Evolution of new species requires few genetic changes

Oct 31, 2013
Evolution of new species requires few genetic changes
These are Heliconius cydno and H. pachinus butterflies. Credit: University of Chicago, Marcus Kronforst

Only a few genetic changes are needed to spur the evolution of new species—even if the original populations are still in contact and exchanging genes. Once started, however, evolutionary divergence evolves rapidly, ultimately leading to fully genetically isolated species, report scientists from the University of Chicago in the Oct 31 Cell Reports.

"Speciation is one of the most fundamental evolutionary processes, but there are still aspects that we do not fully understand, such as how the changes as one splits into two," said Marcus Kronforst, Ph.D., Neubauer Family assistant professor of , and lead author of the study.

To reveal genetic differences critical for , Kronforst and his team analyzed the genomes of two closely related butterfly species, Heliconius cydno and H. pachinus, which only recently diverged. Occupying similar ecological habitats and able to interbreed, these butterfly species still undergo a small amount of genetic exchange.

The researchers found that this regular mutes genetic variants unimportant to speciation—allowing them to identify key genetic areas affected by . The butterfly species, they discovered, differed in only 12 small regions of their genomes, while remaining mostly identical throughout the rest. Eight of these coded for wing color patterning, a trait important for mating and avoiding predation, and under intense selection pressure, while the other four remain undescribed.

"These 12 spots appear to only function well in the environment their species occupies, and so are prevented from moving between gene pools, even though other parts of the genomes are swapped back and forth," Kronforst said.

Evolution of new species requires few genetic changes
This is a top down view of Heliconius cydno and H. pachinus butterflies. Credit: University of Chicago, Marcus Kronforst

The team also compared the genomes of these two groups to a third species, still closely related but further removed on an evolutionary time scale. Here, they found hundreds of genomic changes, indicating that the rate of accelerated rapidly after the initial changes took hold.

"Our work suggests that a few advantageous mutations are enough to cause a 'tug-of-war' between natural selection and gene flow, which can lead to rapidly diverging genomes," Kronforst said.

The evolution of new species might not be as hard as it seems, even when diverging populations remain in contact and continue to produce offspring. That's the conclusion of studies, reported in the Cell Press journal Cell Reports on Oct. 31, that examine the full genome sequences of 32 Heliconius butterflies from the Central American rain forest, representing five different species. Credit: Marcus Kronforst

Kronforst and his team plan to characterize the remaining four divergent genome areas to look for functions important to speciation. They also are studying why species more commonly arise in tropical areas.

"It is possible that this type of speciation, in which natural selection pushes populations apart, has been important in the evolution of other organisms. It remains to be seen whether it is a common process though," Kronforst said.

Explore further: Long-held assumption about emergence of new species questioned

More information: "Hybridization reveals the evolving genomic architecture of speciation," Cell Reports, 2013. dx.doi.org/10.1016/j.celrep.2013.09.042

Related Stories

Reproductive isolation driving evolution of species

May 16, 2012

Evolution of species remains a hot topic since Darwin’s theory of natural selection. A European initiative addressed the issue of speciation from the viewpoint of reproductive isolation.

Chromosomal 'breakpoints' linked to canine cancer

Nov 03, 2011

North Carolina State University researchers have uncovered evidence that evolutionary "breakpoints" on canine chromosomes are also associated with canine cancer. Mapping these "fragile" regions in dogs may also have implications ...

Recommended for you

Plants with dormant seeds give rise to more species

Apr 18, 2014

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants need to be more careful. In the wild, a plant whose seeds sprouted at the first warm spell or rainy day would risk disaster. More ...

Researchers successfully clone adult human stem cells

Apr 18, 2014

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

User comments : 4

Adjust slider to filter visible comments by rank

Display comments: newest first

mzso
1.3 / 5 (13) Oct 31, 2013
So much for equalization of human races.
Sinister1811
3.1 / 5 (17) Oct 31, 2013
I wonder how many generations it takes before a population starts developing different traits.
JVK
1 / 5 (9) Nov 01, 2013
http://download.c....lrg.jpg

Will someone with graphics capabilities help address this issue by replacing "Hybridization" in frame one of this graphic with "Mutation" and change frame two with a picture of a snake in a tree attempting to ingest a monkey? That would be one way to graphically illustrate for comparison the snake-centric theory of human brain evolution via predation.

Frame four could also be replaced with a picture from what is now central China that compares the physical traits of the adaptively evolved human population that arose during the past 30,000 years to those of any monkeys found in the trees of the same region.
goracle
1 / 5 (5) Nov 04, 2013
http://download.cell.com/images/journalimages/2211-1247/PIIS2211124713005652.fx1.lrg.jpg

Will someone with graphics capabilities help address this issue by replacing "Hybridization" in frame one of this graphic with "Mutation" and change frame two with a picture of a snake in a tree attempting to ingest a monkey? That would be one way to graphically illustrate for comparison the snake-centric theory of human brain evolution via predation.

Frame four could also be replaced with a picture from what is now central China that compares the physical traits of the adaptively evolved human population that arose during the past 30,000 years to those of any monkeys found in the trees of the same region.

Better, will someone with moderation capability get rid of posts that are off topic?

More news stories

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Biologists help solve fungi mysteries

(Phys.org) —A new genetic analysis revealing the previously unknown biodiversity and distribution of thousands of fungi in North America might also reveal a previously underappreciated contributor to climate ...

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.