What Makes Some Individuals More Likely to Survive and Have Offspring?
18.1B: Charles Darwin and Natural Selection
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Charles Darwin and Alfred Wallace independently developed the theories of evolution and its main operating principle: natural selection.
Learning Objectives
- Explicate how natural pick can lead to evolution
Fundamental Points
- Wallace traveled to Brazil to collect and observe insects from the Amazon rainforest.
- Darwin observed that finches in the Galápagos Islands had dissimilar beaks than finches in South America; these adaptations equiped the birds to learn specific food sources.
- Wallace and Darwin observed similar patterns in the variation of organisms and independently developed the same explanation for how such variations could occur over time, a machinery Darwin called natural selection.
- According to natural selection, also known as "survival of the fittest," individuals with traits that enable them to survive are more reproductively successful; this leads to those traits becoming predominant inside a population.
- Natural selection is an inevitable outcome of three principles: most characteristics are inherited, more offspring are produced than are able to survive, and offspring with more than favorable characteristics will survive and have more offspring than those individuals with less favorable traits.
Key Terms
- natural selection: a procedure in which individual organisms or phenotypes that possess favorable traits are more probable to survive and reproduce
- descent with modification: change in populations over generations
Charles Darwin and Natural Pick
In the mid-nineteenth century, the mechanism for evolution was independently conceived of and described by two naturalists: Charles Darwin and Alfred Russel Wallace. Importantly, each naturalist spent fourth dimension exploring the natural world on expeditions to the torrid zone. From 1831 to 1836, Darwin traveled around the world to places similar S America, Commonwealth of australia, and the southern tip of Africa. Wallace traveled to Brazil to collect insects in the Amazon rainforest from 1848 to 1852 and to the Malay Archipelago from 1854 to 1862. Darwin'south journey, equally with Wallace's subsequently journeys to the Malay Archipelago, included stops at several island bondage, the last being the Galápagos Islands westward of Ecuador. On these islands, Darwin observed that species of organisms on different islands were conspicuously similar, yet had distinct differences. For case, the ground finches inhabiting the Galápagos Islands comprised several species with a unique beak shape. The species on the islands had a graded series of beak sizes and shapes with very pocket-sized differences between the virtually like. He observed that these finches closely resembled another finch species on the mainland of Southward America. Darwin imagined that the isle species might be modified from one of the original mainland species. Upon further study, he realized that the varied beaks of each finch helped the birds acquire a specific type of food. For example, seed-eating finches had stronger, thicker beaks for breaking seeds, while insect-eating finches had spear-similar beaks for stabbing their casualty.
Natural Selection
Wallace and Darwin observed similar patterns in other organisms and independently developed the same explanation for how and why such changes could have identify. Darwin called this machinery natural selection. Natural selection, besides known as "survival of the fittest," is the more than prolific reproduction of individuals with favorable traits that survive environmental modify because of those traits. This leads to evolutionary change, the trait becoming predominant inside a population. For example, Darwin observed that a population of giant tortoises establish in the Galapagos Archipelago accept longer necks than those that lived on other islands with dry out lowlands. These tortoises were "selected" because they could accomplish more than leaves and access more food than those with short necks. In times of drought, when fewer leaves would be available, those that could achieve more leaves had a better take chances to swallow and survive than those that could not reach the nutrient source. Consequently, long-necked tortoises would more probably be reproductively successful and pass the long-necked trait to their offspring. Over time, merely long-necked tortoises would be present in the population.
Natural option, Darwin argued, was an inevitable outcome of three principles that operated in nature. First, nearly characteristics of organisms are inherited, or passed from parent to offspring, although how traits were inherited was unknown. Second, more offspring are produced than are able to survive. The capacity for reproduction in all organisms outstrips the availability of resources to back up their numbers. Thus, there is competition for those resources in each generation. Both Darwin and Wallace were influenced by an essay written by economist Thomas Malthus who discussed this principle in relation to human populations. Tertiary, Darwin and Wallace reasoned that offspring with the inherited characteristics that permit them to best compete for express resources will survive and accept more offspring than those individuals with variations that are less able to compete. Considering characteristics are inherited, these traits will be better represented in the side by side generation. This will lead to change in populations over successive generations in a process that Darwin called descent with modification. Ultimately, natural choice leads to greater adaptation of the population to its local environment; information technology is the only mechanism known for adaptive evolution.
Papers by Darwin and Wallace presenting the idea of natural pick were read together in 1858 earlier the Linnean Society in London. The following year, Darwin's book, On the Origin of Species, was published. His volume outlined his arguments for evolution by natural selection.
Source: https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book:_General_Biology_%28Boundless%29/18:_Evolution_and_the_Origin_of_Species/18.1:_Understanding_Evolution/18.1B:_Charles_Darwin_and_Natural_Selection
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