88-514: Indian Runners are a breed of Anas platyrhynchos domesticus , the domestic duck . They stand erect like penguins and, rather than waddling, they run. The females can lay as many as 300 to 350 eggs a year. They were bred on the Indonesian islands of Lombok , Java and Bali . These ducks do not fly and only rarely form nests and incubate their own eggs. They run or walk, often dropping their eggs wherever they happen to be. The breed arrived in
176-588: A promoter sequence. The promoter is recognized and bound by transcription factors that recruit and help RNA polymerase bind to the region to initiate transcription. The recognition typically occurs as a consensus sequence like the TATA box . A gene can have more than one promoter, resulting in messenger RNAs ( mRNA ) that differ in how far they extend in the 5' end. Highly transcribed genes have "strong" promoter sequences that form strong associations with transcription factors, thereby initiating transcription at
264-552: A 1941 children's picture book by Robert McCloskey, tells the story of a pair of mallards who decide to raise their family on an island in the lagoon in Boston Public Garden. It won the 1942 Caldecott Medal for its illustrations. The Disney cartoon character Donald Duck , one of the world's most recognizable pop culture icons, is a domestic duck of the American Pekin breed. The domestic duck features in
352-633: A cluster that was sister to the White Pekin duck (a breed derived from ducks domesticated in China), while Muscovy ducks are from another genus. Muscovy duck Other breeds White Pekin Assam duck Other Indian breeds ( Kuttanad , Keeri , Sanyasi ) Ducks have been farmed for thousands of years. They are reared principally for meat, but also for duck eggs . Duck husbandry is simplified by aspects of their behaviour, including reliable flocking and
440-445: A continuous messenger RNA , referred to as a polycistronic mRNA . The term cistron in this context is equivalent to gene. The transcription of an operon's mRNA is often controlled by a repressor that can occur in an active or inactive state depending on the presence of specific metabolites. When active, the repressor binds to a DNA sequence at the beginning of the operon, called the operator region , and represses transcription of
528-498: A double-helix run in opposite directions. Nucleic acid synthesis, including DNA replication and transcription occurs in the 5'→3' direction, because new nucleotides are added via a dehydration reaction that uses the exposed 3' hydroxyl as a nucleophile . The expression of genes encoded in DNA begins by transcribing the gene into RNA , a second type of nucleic acid that is very similar to DNA, but whose monomers contain
616-488: A few genes and are transferable between individuals. For example, the genes for antibiotic resistance are usually encoded on bacterial plasmids and can be passed between individual cells, even those of different species, via horizontal gene transfer . Whereas the chromosomes of prokaryotes are relatively gene-dense, those of eukaryotes often contain regions of DNA that serve no obvious function. Simple single-celled eukaryotes have relatively small amounts of such DNA, whereas
704-434: A gene - surprisingly, there is no definition that is entirely satisfactory. A gene is a DNA sequence that codes for a diffusible product. This product may be protein (as is the case in the majority of genes) or may be RNA (as is the case of genes that code for tRNA and rRNA). The crucial feature is that the product diffuses away from its site of synthesis to act elsewhere. The important parts of such definitions are: (1) that
792-573: A gene corresponds to a transcription unit; (2) that genes produce both mRNA and noncoding RNAs; and (3) regulatory sequences control gene expression but are not part of the gene itself. However, there's one other important part of the definition and it is emphasized in Kostas Kampourakis' book Making Sense of Genes . Therefore in this book I will consider genes as DNA sequences encoding information for functional products, be it proteins or RNA molecules. With 'encoding information', I mean that
880-410: A gene may be split across chromosomes but those transcripts are concatenated back together into a functional sequence by trans-splicing . It is also possible for overlapping genes to share some of their DNA sequence, either on opposite strands or the same strand (in a different reading frame, or even the same reading frame). In all organisms, two steps are required to read the information encoded in
968-404: A gene's DNA and produce the protein it specifies. First, the gene's DNA is transcribed to messenger RNA ( mRNA ). Second, that mRNA is translated to protein. RNA-coding genes must still go through the first step, but are not translated into protein. The process of producing a biologically functional molecule of either RNA or protein is called gene expression , and the resulting molecule
