Navigation Links
Of lice and men (and chimps): Study tracks pace of molecular evolution
Date:1/7/2014

CHAMPAIGN, Ill. A new study compares the relative rate of molecular evolution between humans and chimps with that of their lice. The researchers wanted to know whether evolution marches on at a steady pace in all creatures or if subtle changes in genes substitutions of individual letters of the genetic code occur more rapidly in some groups than in others.

A report of the study appears in the Proceedings of the Royal Society B.

The team chose its study subjects because humans, chimps and their lice share a common historical fate: When the ancestors of humans and chimps went their separate ways, evolutionarily speaking, so did their lice.

"Humans are chimps' closest relatives and chimps are humans' closest relatives and their lice are each others' closest relatives," said study leader Kevin Johnson, an ornithologist with the Illinois Natural History Survey at the University of Illinois. "Once the hosts were no longer in contact with each other, the parasites were not in contact with each other because they spend their entire life cycle on their hosts."

This fact, a mutual divergence that began at the same point in time (roughly 5 million to 6 million years ago) allowed Johnson and his colleagues to determine whether molecular evolution occurs faster in primates or in their parasites.

Previous studies had looked at the rate of molecular changes between parasites and their hosts, but most focused on single genes in the mitochondria, tiny energy-generating structures outside the nucleus of the cell that are easier to study. The new analysis is the first to look at the pace of molecular change across the genomes of different groups. It compared a total of 1,534 genes shared by the primates and their parasites. To do this, the team had to first assemble a rough sequence of the chimp louse (Pediculus schaeffi) genome, the only one of the four organisms for which a full genome sequence was unavailable.

The team also tracked whether changes in gene sequence altered the structure of the proteins for which the genes coded (they looked only at protein-coding genes). For every gene they analyzed, they determined whether sequence changes resulted in a different amino acid being added to a protein at a given location.

They found that at the scale of random changes to gene sequence the lice are winning the molecular evolutionary race. This confirmed what previous, more limited studies had hinted at.

"For every single gene we looked at, the lice had more differences (between them) than (were found) between humans and chimps. On average, the parasites had almost 15 times more changes," Johnson said. "Often in parasites you see these faster rates," he said. There have been several hypotheses as to why, he said.

Humans and chimps had a greater percentage of sequence changes that led to changes in protein structure, the researchers found. That means that even though the louse genes are changing at a faster rate, most of those changes are "silent," having no effect on the proteins for which they code. Since these changes make no difference to the life of the organism, they are tolerated, Johnson said. Those sequence changes that actually do change the structure of proteins in lice are likely to be harmful and are being eliminated by natural selection, he said.

In humans and chimps, the higher proportion of amino acid changes suggests that some of those genes are under the influence of "positive selection," meaning that the altered proteins give the primates some evolutionary advantage, Johnson said. Most of the genes that changed more quickly or slowly in primates followed the same pattern in their lice, Johnson said.

"The most likely explanation for this is that certain genes are more important for the function of the cell and can't tolerate change as much," Johnson said.

The new study begins to answer fundamental questions about changes at the molecular level that eventually shape the destinies of all organisms, Johnson said.

"Any difference that we see between species at the morphological level almost certainly has a genetic basis, so understanding how different genes are different from each other helps us understand why different species are different from each other," he said. "Fundamentally, we want to know which genetic differences matter, which don't, and why certain genes might change faster than others, leading to those differences."


'/>"/>

Contact: Diana Yates
diya@illinois.edu
217-333-5802
University of Illinois at Urbana-Champaign
Source:Eurekalert  

Related biology news :

1. Study by UC Santa Barbara researchers suggests that bacteria communicate by touch
2. Law that regulates shark fishery is too liberal: UBC study
3. New study will help protect vulnerable birds from impacts of climate change
4. Study jointly led by UCSB researcher supports theory of extraterrestrial impact
5. BYU study: Using a gun in bear encounters doesnt make you safer
6. 15-year study: When it comes to creating wetlands, Mother Nature is in charge
7. Pycnogenol (French maritime pine bark extract) shown to improve menopause symptoms in new study
8. Crystal structure of archael chromatin clarified in new study
9. EU-funded study underlines importance of Congo Basin for global climate and biodiversity
10. University of Houston study shows BP oil spill hurt marshes, but recovery possible
11. Study demonstrates cells can acquire new functions through transcriptional regulatory network
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Of lice and men (and chimps): Study tracks pace of molecular evolution
(Date:4/13/2017)... According to a new market research report "Consumer IAM Market by ... Service, Authentication Type, Deployment Mode, Vertical, and Region - Global Forecast to ... USD 14.30 Billion in 2017 to USD 31.75 Billion by 2022, at ... ... MarketsandMarkets Logo ...
(Date:4/11/2017)... , April 11, 2017 NXT-ID, Inc. ... technology company, announces the appointment of independent Directors Mr. ... to its Board of Directors, furthering the company,s corporate governance ... Gino ... we look forward to their guidance and benefiting from their ...
(Date:4/5/2017)... April 4, 2017 KEY FINDINGS ... expand at a CAGR of 25.76% during the forecast ... the primary factor for the growth of the stem ... https://www.reportbuyer.com/product/4807905/ MARKET INSIGHTS The global stem cell ... application, and geography. The stem cell market of the ...
Breaking Biology News(10 mins):
(Date:10/9/2017)... 9, 2017  BioTech Holdings announced today identification ... its ProCell stem cell therapy prevents limb loss ... Company, demonstrated that treatment with ProCell resulted in ... as compared to standard bone marrow stem cell ... in reduction of therapeutic effect.  ...
(Date:10/9/2017)... ... October 09, 2017 , ... The Giving Tree Wellness ... targeting the needs of consumers who are incorporating medical marijuana into their wellness ... Arizona. , As operators of two successful Valley dispensaries, The Giving Tree’s two ...
(Date:10/7/2017)... ... October 06, 2017 , ... ... Hi-C metagenome deconvolution product, featuring the first commercially available Hi-C kit. Researchers ... perform Hi-C metagenome deconvolution using their own facilities, supplementing the company’s full-service ...
(Date:10/6/2017)... ... October 06, 2017 , ... ... discussion and webinar on INSIGhT, the first-ever adaptive clinical trial for glioblastoma (GBM). ... Institute. The event is free and open to the public, but registration is ...
Breaking Biology Technology: