Guppy Dictionary
From Guppy Wiki
A | |
| Albinism (Albino) | A guppy with a mutation that causes it to fail to show black color cells. There are two basic forms. In one form there is a total lack of black pigment, often called RREA (Real Red Eye Albino). In the second form, a little pigment is produced. It is sometimes called WREA (Wine Red Eye Albino) or ruby-eye or lutino. The guppies have slightly darker eyes and some pale greyness in the body. |
| Allele | Alternate version of a gene. New versions are created through mutations. |
| Asian Blau | A mutation affecting all the color cells. Its effect differs according to whether the autosomal mutant gene is homozygous or heterozygous. When it is heterozygous, only red color cells are affected. Their absence reveals blue iridophores, a type of reflecting color cell. In the homozygous state, all color classes of color cells are affected, producing a grey guppy with dull black patches. Sometimes called "r2" in Europe. |
| Autosomal | Chromosomes other than the guppy's sex chromosomes (X- and Y-chromosomes). See X-linked and Y-linked. |
| Autosomal Dominant | A gene is considered "autosomal dominant" when it is expressed in the first generation of a cross. Only one autosomal dominant gene of a pair is necessary for the trait to be expressed, unlike recessive autosomal genes, where two identical genes are required. Crossing such a heterozygous hybrid to a normal guppy affects 50% of the offspring. Crossing a homozygous mutant affects 100% of offspring. |
B | |
| Back Cross or Backcross | Breeding daughter to father, or son to mother. Or breeding the offspring of a cross back to the original strain. |
| Blond | Scientific name for a recessive mutation affecting the black color cells. Also called Gold (U.S. and Asia). A type of black color cell mutation that causes them to lack visibility to the naked eye. The guppy looks like an albino with black eyes. See Golden. |
| Bronze | Name given to the golden mutation in the IFGA. See Golden. |
C | |
| Caudal | Tail fin of the guppy. |
| Chromosome | Genes are located on cellular structures called chromosomes. Guppies and humans have 23 pairs of chromosomes. |
| Co-dominant | A relationship between a gene and its allele in which neither is dominant. The offspring show traits of both parents. Also see Incomplete Dominance. |
| Cross Over or Crossover or Crossing Over or Homologous Recombination | During the formation of eggs and sperm, chromosomes lie over top of each other. They may break and recombine. This allows alleles to swap locations. Some genes cross over readily, such as the snakeskin gene, resulting in Y-linked or X-linked snakeskins. Crossing over is a kind of shuffling of the genetic deck for increased diversity. |
D | |
| Dominant | Dominance means that a gene or a trait is expressed at the expense of another. On the molecular level, the dominant allele is expressed while the recessive allele is not. On the phenotypical level, one trait is expressed at the expense of another trait. See Recessive. |
| Dorsal | Top part of the guppy. The dorsal fin is on top of the guppy. |
| Drop | A single spawn of guppies. The female is said to "drop" her fry during birthing. |
E | |
| Epistatis (Epistatic) | One gene affects the expression of another gene. Usually this means the gene masks the expression of a gene for a different trait. However it is sometimes used to describe any kind of modification of another gene's expression. |
| Erythrophore | Red color cell. |
| Expression | See gene expression. |
| Expressivity | The extent to which a trait is expressed, or how much gene product is produced using a gene as a template. |
F | |
| Filigran | Another word for the snakeskin pattern on the guppy. See Snakeskin. |
| F1, F2, F3 ... | The "F" stands for "filial." It is used to denote the generation of a cross, as in "first filial generation" or F1. |
G | |
| Galaxy | A type of pattern that is influenced by the snakeskin and metal (iridophore) genes. Similar to a Medusa, but not identical. |
| Gene | Genes are segments of DNA, a complex molecule that makes up chromosomes. Chromosomes are located in the cell's nucleus. Genes store the body's blueprints. It's like the body has a library. When a new part of the body needs to be built, the blueprint is read and the part needed is created from that blueprint. The gene is inherited by the next generation. |
| Gene Expression | Gene expression refers to the products (usually proteins) made by a gene. For example, black pigment is an expression of several genes acting in concert. Stated another way, proteins are the physical expression of the inheritable information stored in genes. |