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#17327804645471056-578: A gene: that of bacteriophage MS2 coat protein. The subsequent development of chain-termination DNA sequencing in 1977 by Frederick Sanger improved the efficiency of sequencing and turned it into a routine laboratory tool. An automated version of the Sanger method was used in early phases of the Human Genome Project . The theories developed in the early 20th century to integrate Mendelian genetics with Darwinian evolution are called
1144-439: A gene; however, members of a population may have different alleles at the locus, each with a slightly different gene sequence. The majority of eukaryotic genes are stored on a set of large, linear chromosomes. The chromosomes are packed within the nucleus in complex with storage proteins called histones to form a unit called a nucleosome . DNA packaged and condensed in this way is called chromatin . The manner in which DNA
1232-448: A high rate. Others genes have "weak" promoters that form weak associations with transcription factors and initiate transcription less frequently. Eukaryotic promoter regions are much more complex and difficult to identify than prokaryotic promoters. Additionally, genes can have regulatory regions many kilobases upstream or downstream of the gene that alter expression. These act by binding to transcription factors which then cause
1320-572: A new expanded definition that includes noncoding genes. However, some modern writers still do not acknowledge noncoding genes although this so-called "new" definition has been recognised for more than half a century. Although some definitions can be more broadly applicable than others, the fundamental complexity of biology means that no definition of a gene can capture all aspects perfectly. Not all genomes are DNA (e.g. RNA viruses ), bacterial operons are multiple protein-coding regions transcribed into single large mRNAs, alternative splicing enables
1408-400: A process known as RNA splicing . Finally, the ends of gene transcripts are defined by cleavage and polyadenylation (CPA) sites , where newly produced pre-mRNA gets cleaved and a string of ~200 adenosine monophosphates is added at the 3' end. The poly(A) tail protects mature mRNA from degradation and has other functions, affecting translation, localization, and transport of the transcript from
1496-419: A protein-coding gene consists of many elements of which the actual protein coding sequence is often only a small part. These include introns and untranslated regions of the mature mRNA. Noncoding genes can also contain introns that are removed during processing to produce the mature functional RNA. All genes are associated with regulatory sequences that are required for their expression. First, genes require
1584-652: A racy appearance, a breed trait. Eye placement is high on the head. Indian Runners have long, slender necks that smoothly transition into the body. The body is long, slim but round in appearance. Indian Runner ducks are domesticated waterfowl from the archipelago of the East Indies (Indonesia). They appear to be represented in stone sculptures in Java from c. 1000 AD. In 1856, the naturalist Alfred Russel Wallace recorded in The Malay Archipelago that
1672-518: A range of ancient artefacts , which revealed that they were a fertility symbol. [REDACTED] Media related to Domesticated ducks at Wikimedia Commons [REDACTED] Duck at the Wikibooks Cookbook subproject Gene In biology , the word gene has two meanings. The Mendelian gene is a basic unit of heredity . The molecular gene is a sequence of nucleotides in DNA that
1760-539: A single domestication event of mallards during the Neolithic , followed by rapid selection for lineages favouring meat or egg production. They were probably domesticated in Southern China around 2000 BC – by the rice paddy -farming ancestors of modern Southeast Asians – and spread outwards from that region. There are few archaeological records, so the date of domestication
1848-412: A single genomic region to encode multiple district products and trans-splicing concatenates mRNAs from shorter coding sequence across the genome. Since molecular definitions exclude elements such as introns, promotors, and other regulatory regions , these are instead thought of as "associated" with the gene and affect its function. An even broader operational definition is sometimes used to encompass
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#17327804645471936-475: A strict definition of the word "gene" with which nearly every expert can agree. First, in order for a nucleotide sequence to be considered a true gene, an open reading frame (ORF) must be present. The ORF can be thought of as the "gene itself"; it begins with a starting mark common for every gene and ends with one of three possible finish line signals. One of the key enzymes in this process, the RNA polymerase, zips along
2024-409: A true gene, by this definition, one has to prove that the transcript has a biological function. Early speculations on the size of a typical gene were based on high-resolution genetic mapping and on the size of proteins and RNA molecules. A length of 1500 base pairs seemed reasonable at the time (1965). This was based on the idea that the gene was the DNA that was directly responsible for production of
