Navigation Links
Long-held assumption about emergence of new species questioned
Date:9/2/2013

ANN ARBORDarwin referred to the origin of species as "that mystery of mysteries," and even today, more than 150 years later, evolutionary biologists cannot fully explain how new animals and plants arise.

For decades, nearly all research in the field has been based on the assumption that the main cause of the emergence of new species, a process called speciation, is the formation of barriers to reproduction between populations.

Those barriers can be geographicsuch as a new mountain, river or glacier that physically separates two populations of animals or plantsor they can be genetic differences that prevent incompatible individuals from producing fertile offspring. A textbook example of the latter is the mule; horses and donkeys can mate, but their offspring are sterile.

But now a University of Michigan biologist and a colleague are questioning the long-held assumption that genetic reproductive barriers, also known as reproductive isolation, are a driving force behind speciation. Their study is scheduled for online publication in the Proceedings of the National Academy of Sciences on Sept. 2.

"Most research on the formation of species has assumed that these types of reproductive barriers are a major cause of speciation. But our results provide no support for this, and our study is actually the first direct test of how these barriers affect the rate at which species form," said Daniel Rabosky, assistant professor in the U-M Department of Ecology and Evolutionary Biology and a curator of herpetology at the Museum of Zoology.

Rabosky and Daniel Matute of the University of Chicago reasoned that if genetic barriers to reproduction are a leading cause of new species, then groups of organisms that quickly accumulate those genes should also show high rates of species formation.

They tested that idea by comparing speciation rates to genetic indicators of reproductive isolation in birds and fruit flies. They chose birds and fruit flies because extensive data sets on interspecies breeding experiments exist for both groups. The researchers used evolutionary tree-based estimates of speciation rates for nine major fruit fly groups and two-thirds of known bird species.

Rabosky and Matute created computer models to carry out the comparison, and the results surprised them.

"We found no evidence that these things are related. The rate at which genetic reproductive barriers arise does not predict the rate at which new species form in nature," Rabosky said. "If these results are true more generallywhich we would not yet claim but do suspectit would imply that our understanding of species formation is extremely incomplete because we've spent so long studying the wrong things, due to this erroneous assumption that the main cause of species formation is the formation of barriers to reproduction.

"To be clear, reproductive barriers are still important on some level. All sorts of plants and animals live together in the same place, which couldn't happen without reproductive barriers. But our results question whether genetic reproductive barriers played a major role in how those species formed in the first place."

While speciation is often defined as the evolution of reproductive isolation, the new findings suggest that a broader definition may be needed, Rabosky and Matute conclude.

Over the last decade or so, the pursuit of the genetic underpinnings of speciation has led to reports on the discovery of a handful of "speciation genes," defined as genes that contribute to reproductive isolation between species. The studies include a 2008 Nature paper that reported the first speciation gene in a mammal.

But if the findings of Rabosky and Matute prove to be more widely applicable to other organisms, speciation genes probably play a minimal role in the formation of species, they said.

"The whole enterprise of finding 'speciation genes' is potentially irrelevant to understanding the origin of species," Rabosky said. "But our study is certainly not going to be the final word on this. If anything, our results indicate that a lot more data will be needed before we can conclusively link the mechanisms we usually study in the lab to the patterns of species formation we see in the natural world."

The researchers speculated that part of what is missing from speciation studies is, paradoxically, extinction. Some researchers have suggested that speciation might be limited primarily by factors associated with the persistence of new species. These models propose that it is relatively easy for a species to split into new species, but the vast majority of new species do not persist over geological timescales.


'/>"/>

Contact: Jim Erickson
ericksn@umich.edu
734-647-1842
University of Michigan
Source:Eurekalert

Related biology news :

1. New Geology study raises questions about long-held theories of human evolution
2. True grit erodes assumptions about evolution
3. Answering crucial questions about anthrax exposure
4. Cultural mythologies strongly influence womens expectations about being pregnant
5. Veeries very quiet when owls are about
6. New knowledge about permafrost improving climate models
7. What can plants reveal about global climate change?
8. First human tests of new biosensor that warns when athletes are about to hit the wall
9. Study finds surprising benefits about diary cow inflammation
10. AMP concerned about the structure and application of gap fill payment amounts
11. MacaInfo.org Offers In-Depth Answers the 20 Most Common Questions People Have about Maca
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:11/30/2016)... Nov. 30, 2016  higi SH llc (higi) ... initiative targeting national brands, industry thought-leaders and celebrity ... respective audiences for taking steps to live healthier, ... in 2012, higi has built the largest self-screening ... 38 million people who have conducted over 185 ...
(Date:11/29/2016)... 29, 2016 Nearly one billion matches per second ... ... DERMALOG is Germany's ... efficient Identity Management. (PRNewsFoto/DERMALOG Identification Systems) ... DERMALOG is Germany's largest Multi-Biometric supplier: The company's Fingerprint Identification ...
(Date:11/22/2016)... , November 22, 2016 According to the ... IRIS, Palm Print, Face, Vein, Signature, Voice), Multi-Factor), Component (Hardware and Software), ... published by MarketsandMarkets, the market is expected to grow from USD 10.74 ... CAGR of 16.79% between 2016 and 2022. ... ...
Breaking Biology News(10 mins):
(Date:12/2/2016)... Diego, CA (PRWEB) , ... December 01, 2016 , ... ... data from its Phase I/II clinical trials for AC0010 at the World Conference on ... forward to providing an update on the phase I/II clinical trials for AC0010 in ...
(Date:12/2/2016)... ... 01, 2016 , ... The Conference Forum has announced that the 3rd annual ... place on February 1-3, 2017 at the Roosevelt Hotel in New York City. Led ... a unique 360-degree approach, which addresses the most up-to-date information regarding business aspects, clinical ...
(Date:12/2/2016)... ... December 02, 2016 , ... Robots will storm the Prudential ... December 3rd, 2016. The event, which is held on the United Nations International Day ... with Disabilities back into the workplace. Suitable Technologies is partnering with NTI to showcase ...
(Date:11/30/2016)... ... November 30, 2016 , ... BEI Kimco, a brand of ... flexure design that ensures high alignment accuracy by preventing unwanted shaft rotation. The ... where extreme precision is required, such as in medical equipment, laboratory instrumentation, clean ...
Breaking Biology Technology: