The gametophytes used in this experiment are of C-ferns. They tend to mature and produce spores at temperature of 28oC and conditions of high humidity. The spores that germinate first are hermaphrodites. Hermaphrodites tend to produce a pheromone called antheridiogen. It is this pheromone that causes later germinating spores to become male.
In wild type culture of C-ferns, it is expected that there will be a high concentration of antheridiogen since the hermaphrodites are producing antheridiogen. The greater the population density of C-ferns, the higher the concentration of antheridiogen; hence a high percentage of male gametophytes in the wild type cultures.
In the experiment, a culture of her1 culture was used to investigate the effect of population density on sexual development of the C-fern Gametophytes. What was unusual about the her1 culture is that no males were present in the culture.
It is either that no antheridiogen was produced by the her1 hermaphrodites hence the absence of male gametophytes or the her1 gametophytes do not have receptors to perceive the antheridiogen which could result in the absence of the male gametophytes.
If the hypothesis that the her1 hermaphrodites do not produce antheridiogen is correct, the wild type culture and her1 filtrate will have the same percentage of males as the wild type culture and distilled water. If the hypothesis that her1 do not have receptors that perceive antheridiogen is correct, then her1 culture and wild type filtrate will have the same percentage of males as her1 culture and distilled water.
Results
As the population density increased, so did the male gametophytes of the wild type strain; but there were no male gametophytes at any population density in the Her ...
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...ermine which gametophytes were less responsive to antheridiogen from the number of males that were produced after we set-up the experiments. Just the same way as the authors, we had to determine the cause of the insensitivity in response of the insensitive gametophytes by carrying out different experiments with different conditions to determine whether the gametophytes did not produce antheridiogen or maybe they did not perceive the antheridiogen. In the same way we found out that her1 culture could not perceive antheridiogen just the same way as the authors found out that the insensitive mutant could not perceive antheridiogen.
References
• Thomas R. Warne, Leslie G. Hickok and Rodney J. Scott. (1988). Botanical Journal of the Linnean Society. Characterization and genetic analysis of antheridiogen-insensitive mutants in the fern Ceratopteris. 96 (1), 371-379.
3. The position of the archegonium and antheridum relate to their reproductivbe function by having archegonium have their eggs under them so when the antheridum sperm is dispersed it will reach the egg better. Antheridum are upright so that the sperm is dispersed on top to be able to reach the archegonium egg and fertilize the plant. They are also located near each other so that when there is rain fall the sperm splashes out and onto the atchegonium.
Nettie studied Tenebrio molitor beetles and found that unfertilized eggs in female beetles always contain an X chromosome. Sperm from male beetles contain either an X chromosome or a Y chromosome. She found that eggs fertilized by sperm carrying the X chromosome produce female beetles. The combination of egg and Y-chromosome sperm produce male beetles.
After the week our results we had unexpected results. As shown above in Figure 2 and 3, we had ended up with more planarian than expected. In Figure 3, which was the 2nd Planarian that we cut into three pieces there were about 4 different pieces that were shown. And even in the control group, which is Figure, we had more Planarian show up then we actually put in. After doing further research, there is a possible explanation to seeing more Planarians inside these petri dishes. The most realistic explanation is that the planarian that we had acquired were the type of planarian that did both asexual and sexual reproduction (Motonori et al. 2003). Since the cut planarian had grown, they had grown asexually but with the added planarian they would have been made sexually. The only other reason would be someone adding planarians to all of the petri dishes, but that is highly unlikely. So in conclusion our hypothesis that the identically cut planaria would re grow and be identical was supported by our
Pat Willmer, Pollination and Floral Ecology (Princeton, New Jersey: Princeton University Press, 2011), 536.Dressler, L. Robert. The Orchids: Natural History and Classification. Cambridge, Massachusetts: Harvard University Press, 1981.
"Persistent female choice for a particular male trait values should erode genitive variance in male traits and thereby remove the benefits of choice, yet choice persists” (Miller, Christine and Allen Moore). This phenomenon is know as the Lek Paradox and has puzzled scientists for many years. Throughout all species there has been abundant evidence showing continuous female choice of male traits, yet there is still no definite answer as to what allows for genetic variance to be maintained, and why a specific trait never becomes fixed. Many hypotheses have been theorized and researched, all providing some explanation as to how this variance in species is maintained, from traits signaling resistance to parasites, according to Hamilton and Zuk, to the hypothesis of mutational and environmental affects. Condition-dependence can also provide information as to how the lek paradox is able to exist; this hypothesis will be looked at in this paper.
The word “monotreme” is Greek for “one-hole,” referring to the cloaca that is the exit for the urinary, reproductive, and excretory systems (Dawson, 1983). The creatures are oviparous--the females lay eggs that develop outside of her body. This paper will explain the background of the animals, the anatomy of the tract and egg, breeding behavior, and genetics behind this unique reproductive system. It will pay special attention to the similarities of the monotreme reproductive system to those of animals we are more familiar with.
[2] Michod, Richard E. (1998). Origin of Sex for Error Repair. Theoretical Population Biology, 53, 60-74
For the smaller, less dominant male cuttlefish to fool their rival males, the cuttlefish disguises himself as a female through the use of the color-changing cells on his skin called chromophores. This disguise allows the male cuttlefish to sneak by the other herd of males and mate with the female. This camouflage has proven to be evolutionary advantageous as the female cuttlefish will select the “cross-dressing” male’s sperm packet 70% of the time.