2112-456: Is called a gene product . The nucleotide sequence of a gene's DNA specifies the amino acid sequence of a protein through the genetic code . Sets of three nucleotides, known as codons , each correspond to a specific amino acid. The principle that three sequential bases of DNA code for each amino acid was demonstrated in 1961 using frameshift mutations in the rIIB gene of bacteriophage T4 (see Crick, Brenner et al. experiment ). Additionally,
2200-400: Is nearly the same for all known organisms. The total complement of genes in an organism or cell is known as its genome , which may be stored on one or more chromosomes . A chromosome consists of a single, very long DNA helix on which thousands of genes are encoded. The region of the chromosome at which a particular gene is located is called its locus . Each locus contains one allele of
2288-455: Is often played by an incubator . However, young ducklings rely on their mothers for a supply of preen oil to make them waterproof; a chicken does not make as much preen oil as a duck, and an incubator makes none. Once the duckling grows its own feathers, it produces preen oil from the sebaceous gland near the base of its tail. In East and Southeast Asia, rice-duck farming is widely practised. This polyculture yields both rice and ducks from
2376-403: Is still part of the definition of a gene in most textbooks. For example, The primary function of the genome is to produce RNA molecules. Selected portions of the DNA nucleotide sequence are copied into a corresponding RNA nucleotide sequence, which either encodes a protein (if it is an mRNA) or forms a 'structural' RNA, such as a transfer RNA (tRNA) or ribosomal RNA (rRNA) molecule. Each region of
2464-399: Is stored on the histones, as well as chemical modifications of the histone itself, regulate whether a particular region of DNA is accessible for gene expression . In addition to genes, eukaryotic chromosomes contain sequences involved in ensuring that the DNA is copied without degradation of end regions and sorted into daughter cells during cell division: replication origins , telomeres , and
2552-410: Is transcribed to produce a functional RNA . There are two types of molecular genes: protein-coding genes and non-coding genes. During gene expression (the synthesis of RNA or protein from a gene), DNA is first copied into RNA . RNA can be directly functional or be the intermediate template for the synthesis of a protein. The transmission of genes to an organism's offspring , is the basis of
2640-792: Is unknown; the earliest written records are in Han Chinese writings from central China dating to about 500 BC. Duck farming for both meat and eggs is a widespread and ancient industry in Southeast Asia. Wild ducks were hunted extensively in Egypt and other parts of the world in ancient times, but were not domesticated. Ducks are documented in Ancient Rome from the second century BC, but descriptions – such as by Columella – suggest that ducks in Roman agriculture were captured in
2728-623: The Pekin duck . As soon as the Indian Runners became fashionable, a demand for egg-layers and general purpose breeds developed. Using Runners crossed to Rouens, Aylesburys and Cayugas (the large black American breed), William Cook produced his famous Orpington Ducks . Mrs Campbell crossed her fawn-and-white Runner duck to a Rouen drake to create the Campbell ducks introduced in 1898. Later, she introduced wild mallard blood and managed to create
Indian Runner duck - Misplaced Pages Continue
2816-525: The Royal Ballet's The Tales of Beatrix Potter . It is the story of how Jemima, a domestic duck, is saved from a cunning fox who plans to kill her, when she tries to find a safe place for her eggs to hatch. The Story About Ping is a 1933 American children's book by Marjorie Flack , illustrated by Kurt Wiese , about a domestic duck lost on the Yangtze River . Make Way for Ducklings ,
2904-511: The aging process. The centromere is required for binding spindle fibres to separate sister chromatids into daughter cells during cell division . Prokaryotes ( bacteria and archaea ) typically store their genomes on a single, large, circular chromosome . Similarly, some eukaryotic organelles contain a remnant circular chromosome with a small number of genes. Prokaryotes sometimes supplement their chromosome with additional small circles of DNA called plasmids , which usually encode only
2992-401: The central dogma of molecular biology , which states that proteins are translated from RNA , which is transcribed from DNA . This dogma has since been shown to have exceptions, such as reverse transcription in retroviruses . The modern study of genetics at the level of DNA is known as molecular genetics . In 1972, Walter Fiers and his team were the first to determine the sequence of
