6 April Science 7 Explaining Diversity through GDR and Natural Selection

We have finished 2 field studies in which you have had the opportunity to observe living things in the environment. One major emphasis in these studies has been the fact of biodiversity–that there are many kinds of living thing. We have related biodiversity to geography, the fact that there are patterns in the distribution of kinds of living thing in the world. We have also talked about the fact that more offspring are produced than survive. This fact sets the stage for differential survival (and consequently, reproduction) with respect to environmental conditions. The organisms that survive and reproduce pass their genetic characteristics to the next generation. In this manner, populations of organisms can change over time. One important question to consider is how variation arises. Sexual reproduction is one way that genetic material is mixed in offspring so that variation is  built into the process of reproduction. The various means by which genetic information is translated into the material bodies of organisms and even into patterns and potentials of behavior is important for a comprehensive and coherent explanation of how populations of organism change over time.

There are many places to become confused as we try to understand the grand scientific arguments of how the evolution of species takes place. The “dilemma of detail” is ever present in addressing questions of how genes work and how species evolve.

Be sure to ask and record your questions. Be sure to examine pre-existing ideas you might already have. Be sure to keep an open mind. It is possible you may need to revise, reject, develop more completely ideas you already have. Certainly you will encounter new ideas.

Let’s begin by writing down what you already know or think you know about seeds.

What questions do you have about seeds?

Examine the kernels of corn (popcorn / field corn / etc. depending on what we have). What do you notice?

Let’s prepare the corn for germination (what does that mean?) in a couple of ways. Record your procedure and your expectations. Wash your hands well after handling the soil.

Together we will view a segment of episode 3 Hidden World from Botany: A Blooming History. You should watch the entire episode on your own.

Segment on Nikolay Vavilov: https://vimeo.com/26072111

Entire episode of Hidden World (Sound is absent for a short part at the beginning, be patient. Use captions!): http://www.justgamingvideo.com/video/75b6DzNIU9A

Let’s discuss some of the ideas connected with the story of Vavilov and his work.

Next let’s sample some popcorn. What do you know about popcorn?

Popped Secret: The Mysterious Origin of Corn is a very important example in our quest to find out how scientists investigate and explain how species change. We will refer to it again and again. Be sure to ask questions.

https://www.hhmi.org/biointeractive/popped-secret-the-mysterious-origin-of-corn

Be sure to have a complete and thoughtful DSN entry for today.

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