Natural Selection: asexual, sexual, and unisexual

whiptail lizard1

 

Reproduction among the animal kingdom appears to be a hit-and-miss proposition. Even evolutionary biologists cannot come to one accord on a given direction with natural selection. Throughout the history of science sexual reproduction – the fertilization of the egg by sperm – has predominantly been considered status quo. However, early in the twentieth century scientists began noticing unisexual species, and further discoveries included asexual species to the growing list. In fact, in less than one hundred years there is now a list of over fifteen-hundred nonsexual species recorded.

The initial assumption arrived at by the majority of researchers in the biological field was that they were seeing the beginning of natural selection paving the way for the next evolutionary step in the reproduction of species. But was that truly the case? They thought so at first, after the initial fifty or so discoveries. But as the number of species elevated rapidly that hypothesis no longer seemed to hold up. Furthermore, technology improved, which played a role in many of the initial discoveries. And as technology continued to progress biologists realized that evidence seemed to suggest some of the nonsexual species they had found, along with species that reproduced both sexually and nonsexually, were hundreds of thousands of years old: with several they even believed to be as much as two-million years old.

Species that were hundreds or a few thousand years old were considered too young, by evolutionary biologists, to have seen a complete evolutionary change in their sexual reproduction. But the older species tore apart the belief that natural selection had only recently (in evolutionary terms) begun to make the next major evolutionary leap in animal reproduction.

I am not quite sure I agree with that initial hypothesis. After all, Darwin recorded noticeable evolutionary changes in certain species (like the finches) from one generation to the next as a result of the change in available food supply. There has also been a wide variety of recorded information in the past fifty years showing species in controlled environments going from sexual to unisexual, and sexual to asexual species in one or two generations. However, some species fail to mutate in controlled conditions, while others mutate sporadically with as little as one-to-six percent transforming. And yet, other species have shown one-hundred percent mutation in a single generation: and their offspring reproduced without sex… though some species still needed fertilization of the egg, but without the sex act.

The result of the diverse findings has led to a hodge-podge of beliefs. No one has come up with anything close to a universal hypothesis to explain the absence of uniformity in animal reproduction.

Most evolutionary biologists question the need for sexual reproduction: “If reproduction can occur without sex, why does sex occur at all?” (Johnson, 2012) One train of thought contends that there appears to be an inevitable limit to long-term species survival inherent in clonal reproductions (Johnson, 2012). It is a phenomenon known as the ratchet mechanism, or Muller’s Ratchet, after Noblest Herman Muller, in the early sixties (Simon et al 2003).

Another contention, called the Red Queen Hypothesis, asserts that there is an instant advantage with sexual reproduction in producing genetically diverse offspring that make it tough to be targeted by harmful parasites (Simon et al 2003). This hypothesis was tested using Crucian Carp: the diploid sexual had fewer parasites than the triploid gynogens (cited in Simon et al 2003).

A third contention is known as the DNA Repair Hypothesis. Various geneticists believe sex continues because “only a diploid cell can effectively repair certain kinds of chromosome damage,” (Johnson 2012), primarily double-strand breaks in DNA. They suggest that synapsis “which in early stages of meiosis precisely aligns pairs of homologous chromosomes, may well have evolved originally as a mechanism for repairing double-strand damage to DNA” (Johnson 2012).

After reading up on the abundant variations of asexual and unisexual, along with the equally diverse methods of research, I came away with far more questions than answers. One of the biggest problems I saw in the research is that there is no standard methodology for studying or recording the information and data acquired. It is impossible to arrive at a universal answer to the basic ongoing questions when every scientist and research group alters their methodology to accommodate their resources, and often their hypothesis. For instance, certain scientists I read about confirmed that specific species have had no known mutations in sexual reproduction in their natural environment. But that did not stop them from isolating the species in a controlled environment to force mutation: and even after the forced mutation the mutated species never took hold in the natural habitat after they released it into its known environment.

Similarly, there are examples of natural mutation that have failed to show identical results in controlled settings. This raises additional questions of validity with regards to natural selection. How many of the alleged fifteen-hundred-plus asexual and unisexual species have honestly been naturally selected or genetically mutated (engineered) by humans? Which creates another question in a similar vein: how much of the human pollution, and toxic or nuclear waste, has added to the mutation level in the natural environments of many of these mutated species?

For instance, I know of several areas, such as dams and reservoirs, where the fish, fowl, and other local species have shown dramatic mutation in size, appearance, and behavior. Yet, not once in all the examples of research into mutated species on sexual reproduction that I have read did the scientists consider unnatural or external elements in the species natural environments a possibility  for mutation: to prove or disprove. That seems highly unprofessional, and yet it is the standard practice (as far as I can tell), to automatically discard the possibility of something that has been confirmed many times over, in many areas, simply because it does not fit their initial hypothesis.

Instead of learning what I hoped to learn while researching this paper, all I ended up discovering was my distrust for the recorded findings. So much of the methodology proves more about the genetic manipulation by humans with career aspirations than it does about natural selection. I admit that I am not a geneticist or evolutionary biologist, and will never be. But I was an investigator for many years, and I know a lot about eliminating suspects (or non-truths) to get at the right culprit (or truth). And as I read the research, if I only looked at the alleged data (like the proverbial tree) it seemed valid, but when I looked at the big picture (like the proverbial forest) all I saw was a lot of window dressing to validate their hypothesis in order to keep their grants coming in: there are just too many unanswered questions and areas never considered.

 

References

American Museum of Natural History. (2012). Web.

Johnson, G. (2012). The Living World. McGraw-Hill, NY. (180-181).

Patrusky, B. (1982). Where Males Don’t Count. Mosaic. (2-8).

Schlupp, I. (2005). The Evolutionary Ecology of Gynogenesis. (399-412).

Simon, J., Delmotte, F., Rispe, C., and Crease, T. (2003). Phylogenetic relationships between parthenogens and their sexual relatives: the possible routes to parthenogenesis in animals. Biological Journal of the Linnean Society (151-163).

 

Waya: See the Wolf

wolf cub1

 

See the wolf.

 

See the wolf pup.

See it nip.

See it yip.

See it roll.

See it grow.

See it cute.

See it cuddle.

See it whine in the mud puddle.

See its fur shine in the sun.

See the twinkle in its eye,

the joy of life,

and first howl at the sky.

He told Moon a magnificent tale,

how he circled and circled

and caught his own tail.

He ran fast… and then faster

until his tail was in reach.

He bit down and he yelped

and Hawk gave a screech:

“a lesson it is,

a lesson to teach.”

Moon did agree

and spoke quite plain:

“Don’t bite your own tail,

don’t cause yourself pain.

The ruckus you cause

could easily bring Man,

and at this point pup,

you’d fit in his hand.”

 

See the wolf.

 

See the wolf grown.

See it bay.

See it play.

See it prowl.

See it growl.

See it chase.

See it bound.

It’s canis lupis:

much more than a hound.

See it hunt:

part of the Pack.

See how deadly:

Nature’s way,

removes the weak

each passing day.

Strength of limb,

strong of heart,

oh how he thought

he’d make a new start.

A challenge he did make

with the Alpha of the Pack.

It was brutal… and muddy

and they both ended bloody.

But he failed in his attack.

Ousted to roam

alone,

a lone wolf.

He bit the paw

that led them all

before his time to lead.

He failed the test,

now begin the quest,

maturity is earned in the deed.

 

See the wolf.

 

See the wolf rogue.

See it stare.

See it glare.

See it hide.

See it glide.

See its effort.

See its ease.

The smell of prey born on the breeze.

Hunter,

ganohalidohi:

He wins a mate

and makes a stand:

marks his turf,

defends his den.

Alpha male, he bears it well:

this scar and that scar

record his whole tale.

“How goes the Wolf?”

asks Moon of Hawk.

“Waya is good

as you yourself know.

I’ve watched you guide him

with your light and your glow.”

Wolf did howl

to Hawk and to Moon:

“One with insight,

the other so bright,

you both taught me well.

