier construction that expresses motion or location (sometimes called "entity classifiers"). Instead, AdaSL uses several types of serial verb constructions also found in the surrounding spoken language, Akan. Frishberg suggests that AdaSL may be related to the "gestural trade jargon used in the markets throughout West Africa". Thus AdaSL provides an interesting domain for research on cross-linguistic sign languages. For over

688-401: The contribution of modifier genes . In 1929, American geneticist Sewall Wright responded by stating that dominance is simply a physiological consequence of metabolic pathways and the relative necessity of the gene involved. In complete dominance, the effect of one allele in a heterozygous genotype completely masks the effect of the other. The allele that masks are considered dominant to

731-469: The deafness is dominant, and restricted to one extended family, but the houses of different families are intermixed within the village, so nearly all hearing people have deaf neighbors, and signing is widespread among all-hearing families. Village sign contrasts with deaf-community sign languages , which arise where deaf people come together to form their own communities. These include school sign, such as Nicaraguan Sign Language , Penang Sign Language , and

774-534: The dominant gene. However, if the F1-generation is further crossed with the F1-generation (heterozygote crossed with heterozygote) the offspring (F2-generation) will present the phenotype associated with the dominant gene ¾ times. Although heterozygote monohybrid crossing can result in two phenotype variants, it can result in three genotype variants -  homozygote dominant, heterozygote and homozygote recessive, respectively. In dihybrid inheritance we look at

817-463: The hearing community and only used secondarily by the deaf, if they (rather than home sign ) are used by the deaf at all, and (at least originally) are not independent languages. Village sign languages have historically appeared and disappeared as communities have shifted, and many are unknown or undescribed. Attested examples include: The alleged Rennellese Sign Language of the Solomon Islands

860-408: The hearing population. There appear to be grammatical differences between village and deaf-community languages, which may parallel the emergence and development of grammar during creolization. Sign space tends to be large. Few village sign languages use sign space for abstract metaphorical or grammatical functions, for example, restricting it to concrete reference, such as pointing to places or where

903-406: The idea of dominance in the 1860s. However, it was not widely known until the early twentieth century. Mendel observed that, for a variety of traits of garden peas having to do with the appearance of seeds, seed pods, and plants, there were two discrete phenotypes, such as round versus wrinkled seeds, yellow versus green seeds, red versus white flowers or tall versus short plants. When bred separately,

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946-417: The inheritance of two pairs of genes simultaneous. Assuming here that the two pairs of genes are located at non-homologous chromosomes, such that they are not coupled genes (see genetic linkage ) but instead inherited independently. Consider now the cross between parents (P-generation) of genotypes homozygote dominant and recessive, respectively. The offspring (F1-generation) will always heterozygous and present

989-412: The language to develop. Perhaps as a result, Providencia Sign is rather simplistic, the hearing speak to the deaf as if they were stupid, and the deaf are not well integrated into the community. In most recorded cases of village sign, it appears that recessive deafness is at work. Where the deafness is genetically dominant , on the other hand, deafness is largely restricted to particular families, such as

1032-485: The level of dominance the alleles expresses towards each other. Pleiotropic genes are genes where one single gene affects two or more characters (phenotype). This means that a gene can have a dominant effect on one trait, but a more recessive effect on another trait. Epistasis is interactions between multiple alleles at different loci. Easily said, several genes for one phenotype. The dominance relationship between alleles involved in epistatic interactions can influence

1075-450: The locus for the beta-globin component of hemoglobin , where the three molecular phenotypes of Hb /Hb , Hb /Hb , and Hb /Hb are all distinguishable by protein electrophoresis . (The medical condition produced by the heterozygous genotype is called sickle-cell trait and is a milder condition distinguishable from sickle-cell anemia , thus the alleles show incomplete dominance concerning anemia, see above). For most gene loci at

1118-455: The molecular level, both alleles are expressed co-dominantly, because both are transcribed into RNA . Co-dominance, where allelic products co-exist in the phenotype, is different from incomplete dominance, where the quantitative interaction of allele products produces an intermediate phenotype. For example, in co-dominance, a red homozygous flower and a white homozygous flower will produce offspring that have red and white spots. When plants of

1161-418: The nature of deafness in the community. Where deafness is genetically recessive , deaf children may not have immediate family who are deaf, but instead have more distant deaf relatives. Many largely hearing families have deaf members, so large numbers of hearing people sign (though not always well). In Desa Kolok on Bali, for example, two thirds of villagers sign even though only 2% are deaf; in Adamorobe, Ghana,

1204-479: The number of hearing signers is ten times the number of deaf people. This means there is generally good communication between the deaf and hearing people outside of their families, and thus a high degree of intermarriage between the deaf and hearing. In extreme cases, such as on Providencia Island of Colombia, nearly all conversations deaf people have are with the hearing, and there is little direct communication between deaf people themselves, and so little opportunity for

1247-419: The observed phenotypic ratios in offspring. Adamorobe Sign Language Adamorobe Sign Language or AdaSL is a village sign language used in Adamorobe, an Akan village in eastern Ghana . It is used by about 30 deaf and 1370 hearing people (2003). The Adamorobe community is notable for its unusually high incidence of hereditary deafness ( genetic recessive autosome ). As of 2012, about 1.1% of

