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.
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
2)Campbell, Neil A., and Jane B. Reece. Biology. San Francisco, CA: Benjamin Cummings, 2008. Print.
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.
Holt, Ben F. and Gar W. Rothwell. 1997. Is Ginkgo biloba really an oviparous plant? American Journal of Botany 84(6): 870-873.
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.
of this species, but it is believed to spawn externally. This means that the males
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.
Sexual reproduction is that the union of male and feminine gametes to create a fertilised egg or zygote. The ensuing offspring inherit one-half their traits from every parent. Consequently, they 're not genetically similar to either parent or siblings, except within the case of identical twins. As theorised by Mendel, adults are diploid, meaning as 2N, having 2 alleles offered to code for one attribute. The gametes should be haploid, signified by N, containing just one allele in order that once 2 haploid gametes mix, they manufacture a traditional diploid individual. The method where haploid sex cells are created from diploid parents is known as meiosis, and it happens solely within the reproductive organs.
Bracken fern (Pteridium aquiline var. pubescens) are deciduous and grow from brown to black woody rhizomes, forming large often dense patches. The leaves emerge from erect fronds and are pinnately compound, scattered, erect, coarse, narrowly or broadly triangular, to 2 m in height. Fronds (leaves) are pinnules (ultimate segments), entire in the apices of the pinnae, lobed toward the stalk. Reproduction is by spores produced in sporangia lining the under surface margins of the photosynthetic fronds when reproductive, covered by the narrow recurved edge of the leaf (Burrows and Tyrl, 2001, Panter et al., 2011).
As you can see, it is important to research sexual selection across various species’. Similar mechanisms of selection are present in all animals. By learning how these mechanisms act in one species, it is possible to gain insight into the behavior of all animals, including human beings.
I also did a stem and leaf diagram which shown me that most males were
Grävingholt, J. (1999b). Regionale Autonomie und postsowjetischer Autoritarismus: Die Republik Baschkortostan. Teil II: Herrschaftspraxis und föderale Beziehungen. Berichte des Bundesinstituts für ostwissenschaftliche und internationale Studien 17. Köln: BIOst.
When mosses and liverworts first evolved, they dominated the terrestrial environment. But they were soon challenged by the more advanced tracheophytes. The ferns and "fern allies" formed the great planetary forests of the late Paleozoic. By the end of the Paleozoic, a new group of plants was challenging the 150 million-year domination of the ferns and fern allies. The seed plants protected the embryonic sporophyte from drying up by encasing it in a tough waterproof seed coat. The evolution of the seed is as profound a step as the evolution of the shelled egg in reptiles. Just as the evolution of the amniotic egg enabled reptiles to become the first truly
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...