3080-419: The centromere . Replication origins are the sequence regions where DNA replication is initiated to make two copies of the chromosome. Telomeres are long stretches of repetitive sequences that cap the ends of the linear chromosomes and prevent degradation of coding and regulatory regions during DNA replication . The length of the telomeres decreases each time the genome is replicated and has been implicated in
3168-554: The modern synthesis , a term introduced by Julian Huxley . This view of evolution was emphasized by George C. Williams ' gene-centric view of evolution . He proposed that the Mendelian gene is a unit of natural selection with the definition: "that which segregates and recombines with appreciable frequency." Related ideas emphasizing the centrality of Mendelian genes and the importance of natural selection in evolution were popularized by Richard Dawkins . The development of
3256-475: The neutral theory of evolution in the late 1960s led to the recognition that random genetic drift is a major player in evolution and that neutral theory should be the null hypothesis of molecular evolution. This led to the construction of phylogenetic trees and the development of the molecular clock , which is the basis of all dating techniques using DNA sequences. These techniques are not confined to molecular gene sequences but can be used on all DNA segments in
3344-750: The operon ; when the repressor is inactive transcription of the operon can occur (see e.g. Lac operon ). The products of operon genes typically have related functions and are involved in the same regulatory network . Though many genes have simple structures, as with much of biology, others can be quite complex or represent unusual edge-cases. Eukaryotic genes often have introns that are much larger than their exons, and those introns can even have other genes nested inside them . Associated enhancers may be many kilobase away, or even on entirely different chromosomes operating via physical contact between two chromosomes. A single gene can encode multiple different functional products by alternative splicing , and conversely
3432-449: The population . These alleles encode slightly different versions of a gene, which may cause different phenotypical traits. Genes evolve due to natural selection or survival of the fittest and genetic drift of the alleles. There are many different ways to use the term "gene" based on different aspects of their inheritance, selection, biological function, or molecular structure but most of these definitions fall into two categories,
3520-404: The DNA helix that produces a functional RNA molecule constitutes a gene. We define a gene as a DNA sequence that is transcribed. This definition includes genes that do not encode proteins (not all transcripts are messenger RNA). The definition normally excludes regions of the genome that control transcription but are not themselves transcribed. We will encounter some exceptions to our definition of
3608-450: The DNA sequence is used as a template for the production of an RNA molecule or a protein that performs some function. The emphasis on function is essential because there are stretches of DNA that produce non-functional transcripts and they do not qualify as genes. These include obvious examples such as transcribed pseudogenes as well as less obvious examples such as junk RNA produced as noise due to transcription errors. In order to qualify as
Indian Runner duck - Misplaced Pages Continue
3696-766: The DNA to loop so that the regulatory sequence (and bound transcription factor) become close to the RNA polymerase binding site. For example, enhancers increase transcription by binding an activator protein which then helps to recruit the RNA polymerase to the promoter; conversely silencers bind repressor proteins and make the DNA less available for RNA polymerase. The mature messenger RNA produced from protein-coding genes contains untranslated regions at both ends which contain binding sites for ribosomes , RNA-binding proteins , miRNA , as well as terminator , and start and stop codons . In addition, most eukaryotic open reading frames contain untranslated introns , which are removed and exons , which are connected together in
3784-615: The Indian Runner Duck Club (founded in 1906), particularly the input by John Donald, Joseph Walton, Dr J. A. Coutts and Matthew Smith, can be found in Ashton (2002). The most profound impact of the Indian Runners was on the development of the modern 'light duck' breeds. Before 1900, most ducks were bred for the table. Aylesbury and Rouen ducks were famous throughout the nineteenth century, and these were supplemented or replaced, after 1873–74, by importation from China of
3872-514: The Mendelian gene or the molecular gene. The Mendelian gene is the classical gene of genetics and it refers to any heritable trait. This is the gene described in The Selfish Gene . More thorough discussions of this version of a gene can be found in the articles Genetics and Gene-centered view of evolution . The molecular gene definition is more commonly used across biochemistry, molecular biology, and most of genetics —
