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Compendium-Canaries, Volume 2 E-Book

Norbert E.W. Schramm

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Kategorie: Wissenschaft und neue Technologien
Serie: Compendium - Canaries
Sprache: Englisch

Beschreibung

The second volume of the book series describes in a compact form the colour canaries and the fascinating breeding of carduelid hybrids. The author gives an overview of the history of genetics and the mechanisms of plumage colouration. The latest scientific findings are included. All currently bred and internationally recognised varieties of colour canaries are described in words and pictures. New are the colour descriptions according to the RAL colour system. Furthermore, there are valuable hints on breeding hybrids between canaries and other carduelids or between different carduelid species. Many mating is discussed and presented with pictures. These topics are rounded off with the necessary hints for participation in exhibitions and bird evaluations. In the appendix you will find a whole series of tables for the most diverse mating between individual canary colours.

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Leseprobe

Preface and thanks

Thirteen years ago, I wrote the manuscript for my first book on colour canaries. Already 10 years later, great progress in breeding could be observed. Looking back, it is amazing what an enormous development some colour canaries have taken. Now another five years have passed, and, in this time, new canary colours have been internationally recognised and deposited in the standards. For further colours and mutations, recognition procedures are already underway.

So, it is time to revisit the topic of colour canary breeding and to present the latest developments. This second volume of my "Compendium - Canaries" is therefore dedicated to the branch of colour canary breeding in its third revised edition.

In this volume I briefly go into the history of genetics. To explain the complexity of genetic processes in their entirety would be of no help to the bird breeder. I have therefore presented much in a very simplified manner and hopefully explained only the basic genetic relationships that should be known to any serious breeder. As is to be expected, science has made new discoveries in genetics and in the biochemical development of feather colours. As a result, some of my earlier theoretical considerations have been confirmed, but others have not, so I have had to adapt a few of my explanations.

I very much hope that the scientific knowledge of these subjects will now become general breeder knowledge. Far too often one can still read and hear the wrong and inaccurate theories and rules of earlier times.

Many theoretical and practical hints for the specific breeding of colour canaries are listed and I have described in detail all colour varieties that are recognised today and are in the process of being recognised.

Based on my "Colour Compass for Canaries" I have also in this volume used almost exclusively the colours according to the classical RAL colour system for the representation of the melanin colouration of the feathers.

Closely related to colour canary breeding is also "hybrid breeding". Unfortunately, this branch of bird breeding is often attacked and ostracised. For this very reason, some clarifying – and also critical – words are necessary for this ancient branch of bird breeding.

Among bird breeders there were and are many well-known names. They have discovered new mutations or otherwise rendered outstanding services to bird breeding. Unfortunately, the names of these people are often mentioned in specialist publications without their first names and lifetimes. In order to set a small memorial to these breeders, I have tried to find their first and last names, the year of birth and death or even a portrait. Many thanks to Gerhard Verhaegen, who helped me a lot. If any readers can contribute to this research, I would be very grateful for any information.

I would also like to thank Bernd Debus who made available his excellent essay on the history of opal birds.

Thanks also to the breeder friends Michael Förster and Ludwig Hofmann , who gave me Mogno and Jaspe feathers for examination.

I was able to take many of the bird pictures myself in the course of time, but unfortunately not always the winning birds of large shows. I would like to thank Jose Antonio Abbellán Baños, Dietmar Bäthke, Frans Begijn, Lens Erwin, Eugen Franke, Ricardo López Garcia, Guiseppe Gallo, Olaf Hungenberg, Johan van der Maelen, Edeltraud Schneider and other photographers listed in the picture descriptions for providing me with meaningful pictures.

I would like to thank all unnamed breeding friends whose birds I was allowed to photograph at bird shows.

After my three volumes of the Compendium - Canaries were so successful in the German-speaking countries, I received more and more enquiries whether these volumes were also available in English. I therefore decided to translate the entire compendium into English. This project would not have been possible without my English friend Geoff Walker. Geoff Walker is a renowned breeder, O.M.J. judge, author of numerous technical articles, book author and editor of the Canary Colour Breeders Association - CCBA club newspaper. Geoff spent a lot of time and patience checking my translations and gave me many good hints, because it is not always easy to express the German technical terms in English. Therefore, my special thanks go to Geoff Walker!

I would especially like to thank my dear Annegret, who once again put up with my silent work at the computer for months with patience and understanding and often helped me with advice.

