Evidence for the evolution of many species from a few ancestral species comes from multiple sources. Fossil records show gradual changes in species over time, illustrating transitional forms that link different groups. Additionally, genetic studies reveal similarities in DNA sequences among diverse species, indicating common ancestry. Furthermore, the geographical distribution of species supports the concept of adaptive radiation, where species diversify from a common ancestor in response to varying environmental conditions.
Fossils show clear evidence that the earliest human species had many apelike features & have evolved over the years.
Such a species has undergone divergent evolution as different population groups respond to different selection pressures in their environments. It is believed that this produced the many different finch species on the Galapagos Islands from a single ancestral finch species that arrived there many thousands of years ago. Darwin's study of these finches led to his development of the Theory of Evolution by Natural Selection.
It leads to speciation. many species in nature have evolved by this method.
A radiation event. Called adaptive radiation.
Bird beak sizes, many birds of the same species had different size beaks to pick up different size foods, thus suggesting they 'spontaneous' evolved
A common ancestor.
Many scientists have said so based on the evidence they found.
During Darwins visit to the Galapagos island he observed that these islands had many unique organisms, most of which were similar to but different from the plants and animals from the nearest mainland.... thus this indicated how population evolved. Darwin called this "descent with modification" meaning an ancestral species could diversify into many descendant species by the accumulation of adaptation to various environment. His observation described the theory of evolution.
Answering "http://wiki.answers.com/Q/What_is_advantage_of_asexual_reproduction_for_a_population_of_organisms"
Fossil evidence suggests that Homo sapiens evolved around 300,000 years ago in Africa.
Everything beyond single cell organisms have evolved (and some of those have too!).
Darwin observed that on the island, there were many finches, but each one of them were slightly different.Darwin noticed that beak shapes and sizes differed among the finches. This led him to believe that finches evolved differently in response to different environments.The variation in beak size and body size that showed, at a latter date, that all of these birds he thought were vastly different species (wrens, warblers and such ) were one ancestral finch species adapted to many different niches on the many different Islands of the Galapagos.