Infectious disease? No Worries. Let's domesticate those germs!

Over the last few decades, when thinking of addressing harmful infectious diseases such as Cholera, we often turn to pharmaceutical drugs to solve the problem. However, in recent times, researchers have started to question the effectiveness of this method in combatting infectious diseases.  This is because while drugs can help our body combat and recover from diseases, they can be extremely costly to design and produce. Additionally, drugs can potentially facilitate the emergence of drug-resistant strains of infectious diseases, as my fellow contributor Nkemji Nweke points out in her blog post. In other words, our reliance upon drugs are in fact making these harmful infectious diseases hardier in the long run. This is fundamentally problematic!

In light of this issue, evolutionary biologist, Dr. Paul Ewald started to wonder: Instead of using drugs that can potentially make these bacteria more harmful over time, how can we use the theory of evolution via natural selection to make these harmful organisms more benign instead? In other words, how can we introduce a selection pressure that selects against the more toxic strains of the harmful organisms?

To answer his question, Dr. Ewald turned to investigating whether we can introduce a selection pressure against the more toxic strains of Vibrio Cholerae, which is the bacteria that causes Cholera. Cholera is an infection of the small intestines that often lead to diarrhea.

Cholera can spread via three ways.

1. Person to Person contact.
2. Person to Food to Person.
3. Transmitted through the infected water systems.

Change in Toxicity of V. cholerae in the three
Latin American Countries (Source: TED Talk)

The key difference between these three methods is that the third method does not require the infected individual to be mobile. Since mobility of the infected is not required to spread the disease, studies have found that bacteria strains that spread through water tend to be more toxic and harmful.

Based on this understanding, Dr. Ewald hypothesized that one way to introduce a selection pressure against the more toxic strains of Cholera is to remove the bacteria’s ability to spread via water. This can be done by introducing clean water ways where people would have access to not only clean water, but also stay protected from unsanitary sewage.  With the introduction of clean water systems, the only way in which Cholera can spread is through either method 1 or 2, where each requires the bacteria to be less toxic so the infected individual is able to remain mobile.

To test his hypothesis, Dr. Ewald looked at three countries in Latin America that were affected by the 1991 Cholera epidemic (Peru, Chile, and Ecuador). In this research, Dr. Ewald wanted to see if the standard of the water system in each of the countries influenced how the Cholera bacteria evolved. The results of his study yielded very interesting results. The bacteria strains in Chile, home to one of the most well protected water ways in Latin American, evolved to be much milder in a few years.  On the other hand, the bacteria strains in Ecuador, which has one of the least protected water ways, actually evolved to become much more toxic. Peru, being in the middle in terms of its water systems, saw no change in the bacteria’s toxicity.

In another similar study, Dr. Ewald once again compared the toxicity of the Cholera bacteria strains that were found in different places. Sure enough, the results were similar. The greater the proportion of the population having access to clean portable water regions, the less toxic the Cholera bacteria strains were.

Toxigenicity against Access of population to portable water (%) (Source: Ewald, P. et al. 1998)

All in all, the results from Dr. Ewald’s studies tell us one thing: we actually have the ability to “domesticate” harmful diseases by changing our living conditions so that the new conditions actually select against the more harmful strains of the infectious bacteria! This finding is not only highly fascinating, but also very important. This is because Dr. Ewald has demonstrated that sometimes using natural selection as a force to tackling infectious diseases might be a much better way than traditional drug research!

Perhaps it is time we start re-evaluating the ways we combat infectious diseases. Perhaps it is time we start “domesticating” germs.

By: Ben Ong (685 Words)

References

Ewald, P. 1994. Evolution of Infectious Diseases. Oxford University Press

Ewald, P. et al. 1998. Evolutionary Control of Infectious Disease: Prospects for Vectorborne and Waterborne Pathogens. Mem Inst Oswaldo Cruz, Rio de Janeiro. 93(5): 567-576

Ewald, P. 2002. Plague Time: The New Germ Theory of Disease. Knopf Doubleday Publishing Group.

Faruque, S. M., Albert, M. J. and Mekalanos, J. J. 1998. Epidemiology, Genetics, and Ecology of Toxigenic Vibio cholerae. Microbiol Mol Biol Rev. 62(4): 1301–1314. 

TED Talks: Paul Ewald asks, Can we domesticate germs? 2008. TED Conferences, LLC. http://www.ted.com/talks/paul_ewald_asks_can_we_domesticate_germs.html. Accessed 21 Feb 2013.

The Evolution of Tuskless Elephants due to Human Poaching and Genetic Drift

     Having a “favorite animal” seems to be a hallmark of youth, and most children are more-than-willing to extol the virtues of their chosen animal and explain why it is better than yours. My favorite animal was an elephant: The world’s largest terrestrial animal that is widely represented in popular culture, from children’s movies, such as Dumbo and Tarzan, to short stories, such as Elmer the Patchwork Elephant and Dr. Seuss’s Horton Hears a Who! However, recent studies have revealed that the elephant’s most prominent characteristic, its ivory tusks, may be a thing of the past, as human poaching and genetic drift have led to the prevalence of “tuskless” elephants in both Africa and Asia.
     In the nineteenth century, as the European colonization of Africa reached its zenith, the hunting of large game became incredibly popular, and animal trophies (ranging from elephant tusks to lion pelts) were proudly displayed in aristocratic homes. This hunting frenzy, when combined with extensive poaching, decimated animal populations across Africa. Elephant populations, specifically, experienced drastic declines, with some populations decreasing to as few as 8 individuals. As might be expected, tuskless elephants were highly represented in these remaining populations (due to their lack of ivory). Oddly enough, even as poaching was banned across Africa in the 1950s, the percentage of tuskless elephants continued to increase.
     Anna Whitehouse, a Professor of Terrestrial Ecology at the University of Port Elizabeth, South Africa, has spent years studying the elephant population in Addo Elephant National Park (South Africa), in which the prevalence of tuskless elephants has reached 98%. Poaching was banned in this area in 1954, and the number of elephants on the reserve has since increased from 11 to 324 individuals. The founding population (of 11 individuals) included 4 females and 1 male which were tuskless. As hunting was banned on the reserve, and no migration had since occurred, the prevalence of the tuskless allele could be due to environmental factors (e.g. finding food), sexual selection, or genetic drift. Upon discarding the first two possibilities (tusklessness does not provide advantages in terms of resources and actually decreases an organism’s sexual fitness), she attributed the fixation of the tuskless allele to genetic drift. It is purely by chance, she claims, that this allele has become dominant in the Addo elephant population (as well as in populations across Africa and Asia). The reason for the increasing tusklessness among African and Asian elephant populations, then, might be due to a combination of poaching and genetic drift: Poaching severely reduced elephant populations and resulted in an overrepresentation of tuskless individuals, and genetic drift led to the prevalence of the tuskless allele through chance (the alternative would be that genetic drift led to the loss of this allele).
     The concern with the prevalence of tuskless elephants is not that it will force us to change our childhood ideals of this animal, but that this characteristic seems to affect individual fitness: Elephants use their tusks to search for food and water, for self-defense against their few predators, and for sexual display among males. The dilemma is that individual elephants are capable of surviving without their tusks, but the overall population might not be adapted to do so. Without tusks, how will elephants search for water in droughts, establish social hierarchies, or defend themselves from lions and tigers? As with myriad other organisms, humans have irrevocably altered the course of elephant evolution, and the key question is if elephants will be able to adapt quickly enough to their native environments without the use of tusks? If elephant populations are unable to survive, it is depressing to contemplate that in a few centuries, Dumbo and Horton might be as fantastical to children as T-rexes and velociraptors are today. (623 words)

By: Lauren Lyssy

References

(BBC) British Broadcasting Corporation. 1998. World: Africa Elephants ‘ditch tusks’ to survive.

