It’s about adaptation. Asexual reproduction means that a paramecium that is already well adapted to its environment will be able to produce more well-suited individuals, without risking taking on new alleles for less well adapted traits.

However, conjugation allows for one paramecium to take on a plasmid (genetic segment) from another paramecium. This way, if one has a beneficial trait, that trait can move through the population more quickly, as well as combining with paramecia that may have another well adapted trait.

This is seen in bacteria once antibiotics have been introduced. If one bacterium is resistant, then conjugation can allow for more resistant organisms to be produced quickly, allowing for a resistant colony to be established.

It seems that Khaiy is well versed in this subject, so I will not make any rash statements. 😆 But I read somewhere that conjugation occurs only when the paramecium is in a stressed environment. So I am assuming that if conjugation did not occur, asexual reproduction would also cease and the colony of paramecia would soon die out. 🙁

BTW Khaiy, I enjoyed your answer to this question posed by bionewbe, quite interesting. 😀

A general thing: If you can survive with your present genetic material, (considering that paramecium do not fall in love :lol:( kidding) ) why would you need a partner to produce new offsprings?
Logical isn’t it? 🙂

Poison asked:

If I understand Khaiy right, say the parameciums environment has changed to a point to where its continued existance is questionable. Lets call this paramecium (A) Another paramecium which we will call (B) has the genetic make up to much better survive in the changing environment. By (A) conjugating or mating with (B) the exchange of genetic material which (B) has, is transfered to (A) across the cytoplasmic bridge, which is usually at or near the oral groove during conjugation. With (A) now having acquired this genetic material it can now go on to reproduce via binary fission to produce off spring which are now more adapted to the changing environment. However Jahn in his book, "How to Know the Protozoa," states under the Family Parameciidae, page 235; "the paramecium-groups are separated into species on the basis of paired mating types and certain minor, but constant, morphological and physiological traits." So, both (A) and (B) must be of the same group, of which there are nine groups of species. For example say both (A) and (B) are of the P. aurelia-group. They, (A) and (B) cannot conjugate with those belonging to say the bursaria-group. Now would I be correct in the above statement Khaiy? 🙄

My apologies for the quality of this image. It is an old one from my archives prior to up grading my photographic system. Pls. click on image for a larger view. Thanks. 😀

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Yes, that’s right. It’s about being able to have more organisms producing offspring that are most fit to survive. Good work with your explanation, you described the process very accurately and clearly.

Khaiy replied:

Thanks Khaiy 😀 I had never considered what you had stated in your first response to the question and the statement about how bacteria can become resistant to antibiotics was most interesting. I learned something today Khaiy, thanks again! 😀

bionewbe relies:

I am not familiar with the technique of mounting specimens, especially protozoa but I will go out on a limb and say that yes the cilia should be visible in a well prepared mount of the paramecium. You are correct also in considering the instrument with which the specimen is viewed through. Most student microscopes will show the cilia to an extent, some quite well even but the image quality does depend too on the quality of the instrument being used. At one time I used a Swift 3500D student microscope for the study of protozoa and its optical system performed quite well but not near as good as the Zeiss Axiostar Plus which I am using now. 😀

BTW, do not let anyone ever tell you that asking a question is "stupid." There is no such thing as a "stupid question." In the field of science and the studies it encompasses, the only stupid questions are those not asked. 😉

The following image was taken employing the Axiostar Plus, oblique illumination was used in obtaining the resulting contrast of the paramecium. Notice that the arrows in the upper section of the photograph point to the cilia as they appear on the surface of the pellical and the bottom arrow points the the cilia as they appear around the edges. The entire body or cell is covered with cilia and this lighting technique helps to show those that do not appear around the edges of the cell wall. This photograph was taken of live specimens, not a prepared slide. 😀

Click on Image for Larger View! 😮

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When it comes to advantages or disadvantages I am not sure that there are any in natures design. However odd and cruel they may seem there is a purpose for that particular design. There are some who may debate that statement but everyone has a right to their own thoughts on the matter. 😉

As for the Vorticella, the localized cilia are used primarily for feeding, Vorticella is a filter feeder. Although sessile, Vorticella can become free-swimming by breaking away from its stalk and using its cilia to swim. At this the Vorticella is now in a stage known as being a "telotroch." Not only does it use the cilia that is normally seen around the anterior of the organism but it will oftentimes form a ciliary band around the posterior of the lorica, just above where the stalk is attached and utilize this band of cilia for swimming also but note that this ciliary band is only seen prior to the detachment from the stalk as the "telotroch" stage is developing. Later this band of cilia will disappear. This is an amazing process to observe utilizing the microscope. 😀

Among the Class Peritrichea with its Orders, Suborders and Families, the Vorticella has to be my favorite to photograph and to sit and just observe. It is also possible that one may confuse Vorticella with the Family Epistylididae, this family has loricates in a colony, whereas Vorticella exists independantly on a single stalk. 😀

Is this ok? 🙂

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Poison asked:

Yes it is, a good image of the Vorticella. The blur of the cilia is quite distinct while in motion. Did you know that they spin counter-clockwise. 😮 We were discussing rotation in ciliates while swimming. I forgot to mention that the Vorticella does rotate also while swimming and it too is in a counter-clockwise motion.

