The Sources of Variation What biological processes result in the genetic variation we see in populations?

Group 1-Dogs: Below are several images of a family of Labrador Retrievers. What similarities and differences do you observe between the parents and the offspring? What is the general pattern of variation in this population?

Group 1: Corn Look at the pictures of Indian Summer corn. All kernels on any one ear of corn are siblings. What similarities and differences do you observe among the siblings?

Group 1: Humans Look at this picture of a family who lived during the 1930s. What similarities and differences do you observe among the parents and the offspring?

Conclusion for Group 1 What can you conclude about the variation observed in these various groups? What process results in this type of variation?

Sources of Variation: What is occurring in this diagram? How does this contribute to variation?

Sources of Variation: 1) Sexual Reproduction = Mixing DNA! -Generation of varied gametes through meiosis contributes to sexual reproduction -Both parents contribute their genetic material in the offspring.

Below are images of a milk cow and a beef cow Below are images of a milk cow and a beef cow. What differences do you observe between them? The cow on the right (beef cow) has a mutation in a gene that codes for the production of muscle fibers.

Below are images of a typical cat and the American Curl breed of cat Below are images of a typical cat and the American Curl breed of cat. What differences do you observe between them? The “curled ear” that is characteristic of this breed is a result of a mutation that regulates the cat’s external eat structure.

Below are images of dahlias, a common garden flower Below are images of dahlias, a common garden flower. What differences do you observe among them? The striping and spotting of color in Dahlia flowers is the result of mutations caused by X-rays.

Conclusion for Group 2 What can you conclude about the variation observed in these various groups? How do these new or novel traits appear in offspring that were not observed in their parents? How do changes in DNA arise?

What are mutations and how do they form?

Sources of Variation: 2) Mutations DNA can be altered or damaged by environmental factors or copying errors. Changes in DNA (genotype) are reflected by changes in appearance (phenotype). DNA altered in sex cells may be passed on to offspring. What about changes in DNA in somatic (body) cells?

What are the two sources of variation? 1) Sexual Reproduction 2) Mutations