<http://news.bbc.co.uk/2/hi/africa/180301.stm.>

 

Whitehouse, A.M. 2002. Tusklessness in the elephant population of the Addo Elephant National      Park, South Africa. J. Zool. 257: 249-254.

Steenkamp, G., S.M. Ferreira, and M.N. Bester. 2007. Tusklessness and tusk fractures in free-ranging African savanna elephants (Loxodonta Africana). J. S. Afr. Vet. Assoc. 78: 75-80. 

Image Source 

Girish, Chandra. Evolution of Elephant. 2006. IASZoology.com. Web. 22 Feb 2013.

Glowing Puppies?!

We all love puppies and having them as man's best friend, but scientists have taken it too far in engineering a beagle that glows. Under UV light, the little pup glows green! The scientists inject an embryo with a virus that has the fluorescent glow, and then use a surrogate dog mom. They use dogs becasue of their close gene make up in this allele to humans, and are hoping to soon be able to track all sorts of diseases, such as Alzheimers or Parkinson's, with this same method of transporting the gene. Which then starts the quesiton of animal testing and animal cruelty since the dog is used to track the progression of Alzheimer's. But when Tegon, the glowing dog, does glow, she experiences no harm.
This isn't the first we've heard of glowing animals; scientist in South Korea made glowing cats for the same purpose of genetically engineering animals to further research human disorders. They injected virus into the skin cells of the a cat. They then put that nucleaus into an egg and used a surrogate just like the beagle to foster the glowing cat. The whole point of cloning these animals to make them emit this light is, "... that if you can pass along the easy-to-recognize coding for fluorescent markers through cloning, you could eventually pass along more complex genetic coding.

Scientists have now been experimenting with dogs becasue of their closer gene make up in this allele to humans. I think this is a strange concept that, though the cats and dogs look pretty awesome, in truth it will take way much more to track Alzheimer's than a meer fluourescent virus. We have been engineering different types of animals, and exploring cloning for years now, and each step is in the direction of helping human's with diseases, but it seems like the science only gets cooler for readers and enthusiasts or just plain weird. The actual discoveries of genetically engineered animals haven't crossed over into the realm of human intellectual growth yet. Who knows, in the future maybe a glowing horse will help us find the cure for cancer. word count (355)

Carly Biedul

"Cloned Cats That Glow?!" Cosmic Log. NBC, 13 Dec. 2007. Web. 

Edelman, Robert, and Phyllis M. Hartroft. "Localization of Renin in Juxtaglomerular Cells of Rabbit and Dog Through the Use of the Fluorescent-Antibody Technique." American Heart Association: Circulation Research (2013): n. pag. Web. 

Viegas, Jennifer. "Genetically Modified Beagle." Beta News. Discovery Channel, 1 Aug. 2011. Web. 

Humans on Viruses: Affecting Evolution Since the First Vaccination

Every year doctors and researchers tell us to remain vigilant on vaccinating ourselves and those around us. They always seem to be reminding us that the vaccine that we may have received last year may not be as effective for us this year, and that newer, more up-to-date version of the vaccines. Many wonder...why is it that our immune systems coupled with the power of such advanced vaccines are not enough to fight off a seemingly harmless microscopic organism? Why does it feel like viruses are constantly one step ahead of whatever vaccine that we have prepared for them? The answer is evolution. It affects all organisms around us, biotic or abiotic, on both the macroscopic and microscopic level, and just because we cannot see the change happening right before our eyes, does not mean that it isn't there.

One of the most famous examples of viral evolution is the Influenza A (H1N1) virus, better known as the "Swine Flu." Michael Deem, a bioengineer here at Rice University attributes the swine flu's ability to jump from pigs to human solely on evolution from both humans and the virus. Scientists explain that the reason that the viruses are able to evolve and "attack" other species so quickly comes from the fact that they have multiple strands of RNA that can mix and swap to create many different combinations leaving room for many types of the flu virus with different strengths and weaknesses and leaving much room for mutations. Human bodies are usually very vigilant about building some sort of resistance to most viruses throughout generations. However, viruses are also very vigilant on adapting and even sometimes accidentally mutating in order to increase their chance of fitness and survival throughout their generations. Peter Dasak of the wildlife trust also states that the ability of the virus to spread and replicate so quickly comes from their ability to take advantage of human contact.