1290-418: The other allele, and the masked allele is considered recessive . When we only look at one trait determined by one pair of genes, we call it monohybrid inheritance . If the crossing is done between parents (P-generation, F0-generation) who are homozygote dominant and homozygote recessive, the offspring (F1-generation) will always have the heterozygote genotype and always present the phenotype associated with

1333-470: The parental hybrid plants. Mendel reasoned that each parent in the first cross was a homozygote for different alleles (one parent AA and the other parent aa), that each contributed one allele to the offspring, with the result that all of these hybrids were heterozygotes (Aa), and that one of the two alleles in the hybrid cross dominated expression of the other: A masked a. The final cross between two heterozygotes (Aa X Aa) would produce AA, Aa, and aa offspring in

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1376-496: The phenotype and neither allele masks another. For example, in the ABO blood group system , chemical modifications to a glycoprotein (the H antigen) on the surfaces of blood cells are controlled by three alleles, two of which are co-dominant to each other ( I , I ) and dominant over the recessive i at the ABO locus . The I and I alleles produce different modifications. The enzyme coded for by I adds an N-acetylgalactosamine to

1419-462: The phenotype associated with the dominant allele variant. However, when crossing the F1-generation there are four possible phenotypic possibilities and the phenotypical ratio for the F2-generation will always be 9:3:3:1. Incomplete dominance (also called partial dominance , semi-dominance , intermediate inheritance , or occasionally incorrectly co-dominance in reptile genetics ) occurs when

1462-404: The phenotype of the heterozygous genotype is distinct from and often intermediate to the phenotypes of the homozygous genotypes. The phenotypic result often appears as a blended form of characteristics in the heterozygous state. For example, the snapdragon flower color is homozygous for either red or white. When the red homozygous flower is paired with the white homozygous flower, the result yields

1505-535: The phenotypic outcome. Although any individual of a diploid organism has at most two different alleles at a given locus, most genes exist in a large number of allelic versions in the population as a whole. This is called polymorphism , and is caused by mutations. Polymorphism can have an effect on the dominance relationship and phenotype, which is observed in the ABO blood group system . The gene responsible for human blood type have three alleles; A, B, and O, and their interactions result in different blood types based on

1548-427: The plants always produced the same phenotypes, generation after generation. However, when lines with different phenotypes were crossed (interbred), one and only one of the parental phenotypes showed up in the offspring (green, round, red, or tall). However, when these hybrid plants were crossed, the offspring plants showed the two original phenotypes, in a characteristic 3:1 ratio, the more common phenotype being that of

1591-456: The sex of both the parent and the child (see Sex linkage ). Since there is only one copy of the Y chromosome , Y-linked traits cannot be dominant or recessive. Additionally, there are other forms of dominance, such as incomplete dominance , in which a gene variant has a partial effect compared to when it is present on both chromosomes, and co-dominance , in which different variants on each chromosome both show their associated traits. Dominance

1634-505: The structures of village sign may be strongly influenced by the structure of the spoken languages. For example, Adamorobe Sign Language of Ghana has serial verbs , a linguistic construction that is also found in the language spoken by the hearing people of the community, the Twi language . Deaf sign languages contrast with speech-taboo languages such as the various Aboriginal Australian sign languages , which are developed as auxiliary languages by

1677-430: The sun is in the sky at a particular time. It is thought that such differences may be at least partially due to the sociolinguistic setting of the languages. In the case of village sign, speakers are culturally homogenous. They share a common social context, history, and experiences, and know each other personally. This may allow them to communicate without being as explicit as required for a larger, less intimate society. As

1720-425: The total population is deaf, but the percentage was as high as 11% in 1961 before the local chief instituted a policy prohibiting deaf people to marry other deaf. Deaf people are fully incorporated into the community. Under these circumstances, AdaSL has developed as an indigenous sign language, fully independent from the country's standard Ghanaian Sign Language (which is related to American Sign Language ). AdaSL

1763-420: The two homozygotes, the phenotype is said to exhibit no dominance at all, i.e. dominance exists only when the heterozygote's phenotype measure lies closer to one homozygote than the other. When plants of the F 1 generation are self-pollinated, the phenotypic and genotypic ratio of the F 2 generation will be 1:2:1 (Red:Pink:White). Co-dominance occurs when the contributions of both alleles are visible in

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1806-520: The various Tanzanian and Sri Lankan sign languages , which develop in the student bodies of deaf schools which do not use sign as a language of instruction, as well as community languages such as Bamako Sign Language (Mali), Hausa Sign Language (Nigeria), Saigon, Haiphong, and Hanoi Sign Language (Vietnam), Bangkok and Chiangmai Sign Language (Thailand), which arise where generally uneducated deaf people congregate in urban centers for employment. Deaf-community sign languages are not generally known by

1849-498: Was home sign . It is not clear if the reported Marajo Sign Language in Brazil is a coherent language or home sign in various families; similarly with Maxakali Sign Language , also in Brazil, which is at least very young. With Mehek Sign Language (Papua New Guinea), signs are quite variable, suggesting at most only an incipient coherent village language along with much home sign. Genetically recessive In genetics , dominance

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