Sci 275 Week 4

Topics: Americas, Population, North America Pages: 1 (362 words) Published: May 5, 2010
The four factors that produce changes in population size includes on a global scale, the change in population is due to the number of births and deaths. However, in the local populations, like in the United States, the number of births, deaths, immigrants, and emigrants will affect the population size. The factors that affect population size in the video include but not limited to when the importation of the animals like the Nutria (Myocastor coypus) which are actually native to South America. Brought to the Americas as a potential fur-bearer in the 1930's then in turn, as the fur market declined the overpopulation began. In addition to importation, the adult female Nutria in an average three-year span will have 30 to well over 30 babies; those babies will breed and have babies. “Nutria weighs an average of 12.0 pounds (5.4 kg). Females have four pairs of mammary glands that are located on the side of the body, rather than on the belly. Presumably, this positioning of the mammary glands allows the young to nurse with their nose above the water's surface while the mother is floating” (Nutria.com). The average adult Nutria eats at the least ¼ of their own body weight. “In most of the world, the animal is called coypu, but in North America, the animal is called nutria. In the rest of the world, nutria is the name of the fur of the animal”. (Nutria.com) After all the wetland, damage has been done and “vegetation is removed from the surface of the marsh, as a result of over grazing by nutria, the very fragile organic soils are exposed to erosion through tidal action. If damaged areas do not revegetate quickly, they will become open water as tidal scour removes soil and thus lowers elevation. Frequently the plant's root systems are also damaged, making recovery through vegetative regeneration very slow”. (Nutria.com) I think the Nutria will eventually die of starvation if they do not move on to different areas, they could possibly move to areas other than wetlands...
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