Navigation Links
UCSD biologists find new evidence for one-way evolution

By tracing the 30-million year history of variation in a gene found in plants such as tomatoes and tobacco, biologists at the University of California, San Diego have found new evidence to support an old idea -- that some evolutionary changes are irreversible.

Their study, published this week in an early online edition of the journal Proceedings of the National Academy of Sciences, offers new support for the idea that the loss of complex traits, like eyes, wings or in this case a reproductive mechanism, is often irreversible. In other words, once lost, the traits never revert to their original state.

"This is the strongest evidence yet to support irreversibility," said Joshua Kohn, an associate professor of biology at UCSD who headed the study. "If we had not used the genetic data coding for this reproductive mechanism and only inferred the pattern of evolution based on the traits of living species, we would have come to the opposite conclusion and with high statistical support -- that the trait evolved more than once."

The scientists examined existing variation in the gene used by many members of the Solanaceae family, which include tomatoes and tobacco, to recognize and reject their own pollen, thereby avoiding self-fertilization and the harmful effects of inbreeding. This ability is sometimes lost, as is the case for garden tomatoes, which can set seed by self-fertilization. Apparently, once lost, the ability to reject pollen in order to prevent self-fertilization is never regained.

Irreversible loss of complex traits, which result from the combined interaction of several genes, is an old and at times controversial scientific question. While the late evolutionary biologist Stephen Jay Gould popularized the hypothesis of irreversibility, known as Dollo's Law, studies that use current methods to reconstruct the evolution of complex traits often fail to support it. This is because it is often difficult to reconstruct characteristic s of extinct ancestors with any certainty.

The study contradicts earlier studies of complex trait evolution, which have tended to favor multiple reappearances of complex traits after these organs were lost in ancestral species. The authors suggest that traditional methods for reconstructing the history of trait evolution may be inaccurate.

Discovering irreversible change for this sexual system trait highlights the importance of considering genetic data underlying the trait when reconstructing its evolutionary history.

"Our work implies that evidence for such evolutionary change in other cases may have been missed because the current methods aren't sufficiently refined," said Boris Igic, who conducted the study while a graduate student at UCSD and is now a postdoctoral fellow at Cornell University.

While lending support to the question of unidirectional evolution, the biologists' findings also lead to new questions.

"Apparently, plants that have sex exclusively with other plants and not themselves, enjoy a greater evolutionary advantage," Igic said. "Exactly why is unclear,"

Species capable of rejecting their own pollen in favor of pollen from other individuals, harbor more genetic variation than those that self-fertilize.

"An intriguing aspect of this study is that the mechanism for ensuring cross-fertilization is very old, often lost, and never regained," Kohn said. "That it is still common despite frequent and irreversible loss implies that this trait confers an advantage to species that possess it, perhaps in terms of reduced rates of extinction."


'"/>

Source:University of California - San Diego


Related biology news :

1. Octopuses occasionally stroll around on two arms, UC Berkeley biologists report
2. GeneNotes - A novel information management software for biologists
3. NYU biologists map out early stages of embryo formation
4. FSU biologists describe key role of signal-transcribing gene during cell cycle
5. High-tech tags on marine animals yield valuable data for biologists and oceanographers
6. UC San Diego biologists solve plant growth hormone enigma
7. FSU biologists uncover mechanisms that shape cells for better or worse
8. NYU biologists identify gene that coordinates two cellular processes
9. MIT biologists solve vitamin puzzle
10. Yale biologists trick viruses into extinction
11. Brown cancer biologists identify major player in cell growth
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:2/11/2016)... DENVER , Feb. 11, 2016  According to ... are officially mainstream. More than 200 fingerprint, iris, ... Q1 2013 under 70 brand names. This includes ... Vivo, and ZTE. Acuity projects that 600 million ... of the global installed base. Maxine ...
(Date:2/11/2016)... 11, 2016  Vigilant Solutions announces today that its license ... used by Lee,s Summit Police Department ... and arrest of a homicide suspect. Kansas ... around 65 square miles and is home to roughly 100,000 ... a single mobile license plate reader system and also leverages ...
(Date:2/10/2016)... February 10, 2016 ... to 2016 iris recognition market report, combined ... is more widely accepted for border control. ... fingerprint and iris recognition technology in a ... avoid purchasing two individual biometrics devices. ...
Breaking Biology News(10 mins):
(Date:2/12/2016)... SAN DIEGO , Feb. 12, 2016 Biocom, ... life science community, took a group of San ... as part of its 2016 Precision Medicine Advocacy Fly-In. ... at the Food and Drug Administration (FDA), the Centers for ... (NIH), as well as San Diego U.S. Representatives Susan ...
(Date:2/12/2016)... ... February 12, 2016 , ... ... World Congress Center in Atlanta, Georgia, will include 848 exhibitors (count as of ... will be displaying products and services used by the scientific community in industrial, ...
(Date:2/12/2016)... , Feb. 12, 2016  BD (Becton, Dickinson ... medical technology company, today announced the launch of the ... Biology and Technology (AGBT) Meeting. ... enables genomic research by providing cost effective NGS library ... is a high-throughput, fully integrated, next generation sequencing (NGS) ...
(Date:2/12/2016)... , Feb. 12, 2016  PTC Therapeutics, Inc. ... annual STRIVE (Strategies to Realize Innovation, Vision and ... (DMD). STRIVE provides funds to patient advocacy organizations ... make meaningful contributions to the rare disease community ... of future patient advocates. Mary ...
Breaking Biology Technology: