How Hurricanes Impact Natural Selection

Many of us are familiar with hurricanes and the disaster they cause. This last season brought some of the worst storms ever seen, and the trend indicates more will be coming.

Not only should we be concerned with the devastation this will have on the human population, but we must turn our attention to other species as well.

So when you see this video, don’t be so surprised.

Yes, that’s right. For the sole purpose of science, researchers put lizards on a leaf blower and tried to kick them off. Turns out they are pretty good at riding along.

But, why would scientists torture innocent lizards?

Well, they really didn’t. As it seems, lizards are remarkably talented at staying put when necessary, even during high force wind events, such as a hurricane. Scientists had an incredibly hard time knocking the lizards off (and if they did fall off, there was padding in place to keep them safe).

Biologist Colin Donihue, after recently visiting small islands in the Caribbean and studying the anole lizard, was given a remarkable opportunity.

Not long after his team’s departure, two hurricanes hit the islands, both with wind speeds clocked above 200 kilometers per hour.

The team returned as soon as the coast was clear, and examined the lizards present immediately after the devastating storms.

What they found was interesting. After a quick examination, it was noted that the lizards most present after the storm had larger toepads, longer forelimbs, and shorter hind limbs than what was measured before the storm.

This gave the team from Harvard an idea. Could they replicate a hurricane like experience under a controlled setting and actually show if these traits are favorable? Since I have already shown you the video…. the answer is yes, they could.

Image result for toe pads of lizards
An example of a toepad belonging to a lizard (gecko in this case). Source

It is thought that these traits allow lizards who live in such a climate to latch onto branches in small bushes and hold on for dear life until the storm has passed.

What makes this particular study so unique, is the chance to study a population before a large event, and immediately after. The scientists were able to directly measure the difference between the species and discover what sort of traits enhanced survival. This allows a direct measurement of natural selection, the idea of how evolution works.

While there many other possibilities besides a hurricane that could drive a lizard to have larger toepads or shorter hind limbs, the natural selection process is still present.

More importantly, this small study could provide a glance into how climate change affects species. With the heating of the oceans due to astronomically high temperatures, weather patterns change dramatically. This includes the frequency of large scale storms such as hurricanes.

With hurricanes becoming more common in the tropical areas, such as the Caribbean, this forces animals such as the anol lizard to either adapt or suffer. While it seems this remarkable lizard has developed a method to out ride the storms, and probably give them a severe advantage at rodeos if given the chance, much yet is to be discovered as to how well species adapt with the increasing temperatures, ocean acidification, and frequency of severe weather patterns.

 

Thank you for reading this fun, quick blog!

If you have any questions, comments, concerns, or suggestions, please email us directly or post a comment below. You can also reach out to us on Facebook and Twitter.

And as always, be curious and stay mindful!

 

Sources:

  1. https://www.nature.com/articles/s41586-018-0352-3
  2. https://www.nature.com/articles/d41586-018-05821-7
  3. https://www.nature.com/articles/d41586-018-05822-6 (original video source)
  4. Featured Image- https://www.youtube.com/watch?v=Dx3xgSBjbzk

 

 

 

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The Truth About Telomeres

For centuries, one of the biggest mysteries of the human race as been aging. Through science and medicine, we have been able to increase the quality and longevity of life, but at some point we all reach an age where our body stops working and we die.

A few decades ago, scientists came across a structure within cells that appears to contribute to aging, called telomeres. Today, I want to spend time discussing what they are and the pseudo-scientific claims associated with them.

The Discovery of Telomeres:

I find the discovery of telomeres a remarkable achievement of women in science, and I want to spend a few moments discussing the brilliant scientists responsible.

In 1933, Barbara McClintock, and American biologist focusing on chromosomes and their role in the life of the cell, discovered that when the very tips of chromosomes were missing, they became “sticky” and formed with other parts of the chromosome. This phenomenon is called ring chromosomes From this work she hypothesized that there must be a structure responsible for protecting the ends of chromosomes and named them telomeres. These telomere structures would be non-coding regions of DNA that if lost, would not directly harm the cell.

Barbara McClintock (1902-1992) shown in her laboratory in 1947.jpg
Barbara McClintock in her laboratory. Source

Barbara McClintock later became a well renowned biologist, contributing to the understand of meiosis (division of cells producing the two sex cells, sperm and eggs), mitosis (normal cellular division) and other cellular processes. She eventually went on to earn the Nobel Prize in Physiology or Medicine in 1983 for discovering transposable elements, segments of DNA that jump from one chromosome to another. She remains to this day the only woman to receive this award unshared.

Fast forwarding to the 1970’s a man named Alexey Olovnikov learned through experimentation that DNA replication, a process necessary before a cell splits into two,  occurs with an error.  After each division, the telomeres cannot be fully replicated, and a small segment of telomere DNA is lost. Dr. Olovnikov further suggested that after a certain amount of cell divisions, the telomeres are lost and the cell dies. 

After discovering this phenomenon, Olovnikov predicted that there should exist an enzyme responsible for correcting this mistake and re-lengthening the telomeres. He dubbed it telomerase.

Sure enough, a few years later, Elizabeth Blackburn discovered telomerase and showed it did indeed restore the length of telomeres. From this work, Blackburn received her Nobel Prize in 2009, along with Carol W. Greider and Jack W. Szostak.