3960-610: The Muscovy duck and hybrids, are descended from the mallard, which was domesticated in China around 2000 BC. Duck farming is simplified by their reliable flocking behaviour, and their ability to forage effectively for themselves. Over 80% of global duck production is in China. Breeds such as White Pekin are raised for meat, while the prolific Indian Runner can produce over 300 eggs per year. In East and Southeast Asia, polycultures such as rice-duck farming are widely practised:
4048-464: The Philippines, balut – a fertilised duck egg at about 17 days of development, boiled and eaten with salt – is considered a delicacy and is sold as street food . The domestic duck has appeared numerous times in children's stories. Beatrix Potter 's The Tale of Jemima Puddle-Duck was published by Frederick Warne & Co in 1908. One of Potter's best-known books, the tale was included in
4136-552: The Philippines. The Runner became popular in Europe and America as an egg-laying variety towards the end of the nineteenth century largely as a result of an undated pamphlet called The India Runner: its History and Description published by John Donald of Wigton between 1885 and 1890. Donald's publication is advertised briefly in The Feathered World , 1895, under the title of "The Indian Runner Duck". Donald describes
4224-455: The Western world in the 19th century; they have since been bred to have a wide variety of colours. Indian Runner ducks vary in weight between 1.4 and 2.3 kg (3.1 and 5.1 lb). Their height (from crown to tail tip) ranges from 50 cm (20 in) in small females to about 76 cm (30 in) in the taller males. The erect carriage is a result of a pelvic girdle that is closer to
4312-659: The ability to forage effectively for themselves in wetlands and water bodies. Most breeds of duck may lay some 200 eggs per year, though the Indian Runner may produce over 300 eggs annually. The females of many breeds of domestic duck are unreliable at sitting their eggs and raising their young. Exceptions include the Rouen duck and especially the Muscovy duck . It has been a custom on farms for centuries to put duck eggs under broody hens for hatching; nowadays this role
4400-433: The adenines of one strand are paired with the thymines of the other strand, and so on. Due to the chemical composition of the pentose residues of the bases, DNA strands have directionality. One end of a DNA polymer contains an exposed hydroxyl group on the deoxyribose ; this is known as the 3' end of the molecule. The other end contains an exposed phosphate group; this is the 5' end . The two strands of
4488-624: The breed. Pure breed enthusiasts, exhibitors and show judges wanted to establish standard descriptions. Standards were drawn up in by the Waterfowl Club in England (1897) and America (1898) for the pied colour varieties. These were largely the same until 1915 when the two countries diverged. The American Poultry Association chose a variety with blue in the genotype whilst the English Poultry Club Standard kept to
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#17327804645474576-436: The combined influence of polygenes (a set of different genes) and gene–environment interactions . Some genetic traits are instantly visible, such as eye color or the number of limbs, others are not, such as blood type , the risk for specific diseases, or the thousands of basic biochemical processes that constitute life . A gene can acquire mutations in its sequence , leading to different variants, known as alleles , in
4664-402: The complexity of these diverse phenomena, where a gene is defined as a union of genomic sequences encoding a coherent set of potentially overlapping functional products. This definition categorizes genes by their functional products (proteins or RNA) rather than their specific DNA loci, with regulatory elements classified as gene-associated regions. The existence of discrete inheritable units
4752-424: The dangerous H5N1 strain of avian influenza . Ducks are subject to ectoparasites such as lice and endoparasites such as trematodes , cestodes , and acanthocephalans . A high parasitic load can result in a substantial reduction in the ducks' growth rate. In 2021 approximately 4.3 billion ducks were slaughtered for meat worldwide, for a total yield of about 6.2 million tonnes; over 80% of this production
4840-524: The distinction between a heterozygote and homozygote , and the phenomenon of discontinuous inheritance. Prior to Mendel's work, the dominant theory of heredity was one of blending inheritance , which suggested that each parent contributed fluids to the fertilization process and that the traits of the parents blended and mixed to produce the offspring. Charles Darwin developed a theory of inheritance he termed pangenesis , from Greek pan ("all, whole") and genesis ("birth") / genos ("origin"). Darwin used
4928-459: The duck has been eaten as food. Usually only the breast and thigh meat is eaten. It does not need to be hung before preparation, and is often braised or roasted, sometimes flavoured with bitter orange or with port . Peking duck is a dish of roast duck from Beijing, China, that has been prepared since medieval times. It is today traditionally served with spring pancakes , spring onions and sweet bean sauce . In France, ducks are used for
