Since then, tons of soot have been deposited on the country side around industrial areas. The soot discolored and generally darkened the surfaces of trees and rocks. By 1819, the proportion of dark moths in the population had increased significantly. Researchers found that the light-colored lichens covering the trees were being killed by sulfur dioxide emissions from the new coal burning mills and factories built during the industrial revolution. Without the light colored background of the trees to protect them from the predatory birds, the light colored moths were more visible and lost their selective advantage to the dark colored moths.
The cane toad or Bufo Marinus is native specie to Central America and South America. In 1935, after the cane toad was intentionally introduced from Hawaii, the species began its ecologically sustainable control of the insects (greyback beetle, frenchi beetle) threatening commercial sugar cane, it continued to eradicate, but in a form as a problematic issue. Due to the animal’s large dominant size, reproductive capabilities, generalized eating habits and aggressive behavior, the cane toad phenomenon went from good to disastrous, providing a threat to biodiversity. The cane toad has been reclaimed as an ecological disaster after it has mounted a very successful intrusion into Australia and many other countries around the world. In addition,
It all depends on how sensitive the mean is, for example when it is very sensitive in the extreme values and the distribution is not symmetrical, and the mean will be away from the center and more near the extreme values. In statistics normality is important so the underlying population is normally distributed. (Doane & Seward, 2007) * What effect does sample size, n, have on the estimate of the mean? Is it possible to normalize the data when the population shape has a known skew? How would you demonstrate the central limit theorem to your classmates?
In order for the experiment to be valid it would require an experimental condition and a control condition. A control condition in an experiment is a comparison condition in which participants are not exposed to the same treatment as in the experimental condition. Without a control condition, you cannot be sure that the behavior you are interested in would not have occurred anyway, even without your manipulation. Subjects should be randomly assigned to the experimental and control groups. If a control group doesn’t exist, then there is nothing to compare the experiment to.
Explain and evaluate the effects of the ‘black death’ on late medieval society with reference to the manorial system and the ‘peasant’s revolt’. England in the early fourteenth century was a nation in decline; climate deterioration began around 1300, with colder winters and wetter summers. These conditions combined with rife over-population, eight million people lived in England and Ireland alone - compared to the 12th Century where the population was closer to half that, only four million (The Middle Ages 1154 to 1485, page 1). Both of these were later contributing factors to the Great European Famine of 1315 - 1322, in which millions perished. On top of this, Edward III began the Hundreds years war causing widespread dissatisfaction and grief on a mass scale.
Industrial decisions, such as the addition of lead to paints, dyes, and gasoline, have created an epidemic of lead poisonings. Lead is a naturally occurring substance and can be found in organic and inorganic forms. Lead is a reproductive toxicant detrimental to human semen quality. Decreased sperm count, motility, acid phosphatase, succinic dehydrogenase, fructose, surface reaction of sperm head DNA besides increasing abnormal sperms was reported in occupational exposure of lead in printing press workers in India. Higher lead level lowers sperm’s ability to bind and fertilize the egg.
Is the human species a keystone species? Explain. If humans were to become extinct, what are three species that might also become extinct and three species whose population would probably grow? Humans are likely a keystone species by virtue of their technology and the extreme manner in which they influence their habitat. Were we to become extinct, their domesticates would most likely not survive.
His book, The Origin of Species, was published in 1859, and stated that populations evolve over the course of generations through a process of natural selection. This book was controversial because it contradicted the religious beliefs that underlay the then current theories of biology. Darwin’s theory says that in species that sexually reproduce, no two individuals will be identical. A lot of this variety in offspring is inheritable, and may affect ones ability to survive in a given environment. He says that those who are less adapted to their environment will have less of a chance of surviving and less likely to reproduce.
Misconceptions about Evolution Natural Selection Many People are oblivious to the key elements of how evolution and natural selection play a part in our own world; creating misconceptions of various prospects of survival skills. When we think of survival skills, many unknowingly mishap one of the most influential fundaments of natural selection, which consist of traits that help individuals survive and reproduce in a given environment to survive with constant changes over time; also known to be one basic mechanism of evolution ( “Evolution 101 :Natural Selection”). Understanding natural selection is not as difficult as some may perceive it to be, discoverer Charles Darwin came up with an accessible concept to rationalize the whole progression. In 1859, he published “One the Origins of Spices by Means of Natural Selection” (Park pp45), which explained the natural process of how species come and go through various phenomenon changes and still exist. There are two other selections known as artificial selection, meaning a selection for reproductive success in plants and animals that is directed by humans (Park pp53);and there is sexual selection which acts on an organism’s ability to obtain or successfully copulate with a mate (Evolution 101).
Weaknesses of Causal Comparative Two weaknesses in causal-comparative research are lack of randomization and inability to manipulate an independent variable. A major threat to the internal validity of a causal-comparative study is the possibility of a subject selection bias. The chief procedures that a researcher can use to reduce this threat include matching subjects on a related variable or creating homogeneous subgroups, and the technique of statistical matching. Other threats to internal validity in causal-comparative studies include location, instrumentation, and loss of subjects. In addition, type 3 studies are subject to implementation, history, maturation, attitude of subjects, regression, and testing threats.