Norbert E. W. Schramm

Dresden, Summer 2022

Content

Preface and thanks

The traces of genes

The history of genetics

First attempts at explanation

First milestones

Chromosomes are discovered

The double helix

Deciphering the genetic code

The other, epigenetic code

Bird breeders as researchers

Genetic basics

Cell and chromosome

Chromosomes – carriers of the genes

The chromosome set

Sex chromosomes

The DNA

Genetic code

From gene to protein

Genes and alleles

Gene loci and factors

Wild allele

Gene mutation

The rules of inheritance

Genetic nomenclature

Create heredity formulas

What is dominant, recessive, and intermediate?

Mendel's laws

Uniformity rule and reciprocity rule

Splitting rule

Independence rule

Inheritance of the sex

The Punnett Square

Crossing over

Chromosome mutation and gene insertion

Practical breeding procedures

Selection

Breeding with bought in birds

Inbreeding

Line breeding

Crossbreeding

Breeding book

Basics of plumage colouration

The plumage colours

Light and colour

Colourants and structural colours

The lipochromes

Carotenoids or Lipochromes?

Biochemical structure of carotenoids

Provitamin A and vitamin A

Lutein – the universal substance for the formation of lipochromes

Lipochrome synthesis

Transformation of beta-carotene into red lipochrome

Storage of lipochrome

Effective genes during lipochrome formation

The Yellow-Red Inheritance

The melanins

Melanin cells

Migration of melanoblasts

Melanosomes

Biochemistry of melanin formation

Eumelanin synthesis

Phaeomelanin synthesis

Inclusion of the melanosomes

The colour canaries

About the breed standard

Subjective colour designations

A colour compass for canaries

The names of the colour canaries

General standard requirements

Shape, size, attitude and plumage

Intensity factor (I-Locus)

The traces of genes

The history of genetics

All the domestic animals we know today, and our useful plants have evolved from wild animal and plant species. Early humans hunted animals and gathered plants. Gradually, over the course of many millennia, these activities were replaced by the deliberate reproduction of animals and plants. People no longer had to go after the animals and plants.

The domestic dog is probably the oldest pet of mankind. Scientists estimate that the domestication of the wolf in Europe began about 25,000 years ago.1 A genetic calculation shows that the dog and the wolf separated as a species at least 135,000 years ago, so we must assume that the wolf was a companion of humans much longer than "dog".2

The diversity of today's dog breeds is due to the unconscious application of genetic laws. In many a litter there were puppies that differed slightly from their parents in shape or temperament. For example, individual dogs may have been more eager to hunt, better able to withstand cold or heat, or simply more beautiful in the eyes of humans. Depending on the value of these characteristics, these dogs were increasingly used for further breeding.

What began with the wolf was also attempted with other animals in later millennia. Slowly, step by step, individual breeds developed in this way from different animal and plant species. Without any science, based only on experience – which was certainly also passed on orally – desirable characteristics could be consolidated, and improved, and undesirable ones suppressed. This selection breeding has remained the predominant breeding method worldwide to this day.

Animal and plant breeding always causes artificial evolution, human-directed evolution!

Very often children resemble their parents in a striking way. For example, in their shape, in the colour of their eyes, in the shape of their nose or mouth. Who hasn't heard the saying when looking into the pram: "Just like your father". Perhaps the child also looks much more like its maternal grandfather than its natural father. In any case, the blueprint of these physical features seems to be passed on from ancestors to offspring.

Just as material goods are passed on – "inherited" – from parents to offspring, physical features and character traits seem to be passed on from one generation to the next.

First attempts at explanation

It has been handed down from antiquity that some scholars were already thinking about the laws of heredity at that time. The Greek philosopher ANAXAGORAS (499 to 428 B.C.) believed the daughter was already preformed in the sperm of the left testicle and the son in the sperm of the right testicle (preformation theory), and thus the paternal characteristics were passed on to the offspring. His compatriot ARISTOTELES (384 to 322 B.C.) thought similarly, but he already described those children resembled not only their parents but also their ancestors.

PLATON (428 to 348 B.C.) assumed that father and mother were equally involved in the transmission of characteristics.

The ancient views shaped natural philosophical considerations right up to modern times because the scientific instruments were lacking. Even after the first microscopes were constructed around 1600, the path to knowledge of the inheritance of physical characteristics was still long.

In 1677, ANTONI VAN LEEUWENHOEK (1632 to 1723) developed the microscope to new perfection and used it to discover unicellular organisms, bacteria, blood cells and sperm. But he too saw a complete organism already preformed in the sperm.

It was not until the embryological investigations in 1817 by CHRISTIAN HEINRICH PANDER (1794 to 1865) and the discovery of the egg cell in mammals in 1827 by KARL ERNST VON BAER (1792 to 1876) that the ancient views of heredity came to an end.

In 1831 ROBERT BROWN (1773 to 1858) discovered the nucleus in plant cells, which led THEODOR SCHWANN (1810 to 1882) and MATTHIAS JACOB SCHLEIDEN (1804 to 1881) to establish the cell theory of all living things. In 1857, the Swiss anatomist and physiologist RUDOLF ALBERT VON KÖLLIKER (1817 to 1905) described the mitochondria in muscle cells.

First milestones

JOHANN GREGOR MENDEL was born in 1822 in Heinzendorf near Odrau (Austrian Silesia – today the Czech Republic) as the son of a penniless farmer. Like many children of his time, he had to help his parents in the business from an early age. He thus learned how to graft fruit trees and breed bees. Due to his weak stature, he could not inherit his parents' farm. It was therefore decided that Johann Gregor should become a priest. In 1843 he entered the Abbey of St Thomas in Brünn (today Brno) and became a monk of the Augustinian Order.

From 1844 to 1848 he studied theology at the Brno Theological School and from 1851 to 1853 at the University of Vienna. There he worked with Professor CHRISTIAN DOPPLER (1803 to 1853), the discoverer of the Doppler effect, among others, and also occupied himself with mathematics, chemistry, zoology, botany, and palaeontology.

From 1854 onwards, Mendel began to study the different variants in plants in the monastery garden of Altbrünn Abbey. Over the next eight years he experimented mainly with peas, because the varieties of these pure-bred plants and their seeds could be clearly distinguished in seven different characteristics.

Systematic heredity experiments soon determined his work. He kept meticulous records of the number of plants bred and their appearance. Based on his records and numerical results, he recognised mathematical regularities that occurred from one generation to the next.

In 1865, he summarised his findings on crossbreeding experiments in three basic rules (Mendel's rules), which are still valid

Picture 1 The Augustinian Monk Johann Gregor Mendel

today. In doing so, Johann Gregor Mendel made himself a pioneer of modern hereditary science, which we now call "classical genetics".

In 1868, Mendel became abbot at his monastery and largely discontinued his experiments. Mendel's work and his rules of heredity were not recognised in his time. Even after his death in 1884, his findings did not receive any attention for the time being. His successor on the abbot's chair certainly contributed to this, as he had Mendel's entire estate burnt in the monastery courtyard. Apart from his published writings (including "Versuche über Pflanzenhybriden", published in the Verhandlungen des Naturwissenschaftlichen Vereins von Brünn)3 and a few letters to the botanist CARL WILHELM VON NÄGELI (1817 to 1891), no other documents have survived.

A student of von Nägeli, the German botanist and plant geneticist CARL CORRENS (1864 to 1933), received among other things Mendel's letters from Nägeli's estate around 1900 and recognised their importance. The botanist HUGO DE VRIES (1848 to 1935) and the botanist and geneticist ERICH TSCHERMAK-SEYSENEGG (1871 to 1962) are also regarded today as the rediscoverers of Mendel's rules. Through their own experiments, these three researchers were able to experimentally confirm Mendel's findings.

Since then, hardly a year has passed without researchers and scientists discovering new insights into the structure of plant and animal cells or into mechanisms of heredity. Many of these discoveries can be considered milestones in the history of genetics. Some important milestones are listed here.

Chromosomes are discovered

Shortly after the publication of Mendel's main work, JOHANNES FRIEDRICH MIESCHER (1844 to 1895) discovered nucleic acid in fish sperm and other biological material in 1869 and named it "nuclein" - derived from the Latin nucleus (kernel).

In 1888, the anatomist HEINRICH WILHELM WALDEYER (1836 to 1921) introduced the name "chromosomes" for the stainable nuclei.

EDUARD STRASBURGER (1844 to 1912) discovered the division of the plant nucleus and, together with THEODOR BOVERI (1862 to 1915), described the constancy of the number of chromosomes in different species. Boveri coined the term "centrosome" for the central body of the cell.

