AP Biology class blog for discussing current research in Biology

Author: ddecam198

Gene-swapping: Could our understanding of Evolution be incomplete?

Alloteropsis Cimicina Photo courtesy of Wikimedia Commons under GMU Free Documentation License



Recent scientific evidence has suggested that our understanding of how evolution occurs may be incomplete. Although the passing of genes from parents to offspring will certainly remain the main method by which organisms inherit their DNA, it seems that their may also be another way. Scientists from Universities in the United States, United Kingdom, and France believe to have stumbled across an entirely new way that plants of different species can exchange DNA.

In order to test their theory, this group of scientists investigated the ancestry of two genes that encode enzymes essential to C4 photosynthesis (phosphoenolpyruvate carboxylase and phosphoenolpyruvate carboxykinase) These genes were chosen because they are present in three closely related C4 plants, and their common C3 ancestor.

In order to accommodate the commonly accepted theory of how genes are inherited, it was initially assumed that these genes must have been initially inactive in the C3 plant, and were later modified to become photosynthetic agents for C4 photosynthesis. If this were true, the scientists would discover that the genes for these enzymes in C4 plants would be closely related to the inactive genes of their ancestor. However, this was not the case.

Instead, the scientists found that these two genes were actually closely related to those of completely different species of C4 plants. They found that in four cases, the ppc or pck enzymes found in the Alloteropsis plants (the type of C4 plant that they initially selected to study) were also found in other C4 clades.

The only explanation for these occurrences is what scientists are now calling “lateral gene transfer.” In their current model for this process, the scientists hypothesize that the genetic material from the pollen of a plant of one species is accidentally taken up by a plant of another species in an “illegitimate pollination event.” If it proves to be valid, this discovery would prove that plants have a way of creating biological diversity that was previously completely unknown to us.

What do you think the larger consequences of this discovery are? Do you think we might be able to incorporate genetic material from different species into our own bodies some day?

For the original article, click here

Guppy Love!

Tiger Guppy (domesticated)- CC licensed photo by Leonard Paguia

Guppies (those small, colorful freshwater fish that everyone loves to keep in their fish tanks) have been evolving in the wild for more than 500,000 years, yet one feature has remained constant over all that time. Research conducted by UCLA Biologists has shown that the orange spot found on the wild male guppy has remained not simply the same color, but the same hue of orange since near the beginning of this fish’s existence. The reason for all this effort? That particular shade of orange is the one that female guppies prefer. What is so fascinating about this to biologists is that it proves that evolution is not simply an organisms adaptations to be better suited to its environment.

The two pigments that, when combined, allow a male to have an orange-colored spot are carotenoids (taken in by the guppies through food) and drosopterins (synthesized by the guppies). A higher percentage of carotenoids would make a guppy’s spot appear more yellow, and a higher percentage of drosopterins would make the spot appear more red.

Now one would think that, in order to conserve energy and be able to function more efficiently, a male guppy that had an abundance of carotenoids in its diet would not waste energy on synthesizing drosopterins as it would not need them to have a brightly colored spot. Conversely, one would think that in order to maintain a bright and noticeable spot, a guppy that did not have a lot of carotenoids in its diet would synthesize more drosopterins. However, this is not the case.

As the type and availability of food for male guppies has varied as a result of both time and location (guppies are native to both trinidad and venezuela) they have evolved to match the levels of carotenoids and drosopterins to produce that orange that the females are so attracted to, even if it comes at a high energy cost, or the spot must be more dull to produce the correct shade.

Although we all understand that reproduction is the ultimate goal of all organisms, what these guppies have done over the past half a million years is still not evolution in the way that many of us think about it. What has happened with a great many organisms is that they adapt in ways that make it more easy for them to survive and then these traits become attractive to the opposite sex because their presence indicates that that individual will produce offspring that will also be better suited for its environment. Here, however, male guppies have striven to remain attractive to their mates even when this comes at a high energy cost for many. As a result, the females have not had to change their taste in mates, and the males have been forced to continue playing to their preferences, or risk not reproducing.

Can you think of any other organisms that have adapted to be attractive to mates even when it made them less suited for their environment?

For further reading on the actual experiment conducted by UCLA biologists click here


Intellectual Growth Spurts? They might just be possible

Photo Taken By Reigh LeBlanc

For many years, educators and researchers have been using the IQ test as the most comprehensive way of measuring a person’s intelligence. They have also upheld that this one-time measurement will be accurate throughout a person’s life; in other words, one’s intellectual capacity does not change over time. However, as it turns out, this logic may not be as infallible as it once seemed.

Back in 2004, Cathy Price and a group of other scientists tested the IQ’s of a number of teens and then took structural images of their brains using an MRI scanner. Four years later, the same experiment was conducted on the same individuals, and on average, the IQ scores were the same. Differences in scores that occurred for some students were simply attributed to him/her having an “off-day.”

What scientists are now increasingly interested in, however,  is the brain data for this group of inconsistent students. The MRI scans for these teens are showing that, as opposed to simply having varying levels of concentration during the two tests, they actually underwent significant changes in the density of grey matter in their brains. Grey matter is a major component of the brain, consisting of neuron cell bodies, glial cells, and capillaries. In the cases of these students, an increase in IQ score (sometimes up to 21 points) was accompanied by an increased density of grey matter in certain key areas of the brain, such as the left motor cortex.

If these results are confirmed by further experimentation, they could have a significant effect on our educational system. Proving that teenagers do, in fact, have a “malleable intellect,” would mean that judging kids based on one-time examinations such as the SAT may not be such a good way to determine their potential.

But don’t get too excited kids. If students’ intelligence can change over time, it is more likely that they would be encouraged to take more standardized tests, since they might perform better after allowing their brains to grow a little. In addition, although the exact causes of these spikes in IQ are unknown, it has been proven that certain mental exercises can cause a growth in grey matter. If grey matter density does parallel intelligence, we will se an increase in the emphasis on these activities in the training of young adults.

For these reasons, in the coming years we will likely see an increase in studies on this subject. If certain exercises or activities are proven to boost an individual’s intelligence, as many scientists are hypothesizing, this could revolutionize the way we that we train our children, both in school and at home.

Which activities do you think will be found to increase a person’s intellectual capacity?

For more information on this particular study, visit

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