5016-594: The ducks assist the rice with manure and by eating small pest animals, so that the same land produces rice and ducks at once. In culture, ducks feature in children's stories such as The Tale of Jemima Puddle-Duck , and in Sergei Prokofiev 's musical composition Peter and the Wolf ; they have appeared in art since the time of ancient Egypt , where they served as a fertility symbol . Domestic ducks appear from whole-genome sequencing to have originated from
5104-511: The ducks in the Indonesian island of Lombok "walk erect, like penguins". Rice-duck farming is a polycultural practice of raising ducks as well as growing rice on the same land, providing farmers with additional income, while the manure produced by the ducks benefits the rice crop. This system has existed in different forms for centuries in Asian countries including China, Indonesia, and
5192-422: The dusky and restricted mallard genes, light phase, harlequin phase, blue and brown dilutions, as well as the famous pied varieties named by the geneticist F. M. Lancaster as the 'Runner pattern'. Much of the proliferation of new colour varieties in breeds of domestic duck begins with the importation of these oriental ducks. Original research by R. G. Jaap (1930s) and F. M. Lancaster has allowed breeders to understand
5280-410: The early 1950s the prevailing view was that the genes in a chromosome acted like discrete entities arranged like beads on a string. The experiments of Benzer using mutants defective in the rII region of bacteriophage T4 (1955–1959) showed that individual genes have a simple linear structure and are likely to be equivalent to a linear section of DNA. Collectively, this body of research established
5368-579: The effect of genotypes in managing and creating colour varieties. Simplified information can be found in writings by Dave Holderread, and Mike and Chris Ashton. [REDACTED] Media related to Indian Runner Ducks at Wikimedia Commons Domestic duck Domestic ducks (mainly mallard , Anas platyrhynchos domesticus , with some Muscovy ducks , Cairina moschata domestica ) are ducks that have been domesticated and raised for meat and eggs . A few are kept for show, or for their ornamental value. Most varieties of domesticated ducks, apart from
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#17327804645475456-522: The fact that both protein-coding genes and noncoding genes have been known for more than 50 years, there are still a number of textbooks, websites, and scientific publications that define a gene as a DNA sequence that specifies a protein. In other words, the definition is restricted to protein-coding genes. Here is an example from a recent article in American Scientist. ... to truly assess the potential significance of de novo genes, we relied on
5544-413: The functional product. The discovery of introns in the 1970s meant that many eukaryotic genes were much larger than the size of the functional product would imply. Typical mammalian protein-coding genes, for example, are about 62,000 base pairs in length (transcribed region) and since there are about 20,000 of them they occupy about 35–40% of the mammalian genome (including the human genome). In spite of
5632-630: The gene that is described in terms of DNA sequence. There are many different definitions of this gene — some of which are misleading or incorrect. Very early work in the field that became molecular genetics suggested the concept that one gene makes one protein (originally 'one gene - one enzyme'). However, genes that produce repressor RNAs were proposed in the 1950s and by the 1960s, textbooks were using molecular gene definitions that included those that specified functional RNA molecules such as ribosomal RNA and tRNA (noncoding genes) as well as protein-coding genes. This idea of two kinds of genes
5720-421: The genome. The vast majority of organisms encode their genes in long strands of DNA (deoxyribonucleic acid). DNA consists of a chain made from four types of nucleotide subunits, each composed of: a five-carbon sugar ( 2-deoxyribose ), a phosphate group, and one of the four bases adenine , cytosine , guanine , and thymine . Two chains of DNA twist around each other to form a DNA double helix with
5808-421: The genomes of complex multicellular organisms , including humans, contain an absolute majority of DNA without an identified function. This DNA has often been referred to as " junk DNA ". However, more recent analyses suggest that, although protein-coding DNA makes up barely 2% of the human genome , about 80% of the bases in the genome may be expressed, so the term "junk DNA" may be a misnomer. The structure of
5896-415: The inheritance of phenotypic traits from one generation to the next. These genes make up different DNA sequences, together called a genotype , that is specific to every given individual, within the gene pool of the population of a given species . The genotype, along with environmental and developmental factors, ultimately determines the phenotype of the individual. Most biological traits occur under
