The purpose of this essay is to explore some of the mechanisms involved in the seed dispersal in plants. Plants are some of the most ancient biological organisms on the planet, and over the millennia they have adapted to utilise both the natural resources of the earth and the animals on it in order to spread their seeds. Without a variety of processes plants would be restricted to localised geographical areas, and this would limit their populations. This essay discusses some of the major ways that seeds can be dispersed: wind, water, animals, and gravity. It then includes a brief discussion of the changing globalised landscape, and where this discussion is located in contemporary discourse. The essay closes with a short conclusion.
Biological dispersal describes the movement of individuals (such as animals, plants, and bacteria), and propagules (such as seeds and spores) [1]. Three active phases have been recorded: departure, transfer, and settlement [1]. Each of these contains various different fitness benefits and costs, and as such many different dispersal mechanisms have evolved. Some of these are very easy to see, such as a number of species of Taraxacum, particularly T.officinale [2]. T.officinale's seeds disperse via wind following a mechanism where the dried petals fall away, the bracts reflex, and the parachute ball opens into a full sphere of modified sepals known as pappus which allow the seed to safely drift away into the air. The efficiency of the biological dispersal of T.officinale is such that it has become the bane of gardeners throughout temperate climates, partly because evidence suggests it is resistant to variables such as horizontal variables such as wind speed [3]. However, there are many other innovati...
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... waters: the growing evidence. Acta Oecologica, 37(6), 561-577.
11. Dumais, J., & Forterre, Y. (2012). “Vegetable Dynamicks”: The Role of Water in Plant Movements. Annual Review of Fluid Mechanics, 44, 453-478.
12. Soomers, H., Karssenberg, D., Soons, M. B., Verweij, P. A., Verhoeven, J. T., & Wassen, M. J. (2012). Wind and Water Dispersal of Wetland Plants Across Fragmented Landscapes. Ecosystems, 1-18.
13. Schupp, E. W., Jordano, P., & Gómez, J. M. (2010). Seed dispersal effectiveness revisited: a conceptual review. New Phytologist, 188(2), 333-353.
14. Clobert, J., Baguette, M., Benton, T. G., & Bullock, J. M. (Eds.). (2012). Dispersal ecology and evolution. Oxford University Press.
15. Finkeldey, R., & Hattemer, H. H. (2007). Tropical forest genetics. Springer.
16. Dennis, A. J. (Ed.). (2007). Seed dispersal: theory and its application in a changing world. CABI.
Reproduction and passing on genetic and behavioral traits to an offspring is a common fundamental to all the species on this planet. When studying forest ecology, it is crucial to study the proportion of individuals surviving at each stage of their growth as the lives and mortality experienced in a species population describes a characteristic of the species in question. In the case of American beech and sugar maple, their attempt to produce seeds is analogous to entering lottery, where every seedling has a potential chance of becoming a canopy but only some will survive and reach the canopy size; thus, becoming the fit ‘winners’. Our information shows that together, based on size class distribution, both the species display a ‘winner takes all’ pattern, which supports our hypothesis. The results showed a greater count for seedlings and short saplings than for tall saplings, sub-canopies and canopies. This is evident for a Type III survivorship curve. In Type III curve all individuals initially having a very low chance of survival. However, once the individuals pass their threshold age and survive, they live an advanced age. Only some individuals out the mast seeding production mature to become fully fit canopy trees. On the other hand, our hypothesis of canopy trees representing the bulk of the biomass was supported as the basal areas decreased going from growth stages of canopy to seedlings. This is evidence that once the individuals survive the bottleneck where there is high mortality of young individuals (seedlings), who are then considered as ‘losers’, will allow for the other larger size class individuals to flourish. Here, having considerable amount of dbh (diameter at breast height) accounts for greater surfac...
Allen, John S., and Susan C. Anton. "Chapter 13 The Emergence, Dispersal, and Bioarchaeology of H. sapiens." Pearson Custom Anthropology. By Craig Stanford. Boston: Pearson Learning Solutions, 2013. 200+. Print.
...ough genetic variability is generally a good quality, sometimes plant characteristics that are considered favorable by commercial propagators can be lost through genetic mutation during sexual reproduction of seed propagation. Also, sexual propagation through seeds is not always feasible for commercial propagators because of the length of time from germination until you have a fully developed plant (Horticulture, 2014).
Fragmentation is the product of increased human population, and the expansion of the grasslands (due to human activity). Fragmented Population caused from human interference has led to a lack of gene flow within species. Although this problem poses a legitimate threat, no real action has been taken to prevent fragmentation from continuing. Human activities such as “the expansion of farmland, human occupation, the lack of accessible habitat, and the sparsity of suitable/favorable habitat” (Thalmann et al., 2011) are facilitating this critical issue. Lacking gene diversity is caused from extreme isolation, small numbers, and lack of gene flow (Thalmann et al., 2011).
technology. When they wanted to plant or to crush the seeds that they have gathered they used a
Acer palmatum has many different varieties that have different colors, leaf shapes, and growth habits. The tree openly pollinates, which means that seeds from a specific cultivar will not be an exact clone of the parent tree. For this reason, propagation f...
