Tag Archives: science

Eevee Epigenetics – A Tale of Phenotypic Plasticity

The term Eeveelution bugs me. Scratch that. The term Eeveelution makes my blood boil, the very utterance of its syllables causes every brain cell in my body to go into apoptosis. I already have issues with the fact that the in-game process known as Pokémon “evolution” is nothing of the sorts and is actually closer to metamorphosis in most cases. But this word that the Pokémon fandom has adopted for Eevee is even more misleading.

Eevee does not evolve.

In fact Eevee hardly changes at all.

At a very fundamental level, your dear Vaporeon is still an Eevee, granted, with some obvious differences. But these additions to your Pokémon’s physiology are not due to evolution, but to the power of phenotypic plasticity.

All life (as we know it) speaks the same language, the complex yet elegantly simple language of deoxyribonucleic acid, know more commonly as DNA. Its alphabet is composed of only four letters – adenine, guanine, cytosine, and thymine. Together these four nitrogenous bases order themselves in countless sequences to form the instructions for life. First, DNA is transcribed into messenger ribonucleic acid (mRNA). From there, the mRNA is delivered to a sort of protein factory called a ribosome where – to greatly oversimplify things – the mRNA is used to code for various proteins which are what do the real magic. Thus is the way life continues – from DNA to RNA to protein, the Central Dogma of Biology.

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The Central Dogma of Biology

 

However, in some organisms there lay regions of “silent” DNA that are highly methylated, or in other words, are wound up too tightly to be transcribed, and thus remain quiet and unused. But, there are ways for this silent DNA, or heterochromatin, to unravel and be transcribed.

Without altering any of the nucleotides, an organism’s phenotype can change dramatically through epigenetics, the external modification of DNA. Once that silent heterochromatin is demethylated, the DNA can transcribed and the central dogma can continue, the resulting proteins being expressed as a new phenotype.

A great example can be found in bees. All bees essentially are born with the same genotype, with the vast majority destined to become workers as long as no external forces act on them. But a select few during the larval stage are fed a special food called royal jelly, which demethylates the silenced DNA in the bee larvae and allows transcription of the once silent region to begin. This particular gene sequence happens to be especially important, for it allows for the development of ovaries in place of the normal pollen sacs that a worker would grow. The larvae raised on royal jelly unsurprisingly grow to become fertile queens and allow for the continuation of the species.

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Honey and beeswax are not the only bee products that humans can use, royal jelly actually has nutritional benefits as well.

 

A similar phenomenon appears to occur in Eevee. Regions of Eevee’s genome remain silent until otherwise activated upon the right external stimuli. For the Generation I species, the phenotype is dependent on exposure to a specific elemental stone – Water Stone yields a Vaporeon phenotype, Fire Stone Flareon, and Thunder Stone Jolteon. In Generation II such epigenetic change is dependent on two factors, friendship and the time of the day. Night gives you an Eevee with an Umbreon phenotype, and day produces an Espeon one. Leafeon and Glaceon work similarly to Gen I, with exposure to a specific rock being the determining factor. And lastly Sylveon, who requires great affection to achieve its phenotype, an act similar to how rat mothers lick their pups in order to activate the genes that boost their immune system.

At the end of the day, it’s still an Eevee, despite what those other fallacious Pokémon “professors” claim, rather, each variation of Eevee is simply displaying a different phenotype triggered by the demethylation and subsequent transcription of once silent regions of DNA. After all, the PokéDex constantly repeats how irregular and plastic Eevee’s genes are. Perhaps those irregularities are due to all the regions of silent heterochromatin lying hidden in Eevee’s genome.

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Who is your favorite Eeveelution Eevee phenotype? As a swimmer, mine is Vaporeon. Post yours below!

Exeggutor: A True Freak of Nature

The Pokémon World and our own world are similar in that the natural processes that govern life produce some strange creatures. Perhaps one of the most odd (and unsettling) is Exeggutor, the dual Grass Psychic-type that wanders around with its three grinning coconut heads resembling some unholy hybrid between a palm tree and several stoners. Yet our anthropomorphic palm tree friend is quite the interesting specimen when put under the lens of real-world biology.

 

A Free-Thinker of Many Heads

The most obvious abnormality of Exeggutor at first glance are its three heads, each with their own distinct and unsettling facial expression. According to the PokéDex entry in Pokémon Gold Version, “Its three heads think independently. However, they are friendly and never appear to squabble.”

This leads to quite the impressive nervous system, especially for a plant. But quips about plants not having any neurons aside, it is not unfounded in nature for animals to have multiple “brains” per say. For instance, octopi have nine brains, the main brain being located in its head with eight auxiliary brains in each of its eight tentacles. When an octopus desires to operate one of its arms, the main brain sends a single message to the nerves located in its arms, and then the arm “brain” proceeds to carry out the order all on its own. Even when severed, an octopus arm will still respond and react to stimuli the same way it would if it were attached to the complete organism and main brain1.

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Due to the complexity of their nervous systems, many people have a moral objection to the consumption of cephalopods.

 

However, unlike Exeggutor, the auxiliary brains of an octopus do not have their own consciousness. A severed octopi arm does not a new octopus make.

A particularly fascinating condition is that of polycephaly. A polycephalic organism is born with two or more heads, either as a supernumerary body part or as completely separate beings sharing a body, as the case is with Exeggutor. Usually the result of faulty twinning, polycephaly never results in more than three heads (tricephalic), with two being the norm (dicephalic). Unfortunately, in both humans and animals, dicephalic organisms rarely survive, as the two heads will often fight with each other for control over the body, often becoming disoriented, which makes for difficulty in fleeing predators. Polycephalic snakes have been known to even attack and consume their other head. Thankfully, Exeggutor appears to be a peaceful organism and its heads are very cooperative, as “they never appear to squabble”.

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Those that handler polycephalic organisms often report having to place a barrier between heads in order to prevent one from eating the other during a feeding.

As deleterious as this condition may be in our world, the trait seems to be of advantage in the Pokémon World. In the Crystal Version PokéDex, “Living in a good environment makes it grow lots of heads.” Apparently the selection pressures of the Exeggutor’s ecosystem make it so that having multiple heads is an advantage, running completely counter to our world which usually follows a general rule of the more appendages an organism has to manage the more energy required to maintain them all. In the game of evolution it’s all about the costs and rewards, having an extra head or two is just too taxing and hardly reaps any benefits.

While selection of polycephalic individuals may seem paradoxical at first, there is good reason for the Coconut Pokémon to expend energy growing its extra heads, and the answer lies with the endgame of survival, arguably the purpose of life – reproduction.

 

Dropping Heads: Clonal Fragmentation

Counter to what is portrayed in the videogames, Exeggutor does not need another Exeggutor (or any Pokémon of its egg group) to reproduce. In its natural environment, when not forcibly bred by overanxious trainers eager to create an IV master race, Exeggutor can reproduce asexually simply by parting with one of its heads.

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“If a head grows too big, it falls off and becomes an Exeggcute.” – Diamond/Pearl/Platinum PokeDex

More specifically, Exeggutor appears to reproduce through clonal fragmentation, a form of asexual reproduction most common in flatworms, sponges, annelids, sea stars, as well as mold, lichens, types of cyanobacteria, and many plants.

The process of fragmentation involves a piece of the organism splitting off to regenerate into a complete organism that is also able to reproduce. For example, tapeworms live in the digestive tracks of mammals, usually dogs and sometimes humans (either intentionally or, depending on the type of person, on purpose). As you can imagine finding a mate in the middle of a dog’s small intestine can prove troublesome, but all a tapeworm has to do is release an end segment of its own body down the track, and with some time Rover will have an infestation of new tapeworms, grown from the end bits of the original pioneer that first ventured into his bowels.

D. caninum ex dog.  Given by Peter Schantz

If you find one of these segments in your pet’s feces (or your own), seek medical attention.

As is common in binary fission, this often results in the regenerated fragment being genetically identical to that parent, making all Exeggutors clones of each other, the regenerated offspring of past Exeggutors whose heads grew too large to support. However, this process, as is the case with most forms of asexual reproduction, does have one major drawback, in that since all organisms are effectively clones of each other, there is no variation, and as any good biologist (or PokéBiologist) knows, genetic variation is the driving force of natural selection and therefore evolution. But this shouldn’t be a problem for Exeggutor, they seem to be plentiful enough, and pending an Exeggutor superbug, they will continue to endure for many generations to come.

Of course, there is the unique caveat that with Exeggutor, a single fallen head does not a new Exeggutor make, rather the individual Exeggcute have to swarm together, usually in groups of six in order to eventually “evolve” into an Exeggcute. Communicating telepathically, these eggs seem to form somewhat of a superorganism…but that is a topic for another day.

 

Cited Sources

http://news.nationalgeographic.com/news/2001/09/0907_octoarm.html

Kangaskhan – Parental Bond and Parthenogenesis

Ever since its introduction in the Second Generation, the concept of Pokémon breeding, while greatly appreciated, has spawned a plethora of questions, including, but by no means limited to – how can completely different species successfully copulate? How can they produce fertile offspring that are functional and not riddled with genetic malfunctions? Why is a tiny little cat able to have sex with literally the largest Pokémon known to us thus far? Perhaps one of the largest contributors to this pool of questions is Kangaskhan, a species that is 100% female and is born already equipped with a baby in pouch.

There is much to be said about the Parental Pokémon, aptly named since it literally enters the world a mother. It comes as no surprise that its design is inspired by the kangaroo, yet there is so much more to learn from her. Indeed, Kangaskhan is more than a magical marsupial, she is a shining example of the remarkable process that we in our world know as parthenogenesis.

 

A World Without Men

Time to have a talk. The Talk to be precise.

Excuse me if my heteronormative bias shows here but typically speaking, a man will encounter a woman and either through coercion or brute force insert his penis into her vagina and deposit his half of the reproductive materials via ejaculation. His materials, commonly known as sperm, enter the vagina, with a few lucky individuals making it past the cervix to – if this woman he has taken is ovulating – join with a nice plump egg waiting to be fertilized. The first sperm to penetrate its outer membrane wins the prize of fusing with the ovum to form a zygote and nine months later a baby is born.

We call this process sexual reproduction and it requires the existence of two sexes at minimum (though there can be more in some cases) since its main selling point is the promotion of diversity. Like a college admissions department, diversity is the name of the game when it comes to genes. More variation means more unique individuals with traits that may or may not prove advantageous in life. However, sexual reproduction is not the only way to make a baby.

If diversity is not really your interest and you’re just looking to pass on your legacy without the energy and drama that comes with sex, asexual reproduction may just be what you’re looking for.

In asexual reproduction, no new genetic material is added. The next generation is genetically identical to that before it with no variations other than the random mutations that still occur during DNA replication. Naturally, this leads to severe lack of diversity with very few, if any, differences between individuals, but has the benefit of not needing to expend energy in courtship and actual mating. Additionally, asexual reproduction only requires one sex.

There are many forms of asexual reproduction – budding, binary fission, clonal fragmentation. But perhaps the most interesting form is parthenogenesis, essentially virgin birth. Offspring of parthenogenic organism develop from unfertilized eggs. Most organism that use parthenogenesis do have two sexes, as well as the ability to reproduce sexually, and often fall back to it when conditions become adverse and the diversity is needed1. However, there are some species, such as Kangaskhan, that have abandoned the entire male line in favor of an all-female feminist utopia.

Take for example Aspidoscelis uniparens, the whiptail lizard, a species that contains no genetic males and reproduces completely through parthenogenesis. Oddly enough however, the females of this species do engage in mating rituals similar to that if they were reproducing sexually which enhances ovulation. Furthermore, despite being asexual, whiptails have managed to find a way to preserve some degree of genetic diversity through combining sister chromosomes instead of homologous chromosomes2.

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A conservative’s worst nightmare — a society of promiscuous female lesbians with no male supervision.

 

It appears that Kangaskhan has taken a similar evolutionary path to the whiptail lizard. Being a male-free species can have its benefits especially for a creature as devoted to its young as Kangaskhan. The PokéDex entry in Emerald appropriately states, “If you come across a young Kangaskhan playing by itself, never try to catch it. The baby’s parent is sure to be in the area, and it will become violently enraged.” With sexual reproduction comes competition between not only the sexes but between competing males, each vying for a womb to continue his genetic legacy, and children are often the first casualties in this war, as it is not rare for a male to kill the offspring of another male so to ensure his are the only ones that end up surviving. With Kangaskhan’s identity wrapped up in protecting its baby, a sexual society would prove troublesome, male Kangaskhan mutilating babies while forcing fertile females into copulation. A better situation could be created without the presence of males, one in which the young are protected and mothers rested easily without the threat of a male high on testosterone killing her child.

 

Parental Bond: More than an Ability

Perhaps more than any other class of animals, mammals have mastered the art of motherhood. Few other organisms take on the burden of reproduction to the extent that mammals do. From the moment of conception, the mammalian mother is dealt with the burden of having to carry and support what essentially boils down to a temporary parasite that drains off its energy over whatever period of gestation it takes. Then after the offspring has been born they are still tasked with the job of providing additional nourishment through a unique little gland named mammary (yes, that’s where mammal comes from), in doing so providing them with invaluable proteins, antibodies, and other goodies that’ll help them later in life.

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In humans, oxytocin is released in females during breastfeeding, further forging the bond between mother and child.

But for marsupials in particular, motherhood comes with some additional stakes. A joey (baby kangaroo) is born early in its development, with a gestation of only 30-36 days. The pink gooey bundle of joy resembles its distant cousin the gummy bear more than a kangaroo at this stage in its life, being no larger than a lima bean. Being basically a living fetus, the joey is especially vulnerable in these first months. However, it quickly climbs to the pouch with its barely formed forelimbs and latches on to its mother’s teat where it will reside for the next nine months, feeding on its mother’s milk from the safety of the pouch.

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You will never eat a gummy bear ever again.

 

 

One can imagine that it can get crowded quickly in a pouch. Thankfully, kangaroos have evolved a unique adaptation called diapause, in which a mother essentially freezes the development of an embryo while her pouch is occupied. Once the joey is old enough to leave the pouch for good, the embryo is allowed to continue its growth, thus allowing the kangaroo mother to allot all of her attention to the primary offspring on hand.

This being considered, I find it interesting that in Kangaskhan’s Mega Evolution, the vigilant mother finally lets her current joey from the safety of her pouch to fight side by side with her, herself unchanged by the actual Mega Evolution but her young larger and more plated, starting to resemble its adult form. Perhaps this particular event is more than just temporary battle effect, but the release of Kangaskhan’s current joey and the unpausing of diapause, in which the joey that resides in her pouch post-Mega Evolution is not the same joey that was in battle but the newly developed embryo grown into a joey after months of diapause.

 

 

Cited Sources

COLIN BLAKEMORE and SHELIA JENNETT. “parthenogenesis.The Oxford Companion to the Body. 2001. Encyclopedia.com. 15 Mar. 2016 <http://www.encyclopedia.com>

Lutes, A. A., Neaves, W.B., Baumann, D. P., Wiegraebe, W., Baumann, P. (2010). Sister chromosome pairing maintains heteroozygosity in parthenogenetic lizards. nature.com.

A Dragon in Poison Skin – Goodra and Batesian Mimicry

For five glorious generations of Pokémon games, Dragon-types reigned supreme. With their only weakness being Ice and other Dragons, these creatures were unmatched in competitive play as well as in nature. They were the apex predators, sitting comfortably atop the trophic pyramid without a fear in the world.

 

That is until Generation Six rolled along.

Suddenly the game changed, as life is a constant struggle for survival, and a new elemental-type was introduced – Fairy, and in one fell swoop the hunter become the hunted. No longer could these Dragons loaf around lazily on top of the food chain, they had competition. While other Dragons crumbled and humbly abdicated the throne, one took matters into its own hands.

An isolated population of particularly rotund and bulky Dragons evolved in the region of Kalos. Heavily populated by the notorious Fairy-Types, selective pressures favored certain traits more than others, and through the power of evolution the strange gooey Dragonite rip-off we see today came into existence. At first glance one would assume that it’s the farthest thing from a Dragon, the first type that comes to mind is Poison with its purple skin and green dots all covered in a slimy mucus coat. And that, my friends, is the point.

In biology, we call this phenomenon mimicry – when two or more organisms share a superficial resemblance but are not taxonomically related1. This adaptation is often used by one species to trick its predators into believing it is another, more harmful and potentially dangerous species. Non-venomous milk snakes, for example, mimic the coral snake, a venomous species, in order to deter predators. This resemblance is achieved through mimicry of its color pattern – red touch yellow bad for a fellow (coral snake), red touch black you’re alright jack (milk snake). Although, most predators don’t have the advantage of a cute rhyme to remind them which is which and opt to stay far away from the both of them.

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Note: It’s probably best to avoid both. Just in case.

 

This type of mimicry, when a harmless species adopts the color patterns and warning signals of another, is called Batesian mimicry, named after Henry W. Bates, an English naturalist who first discovered this phenomenon in Brazilian forest butterflies of two distinct species2.

For our pseudo-legendary friend, this adaptation is vital to its survival. The region of Kalos is rife with Fairy-Types, all deadly to Dragons such as Goodra and its pre-evolutions. Its struggles become more challenging considering that Fairies have an immunity of Dragon-Type moves, which leaves most Dragons defenseless as their biggest strength is often their offensive game.

Unable to fight off the Fairies, most Dragons fall victim to their weakness and die off, but one line managed to survive.

Goodra is by far the most bulky of the Dragons, which is no coincidence. A glass cannon such as Haxorus with all its energy invested in Attack would prove useless and ultimately fatal when up against a foe who is immune to such moves. In short, Defense and Special Defense would be selected over a strong offense (though Goodra does maintain a decent offense for other Types). A similar selection would occur in regards to its coloration, as purple and green are associated with Poison-Types, and would increase the fitness of those individuals that had the trait. By mimicking this Fairy weakness, predators would be sure to stay clear of Goodra, thus allowing it to survive in a Fairy-Dominant region such as Kalos.

 

Cited Sources

http://www.britannica.com/science/mimicry