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There are some species that evolve quicky, and there are some species that can take eons to evolve. However, this is only just the beginning, because, Charles Darwin marveled at the “infinite and most beautiful and wonderful forms” created by evolution, there are in fact, by today’s estimates, 1 trillion species living on Earth today. The response can vary widely from one life form to another, depending on the type of creature and the environmental conditions. It can depend chronologically, from the time humans have been seeing it to tens of millions of years.
According to the University of California, Santa Barbara, it is crucial that evolution is inherited, so the reproductive rate or generation time of creature can limit the rate at which new species evolve. For example, bacteria can reproduce so quickly – they can split in two every few minutes or hours – that they can evolve into new species in years or even days, according to the American Museum of Natural History. However, this is also a tricky question, as it is difficult to say which species of bacteria count as a new species. Scientist delineate species based on their ability to interbreed, as bacteria do not reproduce sexually. According to a study publish in 2008 (Proceeding of the National Academy of Sciences), a lineage of bacteria saw for decades has evolved the ability to use citrate as a food source in oxygen-rich environments. This is defining characteristic of E.coli as a species, and researchers believe that this change marks the beginning of a new species. More specifically, one that has evolved over a few years.
In plants, the situation is quite different, because in a phenomenon called polyploidy, they can duplicate their entire genome in the seeds, so in this case, each added chromosome produces added copies and a new species in a generation. By this fact alone, many plants are able to reproduce on their own, so a polyploidy organism can produce additional species. It can thus start a whole population. It is interesting that even in the animal kingdom, speciation can occur within time frame that humans can observe, especially among rapidly reproducing insect. For instance, apple fruit flies historically fed on hawthorn plants, but some move to domesticated apples after arriving in the northeastern United States in the mid – 1800s. According to a 2006 study, the two groups have since become reproductively isolated and are now considered a so-called “host-species”. This was the first step in speciation without physical barriers.
However, there are speed limits, with the record belonging to a group of fish belonging to the cichlids of Lake Victoria in Africa. These fishes exploded with 300 species from a single founder less than 12000 years ago. The upper limit must be found in the speciation due the physical barriers. For example, the boas and pythons of the Americas, which are native to Africa and Asia, meaning more than 100 million years from separation to speciation, with the common ancestor of snakes probably slithering around more than 70 million years ago in the age of dinosaurs. An interesting fact to end with is that South America and Africa split about 140 million years ago.
Information researched by Dezső Sándor.