| Genotype | The actual genetic make-up of a guppy, rather than its visual phenotype. A hybrid guppy often only expresses the dominant gene of a pair. See Phenotype. |
| Glass and Grass | A guppy pattern developed by Japanese breeders. It is characterized by a fine "grass-like" pattern in the fins with a few streaks on the peduncle area of the body. When the fins have a transparent background, it is called "glass." |
| Gray or Grey Allele | See wildtype. |
H | |
| Half-Black Gene | An X- or Y-linked gene creating a half-black pattern on guppies. |
| Heterozygous | Paired genes that are different (alleles). Hybrid guppies are heterozygous for the trait under examination. |
| Homozygous | Paired alleles that are the same and at the same locus on paired chromosomes. |
| Inbreeding | Breeding closely-related guppies, parent-to-child, siblings, or cousins, aunt or uncle to nephew or niece. |
I | |
| Independent Assortment | One of the basic Mendelian laws. Gregor Mendel observed that fundamental traits (like the wrinkled texture of peas) were discrete and inherited without modification. Later scientists discovered genes as the indissoluble unit of inheritance, and developed the idea that one gene determines one nucleotide sequence of a protein. |
| Incomplete Dominance | A trait that is neither dominant or recessive over another, but produces an intermediate expression. |
| Iridophores | The reflecting color cells, usually sandwiched between the black color cells and the red and yellow color cells. Guppies with a lot of iridophores have a metallic or iridescent sheen. |
| J | |
| Japan Blue or Aquamarine | A Japanese guppy with a metallic blue peduncle. The trait is usually Y-linked, but it can be X-linked as well. |
L | |
| Leucophore | White color cells. They are dull. They are often covered with red or yellow color cells. |
| Line breeding or linebreeding | A form of selective inbreeding where two or more versions of a strain are maintained and crossed after two or three generations. |
| Linkage | Genes occupying the same chromosome are said to be linked. "Tight" linkage describes genes located close together, making them less likely to cross over. |
| Locus | Where a gene is located on a chromosome. It's "address." The plural is loci. |
| Lutino | An albino capable of showing a little black color. See RREA and WREA. |
M | |
| Magenta | A mutation affecting the iridophores and the red color cells. |
| Masked Gene or Trait | A gene whose expression is altered or hidden by another, unrelated gene. |
| Melanophore | Black color cell. |
| Melanin | Black pigment in the color cell. |
| Mendelian Genetics | Mendelian genetics are the original theories of inheritance as developed by the Austrian monk, Gregor Mendel, 1822-1884. The two basic laws were the principle of segregation and the law of independent assortment. |
| Metal | A descriptive term for guppies showing a lot of reflecting color cells (iridophores), as in metal guppy or metal color cells. |
| Modifier Gene | Sometimes called Regulatory Gene. A gene closely associated with another gene, modifying its expression. |
| Monohybrid Cross | A cross involving parents differing in only one trait. |
| Multigenic | A trait under the control of more than one gene. Size is an example, since it depends on the growth in length of different parts of the body and on such factors as the strain's ability to metabolize food. |
| Mutant | A guppy with a mutation. |
| N | |
| Nigrocaudatus, Half-Black, or Tuxedo | Terms describing the sex-linked half-black pattern on guppies. |
O | |
| Outcross or Out Cross | Breeding two guppies that are distantly related or not related at all. Usually refers to crosses to other strains. That strain can be the same color (i.e. unrelated strains of Half-Black Pastels). |
| P | |
| Peduncle | The area from the back of the dorsal fin to the caudal (tail fin). |
| Penetrance | Penetrance evaluates the extent to which a trait is expressed. For example, the snakeskin gene expressed by a Galaxy guppy has a high penetrance, whereas it has a low penetrance in the Silver Tiger Moscow. |
| Phenotype | The expression of genes as a visible trait on a guppy. Expression of a gene can be influenced by other genes (epistasis), or controlled by regulatory genes, or influenced by the environment. So the phenotype and the genotype often differ dramatically. See Genotype. |
| Platinum | An old-fashioned and confusing term describing either guppies with a lot of metal (iridophore) color cells, a lot of leucophore color cells, or both. |
| Pleiotrophic (Pleiotrophy) | The expression of a gene in several different traits. For example, both the size and color of a guppy is affected by the albino gene. |
| Pteridine | The chemical compounds making up the yellow and red pigments. |
| Q | |
| Quantitative Trait | A measurable trait (like guppy body size) that shows continuous variation. A trait that cannot be classified into a few discrete types. Such traits are usually due to several genes. Almost all guppy colors and patterns are quantitative traits. A few, like albinism, are due to a single gene pair and are not quantitative traits. |
| R | |
| Recessive | A gene or trait that is not expressed because of the presence of dominant genes. For example, a guppy hybrid with one albino gene and one normal gene is normal colored (grey). It is said to be recessive to the dominant wildtype allele. See Dominant. |
| Reciprocal Cross | Mating the male of one strain to the female of the other and vice versa. |
| Regulatory Gene | A gene which controls the protein-synthesizing activity of other genes. See Structural Gene. |
| RREA | Real Red Eyed Albino. See the Albino entry. |
| Ruby-Eye | See the Albino entry. |
| S | |
| SDR | Sex Determining Region: a part of the Y-chromosome where the sex of the guppy is determined. Male traits located here cross over infrequently. The Moscow trait is an example. |
| Secondary Sexual Characteristic | A trait that appears at puberty, like the beard on a man. In the case of guppies, many of the color and fin shape characteristics, along with the sex organs and body shape, appear at puberty. Such traits are under hormonal control. |
| Segregation | The term is based on the Mendelian "law of segregation." The general pinciple of inheritance holds that genes are inherited independently (segregate) and combine and re-combine in novel arrangements in subsequent generations. |
| Sex-Linked | A gene is said to be sex-linked if it is found on the X- or Y-chromosome, the sex chromosomes. |
| Sex Chromosome | One of the X- or Y-chromosomes. |
| Snakeskin | A sex-linked trait that is usually dominate in the area that it covers (an exception is the half-black pattern). It can cover the entire body or half the body with a fine chain link pattern. |
| Störzbach Metal | Also Stoerzbach Metal. A type of autosomal recessive metal (iridophore) mutation. |
| Strain | The word strain is applied to guppies that usually breed true over several generations (80% of the males are 80% similar to their fathers.) This means a strain usually has a distinct lineage and therefore unique genotype, although the main traits of the strain may vary little from other similar phenotypes, being the result of genetic drift. For example "Smith Albino Reds" refers to a true breeding strain by the (fictional) breeder Smith. The name merely acts as a unique way of referring to a true breeding strain. A more precise way to describe guppies with distinct visual traits is “phenotype.” (See Phenotype and Genetic drift.) |
| Supergene | Several genes found close together in the SDR (sex determining region) of the guppy's Y-chromosome. They act like a single gene. The Moscow trait may be a supergene. The most important difference between a supergene and a gene complex is that the genes do not cross over. See gene complex. |
| T | |
| Tiger | The name given to the golden mutation. See Golden. |
| Tightly linked | Genes on the same chromosome that are very close to each other such that they crossover very infrequently. See Crossover. |
| Triple Recessive | A guppy with three recessive mutations. The term is also used as a strain description. |
| Truebreeding | A strain that produces offspring that look at least 80% similar. The offspring are at least 80% similar to the parents. This means that the strain is highly homozygous. (See homozygous.) |
| Tuxedo | Name given to the half-black phenotype in Asia. The guppy appears to be wearing a black tuxedo. See Half-Black Gene. |
| W | |
| Wildtype | The normally functioning version of a gene. A guppy exhibiting a "normal" phenotype. Another name is the "grey" version, named after the grey base color of wild guppies. |
| WREA | Wine Red Eye Albino. See the Albino entry. |
| X | |
| X-linked | A gene that is located on the X-chromosome. See Y-linked. |
| Xanthophore | Yellow color cell. |
| Y | |
| Y-linked | A gene that is located on the Y-chromosome. Only males have Y-linked genes, so only sons can inherit Y-linked traits. However the particularly way a Y-linked gene is expressed is dependent on the particular relationship it has (e.g. dominant, recessive, co-dominant) with its X chromosome allele. |
Copyright © 2008 Philip Shaddock. Used with permission.
