How long does it take for a new species to evolve?
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Charles Darwin famously marveled at the “most beautiful and most wonderful infinite forms” that evolution produced. earth today Estimated 1 trillion speciesBut how long did it take those species to evolve?
The answer varies greatly from organism to organism. Taxon [type of creature] and environmental conditions,” says Thomas Smith, professor of ecology and evolution biology At the University of California, Los Angeles, he told Live Science.
crucially, because evolution Occurs through inherited change, the reproduction rate of organisms, or generation time, and limits the rate at which new species are formed (known as the speciation rate). University of California, Santa Barbara (opens in new tab) (UCSB). for example, bacteria reproduces very quickly and “splits[ing] Two every few minutes or hours”, they can evolve into a new breed in a matter of years or days. American Museum of Natural History (opens in new tab) in New York City.
But it can be difficult to determine which bacterial species count as new, Smith said. Scientists classify species by their ability to mate, but bacteria do not reproduce sexually.Nevertheless, a 2008 study in the journal Proceedings of the National Academy of Sciences (opens in new tab) reported to be of descent from Escherichia coli (opens in new tab) Observed bacteria over decades have evolved the ability to utilize citric acid as a food source in an oxygenated environment. Escherichia coli As a species,” the researchers say, the change could represent the beginning of a new species.
Related: How long do most species survive before going extinct?
Plants are able to duplicate their entire genome within the seed through a phenomenon known as polyploidy, resulting in additional copies of all chromosomes and new species in a single generation. The resulting reproductive isolation “automatically creates new species,” Smith said.
And because many plants reproduce on their own, new polyploid organisms can still produce new species. UCSB said.
Even in the animal kingdom, speciation occurs on human observable timescales, especially among rapidly developing insects. apple maggot flies (lagoletis pomonella), for example, some people historically ate hawthorn, but after arriving in the northeastern United States in the mid-1800s, moved to cultivated apples. The two groups are reproductively isolated. Annals of the Entomological Society of America (opens in new tab), and is now considered a “host race”. This is the first step in a kind of speciation without physical barriers.
Speciation generally proceeds slowly in vertebrates, but can still occur rapidly.2017 studies published in journals chemistry (opens in new tab) reported that Galapagos finches migrated to new islands, mated with native birds, and produced new strains that were reproductively isolated within three generations. The lineage may represent a very rapid onset of speciation through species hybridization rather than a slow accumulation of adaptations, says study co-author Leif, a geneticist at Uppsala University in Sweden. Anderson told Live Science.
“This is a possible scenario for how new species could form,” said Anderson. “But how stable it will be over time is more uncertain.”
Speed Limit
The complete vertebrate speciation rate record likely belongs to cichlid fish from Africa’s Lake Victoria, Smith said.These fish have exploded into 300 species “from a single originator less than 12,000 years ago.” Several studies, including a 2000 study in the journal Proceedings of the Royal Society B (opens in new tab)questions that timeline, but cichlid speciation is “abnormal,” says Smith.
To find an upper limit on speciation time, look at speciation that occurs because of physical barriers, Smith said. For example, the boa, which is found mainly in the Americas, and the python, which is native to Africa and Asia, diverged after South America separated from Africa. This is likely to take tens of millions to 100 million years from continental breakup to full speciation, Smith said. (The last common ancestor of these snakes was about 70 million years ago. dinosaur ageaccording to Australian National University (opens in new tab)Africa and South America are about 140 million years ago.)
Determining the average or most common time of speciation is difficult, says Andersson, but scientists can estimate the most recent ancestry to get a rough idea. “For birds and mammals, the split between well-developed species usually seems to be about a million years ago,” he said.
A 2015 study published in the journal Molecular biology and evolution (opens in new tab) I gave another estimate. Drawing on data from more than 50,000 species (which included few bacteria), the research team found that speciation generally required accumulation of mutations over two million years, he said. I found This was true across vertebrates, arthropods (a group that includes insects, arachnids, and crustaceans), and plants.
However, other researchers warn that such models require many assumptions. Quanta Magazine (opens in new tab) research story. Scientists have a much firmer stance on the factors that generally slow or speed speciation—environmental pressures and reproductive isolation, Smith said. The less gene flow, the more likely speciation will occur,” he said.
Originally published in Live Science.
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