Elizabeth Blackburn CHF Heritage Day 2012 Rush 001.JPG
Elizabeth Blackburn. Source

With all of this research compiled together, it shows that shortening of telomeres is at least in part contributing to the aging process

How Telomeres and Telomerase Work:

The structure of telomeres is relatively unique, but simplistic in its own way. Telomeric DNA, at the very ends of chromosomes, consist of long sections of repeating nucleotide sequences. Remember, the four “letters” of DNA are A,T,C,G. In species, telomeric DNA all have repetitive sequences, but they differ slightly depending on the organism.

Most vertebrates (including humans) for example have the sequence TTAGGG. Some plants have TTTTTTAGGG.And yeast have TCTGGGTG.But all are relatively similar to each other and are repetitive.

In addition to DNA, there are also proteins involved in creating the structure of the telomere. Certain proteins bind to the telomere section of the chromosome, and provide structural support, and even wrap the DNA like a knot on the end of the rope. This complex structure thus prevents any damage that could occur from the cell (think of the aglets on the end of your shoelaces).

However, as previously mentioned, during DNA replication a small portion of telomeric DNA is lost. Once the telomeres are gone, important genomic DNA is damaged and the cell recognizes it’s time to die.

But that is not always the truth. In certain cells, telomerase is expressed to re-lengthen telomeric DNA.

A rough schematic on the structure of telomeres. Source

Telomerase is a special type of enzyme that is made up of protein and RNA. The RNA included into the protein section will recognize the repetitive sequence, and the enzyme can then replace the missing sequences left during DNA replication.

After the discovery of telomerase, many people were interested in discovering how to use telomerase as a molecular fountain of youth. However, it was quickly realized to be quite dangerous.

Normal adult cells have low expression of the telomerase enzyme, providing a natural end point when the cell must die. Cancer cells however, need to grow without being hindered by the natural fuse telomeres provide. Therefore, they express telomerase in abundance. It is reported that 85-90% of cancers have overexpression of telomerase. This suggests that having telomerase active and available for cells may give them a predisposition to cancer, which of course would not be favorable.

A 3-D structure of the telomerase enzyme. The outer helices represent protein, while the inner wire represents RNA. Source

Much work has been done to develop a method of lengthening telomeres including drugs, and genetic modification, with little success. Therefore, scientists have been trying to understand how environment and other events can shorten telomeres, and thus shorten our lifespan.

The Not-So Scientific Claims of Lengthening Telomeres:

For the past few years, there has been much work done trying to understand if shortening of telomeres is caused not only by regular aging, but also by stress or other life events. And so far, the data has been inconclusive.

Part of the problem is finding trends involving telomeres. There is a wide diversity of telomere length among human individuals, which it makes it difficult to study.

In turn, modelling stress is challenging, and very little work has been done to suggest telomere length is actually affected by stress. The only meta-analysis provided on stress-induced telomere shortening showed a very small decrease in telomere length with higher stress. However, there are so few studies, there appears to be publication bias. Once the bias is corrected, the trend dissapears.

This however, has not stopped the pseudo-scientific community for jumping on the bandwagon.

Hundreds of articles and pseudo-scientific experts claim that decreasing stress, changing diet, meditation, exercising, vitamins and antioxidants, herbal supplements, essential oils, and many other things can lengthen your telomeres and give you longer life.

Even Elizabeth Blackburn, the woman who discovered the enzyme telomerase, claims in her book The Telomere Effect: A Revolutionary Approach to Living Younger, Healthier, Longer that changing your lifestyle has a profound effect on lengthening telomeres and promoting longer life.

“One study has found that people who tend to focus their minds more on what they are currently doing have longer telomeres than people whose minds tend to wander more. Other studies find that taking a class that offers training in mindfulness or meditation is linked to improved telomere maintenance.”

–Elizabeth Blackburn, The Telomere Effect: A Revolutionary Approach to Living Younger, Healthier, Longer

Unfortunately, there is no evidence to support these claims.

In fact, while it seems that telomeres do in fact play a role in the aging process, we have no idea how large of a role it plays. Even if we can lengthen our telomeres back to normal levels, would it make a huge difference? Probably not as big as we think. Would there be another factor that contributes to aging once we solve the telomere problem? I/ guessing yes.

The truth is, aging is a complicated process and likely is a result of multiple factors. Telomeres do seem to be one of those factors, but only lengthening telomeres may not be enough to significantly lengthen your lifespan.

Takeaways:

The science of telomeres is a beautifully example of science and pseudo-science. Hard work and many years have discovered a novel section of chromosomes, and has given us a deeper understanding of how cellular death occurs. Pseudo-science has then taken up the information, and twisted it to sell snake oil. So the next time someone tries to tell you about this magical product that lengthens telomeres and prevents aging, be sure to set them straight.

With that said however, I look forward to the discovering more about telomeres and their contribution to aging. It’s always nice to discover one piece of the puzzle, no matter how big or small it is. I suspect in the next few years, an update will be added to this post,  it just won’t be on how to lengthen telomeres with yoga or diet.

 

Thanks for reading!

If you have questions, comments, concerns, or suggestions please do not hesitate to leave a comment or contact us via email at copernicuscalledblog@gmail.com.

You can also reach us on Facebook and Twitter.

And as always, remember to stay curious, and be mindful!

 

Written by Cody Wolf

 

Featured Image Source: https://med.stanford.edu/news/all-news/2015/01/telomere-extension-turns-back-aging-clock-in-cultured-cells.html