5984-796: The mallard's territorial behaviour, and are less aggressive than mallards. Despite these differences, domestic ducks frequently mate with wild mallard, producing fully fertile hybrid offspring. A wild mallard weighs some 1.1 kg (2.4 lb), but large breeds like the Aylesbury may weigh 4.6 kg (10 lb) (and hybrids even more), while small breeds like the Appleyard may be only 0.7 kg (1.5 lb). Those breeds are raised for meat and eggs, while other breeds are purely ornamental, having been selected for their crests, tufts, or striking plumage, for exhibition in competitions. A phylogenomic analysis found that Indian breeds of ducks formed
6072-1059: The most prolific egg-layer, the Khaki Campbell (announced in 1901). Other breeds followed, some of which emerged as direct mutations of the Khaki Campbell, along with crosses back to Indian Runners, the most famous being the Abacot Ranger (known in Germany as the Streicher) and the Welsh Harlequin . Currently there are eight varieties of Indian Runner recognized with the American Poultry Association. They are, in order of recognition, Fawn & White, White, Penciled, Black, Buff, Chocolate, Cumberland Blue, and Gray. Indian Runner ducks brought in unusual plumage colour mutations. These included
6160-497: The musical composition Peter and the Wolf , written by the Russian composer Sergei Prokofiev in 1936. The orchestra illustrates the children's story while the narrator tells it. In this, a domestic duck and a little bird argue on each other's flight capabilities. The duck is represented by the oboe. The story ends with the wolf eating the duck alive, its quack heard from inside the wolf's belly. Domestic ducks are featured in
6248-707: The names 'Penguin Ducks' and 'Baly Soldiers'. Harrison Weir's Our Poultry (1902) describes the Penguin Ducks belonging to Mr. Edward Cross in the Surrey Zoological Gardens between 1837 and 1838. These may well have been imported by the 13th Earl of Derby. Darwin describes them (1868) as having elongated " femur and meta-tarsi ", contrary to Tegetmeier's assertions. The Cumbrian importations, according to Matthew Smith in 1923, included completely fawn Runners and completely white Runners as well as
6336-413: The nucleus. Splicing, followed by CPA, generate the final mature mRNA , which encodes the protein or RNA product. Many noncoding genes in eukaryotes have different transcription termination mechanisms and they do not have poly(A) tails. Many prokaryotic genes are organized into operons , with multiple protein-coding sequences that are transcribed as a unit. The genes in an operon are transcribed as
6424-431: The phosphate–sugar backbone spiralling around the outside, and the bases pointing inward with adenine base pairing to thymine and guanine to cytosine. The specificity of base pairing occurs because adenine and thymine align to form two hydrogen bonds , whereas cytosine and guanine form three hydrogen bonds. The two strands in a double helix must, therefore, be complementary , with their sequence of bases matching such that
6512-526: The pied (fawn-and-white and grey-and-white) varieties. The most successful attempt to import fresh bloodlines was by Joseph Walton between 1908 and 1909. Accounts of these ventures can be found in Coutts (1927) and Ashton (2002). Walton shipped in birds from Lombok and Java, revolutionizing the breeding stock which, according to Donald, had become badly mixed with local birds. Further importations by Miss Chisholm and Miss Davidson in 1924 and 1926 continued to revive
6600-408: The pied variety and gives the popular story of the importation into Cumbria (Northwest England) by a sea captain some fifty years earlier. The breed is unusual not only for its high egg production but also for its upright stance and variety of colour genes , some of which are seen in seventeenth-century Dutch paintings by the d’Hondecoeter family and others. Other references to such domestic ducks use
6688-459: The production of foie gras de canard . In some cultures the blood of ducks slaughtered for meat is used as food; it may be eaten seasoned and lightly cooked, as in Ireland, or be used as an ingredient, as in a number of regional types of blood soup , among them the czarnina of Poland and the tiết canh of Vietnam. Duck eggs are eaten mainly in Asian countries such as China; in
6776-465: The pure form described by Donald in his original pamphlet. Other colours followed making use of black genes brought in by some of Walton's birds. These were to produce black, chocolate and Cumberland blue. Later were developed the mallard, trout, blue trout, and apricot trout versions. Slightly different names and descriptions can be found in American and German standards. An account of the influence of
