CHARACTERIZATION OF A TRI-SEXUAL, TRI-CHROMOSOMAL BIOLOGICAL SYSTEM
by Helen E. Davis
Table of Contents
Nucleic Acid and Biochemistry
Higher Plant Life
Small Flying Phyla (SFF)
The Terrestrial Phyla
Social Implications of a Tri-Sexual Species
In the late eighties I found myself taking a college class that I needed for the credit, but not for the material. I had already survived undergraduate years as a Biology Major and two years as a graduate student in Cell Biology, but in order to qualify for a program to become a High School Biology teacher I needed to have basic genetics on my transcript. So I signed up and started attending.
It was not a well-taught class.
Like any good student I sat there and took notes. They were not, however, notes on what the professor said. They were notes on what he should have been saying. In between those occasional important bits I began working on a side project: working out the implications of a Tri-sexual, tri-genomic biological system. I think I learned more from my own manipulations of the natural system than what was presented in the course.
Using the principles of biological evolution, I developed more and more complex creatures until I had a viable, alien, intelligent species. I called them Arlians at first. Years later, when working on the Silent Runner stories, I brought out these Arlians and renamed them Pupfish. I also changed a few facts of their society and social behavior, to better fit the story.
This then is the original background material for the Pupfish. It is not completely accurate as far as the story is concerned, but that is because things must change to fit new environments, new situations. It's a peak at the past -- but it also contains the seeds for future development of the story of the Pupfish in Space.
Triploid, with one set of chromosomes received from each parent. Triple helix in the nucleic acids, which would most certainly not be DNA. Mitotic division would result in three daughter cells, meiotic division would result in nine gametes.
Two sex chromosomes, with gender determined by the relative frequency of the Y to the X. 5:2:2 ratio, males:females:pouchers. XXY = father, producer of sperm. XYY = mother, receiver of sperm and producer of egg. XXX = poucher, receiver of larvae or egg, and producer of a sex cluster, a syncial cell of haploid nuclei, all derived from a single gametic nuclei. Males mate with females, producing a diploid zygote that develops into either a free swimming larvae or a embryo within an egg, and then the females deposit the eggs or the larvae into the pouch of the poucher where each one accepts a sex cluster. After a sex cluster is accepted by a larva or embryo, it transforms into a mycelium. The hyphae then work their way through the body of the larva or embryo, transferring nuclei into the diploid cells. Triploid cells would be immune to further invasion. Approximately twelve hours after the nuclei of the cell cluster invade the diploid cells of the larvae, those cells become intolerant to the presence of any remaining diploid or haploid tissue. Development would then continue in the embryo or larvae, until an infant form of the organism is reached.
This biological system would be more genetically stable, due to the fact that recessive conditions would be minimal. It would do well under conditions where populations were frequently isolated, as in frequent ice-ages, droughts, earthquakes, or other climatic disasters, because of this genetic stability and because this system would allow re-seeding of a population from a very few individuals. A greater genetic variability could be carried on three sets of genes than on two. Also, a single poucher could receive several larvae or eggs from a single mother, all with different fathers, allowing for greater genetic variability between siblings and lessening the dangers of inbreeding should this set of siblings (and poucher parent) become an isolated population.
Would be able to resist high percentage of mutagenic factors found on home planet.
This system would result in a much slower rate of evolution of new species. There would be few, if any, closely related species, and there would not be a diversity of life forms on the planet. There would probably be only one major tract of phylogenetic development, and intelligent life may not arise until close to the end of the star's life.
Nucleic Acid and Biochemistry:
The basic nucleic chemical is in the form of a triple helix, and from any one strand the other two can be built. In replication, therefore, one chromosome becomes three. There are nine bases, and codons are doublets, not triplets. There are 81 possible ways that the nine bases can be arranged in doublets, and therefore 81 "transfer RNA's", and thus no more than 81 possible "ammino acids." (Or whatever they have that passes as the basic building block of their "proteins." The bases are complimentary and unique to the set, so that the three bases that make a base set join together in an interlocking structure. This contributes to the stability of the gene, almost to a repressive state.
Evolution must depend, then, upon the breakage and rearrangements of chromosomes. Transposons and viral vectors play a part in this, as does a mutation gene -- the number of copies of this gene within a cell determines its mutation rate. Duplication of genes by this mechanism would allow separate proteins to evolve from separate copies of the same original gene, thus most of the proteins within these creatures would be closely related to a set of other genes, and there would be relatively few of these protein "families." Also, we could expect that most genes would have functions in several different biochemical pathways -- thus the pathways would be much more complicated and interwoven than Terran ones. Genes would be more pleiotrophic, but mutations would likely be more fatal.
Some genetic rearrangement is possible through transposons and viral vectors.
Although there would be found a high stability against discrete genetic changes, there would be a wide range of phenotypes within a population due to quantitative genes. This would be helped by the variable number of copies of genes passed with each generation, due to chromosomal duplications and deletions. Since quantitative genes are highly influenced by the environment, a lot can be said about an individual's birth and growth period. Furthermore, phenotypes will probably change a bit depending upon the conditions an individual finds itself in. Therefore, there will be little designation of a person into a particular class based mostly on genotype -although the caste that a person has been assigned to may influence the environment -- and therefore the phenotype -- of the individual.
Although phenotypes within a species may be quite varied, the phylogeny of the life forms would not be as broad as that found on Terra, due to the limited scope of evolution and the high lethality of mutations -- all life forms would most probably be represented by 4-6 major phyla of structurally similar organisms. If we determine the basic form of the phyla, then by minor, very minor, adjustments, we can form separate species within the phyla.
Body forms are determined by:
1) Embryology. Development leaves indelible marks upon the adult form, and various structures and patterns which are adapted for optimal fetal or neonatal existence are often retained in the adult -- for example, the lips, the arrangement of some of the internal organs, and various vestigial structures.
2) Environmental Constraints. The most successful organisms in any area will be those that have best adapted themselves to living in that area. Conversely, adaption of a new structure may also open up a previously unexplored area -- for example, wings in birds probably predated their living in trees and traveling through the air. Also, if the area is mountainous, organism will probably have long claws for climbing, or small bodies. Also, body forms will be affected by what the organism has to do to feed.
3) Evolution. We are the result of one form being made into another form, and thus the form of our ancestors will be a basic blueprint for our present form. Therefore, any complicated forms must be seen as being able to rise from a simpler pattern.
These are the one-celled organisms with a centralized nucleus and organelles; they all reproduce by asexual fission -- where one parent produces three daughter cells -- or by colonial sexual reproduction. Under times of stress, fissioning daughter cells will not separate completely, but will develop into large clusters of cells. Two types of clusters are formed, depending upon the sex of the original parent cell, XYY clusters will remain as clusters until the resting trigotes are formed. XXY (male) and XXX (poucher) clusters break up into individual gametes in the presence of a XYY (female) cluster, and individual gametes will fertilize individual cluster gametes. After a XYY cluster has been fertilized twice, the cluster breaks apart, the trigotes having formed resting shells, and the trigotes lay dormant until more reasonable conditions return.
The one-celled organisms have both the ability to utilize sunlight as an energy source and can phagocytize energy from other sources. They are the decompositive force on the planet, breaking down dead things and recycling the nutrients, and are the basic food source for the filter feeding water dwellers. Since they utilize blue light (instead of red), the organisms have an orangish color.
Higher Plant Life:
Found both in the very shallow water and on the land, the plant life is all orange. All plants have very short trunks, although the water plants have trunks up to three feet tall -- just enough to reach the surface of the water. A circle of branches comes off at the top of the trunk, and each branch supports a single very large, fleshy leaf. The entire shoot of the plant can die off in bad weather, or be torn away by a hungry predator, and a new plant will rise from the complex underground root system. Energy is stored in extremely large underground tubers.
All plants have three sexes. During breeding years, a slender spike rises high from the top of the trunk. At the top of the spike is a tassel, below it is a cluster of delicate flowers. The flowers always open about a week before the tassel matures, giving the flowers a chance to be out-pollinated first. Pollen is carried from tassel to the flowers by either the wind or by small flying forms. The pollen travels through the mother plant from the flowers to the ovules, which are located in the base of the trunk. A diploid larvae is formed. This diploid larvae crawls out of the trunk, and blindly makes its way for several hours to days, finally coming to rest in the shade of another plant. It sets out a very simple root system and sends up some very simple leaves. Later on in the year it begins to send up a stout spike, and the top part swells into a sticky ball. At the same time the triploid plants began developing tassels on the surface of their leaves. The pollen from these tassels lands on the sticky ball, and it fertilizes the diploid cells within the ball so that they form triploid seeds. These seeds come with wings, so they can ride the wind and be more easily dispersed. After a majority of the cells in the ball have been fertilized, the ball splits and the triploid cells scatter out.
Various parts of the plants are edible to the herbivores. These include:
1) Leaves, which are also reservoirs of water in dry land areas.
2) Tubers, which are high in starch content, and may be pounded into an all-purpose flour.
3) Immature sticky seed balls. The mature seeds, however, are light, dry, and have very little edible food per total weight.
4) Diploid larva form. These are very tasty and oil-rich, easy to catch, but hard to cook -- they continue to move until they are completely roasted.
Differences between species are seen only in the relative size of the stalks, leaves, flower shape and color, area of habitation, and flavor.
This phyla contains the ancestors of all the other animal phyla on the planet.
The basic member of this phyla is a filter-feeding polyp with eyes, gills located in pouches beneath the mid-torso ring of anchor tentacles, and a torsion-twist tail. All animals of this phyla, and those descended from it, show spiral symmetry. The oral opening is located at the cranial end of the animal, and it is ringed by a set of mouth tentacles. These are long and covered with mucus, and as they wave through the water the mucus traps unicellular organism and debris. The mucus is moved by cilia down to the oral cavity. These mouth tentacles are also strong enough to grab small animals and plant larvae, and stuff them into its mouth. The oral cavity is large, and quite extendable. Digestion of food begins here, and nutrients are absorbed along the length of the digestive tract. This tract is packed completely into the torso, and the anal opening is just between the juncture of the torso and the tail, below the gill pouch openings.
Just behind the mouth tentacles, a spiral ring of eyes are located. These are light-sensitive, and can detect movement. Below these are a pair of triangular fins which are flexible enough to be pulled close to or extended from the body. These fins contain flexible spines, for rigidity. The anchor tentacles ring the mid-torso. These are very long and flexible, and they have grasping claws at the end. When the polyp is resting , these tentacles hold onto a rock or the sea floor. The gills are located in deep pouches just below the anchor tentacles, and the gametic openings are located between the pouch openings..
The torsion-twist tail is about a third as long as the torso, when extended. When retracted, it is only an eighth as long. Spiral muscles encase a flexible hydroskeletal rod -- when contracted, the muscles tighten up like a spring and compress the flexible rod. When released, the rod pushes the polyp off of the rock or sea floor with a burst of energy. Also, polyps swim by regular compression and release of their tails. The unwinding of the tail gives a spiral twist to the polyp's swim.
The supporting structure of the polyps is formed either of hydroskeleton (tail) or cartilage. The torsal area is encased in a sub-dermal shield of cartilage, and this shield is connected by a network of spicules to a central supporting rod. The rod encases the central nervous system, from the neural knot located just behind the oral cavity, to the spinal cord that runs the length of the torso. Peripheral nerves run from the spinal cord to the muscles, traveling alongside the spicules.
The gut tub winds around the central rod in a spiral pattern, passing between the spicules, and various digestive glands are located alongside it. The hearts are located directly underneath the gills -- pushing fluid through the gills and then either along the central rod towards the brain knot, or alongside the intestine. At the brain knot the vessels fountain out, run along the subdermal shield, and return alongside the spicules to the central vein.
