Lamarck's hypothesis of evolution is an idea that really makes sense. He thought that a change in the environment caused the organism to evolve in order to survive. Also that through use or non use the organism develops the features needed to survive. Later the organism passes on the genes to offspring who then continue to develop the feature until perfected. Then over many generations enough differences will have occurred that it can be called a new species.
Darwin's Hypothesis was developed around the idea of natural selection. One of his ideas was on overpopulation. He says more offspring produced than what will ultimately survive and reproduce
A second idea was variation which included inheritable features that vary from individual to individual.
Also that the change in environment including climate, topography, food supply, predators, etc.
The struggle for existence he mainly thinks about the competition within the species, for food, habitat, survival from being eaten. He also believed in "Survival of the fit" (not necessarily the strongest): Those with more adaptive traits tend to survive longer
and/or produce the most offspring; these are the “naturally selected”. Inheritance of "selected" features Traits involved are already inheritable, but may involve new combinations. Also he looked at new species that were better adapted to the new environment: When the collective traits of the population differ
significantly from the earlier population, and can no longer reproduce with the earlier population.
SCENARIO A.
A change in the environment increased competition between the birds, and resulted in a
depletion of the food supply in the shallow waters. This created a need for the short-legged birds to wade into
deeper water in order to survive, which forced them to stretch their legs, because they didn't want to get knocked
over by the little waves. This stretching caused their legs to get a little longer.
When these birds produced chicks, the baby birds grew up with the slightly longer legs inherited from
their parents. These offspring birds needed to wade out even further, so they stretched their legs even more, and
made them a little bit longer yet. And their chicks grew up with even longer legs inherited from their parents.
And so on...
Eventually, after many generations of this, the legs of these birds were so much longer than the ancestral
birds that the new birds could be described as a new species.
SCENARIO B.
Within the species of ancestral short-legged shore birds, there is a range of leg lengths,
from a little bit shorter to a little bit longer than the average leg length, and these leg lengths tended to run in
families (i.e., leg length was hereditary).
A change in the environment increased competition between the birds, depleting the food supply in the
shallow waters. The birds with slightly longer legs, of course, could wade out a little farther. As a result, they
got more food, lived a little longer, and therefore produced more chicks. Those with the shorter legs would tend
to starve to death. Since the tendency for leg length was already inheritable, the surviving "long-leggers" tended
to have more long-legged chicks, which likewise tended to get more food and produce more chicks. And so
on...
Eventually, after many generations of this, the average leg length of these birds was so much longer than
in the ancestral birds (along with other connected changes) that the new birds could be described as a new
species.
1. Scenario B. looks like a result from the idea that Darwin would make because it was more of a survival of the fittest and resulted in the shore birds reproducing with other longer legged birds which resulted in more and more long legged birds which then over time created a new species.
2. Scenario A. looks like a result from the idea that Lamarck would make because it says that the birds changed themselves and the results were seen in the offspring which grew longer legs due to the stretching of the legs by the adults.
3. Darwin's idea supports the survival of the fittest while Lamarck's idea leads more to the idea of a change over time. Darwin liked the idea that when the environment changed only the special organisms from the species would survive because they were better adapted to the change in environment. Lamarck was more for the thought that the species would adapt and change on its own and at its own pace through the generations.
4.I believe that Darwin's hypothesis is more correct because it shows more of a reason for the change and makes sense in the way of how life is. If the organism is unable to live as long, they will be unable to reproduce as often and soon the more adapted organisms in the species will live and reproduce. Over time creating a new and improved species that is adapted to live in the changed environment.
5. http://www.youtube.com/watch?v=thlGxl7FdeI
Scenario A. The trees in Africa were starting to loose lower branches. Giraffe's were unable to reach the new leaves up high in the trees. Since they were unable to reach the leaves they stretched their necks out. Over time the Giraffe's neck started to grow and get longer through generations. So now they are able to reach the tall branches and leaves in order to live. (In the idea of Lamarck)
Scenario B. The trees in Africa were starting to loose lower branches. Giraffe's were unable to reach the new leaves up high in the tree's except for the occasional long necked Giraffe. Over time the shorter necked Giraffes started to starve out and die not allowing them to reproduce as often as the longer necked Giraffes. Over generations Giraffes started to have a long neck on a regular basis and a new species was made.