In 1902/04, Boveri and WALTER STANBOROUGH SUTTON (1877 to 1916) discovered that chromosomes occurring in pairs behave in exactly the same way as the hereditary factors described by Gregor Mendel and thus founded the chromosome theory of heredity.

The British geneticist WILLIAM BATESON (1861 to 1926) contributed significantly to the dissemination of Mendel's ideas and coined the term "genetics" in 1906, which was soon officially applied to the entire new branch of science.

The US zoologist and geneticist THOMAS HUNT MORGAN (1866 to 1945) used the fruit fly (Drosophila melanogaster) for the first time in his crossbreeding experiments, and it has been the most frequently used experimental animal by geneticists ever since.

Morgan provided evidence that it is indeed in the chromosomes that hereditary traits (genes) are located and present there in a specific order and at specific intervals. He also found out that there are traits that are usually inherited together (linked genes) and are then located on the same chromosome.

With his co-workers, Morgan described the phenomenon of "crossing over" and was thus able to determine the relative positions and distances of the different genes on the chromosome. In 1911, he and his colleagues summarised these findings in the first chromosome map (gene map) of the fruit fly.

He was awarded the Nobel Prize for Medicine in 1933 for his groundbreaking achievements. Morgan is considered one of the leading biologists of his time. The unit "centiMorgan" (cM), which indicates the relative distance between two genes on a chromosome, was also named in his honour.

Picture 2: Thomas H. Morgan.

Picture 3: Fruit fly.

The double helix

In 1944, the researchers OSWALD AVERY (1877 to 1955), COLIN MCLEOD (1909 to 1972) and MACLYN MCCARTY (1911 to 2005) recognised that DNA is the carrier of genetic information.

In 1953, the researchers JAMES DEWAY WATSON (born 1928), FRANCIS CRICK (1916 to 2004), MAURICE WILKINS (1916 to 2004) and ROSALIND FRANKLIN (1920 to 1958) presented the molecular double helix structure of DNA to the public. They discovered that the DNA molecule is composed of a long amino acid thread and forms a three-dimensional, spiral-shaped double strand that lies finely twisted in the cell nucleus. Inside the double helix, the four organic bases join in pairs.

The scientists found out that this structure can copy itself and thus explained the mechanism of heredity. For this discovery, Watson, Crick and Wilkins received the Nobel Prize for Medicine in 1962. Rosalind Franklin, who had contributed significantly to the discovery of the DNA structure with X-rays, had already died by then, so she could no longer be nominated for this prize.

The US biochemist ARTHUR KORNBERG (1918 to 2007) isolated the DNA polymerisation enzyme (today: DNA polymerase I) from a bacterium in 1956. Together with SEVERAOCHOA (1905 to 1993), he discovered the "mechanism in the biological synthesis of RNA and DNA", for which both were also awarded the Nobel Prize in Physiology or Medicine in 1959. Ochoa was also instrumental in deciphering the genetic code.

Deciphering the genetic code

The US biochemist and geneticist MARSHALL WARREN NIRENBERG (1927 to 2010) and his German colleague HEINRICH MATTHAEI (born 1929) planned what was probably the most important experiment in 20th century genetics. The so-called Poly-U experiment was the key to deciphering the genetic code. Although Matthaei alone succeeded in the experiment in the joint laboratory in May 1961, Nirenberg and Matthaei always published together as authors. With this successful experiment, it was possible for the first time to understand the mechanisms of the genetic code, which subsequently made the complete deciphering of the code possible.

ROBERT WILLIAM HOLLEY (1922 to 1993) succeeded in isolating certain RNA sequences in 1962. Together with Nierenberg and HAR GOBIND KHORANA (1922 to 2011), Holley received the Nobel Prize in Physiology or Medicine in 1968 for the "interpretation of the genetic code and its function in protein synthesis".

Khorana, in turn, was the first scientist to succeed in artificially synthesising a gene in 1970. This opened the way for another science and industry – genetic engineering.

The US biochemist HERBERT WAYNE BOYER (born 1935), together with his colleague STANLEY NORMAN COHEN (born 1935), developed a technique to insert foreign DNA into bacterial cells. Both founded the first biotechnology company called "Gentech" in 1976, where the first synthetic insulin was produced in 1978. In 1982, the USA approved this genetically engineered insulin as a medicinal product.