6864-493: The same land; the ducks eat small pest animals in the crop; they stir the water, limiting weeds, and manure the rice. Other rice polycultures in the region include rice-fish-duck and rice-fish-duck- azolla systems, where fish further manure the rice and help to control pests. Domestic ducks have the advantage over other poultry of being strongly resistant to many bird diseases, including such serious conditions as duck plague (viral enteritis). They are however susceptible to
6952-467: The strand of DNA like a train on a monorail, transcribing it into its messenger RNA form. This point brings us to our second important criterion: A true gene is one that is both transcribed and translated. That is, a true gene is first used as a template to make transient messenger RNA, which is then translated into a protein. This restricted definition is so common that it has spawned many recent articles that criticize this "standard definition" and call for
7040-461: The sugar ribose rather than deoxyribose . RNA also contains the base uracil in place of thymine . RNA molecules are less stable than DNA and are typically single-stranded. Genes that encode proteins are composed of a series of three- nucleotide sequences called codons , which serve as the "words" in the genetic "language". The genetic code specifies the correspondence during protein translation between codons and amino acids . The genetic code
7128-414: The tail than other breeds of domestic duck. This structural feature allows the birds to walk or run, rather than waddle, as seen with other duck breeds; they do not fly. Indian Runner ducks have a long, wedge-shaped head. The bill blends into the head smoothly being as straight as possible from bean to the back of the skull. The head is shallower than is seen with most other breeds of duck. This effect gives
7216-809: The term gemmule to describe hypothetical particles that would mix during reproduction. Mendel's work went largely unnoticed after its first publication in 1866, but was rediscovered in the late 19th century by Hugo de Vries , Carl Correns , and Erich von Tschermak , who (claimed to have) reached similar conclusions in their own research. Specifically, in 1889, Hugo de Vries published his book Intracellular Pangenesis , in which he postulated that different characters have individual hereditary carriers and that inheritance of specific traits in organisms comes in particles. De Vries called these units "pangenes" ( Pangens in German), after Darwin's 1868 pangenesis theory. Twenty years later, in 1909, Wilhelm Johannsen introduced
7304-436: The term gene , he explained his results in terms of discrete inherited units that give rise to observable physical characteristics. This description prefigured Wilhelm Johannsen 's distinction between genotype (the genetic material of an organism) and phenotype (the observable traits of that organism). Mendel was also the first to demonstrate independent assortment , the distinction between dominant and recessive traits,
7392-412: The term "gene" (inspired by the ancient Greek : γόνος, gonos , meaning offspring and procreation) and, in 1906, William Bateson , that of " genetics " while Eduard Strasburger , among others, still used the term "pangene" for the fundamental physical and functional unit of heredity. Advances in understanding genes and inheritance continued throughout the 20th century. Deoxyribonucleic acid (DNA)
7480-725: The wild, not domesticated; there was no duck breeding in Roman times, so eggs from wild ducks were needed to start duck farms. Mallards were domesticated in Eurasia. The Muscovy duck was domesticated in Mexico and South America. Most breeds and varieties of domestic duck derive from the mallard , Anas platyrhynchos ; a few derive from Cairina moschata , the Muscovy duck, or are mulards , hybrids of these with A. platyrhynchos stock. Domestication has greatly altered their characteristics. Domestic ducks are mostly promiscuous , where wild mallards are monogamous . Domestic ducks have lost
7568-450: Was first suggested by Gregor Mendel (1822–1884). From 1857 to 1864, in Brno , Austrian Empire (today's Czech Republic), he studied inheritance patterns in 8000 common edible pea plants , tracking distinct traits from parent to offspring. He described these mathematically as 2 combinations where n is the number of differing characteristics in the original peas. Although he did not use
7656-420: Was in China, where more than 3.6 billion ducks were killed, yielding some 4.9 million tonnes of meat. Worldwide production of duck meat was substantially lower than that of chicken – 73.8 billion birds slaughtered, 121.6 million tonnes – but considerably greater than that of goose – about 750 million birds killed for 4.4 million tonnes of meat. Feathers are a by-product of duck farming. Since ancient times,
7744-430: Was shown to be the molecular repository of genetic information by experiments in the 1940s to 1950s. The structure of DNA was studied by Rosalind Franklin and Maurice Wilkins using X-ray crystallography , which led James D. Watson and Francis Crick to publish a model of the double-stranded DNA molecule whose paired nucleotide bases indicated a compelling hypothesis for the mechanism of genetic replication. In
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