BioSec: Evolution - Revision history

Dsouza3190: /* CHAPTER III. STRUGGLE FOR EXISTENCE */

2012-02-06T21:33:27Z

CHAPTER III. STRUGGLE FOR EXISTENCE

← Older revision		Revision as of 21:33, 6 February 2012
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	== CHAPTER III. STRUGGLE FOR EXISTENCE ==		== CHAPTER III. STRUGGLE FOR EXISTENCE ==
	(Cheryl)		(Cheryl)

			In this chapter Darwin explains how different species are created. His entire argument is based on two concepts: the struggles for existence and natural selection.

			He explains the struggle for existence is the reason why some species’ characteristics survive and other go extinct. In addition, he notes that the huge amount of variation in species has permitted for species to adapt very well to their environments. That is, due to the unique characteristics that certain organisms have developed they can thrive in their specific environment. In addition, Darwin notes that only the characteristics that prove to be most advantageous is passed from one generation onto the next. The second concept, natural selection, is the result of these particular advantageous characteristics still present.

			Other concepts that Darwin explains in this chapter is the struggle for life and the limits of population increase. Nature can provide enough food and shelter for all the species that is inhabitants and at the same time be very destructive (natural disasters, animals prey on other species, etc.). This in turn causes species to struggle for their lives, and essentially prohibits some organisms to survive. The concept of limits of population increase (borrowed from Thomas Malthus) basically states that each generation of increases the population of the species exponentially, which in turn implies that the population of the entire world is increasing constantly. However, this poses the problem of the world running out of room for the species to occupy. That is if the birth rate increases exponentially while the death rate remains the same from one generation to the next. This is not the case in reality, thus there must exist a limit that nature imposes on the total number of inhabitants. This in turn gives rise to competition, where each species must compete with each other in order to ensure that they survive thus threatening the survival of the other species.

	== CHAPTER IV. NATURAL SELECTION; OR THE SURVIVAL OF THE FITTEST ==		== CHAPTER IV. NATURAL SELECTION; OR THE SURVIVAL OF THE FITTEST ==

Dsouza3190: /* CHAPTER II. VARIATION UNDER NATURE */

2012-02-06T21:27:14Z

CHAPTER II. VARIATION UNDER NATURE

← Older revision		Revision as of 21:27, 6 February 2012
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	== CHAPTER II. VARIATION UNDER NATURE ==		== CHAPTER II. VARIATION UNDER NATURE ==
	(Cheryl)		(Cheryl)

	In this chapter Darwin basically answers the question: Can variation in species that are present in nature be considered similar to variations that are present in domesticated species?		In this chapter Darwin basically answers the question: Can variation in species that are present in nature be considered similar to variations that are present in domesticated species?

Dsouza3190: /* CHAPTER II. VARIATION UNDER NATURE */

2012-02-06T21:27:05Z

CHAPTER II. VARIATION UNDER NATURE

← Older revision		Revision as of 21:27, 6 February 2012
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	== CHAPTER II. VARIATION UNDER NATURE ==		== CHAPTER II. VARIATION UNDER NATURE ==
	(Cheryl)		(Cheryl)
			In this chapter Darwin basically answers the question: Can variation in species that are present in nature be considered similar to variations that are present in domesticated species?

			He starts answering this question by describing three types of variations. The first type is what he calls monstrosities. These are variations that occur naturally in nature but are not really helpful in terms of survival or development of the species. In some instances, these variations are even harmful for the particular species. In the second case, variations are said to be driven due to environmental change (i.e. climate, temperature, etc.). Lastly, variations are the result of a small variation in genes that are passed from parents to their offspring. Darwin states that the first two cases of variations are most likely not passed from parents to offspring, while the third is.

			The problem lies when trying to differentiate variations within a species from variations that imply the existence of two distinct species. Darwin notes that it is next to impossible to distinguish between varieties within a species. The solution to the problem is somewhat vague but clear enough to distinguish between varieties: “The amount of difference between species must be greater than the amount of difference between varieties within the species”.

			Lastly, Darwin concludes by noting that variations are more likely to occur in a large sample. He does this by arguing that each species is not an act of God. Because if it were an act of God, there would be no real difference in the amount of variety between the smaller and larger groups of species.

	== CHAPTER III. STRUGGLE FOR EXISTENCE ==		== CHAPTER III. STRUGGLE FOR EXISTENCE ==

Elizabeth: /* CHAPTER VII. MISCELLANEOUS OBJECTIONS TO THE THEORY OF NATURAL SELECTION */

2012-01-20T22:03:27Z

CHAPTER VII. MISCELLANEOUS OBJECTIONS TO THE THEORY OF NATURAL SELECTION

← Older revision		Revision as of 22:03, 20 January 2012
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	== CHAPTER VII. MISCELLANEOUS OBJECTIONS TO THE THEORY OF NATURAL SELECTION ==		== CHAPTER VII. MISCELLANEOUS OBJECTIONS TO THE THEORY OF NATURAL SELECTION ==
	(Elizabeth)		(Elizabeth)

			This chapter examines in further detail some more objections to Darwin's theory of natural selection, and Darwin's response and defence against the criticism. Most of the defences in this chapter are aimed at specific criticisms, and Darwin responds to specific authors. The bulk of the chapter is aimed at the criticisms of St. George Mivert, who took it upon himself to collect together objections to the theory. Most of Mivert's questions relate to the question of where the initial components of natural selection come from. Darwin's response is usually to give a collection of examples illustrating how the feature in question 'could' have developed, but in general, these are questions about the theory that have no clear answer.

	== CHAPTER VIII. INSTINCT ==		== CHAPTER VIII. INSTINCT ==

Malsharn: /* CHAPTER XII. GEOGRAPHICAL DISTRIBUTION */

2012-01-20T09:02:19Z