Matter of Selection

Through this Story of The Seed experiment the garden has accumulated many species of Brassica
oleracea.  These plants grow more and more each day, with that comes more and more variation each day. These plants may be related but have many differences.  The trait that exhibited the most variation was the leaves. The leaves could be anywhere from 7 cm all the way to 17 cm. The leaves aren't just different in size but also in shape and color.  From the pictures you can see how different these leaves are in shape. Some are round as basketballs and others are jagged like swords. The colors are also very different as you can see by how some of the leaves are dark green and light green, with some having hints of purple.  The quality that showed the greatest range of difference was the size of the the stems. Due to the stems being too hard to reach or too long I couldn't get measurements, but the pictures show an obvious difference in size. For example the cabbage plant has a very short and stocky stem to hold all the weight, the collard green's stem had a medium diameter but was pretty short, and the kale had a very tall stem and was a relatively skinny.  With the leaves there were many variations, with the stems there is one common difference which is height.

	Plant 1	Plant 2	Our Plant	Plant 4
Leave Length	9.5 cm	7.5 cm	17 cm	9 cm
Leave Width	5 cm	1.5 cm	13 cm	6.5 cm
Stem Height	56 cm	45 cm	16 cm	50 cm
Stem Thickness	7 cm	5 cm	8 cm	6cm

Since most forms of Brassica are eaten by us humans, people used artificial selection to create specific phenotypes for the Brassica.  For example maybe they wanted to make larger cabbage so the used this to get that larger trait from the plant. Some of the different species could have needed to adapt to a certain habitat or area which created descent with modification.  Selective breeding is very similar but happens naturally in the wild and creates better fit plants. Lets take a step back here. All these traits we are talking about aren't just qualities the organism has, these traits are phenotypes. These phenotypes are coded in DNA by genes in the chromosomes.  Phenotypes can be obtained in many ways. For example, artificial selection, selective breeding, mutations, adaptation, or descent with modification. Mutations sound harmful, but aren't always. While all mutations alter the phenotype, some do it for good or don't harm it at all. The last thing I would like to share is descent with modification and adaptations.  These are connected in a way. First of all, an adaptation is a trait gained by an organism to make it more fit to the environment it lives in. Descent with modification is when an animal adapts and survives natrual selection and then reproduces and that organism has a new trait with out doing anything of the above. This also happens if either of the parents have the new trait.

This might sound silly or obvious but the thing the plants have in common is color.  They are all green. Well you probably could have guessed that, but there is a reason they are all green.  These plants possibly didn't start this exact color from the beginning of their ancestors. The reason for this is simple.  The world has changed so the plants had to change. The gradual change of the earth affects almost everything. As technology advances the more and more greenhouse gases are used this increases temperature and this changes habitats, which maybe could have altered the color if the habitats of the Brassica was affected.  Once the Brassica adapted to the "new" world they didn't die off from natural selection and reproduced creating descent with modification.

Breeders or farmers want to sell bigger and better plants. Most want their plants to look better too so they're more appealing.   Farmers don't get to live where they want, but with plant modification they can grow corn in drought areas, soy beans in a highly bug populated area, or even grapes in the dessert.  They way they can reach these "perfect" plants is to do plant breeding or a more effective was is genetically modifying the seeds. To modify a seed and get the trait desired they find something that has the trait they want, then they take that gene and put a copy into the DNA of host plant cells.  Then that plant is grown and matured and produces seeds. Then those seeds have to be approved by the government and then finally can be sold.