Another example of a continuously evolving virus is the human flu virus. The vaccine for this virus is constantly changing because the rate at which the virus reproduces is incredibly fast. With so many chances for the virus to reproduce, it makes it gives the viruses more chances to create more diverse offspring and more chances for the offspring to contain mutations that have a resistance against the vaccines and our own natural immune systems. As the human body continues to adapt and grow resistance to certain strains of the human flu, the human influenza virus is also finding its own ways to survive. It almost seems as though the influenza virus is evolving along side with the human immune system, which is why it seems as though humans are having a huge impact on the way the viruses evolve.

The biggest contributors to viral evolution are the vaccines themselves. Researchers have come up with what seems like a vaccine for every virus that they know will infect human bodies. Vaccines work by injected a small amount of a seemingly harmless strain of whatever virus researchers feel will be the most prevalent that season against humans that way the human immune system can begin to secrete the antibodies necessary to combat the virus when you come in actual contact with it. However, because of the high rate of replication and mutation in viruses, usually by the next year, viruses have found a way to combat the vaccine for the strain in the previous year, or have an entirely new strain altogether. With that being said, it seems as though the vaccinations we receive have the biggest affect on viral evolution to date.

Although it may not seem so, every action we take might be another step towards building our immune system to help combat another strain of virus, which in turn causes the virus itself to evolve as well. There is no “solution” to viral evolution, because to stop viral evolution would most likely mean the stop viral reproduction completely. Whether it be the glass of orange juice you drank to help bolster your immune system a little, or the vaccination that you receive at the doctor’s office to help you immune system a lot, humans have been a direct source of evolution for many viruses and will continue to evolve alongside these viruses for many more years to come.

word count: 721

References:

Britt, Robert R. "Swine Flu Is Evolution in Action." LiveScience.com. Live Science, 28 Apr. 2009. Web. Feb. 2013.

MacLachlan, Allison. "Everyday Evolution Revealed in Flu Shots." LiveScience.com. Live Science, 06 Oct. 2011. Web. Feb. 2013. <http://www.livescience.com/16433-everyday-evolution-flu-shots.html>.
 
Zimmer, Carl. "10 Genes, Furiously Evolving." The New York Times. The New York Times, 4 May 2009. Web. Feb. 2012. <http://www.nytimes.com/2009/05/05/health/05virus.html?pagewanted=all>.

Image from: Bioquell

Human Selection - Domestication and Flowers

Domesticate, as defined by the Merriam-Webster dictionary, is to adapt (an animal or plant) to life in intimate association with and to the advantage of humans. From our evolution course we know that adaption means a characteristic that increases the Darwinian fitness of an individual compared to individuals without the trait. (We recall that Darwinian fitness is the ability of an individual to survive and reproduce in its environment.) Thus, domestication is the change in an organism to make it better suited to life with humans.

Moving away from definitions, if you take a look around you, you will see myriad domestic organisms. For example, your pet dog or cat or rabbit are domesticated animals. The houseplants that you forget to water are domesticated. The daffodils and tulips planted in your mother’s garden, the magnolia tree that stands by the backdoor, and the aromatic lavender patch along the pathway are all domesticated plants known as ornamentals. According to Gessert’s paper, “Flowers of Human Presence: Effects of Aesthetic Values on the Evolution of Ornamental Plants,” certain plants were domesticated based on the selection for aesthetics. These included characteristics such as color, pattern, size, form, and texture (and aroma, which ties into a plants aesthetic value). Humans chose these traits not for the "good" of the plant but because they appear visually (and olfactory) stimulating. 