It’s time to take leave

and leave me to live,

go seek a new tale

for you each to tell.”

wolf1

© JW Thomas

No Love for Twister

Twister1

Stars shine bright on an indigo night

Vision far-seeing and focused

Moon mirrors my love for you

Day breaks forth when Morning comes

Sun steps on-stage to set Earth Mother aglow

It glows brightest where you stand

Evidence of pleasure without measure

Satisfaction complete with morning dew

Cleansing need inspires naked rain dance

Bathing beat in rain – spellbinding attraction

Lures Lightning’s attention and flashing affection

Bolts of synergy and sexual arousal

Thunder hears, Thunder sees, and Thunder roars

At Lightning’s illuminated faux pas

Moving to the beat of a mortal

Twister heard Thunder tales, came to see ‘tis true

He laughed at Lightning’s shocking antics

Then saw you and loved at first sight

He tried to wind his way into your heart

Your rebuff smacked his spiral hard

He cried awhile… fizzled… and was no more

© JW Thomas

Masters of the World?

[Thoughts for Earth-Day.]

 

Can we tell the four winds when, where, and how to blow?

Can we tell Otter he must be as solemn and thoughtful as Great Horned Owl… or prove to Barn Owl it is us “Who-who” he seeks?

Can we tell Hawk and Eagle to soar no more?

Can we tell Rabbit that procreation with such fervor merely soils his reputation, and casts no shame upon us for our limited output?

Can we ground Bee indefinitely because he does not meet our aviation specifications?

Can we have Firefly’s light show cancelled in order to conserve energy?

Can we command noble Thunder to whisper his love-song to Lady Lightning? Or demand Wolf cease debating with Moon? Or arrest Winter when he loiters till June?

Can we insist Salmon spawn downstream because swimming upstream is suicide?

Can we tell Black Widow and Praying Mantis to forego patricide while never questioning our use of insecticide?

Can we order Sky Father, Earth Mother, and Old Man River to “heal thyself” so we need not be bothered?

Can we tell stars that if they must twinkle it must now be in Morse code?

Can we tell Cock and Hen that chickens are now banned from crossing the road? And, of course, it has nothing to do with an aversion to those on the other side.

Can we tell primates to stop monkeying around, and proclaim we’ll never patronize their monkey business?

And can we tell Ant that all work and no play is soooo… twentieth century?

Can we say all this and more?

We can… we have… to no avail.

Perhaps we do not have as much control as we would like to believe.

Masters of the world?

You decide.

Sexiest Gardner 3

© JW Thomas

Fluid Emotion

Morning dew is evidence of sweet release upon vestal valleys and rolling hills of Mother Earth.

Passion spent now heat must vent, vapor rise and evaporate with tent while emotion bent, the off-shore fog rolls in.

Fresh spring flowers to while-away the hours, while coaxing green and budding things to cover Earth Mother anew.

Drizzle maybe happy tears if most the day still shines; but when the day stays dull and gray, and blustery defines it well, listen for the bells that tell the heartfelt pain of loss when nature-born is spirit-bound, and bids this world adieu.

Hurricanes and himmicanes bring spousal trouble to bear when Nature’s give-and-take has forgotten how to share; and nothing gets said easily, every word is an accusation till it peters out with sad frustration leaving a tail in its wake of mass destruction.

Steady rain is a time to dance, Sky Father is playful and giving; his candle is lightning, his music is thunder, his flowers the scent of the living… as he bathes his true love with sacred tears.

If you find your path is flooded with a deluge pouring down, you know mankind once more has fallen and the Creator’s wrath abounds; so don’t open your umbrella, stay behind closed doors, and wait for signs of joy before you venture forth; for many who tempt the waters wind-up drowning in their fears.

 

© JW Thomas

Black River

Red Tail Hawk soars

over long black river,

river his ancestors

many moons past

never saw.

Salmon waters,

white-eye Deschutes,

still flow

not as free

not with abandon.

Endless flow of tears

constant hunger

yearning for lost

multitude of life

once in her depths – depleted.

Hawk’s heart is hers

wavering when necessary

when hunger screams

when he fears

little beaks fall silent.

Hawk wonders

why Earth Mother

allow black river

indifferent

womb-less.

Barren

no depths

hard-hearted

traversed with peril

nothing sacred.

Hawk figures

Earth Mother know

Winter often stubborn

allow black river

so starving hawk-lings

survive on road kill.

© JW Thomas