Mass matings are the rule for reproduction. Some stimulus -- temperature drop, full moon, increase in the unicellular population -- causes the polyps to aggregate into large mating clusters. Males and females release their gametes into the water, and fertilization is random. The eggs develop into free-swimming larvae, and these make their way to the poucher animals, who have collected their gametes in their gill pouches, where they have formed sex clusters, a syncial capsule of haploid cells derived from a single gamete. The larvae take the sex clusters into their oral cavity, where the first one to take root sends hyphae through the gut lining and to all parts of the larval body. Haploid nuclei pass from the hyphae and into diploid cells -- the nuclei then fuse and form a triploid nucleus. Later, the mycelium and the haploid cells that did not find a way into a larval cell are attacked by the larval defenses and destroyed. The larvae then develop into juveniles within the pouch.
Polyps are quite edible, and are devoured by amphibious forms and mammals, with relish.
Small Flying Phyla (SFF):
These have descended directly from the aquatic polyp. They are rather small, ranging in size from 2mm to 4cm. They have long, thin bodies, and about half of it is taken up by the torsion-twist tail. The fins are longer, extending beyond the end of the body when folded, thinner, and can be extended 1100 from the body, resulting in a very wide sailing flap. The anchor tentacles have remained the same, and are used as legs, and the animal rests on its tail with its mouth pointing skyward, and it feeds in the opposite orientation. The torsion-twist tail has remained the same in shape and function, but is now capable of launching the animal many feet into the air, where it can spread its wings and fly. The mouth tentacles, however, have fused into a piercing-sucking tube. SFF feed on the juices of plants and animals, and on the nectar of flowers. The eyes have remained the same, except that they are now more competent at recognizing shapes and colors.
Oxygen exchange still takes place across the gills, which are located in the gill pouches. These gills must be kept moist, yet are a heavy moisture drain. The SFF take frequent baths, and at these times they are vulnerable to predation by polyps and amphibious forms.
Mating occurs in mass, when the adults gather into large swarming balls. Eggs, sperm, and cell clusters are all laid into a rich foam. Fertilization takes place and then eggs are invaded by sex clusters. The trigote develops into an instar, which crawls from the ball of foam and into the mud beneath. The instar looks very much like an adult except for size and lack of fins or anchor tentacles.
Instars live their entire juvenile life in the mud, burrowing through the ground with the aid of the torsion-twist tail. They feed on plant roots and fibers, and are predated on by amphibious forms which dig them up, or by the parasitic instars of other SFF. Depending on the environment, they may spend from a few days to several years at this stage.
At the time of metamorphosis, the plump instars crawl to the surface of the mud or, even better, onto a rock or a plant. They evert fins and anchor tentacles from developmental pockets and pump them into shape with bodily fluids. This takes only minutes, as the instars are quite vulnerable to predation from amphibians at this time. To help offset this, the instars often metamorphose in large masses.
Although small, both instar and adult SFF are edible and make for good eating.
The amphibious phyla is also descended directly from the aquatic phyla, but is the predecessor of the major terrestrial phyla. Along with physiological changes which allow for some survival on land, the amphibious phyla have also adopted a pseudo-bilateral symmetry. The body form has become flattened on one side, allowing the animal to lay flat on the ground, and this ground (ventral) side has lost features which are continued on the above (dorsal) side: eyes, gills, and vibration sensors, which are the vestigal remains of the anchor tentacles. The poucher sex retains its ventral pouch, as a breeding pocket, but it is lost in the other two sexes. The torsion twist tail has split, forming two lower limbs that lie to either side of the central plane. These lower limbs are used to push the animal through the mud when it is lying flat, and also propels the animal through the water while swimming, by alternately expanding and contracting. The fins have lost their flap-like connection to the body and their supporting fin, and are now used as tentacles that can pull, dig, or attack prey. The claws that were on the ends of the anchor tentacles in the aquatic form are now found on the ends of the "arms" and "legs." The mouth tentacles have degenerated into taste nodules which ring the mouth. The skin is now covered with leathery scales, which protect against scraping, drying out when on land, and attack.
