The theory of evolution by natural selection, first formulated in Darwin's book "On the Origin of Species" in 1859, is the process by which organisms change over time as a result of changes in heritable physical or behavioral traits.
. Alleles are variant forms of a gene that are located at the same position, or genetic locus, on a chromosome. An allele frequency is calculated by dividing the number of times the allele of interest is observed in a population by the total number of copies of all the alleles at that particular genetic locus in the population. Allele frequencies can be represented as a decimal, a percentage, or a fraction. In a population, allele frequencies are a reflection of genetic diversity. Changes in allele frequencies over time can indicate that genetic drift is occurring or that new mutations have been introduced into the population.
Summary and analysis of Charles Darwin's On the Origin of Species. In this video, we will explore Charles Darwin's seminal work on evolution titled, On the Origin of Species, and hopefully dispel some of the confusion surrounding his ideas.
Scientists have proved one of Charles Darwin's theories of evolution for the first time -- nearly 140 years after his death. Researchers discovered mammal subspecies play a more important role in evolution than previously thought. Her research could now be used to predict which species conservationists should focus on protecting.
A new study shows that fluctuations in population sizes in the past have had a significant effect on contemporary seal populations, and estimates the risk of genetic impoverishment in the species investigated.
Researchers have found that higher levels of aneuploidy lead to much greater lethality among prostate cancer patients. This suggest a mechanism for how some prostate cancers become lethal, and could be used to alert doctors which patients might need to be treated more aggressively.
Despite the traditional view that species do not exchange genes by hybridisation, recent studies show that gene flow between closely related species is more common than previously thought. A team of scientists now reports how gene flow between two species of Darwin's finches has affected their beak morphology.
An international research team has studied genetic diversity among fish around the world for the first time. Their research produced a map that will serve as a tool in improving the protection of species and genetic diversity in the future.
A 380-million-year-old fossil of a fish has revealed that fingers evolved in vertebrates before the creatures wriggled out of the sea and evolved into land-dwelling creatures, as a new study describes.