EVOLUTION Charles Darwin

What evolution is NOT An explanation of how the universe began ONLY about “monkey to man” Addressing the change in an individual over its lifetime A description of how the first living cell came to be Mutually exclusive of faith or religion

Lamarck Law of Use and Disuse The parts of an organism that are used most frequently become stronger and better developed. This law is observable in nature The Inheritance of Acquired Characteristics The characteristics of an organism that were developed during the use and disuse (first part of the theory) would be passed on to its offspring Ex: giraffe necks This idea is false: using or practicing something does not change the DNA in an organism’s gametes!

Darwin He had a strong science background: his father was a doctor He started studying medicine but did not care for it, so began studying to be a minister instead At age 22, he applied to be the naturalist on board the HMS Beagle that was going to map the coastline of South America and Pacific islands The trip was supposed to be a 2-year break from school, but it ended up taking 5 years. He would frequently leave the ship and go inland on the islands to make observations, then rejoin the ship later.

Darwin cont. . . Darwin had been reading geological theories on the change in the Earth over time, and it got him thinking about whether populations could change over time He noticed a difference in the organisms as they traveled to various islands. The group of Galapagos Islands were the most revealing. Each one of the islands had a finch (type of bird) that was similar to another islands’ finch, but a distinct species Similar observations in comparing insects, plants and other organisms between the islands and the mainland

Darwin’s finches

Darwin cont. . . Darwin began to think that the various species had originally reached the island from the mainland, then adapted due to the isolation on the islands. He returned after the voyage and spent years studying others’ research and ideas while trying to make sense of the observations he had made on the voyage. He eventually published his book On the Origin of the Species by Means of Natural Selection

Six Points of Darwin’s Theory Overproduction Competition Variation Adaptations Natural selection Speciation

Overproduction Most species produce far more offspring than are needed to maintain the population. Not all the offspring will live to reproduce.

Competition Since living space, food, and resources are limited, offspring of each generation must compete with each other and with other species to survive. Only a small fraction can live long enough to reproduce.

Variation The characteristics of individuals in any species are not exactly alike. These differences are called variations. Many variations occur, and new ones can arise from mutations. Some variations are not important. Other variations may affect the organism’s ability to get food, escape enemies, or find a mate. These type of variations are important.

Adaptations Because of variations, some individuals will be better adapted to survive than others of the species. An adaptation is any kind of inherited trait that improves an organism’s chances of survival and reproduction in a given environment.

Natural Selection The environment selects organisms with the best adaptation Individuals with variations that are the most successful in an environment will be more likely to survive and reproduce than the poorly adapted organisms. Eventually the genes of the poor adaptations are no longer passed on as frequently in the population

Speciation

Speciation

Speciation Over many generations, the results of natural selection result in a new species because so many of the undesirable characteristics are removed from the gene pool. This is the only controversial point of evolutionary theory today! Don’t discount Darwin’s entire theory just because you don’t agree with the evidence for one point