The "genetic fingerprint" was developed in 1984 by ALEC JOHN JEFFREYS (born 1950). The first genetically modified animals soon followed, with the "Harvard cancer mouse" being the first animal patented in 1987.

Scientists launched another high point in genetics in 1990 with the Human Genome Project (HGP). They set themselves the goal of decoding the entire human genome by 2003.

On the way to this goal, researchers deciphered the complete genome of the bacterium Haemophilus influenzae in 1995. This was followed in 1996 by the decoding of the genome of a higher creature – the baker's yeast Saccharomyces cerevisiae.

The first genetically decoded animal was a nematode in 1998. In 1999, chromosome 22 was the first human chromosome to be completely decoded, followed by the complete decoding of the fruit fly genome in 2000 and the mouse genome in 2002. In 2003, the Human Genome Project (HGP) was completed: The human genome was decoded.

CRAIG VENTER (born 1946) was significantly involved in this project. Today, Venter is considered one of the most ingenious researchers of our time, even though his methods are often controversial, and he often moves in the grey areas of ethics with his private research institute. In 2007, Venter succeeded in producing the genetic material of a bacterium completely synthetically. In 2010, he inserted a complete gene code, written by himself, into a bacterium from which the natural genetic material had previously been removed.

At the Technical University of Dresden, a group of researchers under Professor of Biophysics PETRA SCHWILLE (born 1968) is working on the production of a completely artificially produced cell.

Picture 4: Jean-Baptiste de Lamarck.

The other, epigenetic code

The French botanist and zoologist JEAN-BAPTISTE PIERRE ANTOINE DE MONET, CHEVALIER DE LAMARCK (1744 to 1829) developed one of the first theories of evolution. He was convinced that organisms pass on the characteristics they have acquired during life from generation to generation. This theory, known as Lamarckism, was long condemned by many geneticists as non-existent because it contradicted classical genetics.

In recent decades, phenomena have been observed that cannot be explained by classical genetics. For example, it was found that in one region of Sweden, the poor eating habits of grandparents influenced the risk of disease in the grandchildren. Women who starved during the Second World War gave birth to smaller children, which is quite explainable. What is unusual, however, is that these children who did not suffer from hunger also gave birth to significantly smaller children.

Researchers found something similar in animal experiments. They exposed fruit flies to a heat shock that changed their metabolism. The offspring of these flies showed the same altered metabolism as their parents. Mice, which take care of their offspring sacrificially, apparently also pass on this characteristic to their offspring.4 Bird breeders have also been able to make this observation for a long time and apply this experience in the breeding process.

Such observations allow only one conclusion: there must be substances that can "remember" acquired experiences and experiences and pass them on to their offspring.

Today we know that environmental conditions do indeed affect heredity mechanisms, as these external influences can control gene activity. This science, known as epigenetics, was founded in 1942 by the British developmental biologist, palaeontologist, geneticist, embryologist, and philosopher CONRAD HAL WADDINGTON (1905 to 1975). For a long time, this branch of science was not taken seriously or was even dismissed as pseudoscience.

This new scientific discipline revises the old ideas of rigid unchanging genes. Genes are thus malleable throughout life and can be influenced by lifestyle, such as diet, and passed on to children and grandchildren beyond one's own lifetime.

It is still true that the DNA giant molecules with their genes represent the blueprint for the body structure and its functions. To execute the genetic programme, however, the genes need instructions as to when which step is to be carried out. Control genes are integrated in the chromosomes for this purpose. However, there is increasing evidence that the activity of many genes is influenced from the outside.

Epigeneticists have discovered that genes or gene segments can be either active or inactive, switched on or off. Chemical appendages ("switch molecules", proteins and other signalling substances) distributed along the DNA strand serve as switches. They help to bring the right enzyme into position that reads the genetic code of the corresponding gene.

It is now becoming increasingly clear that this "epigenome" is just as important for the development of a healthy organism as the "genome" with its DNA. It is also becoming increasingly clear that this epigenome is much more easily changed by environmental influences than is the case with genes. For example, these epigenetic switches control the development of cancer. The biggest surprise, however, is that epigenetic signals are passed on from parents to children.

Deciphering the epigenetic code is currently one of the greatest challenges in science and holds enormous potential. Although research into epigenetic phenomena is still in its infancy, many important questions can already be answered today.

Bird breeders as researchers

Bird breeders have also grappled with the phenomena of heredity. As in all other areas of animal and plant breeding, it was above all the application of consistent selection of parents for further breeding that made the sometimes-enormous progress in breeding possible.

