Variation What is variation? Variation Lab – Day 1 Variation Lab – Day 2 How does variation arise?

Variation - a difference or deviation in structure or character from others of the same species or group

Single-gene Traits – traits controlled by a single gene that has two alleles  Examples – cleft chin, hitchhiker’s thumb, tongue rolling, attached/unattached earlobes

Polygenic Traits– traits controlled by two or more genes  Range of phenotypes  More than two genes  Examples – height, performance on IQ tests, skin color, eye color

Variation Lab – Definitions  Species - a group of organisms capable of interbreeding and producing fertile offspring  Population – groups of individuals of the same species that interbreed  Gene Pool – all genes that are present in a population

Variation Lab – What will you be doing?  Mealworms – LENGTH of mealworm (mm)  Peanuts – LENGTH of inside nut, or cotyledon (mm)  Hand – LENGTH of hand spread from thumb to little finger

Variation Lab - Predictions

Variation Lab - Graphing

Variation Lab – Graphing Instructions  Label the x-axis (independent variable) and the y-axis (relative frequency).  Determine the maximum and minimum values for each variable and a standard width for each bar and set them on your axes.  Draw a bar for each range of values that shows how many organisms have a trait that measures within that range. Repeat this for all ranges of measurements.

Mealworm (mm)Peanut (mm)Hand Size (mm) SizeNumberSizeNumberSizeNumber < >28 < >28 < >26

Genetic Variations  Mutations Due to mistakes in the replication of DNA or radiation or chemicals in the environment  Gene Shuffling Occurs during meiosis

Genetic Variations – Mutations: Sickle Cell Anemia

Sickle Cell Anemia Mutation – Harmful or Beneficial?  NN – normal round blood cells  NS – normal round blood cells; immune to malaria  SS – sickle-celled blood cells