Genetics

Brain mechanism underlying evolution of anxiety

Monoamine neurotransmitters such as serotonin and dopamine play important roles in our cognitive and emotional functions. Their evolutionary origins date back to metazoans, and while the function of related genes is strongly ...

Genetics

IVF: How genetics may be affecting its success

It has been almost 44 years years since the first in vitro fertilization (IVF) procedure was successfully performed in 1978 in Lancashire, England. Since then, more than 8 million babies have been born worldwide to assisted ...

Obstetrics & gynaecology

Mothers of twins are not more fertile, just lucky

Are women who have twins more fertile? While previous studies concluded they are, a detailed analysis of more than 100,000 births from pre-industrial Europe by an international team of scientists shows they are not. The results ...

Genetics

Omicron genetics and early transmission patterns characterized

The omicron variant of SARS-CoV-2 diverged from previous SARS-CoV-2 variants as a result of adaptive evolution, in which beneficial mutations are passed on to future generations through natural selection, rather than through ...

Diseases, Conditions, Syndromes

What we know about the SARS-CoV-2 Delta variant

The Delta variant is likely to become the most dominant strain globally. What does that mean for current and future variants? Natural selection has shaped the evolution of all living things on our planet, including viruses. ...

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Natural selection

Natural selection is the process by which heritable traits that make it more likely for an organism to survive and successfully reproduce become more common in a population over successive generations. It is a key mechanism of evolution.

The natural genetic variation within a population of organisms means that some individuals will survive and reproduce more successfully than others in their current environment. For example, the peppered moth exists in both light and dark colors in the United Kingdom, but during the industrial revolution many of the trees on which the moths rested became blackened by soot, giving the dark-colored moths an advantage in hiding from predators. This gave dark-colored moths a better chance of surviving to produce dark-colored offspring, and in just a few generations the majority of the moths were dark. Factors which affect reproductive success are also important, an issue which Charles Darwin developed in his ideas on sexual selection.

Natural selection acts on the phenotype, or the observable characteristics of an organism, but the genetic (heritable) basis of any phenotype which gives a reproductive advantage will increase in frequency over the following generations (see allele frequency). Over time, this process can result in adaptations that specialize organisms for particular ecological niches and may eventually result in the emergence of new species. In other words, natural selection is an important process (though not the only process) by which evolution takes place within a population of organisms.

Natural selection is one of the cornerstones of modern biology. The term was introduced by Darwin in his groundbreaking 1859 book On the Origin of Species, in which natural selection was described by analogy to artificial selection, a process by which animals with traits considered desirable by human breeders are systematically favored for reproduction. The concept of natural selection was originally developed in the absence of a valid theory of heredity; at the time of Darwin's writing, nothing was known of modern genetics. The union of traditional Darwinian evolution with subsequent discoveries in classical and molecular genetics is termed the modern evolutionary synthesis. Natural selection remains the primary explanation for adaptive evolution.

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