bionewbe asked:

Yes, I have tons of them! 😆

Click on images for a larger view! 😮

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bionewbe asks:

You have me on that question there. 🙄 😆 Maybe Khaiy or some of the others can answer that, it is a little out of my territory at present. 😀

To the best of my knowledge, I would say that because fission is the process of splitting or dividing of ones self to reproduce, where as conjugation is the coupling, joining or mating of two organisms in order to reproduce. You must also keep in mind that we are talking about single celled micro organisms here also or unicellular forms of life. 😀

This is after becoming free-swimming or in the telotroch stage. 😀

Well, as for the zygote, it’s important to point out that we’d only be talking about multicellular life, not unicellular anymore. A zygote will not undergo meiosis, but rather mitosis. Meiosis only occurs to produce gametes, which combine to create an individual with the correct number of chromosomes for its species (for example, in humans the necessary number of chromosomes is 46. When the gametes are being produced, sperm for males and eggs for females, meiosis occurs to produce cells that have one half that number, or 23 chromosomes. When the gametes combine during sexual reproduction, the zygote formed would have 46 chromosomes, in 23 pairs).

Therefore, if the zygote underwent meiosis it would produce cells with 23 chromosomes once more, and not be able to produce a functional individual. But undergoing mitosis allows for more cells to develop, leading to a functional individual without disrupting the chromosome number.

I can’t think of any situation in which a zygote would not undergo mitosis right away (since there wouldn’t be much point to delaying the mechanism that allows the individual to develop), but I suppose that there could be. Nature has done stranger things.

As for why fission is not considered a sexual process, ken got it right. It’s only considered a sexual process when the genetic material of two organisms is combined to create offspring that have some combination of the genes of its parents. Since fission is an asexual process, only genes from one individual are present in the offspring, and no combinations with other organisms take place. And ken is also right that fission is for unicellular organisms.

It’s possible, some organisms are haploid. I just have never heard of an organism that behaves like the Chlamydomonas you described before. In that light, I would only be describing diploid individuals, and specifically eukaryotes (because prokaryotes don’t need to divide to develop). Thanks for pointing that out!

EDIT: A bit of research yielded the information that Chlamydomonas can grow as either haploid or diploid, so they don’t have to undergo meiosis.

Sure. Alternation of generations just means that there is a mitotic phase and a meiotic phase necessary for sexual reproduction. I’ll use humans again as an example. If there were no meiosis, then gametes would each be diploid cells (2n, or 46 chromosomes). When these combine, they would create an individual with 92 chromosomes. This process would continually produce individuals with progressively higher and higher numbers of chromosomes. This would be bad for the organism. However, if there were no mitosis, then the number of chromosomes would decrease with each successive division of cells. This would mean that your life would be very short, as your cells could only divide so many times before your cells would all be haploid.

It’s the balance of these two that allow animals to live the way that they do; your cells reproduce mitotically to preserve the number of chromosomes, and then meiotically to create gametes capable of producing a new individual with the appropriate number of chromosomes. When the gametes fuse you have a zygote, the cells of which will reproduce mitotically until it is ready to produce gametes itself.

In plants, the process is a bit different. There is a generation that is diploid, called the sporophyte generation, which will produce haploid cells by meiosis (these are called spores). These give rise to haploid individuals (because those haploid cells reproduce by mitosis), which is called the gametophyte generation. These haploid individuals cannot undergo meiosis (because they are already haploid). They produce gametes (reproductive cells that are haploid) by mitosis, and then these gametes fuse together, which produces a diploid organism. When the gametes first fuse, the structure formed is called a zygote.

I’m glad you pointed this out, because I was wrong above. When I said that a haploid organism could not function, I was responding too quickly. Had I stopped to think a moment longer, I would have realized that I was only describing animals. As I said above, plants obviously have functional haploid individuals, and as you pointed out there are other organisms as well that can function as haploids, like the Chlamydomonas.

You know I remember studying this many years ago in school but it never really sank in, so it has always been a gray area in my studies, in trying to understand the reproductive nature of life in some species of both plants and animals. Some good stuff both of you have brought forward in this discussion here. Continue on. 😉

As far as variations in the gender of each gamete is concerned, it’s a lot like in animals. Plants produce eggs which are then fertilized by sperm (which can be anything from the sperm that swim through moist media like in ferns, or pollen like in angiosperms).

Exactly how the alternation of generations is handled depends on the type of plant. For example, in ferns the gametophyte generation is dominant in the life cycle, but they still produce spores that give rise to the haploid generation, which is the part of the plant that you see.. But in angiosperms, divisions of the megaspore are the only component of the gametophyte generation, and the plants you see are sporophytes.

Plants have ‘gender’, similar to animals (although plants tend to have both reproductive structures). Alternation of generations only describes whether or not the plant is haploid or diploid, having nothing to do with gender.

Yup. The haploid part goes through mitosis to produce haploid reproductive cells, which are the gametes. These are just like the gametes in humans, n chromosomes that fuse with another gamete to create the diploid individual.

The diploid individual will produce spores by meiosis (making haploid cells). These spores give rise to the haploid individuals, which starts the alternation of generations cycle all over again.