Especially the breeders of song canaries from St. Andreasberg – the merchant and plumber PETER ERNTGES (1812 to 1896), the miner WILHELM TRUTE (1836 to 1889) and HEINRICH SEIFERT (1862 to?), who came from St. Andreasberg and moved to Dresden in 1885 – succeeded in breeding a new race from the land canary: the Harzer Edelroller.

During the 1st World War, hybrid breeders – the military envoy GEORG BAUM-PELZER from East Prussia, the retired factory director CARL BALSER from Fulda and the railway inspector LUDWIG DAHMS from Königsberg – discovered that the male hybrids from the crossbreeding of the red siskin with the (yellow) canary were partly fertile. The East Prussian civil servant BRUNO MATERN continued breeding with Dahms' breeding birds. He recognised the enormous potential for colour canary breeding and tried to transfer the red of the red siskins to the canaries, which until then had only been yellow-ground and white-ground.

These well-known canary breeders certainly never heard about Mendel's rules of inheritance. They had to fall back on the well-tried method of selection breeding, which they succeeded in doing excellently.

The also very famous canary breeder KARL REICH (1871 to 1944) from Bremen remembered that already in the 18th century the Tyrolean miners bred the famous singing canaries with nightingales. He tried to prolong the singing time of the nightingales with the help of special feeding in order to use them as tutors for his singing canaries. Later, he had the idea of using gramophone records of the nightingale song.

On an August day in 1921, Doctor HANS JULIUS DUNCKER (1881 to 1961), the then already very well-known ornithologist, hereditary biologist, and racial hygienist from Bremen, was walking along a street and heard a nightingale singing. Since Duncker knew that nightingales no longer sing in August, he went after the sounds and met the song canaries with nightingale song in Karl Reich's flat. Researcher and breeder became good friends and from this friendship grew Doctor Hans Duncker's fruitful research work on the inheritance rules of canaries and other small birds. In the course of time, Karl Reich provided several hundred canaries for this work.

Picture 5: Hans Duncker

The wealthy Bremen merchant Consul General CARL HUBERT CREMER (1858 to 1938) devoted his free time to his flowers, exotic fish, and his extensive avicultural collection. For Duncker's very extensive breeding experiments, he made his breeding facilities available in his country house from 1925 onwards and very generously sponsored the breeding programmes.

Duncker devoted many years to the investigation of the heredity of physical characteristics of canaries (colouring, variegation, crest etc.). The basis of his considerations were Mendel's rules, which he creatively and systematically developed further, experimentally, and theoretically underpinned with examples from bird breeding.

Duncker also recognised Matern's preliminary work on the breeding of a red canary, devoted himself intensively to this problem and established the first inheritance rules for it.

It is Duncker's merit to have successfully combined the practice of bird keeping and the theoretical natural sciences. He published his findings in more than 75 publications, of which his two works "Genetics of Canaries" and "Brief Heredity for Breeders of Small Birds" are still regarded today as easily understandable standard works for bird breeders. His heredity tables for budgies are still in use today.

As a geneticist, he supported the Nazi ideology of "keeping the race pure", became chairman of the Bremen chapter of the German Society for Racial Hygiene as early as 1930 and advocated the forced sterilisation of the disabled. However, he only became a member of the NSDAP under pressure in 1941. Denazified in 1948, he devoted himself to ornithology again in his retirement and reorganised the bird collection of the Bremen Oceanographic Museum.

Picture 6: Julius Henniger (left) with breeder friend Arthur Birnstein in Dresden 1954.

The enumeration of important personalities around genetics in canary breeding would be more than incomplete without JULIUS HENNIGER (1878 to 1971). Already at the young age of 15 years he dedicated himself to the breeding of canary hybrids. Further Henniger writes about himself:

"In the meantime, I had moved to the then German Protectorate of Samoa in the Pacific Ocean, where I spent my free time observing and researching the tropical bird life there. I succeeded in finding several bird species that were new to Samoa. I also bred finches and European finches, as well as Yorkshire canaries, until I was surprised by the outbreak of World War I in 1914, which resulted in almost six years of civilian internment in New Zealand. After my release I stayed in Auckland, the largest commercial city in New Zealand, and was busy with the introduction of German-white canaries from Germany when I became aware of the two books by Dr. Duncker, with whom I soon began a correspondence that was extremely instructive for me and continued for four years. Already at that time, in April 1930, I established my system of the '18 canary bird colours', ...".5

With his life's work, which culminated in his book "Farbenkanarien", Julius Henniger rendered a lasting service to future generations of breeders. His established rules of inheritance are still valid in many points today.

