Through the Generations: Toothpick Fish!

        Recently in science class, we were allowed the opportunity to kill fish!  Fake, toothpick fish, that is.  Our class used these fake fish in order to create a microcosm of what would happen to a population of fish throughout their lives starting from a first generation of fish to the fourth generation.  Below you will find an analysis of the lab.

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        The Toothpick Fish Lab consisted of toothpick fish, a plastic cup morgue, and a plastic cup ocean.  In the beginning, all of the fish were in the ocean.  There were green fish, red fish, and orange fish (eight for each).  Allele information and combinations are stated subsequently.     

G = green; dominant

r = red; recessive to green and incompletely dominant to yellow

y = yellow; recessive to green and incompletely dominant to red

GG = green

Gr = green

Gy = green

rr = red

ry = orange

yy = yellow

        Randomly created, here is the first generation of fish:

Genes	Color
Gy	green
Gr	green
Gr	green
yr	orange
GG	green
yy	yellow
Gy	green
rr	red
ry	orange
Gr	green
yr	orange
Gy	green

       From this chart, it is seen that there are many more green fish than red, yellow, or orange ones.  This is because of the fact that the green allele is dominant.  If even one green allele is present, a fish will turn out to be green, no matter what the other allele is.  This proves that if the recessive yellow and red alleles are in a genotype with a green allele, the red or yellow color is blocked by the green.  Accordingly, approximately 58% of the fish were green, 8% were red and yellow each, and 25% were orange.  These results were not surprising; the most fish would have had to be green since the green allele is dominant and so any fish that had one would be green.

        The second generation looked like this: 

Genes	Color
GG	green
Gy	green
ry	orange
ry	orange
rr	red
ry	orange
GG	green
ry	orange
rr	red
GG	green
Gy	green
X	X

        Notice that one row is missing.  This occurred because of the lack of camouflage for the yellow fish in the first generation.  Therefore, all of the yellow fish in that generation (one) died out.  On the contrary, the green fish, red fish, and orange fish were able to camouflage themselves using the lush green environment with seaweed and algae.  As can be imagined, the unfortunate yellow fish could not find anywhere to hide from predators, which resulted in the killing of it.  From this chart, it is seen that 45% of the fish were green, 18% were red, 0% were yellow, and 36% were orange.  Although in this particular case, no yellow fish showed up, this was still possible.  This is because the yellow allele is recessive.  If in the previous generation, a yellow allele was masked by a green one, the fish turned out to be green, but it still had the yellow allele.  Had this fish mated with another fish with a hidden yellow allele, the resulting offspring may have been yellow.  This shows that in some cases, a trait that seemed to be wiped out can appear again if it was recessive.

        Next, the yellow fish are eaten again due to a lack of adequate camouflage.  Since no yellow fish appeared in the second generation, the set-up stays as it is.   

        The third generation is as follows: 

Genes	Colors
GG	green
GG	green
rr	red
GG	green
ry	orange
Gr	green
ry	orange
ry	orange
rr	red
yy	yellow
Gy	green
X	X

        In this generation, approximately 45% of the fish were green, 18% were red, 9% were yellow, and 27% were orange.  This generation's results were very similar to the second generation as there were the same amount of green fish and red fish.  However, this time, there was one yellow fish and one less orange fish.  As stated before, it was still possible for a yellow fish to appear since the yellow alleles could be hidden behind a dominant green allele.  Unfortunately, the yellow fish was eaten by a predator again.

        Consequently, the fourth generation looked like this:

Genes	Colors
Gr	green
ry	orange
Gr	green
Gy	green
Gr	green
yy	yellow
Gr	green
Gr	green
Gr	green
Gr	green
X	X
X	X

        The one extra blank row is due to the disappearance of the previously seen yellow in the third generation.  In this generation, 80% of the fish were green, 0% were red, 10% were yellow, and 10% were orange.  This was a rather large change between all the other generations.  There was almost a 40% change from the third generation to this one for the number of green fish.  On the other hand, there were no red fish, an equal amount of yellow, and two less orange fish.  

        Next, the fourth generation of fish is struck by an environmental disaster.  A nearby factory had dumped a large amount of harmful waste.  The previously abundant seaweed and algae are reduced greatly.  This catastrophic event for oceanic organisms result in terrible ramifications for the green fish.  Since the seaweed and algae are now longer in place, rocks and sand that are good camouflage for red, yellow, and orange fish are exposed.  Instead of the yellow fish being killed easily, it is now the green fish who are popular prey.  However, there is a large difference between the killings of the yellow fish and the green fish.  Only two yellow fish were eaten while eight green fish were eaten.  The large difference between the amounts is because of the simple fact that green alleles are dominant.  If even one green allele was present in a fish, that fish would definitely have died because it would be green.  This means that no more green alleles would be present in any of the remaining fish.  On the other hand, due to the fact that the yellow allele is recessive, only a small amount of yellow fish would die because to have a recessive trait, an organism needs to be homozygous recessive (in this case, yy).  These two killings are perfect examples of natural selection -- only the best alleles for the environment are passed on while other, unhelpful ones disappear eventually.  Because of the disappearance of the green fish, the only survivors were the red, yellow, and orange fish.  There were zero red fish, one yellow fish, two orange fish.  The population had decreased by nine fish from the first generation because of all the changes in the surrounding ecosystem.  

        Although the Toothpick Fish Lab showed only one example of what could happen within a population of fish in an ocean, there are still many other ways an ecosystem could go.  For example, if the environment that the fish live in was turned into a popular boat destination and humans carelessly dropped litter into the ocean, many fish could die.  Fish who were looking for an effective place to camouflage (whether it be green, yellow, red, or orange) may mistakenly think that the garbage is a good hiding spot and end up being choked or trapped in the litter.  Another example is if the lab included another type of color of fish, such as white, which could be recessive to green and co-dominant to red and yellow, the results of the lab may be entirely different.  If there were eight white toothpick fish in addition to the others, those fish could be paired with green to create green fish or paired with red or yellow fish to create red and white fish or yellow and white fish.

        As proven from participating in this extremely enlightening lab, many events and basic information contribute to the quality of life, the surrounding environment, and overall population of every and any organism.  These items range from the basic ideas of recessive, dominant, co-dominant, and incompletely dominant alleles to predation and environmental disasters such as the release of harmful factory waste.  One population depends on a multiplicity of variables and this holds true for every, single population that exists in this world.  The Toothpick Fish Lab was an eye-opening lab that displayed how a population changes with its environment. 


        The picture I used came from here. 

~ Starflower794!!!