One Variety Within A Species example essay topic

Differences within a species are indistinguishable at first, but gradually may develop into variety that can restrict one group', range or ability to get food or escape predators... Thus, "varieties tend to become converted into new and distinct species... and throughout nature the forms of life which are now dominant tend to become still more dominant by leaving any modified and dominant descendants". Chapter : Struggle for Existence. ".. When a plant or animal is placed in a new country amongst new competitors, the conditions of its life will generally be changed in an essential manner... If its average numbers are to increase... we should have to give it some advantage over a different set of competitors or enemies".

Each natural being is striving to multiply to be strong, healthy, and to survive - often at the expense of members of its own species or those of a competing species. Chapter IV: Natural Selection; or the Survival of the Fittest The "fitness" of a species is modified by several special processes. For example, sexual choice may occur when males of a population must compete with other males to possess mates. Those possessing some advantage -better weapons, greater energy, or more beautiful song or plumage - are more apt to survive or attract a mate, likely to leave the most progeny.

Over time, such gradual version, along with changing conditions and outside struggle, can cause "an infinite diversity in structure, constitution, and habits, advantageous to one set of offspring over another, or to one variety within a species over another. "This principle of preservation, or the survival of the fittest, I have called Natural Selection... " As buds give rise by growth to fresh buds, and these, if strong, branch out and overtop on all sides many a feebler branch, so by age group I believe it has been with the great Tree of Life, which fills with its dead n d broken branches the coating of the earth, and covers the surface of the planet with its ever-branching and beautiful ramifications. Chapter V: Laws of Variation Reproductive "chance" creates differences. When the conditions of a species alter, those individuals that survive to duplicate may have beneficial modifications - organs or limbs that either become more strong or more useful, or else, when not needed for endurance, weakened and diminished. This is not to say, however, that the development of organs serving little purpose does not occur; it most certainly does.

The human appendix may demonstrate just such a process phenomenon. But any variation within a species is, unavoidably, a long, slow process. Chapter V : Instinct Usual instincts are inherited within each species. Ants and bees build their nests and hives with no previous knowledge. Birds migrate and build homes according to their exclusive inner senses. But instincts too may change over time as "consequences of one general law leading to the advancement of all organic beings... multiply, vary, let the strongest live and the weakest die".

The rest of the book deals with related topics: hybridism; living species compared to those of early geological periods; extinction; geographical sharing of organisms; relationships between species; and the sorting of organisms. Objections to the general theory of evolution are presented in both Darwin's conclusion and dictionary of terms.