Humans have long recognized that flowers are an indication of future fruits. Therefore it was vital for nomadic hunters to remember where in the wild they saw flowers. And further yet each type of flower produced a specific fruit. Thus fruits and flowers had something in common; the preference of one fruit meant the preference of a type of flower. Most often, as in modern times, the most healthy looking flower shows signs that it will produce quality fruit. The beauty of a flower told hunters that a nutritious fruits would ripen after the flowers bloomed. This concept explains how we have evolved toward preferring healthy looking flowers. But how does this explain the security of a plants reproduction? It is necessary to mention that plants not only produce fruits to stop herbivores from eating the plant, but in their own diabolic plan, plants found a new way to spread their seeds through fruits. Herbivores would eat the fruits an...
Discerning the spatial patterns of biodiversity and understanding their ultimate (why) and proximate (how) causes is very dear to biogeography and is one of the key concepts of Macro ecology. Some places on earth contain more species as compared to others. All species occurring at a given space and time either originated (speciated) there or dispersed and arrived from another place and settled there. Biogeographers try to understand the past and current distributions of species by incorporating historical, evolutionary and ecological factors. Earlier biogeographers or the ‘naturalists’ in their sacred quest to serve ‘the creator’, travelled to various parts of the world and imparted valuable knowledge about the diverse patterns and processes of nature. Linnaeus (1743), on the one hand, hypothesized that early Earth was filled with water except for it’s highest mountain top i.e., Mount Ararat which was known to be the site of paradise and as the sea level dropped the exposed land was colonized by plants and animals that migrated down from high elevational zones of Mount Ararat whereas Willdenow (1805) hypothesized that within each geographical region of the earth, plants and animals were first placed and later survived the great flood on many mountain ranges (Lomolino,2001). Von Humboldt and Darwin in the South American Andes and Wallace Southeast Asian islands noticed the decreasing trend in elevational species richness patterns (McCain and Grytnes, 2010). Later work done by Grinnell (1917), Whittaker (1952), Terborgh (1977, 1985) on elevational species richness became accepted and set a established pattern for all species for more than two decades (McCain and Grytnes, 2010). However current researches on elevational gradients are...
It scattered on the hard footpaths where it had no chance to take root, on the thin soil above the limestone rock, in the soil with the thorny roots, and some in the rich soil, which was free from such. The birds ate the seeds that lie exposed on the hard footpaths. (B, 285; C, 74; D, 672; H, 165) " Here the soil had different capacities, but each yielded a good harvest according to its ability." (Hobbs, 165) "
The cause of this change in mass is called osmosis. Osmosis is the movement of water. through cells in plants. I make my prediction on the pretext that water diffuses from high concentration cells to low concentration. cells.
Flowering plants have two main reproductive parts; the male part is called the stamen and produces pollen, while the female part is called the pistil. For pollination to occur, the pollen must be transferred from the stamen to the pistil. This transfer can occasionally be caused by wind, but it is most often facilitated by animals called pollinators. Pollinators do not intentionally set out to fertilize flowers; rather, they unintentionally spread pollen while roaming from plant to plant in search of food. There are many different species – including birds, butterflies, and bats – that act as pollinators, and many of these species are also suffering declines in population. However, honeybees are the most pr...
The plants that we know today as terrestrial organisms were not always on land. The land plants of today can be linked back to aquatic organisms that existed millions of years ago. In fact, early fossil evidence shows that the earliest land plants could have arisen some 450 million years ago (Weng & Chappie 2010). Plants that used to reside strictly in water were able to adapt in ways that allowed them to move onto land. It is speculated the need for plants to move onto land was created by water drying up, causing plants to have less room and pushing them to move onto land. Although the exact cause of plant’s need to move to a terrestrial environment is unclear, it is known that plants had to undergo several adaptations to be able to live on land. These adaptations include: lignin, cellulose, suberin, and changes to plant’s surface, including the formation of a waxy cuticle.
Zacherl, Danielle. “Biology 171 Evolution and Biodiversity.” National Association of Research in Science Teaching 2007 Annual Meeting, New Orleans LA. (2007):n. page. Print.
Insect pollination as we all know, is the process that enables reproduction and fertilization by the transfer of pollen performed by insects. Insects are some of the oldest pollinators of plants. Pollinating insects date back to 140 million years ago. Since then, due to how effective insect pollinators are, these flowering plants have become the major group of terrestrial vascular plants. Flowering plants, also known as angiosperms, have imperative roles within our ecosystems, both natural and agricultural. For instance, insects provide food, fiber and shelter for wildlife and humankind alike (2007). It is commonly know that in humans, high levels of fruit and vegetable consumption are associated with decreased risk of chronic disease (Calderone 2012). Aside from these important roles, plants have also been considered as a viable option for fuel sources (Calderone 2012). There are around 300,00 species of flowering plants in the world and without pollination, the reproductive process would be very difficult since pollination causes the production of seeds (Calderone 2012). Of the 300,000 plant species worldwide, a little over 3,000 of these plants have been used as a source of food. Close to 300 of these species are grown around the world today and only 12 of these plants make up about 90 percent of the food sources in our world. These 12 include the grains...
For many years, nature has cloned organisms. When a plant sends out a stalk and it takes root, the new ...