Darwin wondered if the different species of finches could have descended from a mainland finch.
He wondered if a finch from South America was the same as the types on the Galapagos Islands.
The geographic distance between the islands' isolated populations of birds may have led to the emergence of new species.
The present-day species may have been the result of accumulated changes within each isolated population.
The species change over time and are not fixed entities created by a creator.
He didn't have a way to explain how change could happen in existing species and how new species could arise.
Darwin's idea of natural selection as a mechanism for evolutionary change was fully developed by 1842.
Alfred Russel Wallace proposed a similar concept to Darwin in 1858.
Wallace's views on evolutionary change were helped by eight years of collecting and identifying thousands of species in the Malay Archipelago.
Darwin and Wallace presented the idea of natural selection to the Linnean Society of London in 1858.
Organisms adapt to changing conditions.
In the sections that follow, we consider each of these characteristics.
The members of a population have different functional, physical, and behavioral characteristics.
Variations were not important to the description of "fixed" species and should be ignored.
Darwin emphasized the need for variation in the process of natural selection.
He suspected that there was a mechanism of inheritance, but he didn't have the evidence to support it.
Natural selection requires variation in populations in order to adapt to the environment.
The unit of heredity and the environment are what genes are.
Random mutations can be a source of new genetic variation.
Genetics can be harmful, helpful, or neutral to reproduction.
New variation is as likely to be harmful as helpful or neutral to the organisms when it comes to genetic variation.
Natural selection eliminates harmful variation from the population due to the fact that individuals with these changes often do not survive or reproduce.
In a population, beneficial or neutral variation can be maintained.
Natural selection ignores neutral variation.
There is a chance that an individual will have greater reproductive success if they have a beneficial mutation.
Natural selection operates on heritable variation already present in a population's gene pool, and it has no goal of "improvement" in anticipation of future environmental changes, according to biologists.
Malthus's work on population growth was applied to animal populations by Darwin.
He realized that if all offspring were to survive, there wouldn't be enough resources to support the population.
Assuming an average life span of 100 years and a breeding span of 30-90 years, he calculated the reproductive potential of elephants.
No environment has the resources to support an elephant population of this size.
The geometric ratio of increase is often referred to as the overproduction potential of a species.
Some people have good qualities that allow them to compete for limited resources.
The individuals with favorable traits have more resources and can devote more energy to reproduction.
The most fit individuals capture a larger amount of resources and convert them into a larger number of viable offspring.
Different factors for different populations affect fitness.
The people who live on desert soil are the most fit because of their light coloring.
It is expected that background matching will lead to survival and increased fitness.
The Page 268 population has a variation that allows certain members to survive and reproduce more than other members.
A variation in a desert plant that reduces water loss is beneficial, while a wild dog that increases its sense of smell is beneficial.
The trait that helps an organisms be more suited to its environment is an evolved trait.
Seemingly unrelated organisms living in the same environment display similar characteristics.
Sea turtles have flippers, which help them move through the water.
Other ways in which penguins are adapted to their environment were shown in Section 1.1.
A Venus flytrap, a plant that lives in the nitrogen-poor soil of a bog, is able to get nitrogen-containing nutrients because it has specialized leaves that are adapted to catch and digest flies.
Natural selection leads to the adaptation to specific environments.
Each succeeding generation can cause adaptive traits to increase in frequencies.
Natural selection is the only adaptation process that results in the environment.
Humans can modify desired traits in plants and animals by breeding certain individuals.
Natural selection is possible only because the original population has a variety of characteristics.
Many of the dogs we see today are descended from the wolf.