Adaptation, Natural Selection and Evolution

Natural Selection Response: Natural selection has no intentions or senses; it cannot sense what a species “needs.” If a population happens to have the genetic variation that allows some individuals to survive a particular challenge better than others, then those individuals will have more offspring in the next generation, and the population will evolve. If that genetic variation is not in the population, the population may still survive (but not evolve much) or it may die out. But it will not be granted what it “needs” by natural selection. Survival of offspring that have favorable traits

Developing Theories of Evolution Lamarck did not have enough evidence and was eventually proven wrong Jean Baptiste de Lamarck was one of the first to develop a theory of evolution Lamarck hypothesized that giraffes had short necks and as grasses died their necks had to stretch to eat tree leaves, passing on that trait to offspring

Charles Darwin Why did Darwin think the finches may have had a common ancestor? Why were the beaks shaped differently? Sailed on the HMS Beagle on a 5 year expedition of S. Pacific and S. America where he discovered 13 different species of Finches and different species of tortoises on every island.

Natural Selection is a term used to describe the theory of evolution. Nature favors the organism best suited for their environment. The theory includes the following ideas. Overproduction – species produce more than can survive and not all survive because of lack of food and living space Struggle for Existence – Offspring compete and only a few will live long enough to reproduce Variation- The offspring of each generation differ, they are not exactly the same. Some are stronger or faster. Individuals in a species differ/vary Survival of the Fittest- some variation make organism better suited to survive and pass on their genetic traits/reproduce Evolution of a species – The passing on of favorable traits, make the unfavorable traits disappear creating over time a new species

Environment affects Natural Selection Insufficient resources, like living space, food and water – when organism compete the stronger, faster will survive to pass on their traits Human Activities such as hunting and construction can use up the resources or cause extinction Pollution caused the black peppered moths to blend into the soot covered trees in England, so the gray ones were eaten, now England cleaned up its soot and the gray moth population has risen Extinction occurs when organisms can not adapt to their environment and they die out with out reproducing and passing on their traits. Over hunting and fishing by humans can cause this also.

Humans have changed over time Anthropology the study of the development of man and society. Human like fossils have been discovered dating back 3.5 million years old. Fossil evidence shows related species date back 6 million years. All modern humans are Homo sapiens Earlier man are called Neanderthals ( sloping foreheads and heavy brow ridges, 130,000 – 35,000 years ago) and Cro- Magnons ( look like modern man, 35,000 – 10,000 years ago)

Man Changes Neanderthal