Science

= Science =

Shari - Describe in detail Darwin's theory of evolution. Be sure to include information about his voyage on the Beagle.
On december 27,1831, Darwin sailed on the H.M.S. Beagle from England to survey the coast of South America.He sailed through the Atlantic ocean, to Australia and to the Galapago's Islands. While he was at Galapago's Island Darwin repeatedly saw patterns in how kinds of animal's and plants differed, patterns suggesting that species changed over time and gave rise to new species.Also during his journey, Darwin often left the ship to collect specimens of animals, plants,and fossils. He made careful observations and recorded them in a journal.what Darwin saw on his voyage led him to doubt the idea that species were constant.

Carol - What evidence is there to support Darwin's theory of evolution?
Evidence of Darwin's theory of evolution can be proofed by many sources including studies of fossils, comparisons of the structures of organisms, and the rapidly expanding knowledge about DNA and proteins. Fossils are traces of dead organisms. Scientists have discovered tracks of dinosaur footprints, footprints of human ancestors, insects, and lots of other animals. Evolution is a very slow process. The ages of the fossils are determined upon radioactive dating. Radioactive dating measures the amount of radioactive decay or breakdown of atoms in the rock. Using radioactive dating scientist have determined that the earth is about 4.5 billion years old, ancient enough for all species to have been formed though evolution. Darwin's prediction was that transitional forms between older and newer species would be found in the fossil record. When T//__he Origin of Species__// was published, no intermediates were found. Now there are many good examples of evolutionary transitions. One more example is the modern whale. Whales have a vestigial pelvis that serves no function. This pelvis is a remnant of the whales evolutionary past. They are the decedents of four-legged land animals that are also the ancestors of horses and cows. Fossil intermediates between modern whales and their 60- million year old ancestor show a history of slow transformation. The bones in the front limbs of a bird, a dolphin, and a human are homologous structures. Homologous structures are structures that share a common ancestry. Homologous structures are similar because they are modified versions of structures that occurred in a common ancestor. That is the evidence to support Darwin's theory of evolution.



Bill - Define and and describe the steps of natural selection.
Natural selection is the process by which organisms best suited to their environmental conditions are most likely to survive and reproduce. The steps of natural selection is the variation is the raw material for natural selection Individuals differ cause they carry different alleles for certain traits Example is giraffes were born with alleles for varying neck lengths and some had longer necks than others, living things face a constant struggle for existence Organisms produce more offspring than survive and the offspring emerge into a hostile world where they must evade predators and compete with other individuals for food and living space Example is giraffes with longer necks could reach the leaves in tall trees and shorter necks should not, only some individuals survive and reproduce Some individuals are better able to survive challenges of life than others Example is giraffes with longer necks were better at getting food than giraffes with shorter necks, natural selection results in genetic change each generation consists of the offspring of individuals that successfully reproduce Example is more long necked than short necked giraffes were being born and longed neck giraffes are common and the short necked giraffes become rare and eventually longed necked giraffes replaced short necked giraffes, and species adapt to their environment selection tends to make a population better suited to its environment Example long necked giraffes are well suited for browsing on foliage of tall trees which is out of the reach of most other animals. ======

Matt - Describe the formation of new species, contrast hypothese of punctuated equilibrium and graduation.
The hypothesis that evolution occurs at a slow constant rate is known as gradulism. The hypothesis that evolution occurs as such a irregular rates is know at punctuated equilibria. According to the hypothesis of gradulism the differences between species 1 and 2 accumulated slowly over a long period of time. According to the punctuated equilibria hypothesis the differences between the species evolved rapidly during the relatively short period of time in which the species were forming. After each species formed, it did not change for a long period of time. Because natural selection favors changes that increase an organisms chances of surviving and reproducing, it will continulously shape a species and its enviroment. Over time seperate populations of species can eventually become quite distinct if their environment differ enough. Members of different ecological races are not yet different enough to belong to different species but they have taken the first step.