A Matter of Selection

One part of the Brassica oleracea plants that exhibit the most variation are the leaf length by the stem, lengthwise. For example, one kohlrabi leaf (by the stem) is 12 cm and a collard’s leaf is 38 cm (by the stem). I think that there is a lot of variability in domestic forms of Brassica Oleracea because artificial and selective breeding makes the plants have particular traits plant breeders want in their plants. Another reason is because of descent with modification, along with natural variation and mutations. The plants could randomly change at anytime due to mutations and natural variation. Natural variation is the process where mutations randomly occur when the genes are copied. The part of the plants that seems to be the same is the stems width. I think this is because they all are the same species and they only had mutations that affected other traits. Evidence of this is that 3 kohlrabi stems were about 1 cm in width and 3 collard stems were about 1 cm in width as well. In order for plant breeders to change this characteristic, they would have to breed with other plants or place the plants in an environment so they might be able to adapt to their new environment.

A Matter Of Selection

1. The anatomical trait that has the most variation, in my opinion, would be the shape of the plants’ leaves.  3 groups of plants has smooth-edged leaves, 2 groups had wavy edges, and 1 group had frilly leaves with small limb-like pieces sticking out from the main part of the leaf.  The most ranged trait of the plants was the height of the plants’ stems.  The highest plant’s stem was 4 feet 1 inch, whereas the smallest one was only 10 inches.

Type of leaf	smooth edge	wavy edge	frilly limbs
# of plant groups w/this	3	2	2

2. The reason for the extreme variety in the plants’ traits is due to a long-period change in the gene pool of the species.  Even though all the plants shared a common ancestor, some, due to artificial selection, were mated and whose offspring had inherited traits that were recessive, but were present in both parents.  Also, in some cases, new phenotypes may have entered the population due to mutations.  Natural variation may also have caused so many split-off phenotypes.  Plants with many offspring would have some offspring that had unlikely, recessive genes that resulted in radical (yet useful) phenotypes.  If these offspring mated with similar plants to produce more offspring that had the same outlandish phenotype, then descent with modification predicts that over generations a subspecies would evolve.

3. I believed the most consistent quality of the plants to be the length of their leaves.  While all the plants didn’t have exactly the same length, the similarity is why I thought is to be the least varied trait.  The averages of five species’ plants is shown below.  While a difference of 7 inches (15 being highest and 8 being lowest) may seem large, this is a difference of only about half a foot, not nearly as large as the difference in heights, stated above.

4. For plant breeders to cause this consistency to become non-consistent and create variation, they would have to breed two organisms with the outlier numbers.  If a small-leaved pixie cabbage and a small-leaved kohlrabi were to create offspring, it would be a very likely chance that their offspring would have small leaves.  If these offspring were to mate with other plants that had small leaves, it would be likely that they would produce small-leaved plants.  If breeders were attentive and made sure to mate only the smallest-leaved plants, a new subspecies of plants with tiny leaves would emerge.

Blog Post Assignment 9: A Matter of Selection

1. I think the part of the Brassica oleracea plants that has the greatest variation is leaf shape, texture, and overall appearance, excluding color.  The plants were short and smooth, long and bumpy, wide and round, and plenty more. Just looking, you can tell the different kinds of plants apart easily. The table below shows the differences between 8 plants and some of their leaves’ characteristics. Texture, thickness, leaf length, shape, and other unique qualities define each plant. When a person sees the garden, the different plant shapes are the most obvious difference. If I have to differentiate between different plants, describing the leaf shape is the easiest way to distinguish which plant is which. The second data table expresses the greatest range of difference: height. Within the same species, the 10 inch tall cabbage and the three feet tall broccoli coexist. That is quite a large range; who would imagine the heights could vary so much? The average height is around 22. Each individual plant is very unique, and the height of each one clearly shows how different they are.