Examples of informal doublets

The selection for visual aspects of flowers has caused convergent evolution.

 Species in the Tea, Ranunculus, Nightshade, Rose, and Poppy Families all exhibit informal doublets – many petals of varying sizes and shapes. Species in each of these families were selected for the similar flower trait. Thus, these flowers resemble each other due to convergent evolution of the selected upon trait.

Does knowing the aesthetically pleasing flowers in your garden are the product of human selection make you view them any differently? I would view them with a new appreciation for what natural genetic diversity and human selection can accomplish. However, due to the prescribed nature of care some of these domesticated varieties demand, it makes me wonder if we’ve upset the natural balance. Would these varieties ever exist in nature without the help of humans’ heavy hands? And does this matter? Are we becoming so focused on the exterior beauty that we forget functionality? These are questions for future blog posts. (365 words)

Marion Donald

Reference

Gessert, George. (1993) Flowers of Human Presence: Effects of Esthetic Values on the Evolution of Ornamental Plants, Leonardo 26.1 (37-44). 

Image from George Gesset, 1993  

Evolution on Cattle

Whenever you see a hamburger or a glass of milk do you sometimes  stop to think about how they came about?  We know that these came from cows but what was the process pertaining to it and how did evolution shift for the cows of our time?

 

Cattle have been domesticated since the early Neolithic.  The entire species may have originated from 80 aurochs tamed in Mesopotamia 10,500 years ago in Turkey and Iraq (Wilkins).  Cows are very efficient in that they are very easy to breed because they can survive on such few things like water and grass and still produce copious amounts of milk and efficiently build muscles.  Their anatomy – especially the usage of  the rumen, and the efficiency of selective breeding, are partly the reason why genetically modified cattle are so popular today.    

Early cattle served a triple-purpose. They provided meat, milk and labor to their owners. Eventually their purposes were changed and they were selected more for single or in some cases dual purposes. Today, cows are genetically modified to produce more muscles. These cows generally have shorter legs and a stumpier look.  Humans have exaggerated genetics to get desired traits and there are currently over 800 different modified cattle.  The dairy cattle qualities are focused on the size of the udders and the skin, while the cattle used for meat focuses on the sheer size of the animal. The English longhorn is an example of a cow that is bred purely for beef.  In America, the most popular meat that we use is from the Aberdeen Angus. 

Scientists continue to  selectively  breed cattle to fit human needs.  Research has shown that some genetically modified cows can produce milk that is hypoallergenic.  This would be beneficial to individuals who are lactose intolerant, especially infants.  However, this alters the cattle genome and isn’t beneficial to the cattle.  For example, over the last hundred years milk yield in dairy cattle increased from 2000kg to nearly 8000kg per annum (Gamborg).  Some disadvantages for the cattle are that this excessive breeding for high milk yields creates animal health problems like digestive disorders and reduced fertility (Gamborg).  Another disadvantage is the lack of variety among selective breeding. The differences in genome for ancient cows verses the genome now is extremely minute whereas if it wasn’t for the domestication there would have been more variety. (Wilkins).

I do sympathize with the animals.  Due to human involvement in cattle, they have not evolved naturally in the way that most organisms have.  Yes, they are beneficial to us but at what cost?  Some notable costs are the loss of variety among cattle and the struggle for these animals to become fully adapted to a natural environment without human interference.

 
word count: 455 words

Works Cited

Gamborg, C. and Sandoe, P.  “Breeding and biotechnology in farm animals-ethical issues” RoutledgeFalmer. http://www.dyreetik.dk/English/Production_Animals/~/media/Dyreetik/AnimalEthics/Docs/BreedingAndBiotehcnology.ashx

 

Wilkins, Alasdair. “DNA reveals that cows were almost impossible to domesticate”  http://io9.com/5897169/dna-reveals-that-cows-were-almost-impossible-to-domesticate 28 March 2012.

