(ORDO NEWS) — New species can form surprisingly quickly in some cases, but sometimes the process can take eons.
Evolution can take years or hundreds of thousands of years. In many ways, its rate depends on the rate of reproduction and environmental conditions.
Charles Darwin admired the “endless forms, the most beautiful and the most wonderful” created by evolution.
Indeed, the Earth today is replete with approximately 1 trillion species. But how long did it take these species to evolve?
How long does it take for a new species to appear
The answer is highly dependent on the life form – for the most part, the taxon [type of creature] and environmental conditions play a role here.
Depending on these factors, the rate of emergence of a new species can vary from human-observable time scales to tens of millions of years.
It is important to note that since evolution occurs through inherited changes, the rate of reproduction, or the generation time of creatures, limits the rate at which new species can form.
For example, because bacteria reproduce very quickly, splitting in two every few minutes or hours, they can evolve into new varieties in years or even days, according to the American Museum of Natural History in New York.
However, it is difficult to determine which varieties of bacteria to consider as new species. While scientists define species by whether they can interbreed, bacteria do not reproduce sexually.
However, a 2008 study in the journal Proceedings of the National Academy of Sciences suggests that a decades-long line of E. coli bacteria has evolved the ability to use citrate as a food source in oxygenated environments.
The inability to do so is “the defining characteristic of E. coli as a species”, so a change in such a feature may represent the beginning of a new species that evolved over several years.
Plants in a phenomenon known as polyploidy can duplicate their entire genome in seeds, resulting in extra copies of each chromosome and a new species in one generation.
The resulting reproductive isolation automatically creates a new species, scientists say. And since many plants reproduce on their own, a new polyploid organism can continue to create new species.
Even in the animal kingdom, speciation can occur at human-observable times, especially among rapidly reproducing insects.
For example, the larvae of the apple pit fly (Rhagoletis pomonella) historically fed on hawthorn plants, but some switched to domesticated apples after they appeared in the northeastern United States in the mid-1800s.
The two groups have since become reproductively isolated, according to a 2006 study in the Annals of the Entomological Society of America, and are now considered “host races” – the first step in a type of speciation without physical barriers.
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