  Table 1

	Cauliflower	Kohlrabi	Kale	Cabbage	Collards	Broccoli	Brussels	Romanesco
Thick/ Thin	thick	medium	thin	thick	thick	thick	very thick	thick
Texture	smooth, soft	smooth	rough bumpy	smooth, tough	smooth stalky	smooth	tough,  rigid bumpy	rough
Shape	rounded, slight curves	rounded crinkled edge	crinkly edge, long	round, bowl-like	roundedcurved	round, short curved in	crinkly round	curved, long
Leaf Length	9 inches	12 inches	7 inches	6 inches	11 inches	7.5 inches	7.5 inches	12 inches
Other	thick stalks	bulb bottom		circular ball of leaves	very thick stalks	yellow flowers

 Table 2

	Cauliflower	Kohlrabi	Kale	Cabbage	Collards	Broccoli	Brussels	Romanesco
Height inches	25	21	24	10	16	36	15	29

2. There is so much variability in Brassica oleracea because of many of the ideas in the theory of evolution. We know the common ancestor, the parent plant of the Brassica oleracea, and it doesn’t look much like any of the Brassica oleracea that are in our garden. This is because of many things, some of which being descent with modification, natural variations, and mutations. Descent with modification refers to how a plant's offspring is slightly different from the parent plant, so over time, descendants of the plant look very different. Natural variation and mutations both refer to the random changes in traits that happen to a plant, making it live differently. Both can be passed on to children through their genes, and may continue on through their offspring. With food plants as well as animals, it is also common for humans to modify the plant growth through selective breeding and artificial selection. Both describe the ways that a plants traits can be modified to get the desired result. All these factors have added to the great variation in Brassica oleracea. Naturally, the plants changed and gained different traits in different environment. Then, humans all over the world changed each plant to get what they wanted. Now, all these things caused the diversity of Brassica oleracea.  

3. I think the aspect of the brassica oleracea plants that is the most similar is the color. Most of the plants are a muted, forest green color. Many plants have yellow stalks, or even parts of the leaves are yellow, and a few plants are part purple, but the color scheme with them all is very similar. That may seem silly, because yellow, green and purple are all different colors, but it is the way they appear in the plants. The color is muted and darkish, and there is nothing outrageously bright. You can see clearly the parts of the green plants that fade into purple, and the same with yellow, so the connections between the colors are clear. I think that the colors are similar because for a plant, there is no reason to need a different color. For animals, they might eventually evolve to become a color better matched to their environment for better survival, but plants cannot really hide from whatever will eat them. And humans wouldn’t be inclined to prefer a plant specifically because of its color. Also, the chlorophyll in them makes them appear green, so it may be difficult for them to remain any other color.

Table 3

	Cauliflower	Kohlrabi	Kale	Cabbage	Collards	Broccoli	Brussels	Romanesco
Color	medium green; white stalks	dark green; purple stalks and root	dark green; purple stalks	light purple, some green; light white stalks	Medium green; white stalks	muted, medium green; white stalks	dark, murky green; white stalks	dark green; white stalks

4. To change the color of a plant, breeders just need to breed the plants that have the color they want and ignore the rest. If they bred enough of that one color, they could eventually end up with a majority of a non-green plant if they discarded all the green ones.

Blog Post Assignment 9

Blog Post Assignment 9

All the Brassica Oleracea plants are rather huge now. One example of the variation is the length of the different species of leaves. The broccoli and our collards have the about the same height, at about 30 centimeters, while the kale was the b. oleracea plant with the shortest leaves, only at about 21 cm. The greatest range of variation seemed to be the color of the plants. Most of the plants are mainly green with a little bit of purple mixed in, while the kale is about half and half with green and red.

As the Brassica Oleracea family has been grown, there has been many instances of reproduction between the plants. Whether this was by human hands or nature, it demonstrates artificial breeding and natural selection. As the plants reproduce, descent with modification takes place, which inputs new genes and modifications that assists a plant adapt to its current environment. Natural variations also occur, for some plants mutate on their own, while others die out due to their inability to adapt.

All of the plants in our garden consist of long stems and rather large leaves. However, others have extreme differences, as others have flowers, or shriveled leaves. I believe this is because some may have interbred in the same environment, while others may have grown in an environment with numerous bugs. Therefore, the flowers are meant to attract bugs, while the others are trying to be inconspicuous. Also, this is shown by the fact that the kale and collard greens are similar in length, while cauliflower and kohlrabi are similar in length. This shows the relevance to each other, and also the possibility of interbreeding.

To obtain traits, plants would have to go through selective breeding in hope that the offspring would receive the traits desired and required to survive. However, some situations may require the input of science to input traits that the plant does not have through genetic modification. Therefore, the plant would have the trait through modifica