Speciation how does it occur

All we know is that while we were busy painting cave walls, something caused groups of orcas to split, creating multiple species. There are many different reasons why species diverge. The easiest, and most obvious, is some kind of physical barrier - a phenomenon called Allopatric Speciation. If you look at fish species in the Gulf of Mexico and off the coast of California, you'll find there are a lot of similarities between them.

Indeed, some of the species look almost identical. Scientists have looked at their genes, and species on either side of that thin land bridge are more closely related to each other than they are to other species, even ones in their area. What happened is that a long time ago, the continents of North and South America were separated, and the oceans were connected. When the two land masses merged, populations of species were isolated on either side.

Over time, these fish have diverged enough to be separate species. Species can split without such clear boundaries, too.

When species diverge like the apple maggot flies - without a complete, physical barrier - it's called Sympatric Speciation. Sympatric speciation can occur for all kinds of reasons. All it takes is something that makes one group have less sex with another.

For one species of Monarch flycatchers Monarcha castaneiventris , it was all about looks. At some point, a small group of them developed a single amino acid mutation in the gene for a protein called melanin, which dictates the bird's color pattern. Some flycatchers are all black, while others have chestnut colored bellies. Even though the two groups are perfectly capable of producing viable offspring, they don't mix in the wild.

Researchers found that the birds already see the other group as a different species. The males, which are fiercely territorial, don't react when a differently colored male enters their turf. Like the apple maggot flies, the flycatchers are no longer interbreeding, and have thus taken the first step towards becoming two different species. These might seem like little changes, but remember, as we learned with dogs, little changes can add up.

Because they're not interbreeding, these different groups will accumulate even more differences over time. As they do, they will start to look less and less alike. The resultant animals will be like the species we clearly see today. Perhaps some will adapt to a lifestyle entirely different from their sister species - the orcas, for example, may diverge dramatically as small changes allow them to be better suited to their unique prey types.

Others may stay fairly similar, even hard to tell apart, like various species of squirrels are today. The point is that all kinds of creatures, from the smallest insects to the largest mammals, are undergoing speciation right now. We have watched species split, and we continue to see them diverge. Speciation is occurring all around us. Evolution didn't just happen in the past; it's happening right now, and will continue on long after we stop looking for it. Soltis, D. McPheron, B.

Uy, J. Complete mitochondrial genome phylogeographic analysis of killer whales Orcinus orca indicates multiple species Genome Research. Salsify plate showing two new species from the New Zealand Plant Radiation Network taken from Ownbey, in which the species were described. Flycatchers image by Robert Boyle, as featured on Science Now.

The views expressed are those of the author s and are not necessarily those of Scientific American. Related questions How can speciation be prevented? What is speciation? How do reproductive barriers relate to the biological species concept? Does reproductive isolation apply to humans? What are some examples of the biological species concept? What is sympatric speciation? What are some examples of allopatric speciation? What is allopatric speciation? What is a lineage? How does polyploidy cause variation?

Reproductive isolation. Subscribe to our newsletter. Email Facebook Twitter. More Details Evo Examples Teaching Resources Read about how speciation factored into the history of evolutionary thought. Or explore different modes of speciation , including: Allopatric speciation Peripatric speciation Parapatric speciation Sympatric speciation.

Learn more about speciation: A closer look at a classic ring species: The work of Tom Devitt , a research profile. Sex, speciation, and fishy physics , a news brief with discussion questions. Teach your students about speciation: Anolis lizards , a classroom activity for grades