Sordaria fimicola is a species of microscopic fungus that is an Ascomycete and are used to test for genetic variation in the lab setting (Sordaria fimicola: A Fungus used in Genetics, Volk). These organisms are what are called model organisms, or species that has been widely studied usually because it is easy to maintain and breed in a laboratory setting and has particular experimental advantages (Sordaria fimicola, Volk). S. fimicola, because it is in the Ascomycota phylum, have a distinguishing reproductive structure called the ascus, which is surrounded by the perithecium. This cylindrical sac-like structure houses 8 haploid spores; created through meiosis to produce 4 haploid spores and then mitosis to make 8 (Lab Manual, pg. 59-68). Based on the genotype they will vary in order and color. There are 3 different ratios that can arise from the 8 ascospores: 4:4, 2:2:2:2, and 2:4:2 (black/wild type and tan coloration). The 4:4 ratio suggests that no crossing over had occurred because there is no difference in order of the color parents that were mated. The two other ratios suggest genetic recombination, or crossing over, because of the
This diploid zygote, which undergoes meiosis, forms eight haploid ascospores. The ability of Sordaria to make 8 haploid ascospores is what makes it unique and important for the laboratory exercise done in the lab. The laboratory performed had as a purpose to determine the change in crossing-over frequency or the also called map distance under different environmental conditions in Sordaria sp. This paper has a purpose to analyze, with the help of scientific research, the results obtained in the laboratory exercise. To investigate the crossing over in Sordaria sp., a cross between two mutant strains was performed.
The traditional explication for the maintenance of sex was that the process of meiosis and fertilization engender genetic variation on which natural cull can act.
To conclude, the foremost important details of this section is that females amongst organisms are not as innocent as we assumed
Organisms need their own set of nutrients. These nutrients are what help the cell survive so that the whole organism could survive. Organisms have their own set of nutrients. On earth there are three domains of life. These domains are the bacteria, Archaea, and eukarya (Brooker et al. 2013) most of the cells that are being researched and examined are cells in the domain Eukarya because cells in this domain usually exists in a multicellular complex. In the domain eukarya, the genus that was examined in this lab was Ceratopteris, which is also called c-fern; this plant is used in research to see how plant growth is affected by various changes that affect plant growth. (Lloyd, 1973) The reason that c-fern is used to do research is because of it’s developmental process. The reason why their life cycle is so unique is because it has a biphasic life cycle that has two independent diploid and haploid generations. (Hickok et al., 1995) This is useful because the haploid and the diploid can be isolated which will provide information on how each variable effect each different stage during each life cycle. (Hickok et al., 1995) another advantage of why c-ferns are used in research is because of their short life cycle. After inoculation, germination occurs in the following 3-4 days and full sexual maturity occurs between 6-8 days after germination. After one to two weeks, roots and leaves start to appear on the diploid sporophyte. (Hickok et al., 1995) these are the main reasons why c-ferns were chosen to see the effects of nitrogen on.
Evolutionary developmental biology (evo-devo) was instituted in the early 1980s as a distinctive field of study to characterise the new synthesis of evolution hypothesis (Müller, 2007). Evo-devo is regarded as a new rule in evolutionary biology and a complement to neo-Darwinian theories. It has formed from the combination of molecular developmental biology and evolutionary molecular genetics; their integration has helped greatly to understand both of these fields. Evo-devo as a discipline has been exploring the role of the process of individual development and the changes in evolutionary phenotype, meaning the developmental procedure by which single-celled zygotes grow to be multicellular organisms. Alterations in the developmental program frequently cause differences in adult morphology. When these alterations are helpful, they grow to be fixed in a population and can result in the evolution of new phyla. Evo-devo seeks to figure out how new groups happen by understanding how the method of development has evolved in different lineages. In other word, evo-devo explains the interaction between phenotype and genotype (Hall, 2007). Explanation of morphological novelty of evolutionary origins is one of the middle challenges in current evolutionary biology, and is intertwined with energetic discussion regarding how to connect developmental biology to standard perspectives from the theory of evolution (Laubichler, 2010). A large amount of theoretical and experiential effort is being devoted to novelties that have challenged biologists for more than one hundred years, for instance, the basis of fins in fish, the fin-to-limb change and the evolution of feathers. The biology of development promises to formulate a main contribution to these...
Asexual propagation is the process through which reproduction without passage through the seed cycle occurs. The advantages of asexual propagation are that it preserves genetic makeup, propagates seedless plants, disease control, rapid production, the plants are identical, cheaper, faster and easier reducing or avoiding juvenility. The disadvantages of asexual propagation are that it increases disease and insect susceptibility, plants are bulky, and the mother plants could become contaminated. The goal of this experiment was to determine the development of adventitious roots and shoots, and observe these plants over a period of five weeks. Due to auxin being produced in the tip, tip cuttings should root faster than any other cuttings. Auxin is a plant hormone that is responsible for cell elongation and enlargement, root formation, and growth. There are two forms of auxins; phototropism, which is produced in the tip and moves downward on the side away from the light and gravitropism, which is where plant roots grow downward and plant shoots grow upward.(Plant Auxin 201...