How to reconstruct the model of selection. Population Genetics.

rosophila melanogaster is a small, common fly found near unripe and rotted fruit. It has been in use for over a century to study genetics and behavior. Thomas Hunt Morgan was the preeminent biologist studying Drosophila early in the 1900’s. He was the first to discover sex-linkage and genetic recombination, which placed the small fly in the forefront of genetic research. Due to it’s small size, ease of culture and short generation time, geneticists have been using Drosophila ever since. Fruit flies are easily obtained from the wild and many biological science companies carry a variety of different mutations. In addition these companies sell any equipment needed to culture the flies. Costs are relatively low and most equipment can be used year after year. There are a variety of laboratory exercises one could purchase, although the necessity to do so is questionable. Why use Drosophila? Teachers should use fruit flies for high school genetic studies for several reasons: 1. They are small and easily handled. 2. They can be easily anesthetized and manipulated individually with unsophisticated equipment. 3. They are sexually dimorphic (males and females are different), making it is quite easy to differentiate the sexes. 4. Virgins fruit flies are physically distinctive from mature adults, making it easy to obtain virgin males and females for genetic crosses. 5. Flies have a short generation time (10-12 days) and do well at room temperature. 6. The care and culture of fruit flies requires little equipment, is low in cost and uses little space even for large cultures. By using Drosophila, students will: 1. Understand Mendelian genetics and inheritance of traits 2. Draw conclusions of heredity patterns from data obtained 3. Construct traps to catch wild populations of D. melanogaster 4. Gain an understanding of the life cycle of D. melanogaster, an insect which exhibits complete metamorphosis 5. Construct crosses of caught and known wild- type and mutated flies 6. Learn techniques to manipulate flies, sex them, and keep concise journal notes 7. Learn culturing techniques to keep the flies healthy 8. Realize many science experiments cannot be conducted and concluded within one or two lab sessions National standards covered in these lessons: Content: 1. Organisms require a set of instructions for specifying traits (heredity) 2. Hereditary information is located in genes. 3. Combinations of traits can describe the characteristics of an organism. Students goals: 1. Identify questions and concepts that guide scientific investigations 2. Design and conduct scientific investigations 3. Formulate and revise scientific explanations and models using logic and evidence 4. Communicate and defend a scientific argument The genetics of Drosophila are well documented and several public-domain web sites feature the complete annotated genome. Therefore, those teachers or students wishing to see where their mutations occur have a ready reference available. Since Drosophila has been so widely used in genetics, there are many different types of mutations available for purchase. In addition, the attentive student may find mutations within their own wild-caught cultures since, due to a short generation time, mutations are relatively common compared to other animal species. Classification Domain: Eukarya Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Diptera Family: Drosophilidae Genus: Drosophila (“dew lover”) Species: melanogaster (“dark gut”) Life cycle of Drosophila melanogaster Drosophila melanogaster exhibits complete metamorphism, meaning the life cycle includes an egg, larval (worm-like) form, pupa and finally emergence (eclosure) as a flying adult. This is the same as the well-known metamorphosis of butterflies. The larval stage has three instars, or molts. #PopulationGeneticsFieldOfStudy #GeneticsFieldOfStudy #QuantitativeTraitLocus #PolygenicInheritance #polygenicInheritanceExample #whatIsPolygenicInheritance #normalDistributionCurve #incompletelyDominantTraits #additiveEffect #genetics #exampleOfPolygenicInheritance #skinColorTrait #skinColorTraitInHumans #skinColorInheritance #heightInhertiance #heightTraitInheritance #polygene #polygeneAndAdditiveEffect #NikolaysGeneticsLessons