The head is broader, to accomodate the larger neural knot, and the intelligence level is higher, with the animals capable of some complex thought.
Internally, a pair of long, sac-like lungs now branch off from the gut tube, right behind the mouth. The lungs lay along side the gut tube, spiraling the full length of the body. Cartilage rays encase the neural knot, and a number of rays extend forward and ring the mouth -- creating jaws. The teeth are simple, conical, and covered with enamel.
Mating takes place on the mudflats, during low tide. Some animals flip over onto their backs, and the corresponding partner climbs atop them. Females mate first with males, who transfer sperm to the egg-holding area within her body, and then the females pass the fertilized eggs onto the pouchers. The eggs hatch into larvae while in the breeding pouch, and they are then covered with cluster cells. The trigotes stay in the breeding pouch until they are small juveniles.
During bad weather years, amphibious phyla hibernate in the mud or live in the caves.
Amphibious phyla are a very edible food source. Different species vary in size, color, flavor, and preferred area of habitation (inland/sea, tropical/arctic, cave/open, etc.)
The Terrestrial Phyla:
The terrestrial phyla have adapted to life on the land by developing better protection for the skin and sense organs, enhancing the ability to get around by development of the lower limbs, and by keeping their young by them until they reach adulthood.
The legs have become sturdier, with large foot claws that can support the weight of the animal. Walking is accomplished by shortening one leg, swinging it forward, lengthening it, and shifting weight while shortening the other one. The animals also can move by "hopping", suddenly releasing the tension on the legs.
The entire head region has developed, to allow for stronger jaws and more complicated teeth, so as to handle the tougher terrestrial plants and animals, and to accommodate the larger brain size. Along with the larger brain size is increased neural complexity, and with it, greater dexterity of the hand claws. These have increased in size as have the foot claws, but are more flexible. Warm-bloodedness accompanies the larger brain, as a more complex brain needs greater protection from temperature extremes, and with this comes a skin covering that is insulative as well as protective. Feather-like hairs cover the body, ranging from soft down found within the brood pouch to coarse fur along the back; in some places, as along the claws, the hairs have coalesced into a hard, bony like covering.
The gills and gill pouches have disappeared, and the vibration sensing organs have retreated into pits that can be closed by sphincter muscles. This line of pits, extending along the back of the "waist", are adequate for sensing air vibrations. The eyes have lids, as well as nictitating membranes. The taste nodules have moved to the inside of the mouth.
The terrestrial animals care for their young. Pouchers supply the babies with milk, the teats located within the brood pouch (and thus the animals also have lips and lounges, although the tongue extends from the roof of the mouth) and they secure food for the young. In colonial species, all members of the community work to obtain food for the young.
Fertilization of the zygote takes place within the female's body. Genitals are located on the ventral side of the body, just above the junction of the legs to the torso. Females have a genital slit, males have a penis, and the poucher has a clasper. The clasper resembles the penis except that it is larger. It contains a tunnel that passes up to the bottom of the pouch. During poucher-female copulation the larvae are forced through the tunnel and into the pouch.
Social Implications of a Tri-Sexual Species:
Only the terrestrial phyla show social behavior.
While the number of pouchers born roughly equals the number of females, the number of males is more than the number of pouchers and females combined. 5:2:2 ratio. Therefore, males are more expendable. They are more likely to fight mortally for access to females, are more aggressive, and probably have less of an interest in dealing with young. For the most part they would be nomadic, moving from family group to family group, keeping the gene pool in flux. Females have a slightly greater interest in the young, but not much -- child care is the sole province of the poucher. In clan species, females and pouchers will band together as a family group with the females protecting the pouchers and the young; males are welcome visitors only when bringing food or the females want to mate. In non-clan species, the female may carry the products of several different male-female matings within her womb, in arrested larval development, until she meets a poucher who is unburdened. She then dumps her larvae in the poucher's pouch, and leaves.
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