"Even if his findings in colour canary inheritance have developed to an extent that he could only have guessed at during his occupation with this extensive matter, due to the rapid development and diversity of the colour canaries and the significantly improved scientific accompaniment, his work is undisputedly an important starting point for the upswing of colour canary breeding in Germany."6

Picture 7: Wilhelm Ostwald

Picture 8: Otto Völker

Henniger was able to base his considerations on numerous works by the biochemist Professor OTTO ERWIN JULIUS VÖLKER (1907 to 1986) from Giessen. In the 1950s, Völker worked intensively on the chemical and physical behaviour of lipochrome colours in bird feathers.

Henniger used the "Ostwaldsche Farbnorm (OF)" (Ostwald colour standard) to classify the yellow to red lipochrome colours. This is borrowed from the Ostwald double cone, which the German-Baltic chemist, philosopher, and Nobel Prize winner WILHELM OSTWALD (1853 to 1932) developed for the representation of his harmony theory of the colour system.

Genetic basics

Cell and chromosome

All living things consist of a multitude of cells. Cells are therefore the smallest living units of all organisms. Cells combine to form functional units, forming very different tissues, which in turn form individual organs. Although cells can be very different both in shape and size (e.g., reticular nerve cells, roundish compact bone cells, spindle-like muscle cells), they are identical in their basic structure and individual components.

Each cell is a self-sustaining system, absorbs nutrients and releases metabolic products. When an organism grows, it does so by cell division (mitosis or equational division). Each newly formed cell contains the information and functions of the parent cell.

Picture 9: Structure of an animal cell.

1- Nuclear corpuscle

2- Nucleus

3- Ribosomes

4- vesticle

5- rough endoplasmic reticulum

6- Golgi apparatus

7- microtubules

8- smooth endoplasmic reticulum

9- mitochontria

10- lysosome

11- cytoplasm

12- peroxisomes

13- centrioles

The sex cells (also germ cells or gametes) occupy a special position. They serve exclusively for sexual reproduction and are formed as an egg cell in the ovary or as a sperm cell in the testicle.

The primordial germ cells divide in a different way from other body cells. In order for fertilisable egg or sperm cells to develop, the germ cells must only contain half the chromosome set (haploid). The cell division of the primordial sex cells into germ cells is called reduction division or maturation division (meiosis).

During sexual reproduction, the haploid cell nuclei of the egg cell and the sperm cell fuse together. The fertilised egg cell now has a double (diploid) set of chromosomes, from which a new living being emerges.

During fertilisation, only the nucleus and the centrioles of the sperm penetrate the egg cell. The mitochondria of the sperm remain outside the egg cell. This means that no paternal mitochondrial DNA (mtDNA) is present in the new living being, which population researchers and genealogists take advantage of. They can thus trace back the maternal line of a living being.

Chromosomes – carriers of the genes

The chromosomes made visible are usually listed by size and then numbered.

Picture 10: The chromosome.

The chromosome set

Each species has a very specific number of these chromosomes, the chromosome set. For example, humans have 46, ants 48, cats 64, cattle 60 and carp 104 chromosomes. The complexity or developmental stage of a species cannot be determined by the number of chromosomes.

Picture 11: Karyogram of the chromosome set of a female canary.10

Sex chromosomes

In most species, two chromosomes perform a clearly recognisable task, because they determine the sex of the individual. These two chromosomes are distinguished by their special shape and were therefore called the X- and Y-chromosomes. These sex chromosomes are also called gonosomes. All other chromosomes are given the name autosome or non-sex chromosome.

In most plants and animals, females have two X-chromosomes and males have one X- and one Y-chromosome in all body cells.

In all birds and in some reptiles and butterflies, however, it is different. In these species, the males have two Z-chromosome, and the female birds have one Z- and one W-chromosome in the body cells. The reason for this is said to be that during evolution in birds and reptiles these sex chromosomes have developed from other chromosomes than was the case in mammals. 10 11

Nevertheless, the terms X- and Y-chromosome are often used in avian literature. However, since there are two very different dispositions between birds and other creatures, the Z-W scheme should also be used in bird literature.

The gametes with their halved set of chromosomes can only have one sex chromosome each. The sperm cells of male birds always have only one of the two possible Z-chromosomes, the eggs of female birds either a Z-chromosome or a W-chromosome.

The DNA

Chromosomes are made up of DNA molecules and these in turn are made up of two single-stranded molecules that are wound around each other in a helical fashion and are then called a double helix.

The double helix is comparable in structure to a spiral staircase. The "sides of the stairs" consist of sugar and phosphate. In between are the "stair treads", which are formed from the four organic bases adenine (A), thymine (T), guanine (G) and cytosine (C).

These four bases always join to form identical pairs:

Adenine (A) with thymine (T)

Guanine (G) with cytosine (C)

The total length of DNA in a single nucleus of a single body cell is enormous, so it must fold up extremely to find room. In humans, the rolled-up DNA length can be two metres. On these two metres of DNA are about six billion base pairs, which encode about 50,000 genes.

Picture 12: Structure of the DNA double helix.

Genetic code

These individual DNA bases can be compared to letters in a script. The sequence of three bases ("letters") form a "word" called a triplet or codon.

This so-called triplet code determines (codes) which of the 22 proteinogenic amino acids are to be incorporated at a certain position in a protein. In addition, the beginning (start) and end (stop) of the respective series of instructions must be marked.

A section of DNA with many triplets, including the start codon and a stop codon, form a gene, also called a hereditary unit, hereditary factor or factor.

This highlights the complexity of the gene structure, which is a major reason why the exact number of genes in the human genome is still unknown today, even though the DNA sequences have been decoded.

From gene to protein

Genes are the blueprints for proteins, which are the basic building blocks to produce hormones, muscle fibres, nerve cells, sperm or feathers and many other body structures.

Picture 13: Transcription

The ribosomes located in the cell plasma synthesise the various proteins. The ribosomes receive instructions from the DNA of the cell nucleus as to which proteins they should synthesise. To do this, the corresponding DNA codes must pass from the cell nucleus via the cell plasma to the ribosomes.

This task is performed by various RNA molecules (ribonucleic acid). The RNA molecule is like the chemically closely related DNA-molecule but replaces the amino acid thymine with the amino acid uracil.

This transcription, now anchored in the RNA, migrates to the ribosomes. The RNA thus acts as a messenger and is therefore also called messenger RNA (mRNA).

Once in the ribosome, the RNA produces the individual amino acids with its code. The triplet code "UAU" means, for example, the production of the amino acid "tyrosine".

Many amino acids, in changing sequence and frequency, make up a protein.

Genes and alleles

Certain sections of DNA – a larger number of triplets with three times the number of base pairs – carry fixed hereditary information. These sections are called genes.

Genes are present in every chromosome. If the genes are on a non-sex chromosome (an autosome), they are linked to this autosome and these traits are inherited with it. We call this free inheritance or non-sex-linked or autosomal inheritance.

Even if the genes are on the Z-chromosome (the gonosome), the traits are inherited with it. They are linked to the Z-chromosome. We then speak of sex-linked inheritance or gonosomal inheritance.

The W-chromosome of the female bird also has genes. However, these have no significance for our considerations. Presumably, the genes of the W-chromosome are responsible for typical female characteristics.

The number of genes, their position in the respective chromosome and their genetic information are characteristic for every living being and represent the genetic material (genome).

Proteins that control all biochemical processes in the organism are called enzymes (formerly called ferments). Enzymes act as catalysts, thus triggering substance transformations and/or changing the speed of these processes. Enzymes and polypeptides are ultimately proteins that consist of different numbers of amino acids.

Enzymes usually only act on a very specific biochemical reaction and on a very specific substance or group of substances. The names of enzymes usually have the suffix "-ase".

Picture 14:

Above: One-gene-one-enzyme hypothesis.

Middle: present-day insight into the one-gene-one-polypeptide hypothesis.

Bottom: Mode of action of a gene mutation on enzyme formation.

The scientists GEORGE WELLS BEADLE (1903 to 1989) and EDWARD LAWRI TATUM (1909 to 1975) discovered that the composition of enzymes is controlled by genes and were awarded the Nobel Prize for this in 1958. They assumed that each gene only controls the composition of a very specific enzyme and therefore called their hypothesis the "one-gene-one-enzyme hypothesis".

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