Human Effects on Evolution: Focus on Fitness

Word Count: 699

The observation of evolution has different theories that explain possible operating mechanisms. While many of these theories are heavily supported, they more likely work in conjunction instead of being solely and independently correct. One of the main theories, natural selection, was popularized by Darwin's publication of "On the Origin of Species."

Natural selection is based on four basic principles, which can be paraphrased as follows:

1. The individuals of a population differ from one another in physical traits.

2. These variations can be passed on from generation to generation.

3. These individuals will compete for resources, but specific physical traits better suit an organism to surviving in the specific environment. The organisms who are more likely to survive are more likely to reproduce.

4. Therefore, survival and reproduction are not random. The individuals who are better adapted to their environment are more likely to survive and reproduce.

These can be further simplified to the following:

1. Variation among individuals of a population

2. Variations are inheritable

3. Fitness and adaptation lead to reproduction

4. Natural selection

Darwin himself recognized that variation under domestication was different than variation in the wild. Humans add another variable to evolution by acting as selectors. Fitness is no longer a concrete term because under human care, there is not a true struggle for limited resources. Therefore, genetic drift has become the main mechanism of evolution, right?

Wrong. Humans still decide which organisms to breed. They decide which ones reproduce and form the next generation. As a result, deleterious alleles may and often increase in frequency, considerably compromising the species. In their paper "Captive breeding and the genetic fitness of natural populations," Lynch and O'Hely state that these deleterious alleles can increase in frequency until fixation, resulting in extinction of the populations. Indeed, the risk runs high. If an endangered tiger is pampered in an artificial habitat for its entire life, it will forget how to live in the wild. If its offspring are raised in the same condition, there will be no learned skills passed on from parent to offspring that will be practical in the wild. Eventually, when the population is returned to nature, they will not know how to live in this natural environment.

From a genetic standpoint, suppose that a mutation that would be normally deleterious in nature (such as bones that are too brittle for pouncing on prey) is obtained. Because conservation efforts will seek to preserve all organisms, this allele may propagate through future generations and cripple the population when returned to nature. This, combined with the lack of natural experience and instinct, can result in extinction. The organisms simply are not fit and well-adapted to natural habitats.

Another example is that of the modern chicken. The majority of chickens are bred to grow to large sizes and lay many eggs. This provides the most food for humans. However, many news sources have reported that these chickens are too fat to even walk! The same situation plagues our traditional turkeys, which are simply not traditional anymore. These animals would not survive in the wild.

What then, is the impact of humans on evolution? We have skewed the process, altering fitness to fit our personal preferences. Ultimately, fitness is now a vague term with little meaning when we consider the portion of our own species that is obese and prone to premature death. However, if the human race should go extinct, biodiversity may disappear even more from the face of the earth before ecosystems restore themselves over extended periods of time. The profound effect that humans have had on nature is not ignorable. We need to consider our artificial habitats and breeding habits before we become malevolent "deities" to the creatures helpless to our influence. As insignificant as we may seem in the grand scheme of things, we have managed to veer a natural process off-track.

Does evolution run its course the same way it always has? Should we change our current breeding processes? What can we do to prevent future disaster? Are our present decisions moral, or are they immoral despite having good intentions? Consider that human-accelerated climate change is also affecting the "fitness" of natural organisms and ecosystems.

References

Darwin, Charles Robert. The Origin of Species. Vol. XI. The Harvard Classics. New York: P.F. Collier & Son, 1909–14; Bartleby.com, 2001.www.bartleby.com/11/. 

Lynch, Michael and O'Hely, Martin (2001) "Captive breeding and the genetic fitness of natural populations." Conservation Genetics. Kluwer Academic Publishers, the Netherlands.

Reuters. "Battery Farm Chickens Too Fat, Too Tired to Walk: Study." ABC News. ABC News, 7 Feb. 2008. Web. 16 Feb. 2013. <http://www.abc.net.au/news/2008-02-07/battery-farm-chickens-too-fat-too-tired-to-walk/1035272>

By Anthony Nguyen