Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dramatic diversity of columbine flowers explained by a simple change in cell shape

16.11.2011
To match pollinators' probing tongues, cells in floral spurs elongate, driving rapid speciation

Columbine flowers are recognizable by the long, trailing nectar spurs that extend from the bases of their petals, tempting the taste buds of their insect pollinators.

New research at Harvard and the University of California, Santa Barbara (UCSB) helps to explain how columbines have achieved a rapid radiation of approximately 70 species, with flowers apparently tailored to the length of their pollinators' tongues.

Bees, for example, enjoy the short spurs of Aquilegia vulgaris, whereas hawkmoths favor A. longissima, whose spurs can grow to up to 16 centimeters.

According to results published today in the Proceedings of the Royal Society B, the dramatic diversity in the length of the columbines' spurs is the result of one simple change during development: the extent of cell elongation.

"The evolutionary importance of interactions between flowers and pollinators has been recognized for centuries," says co-lead author Sharon Gerbode, a postdoctoral fellow at the Harvard School of Engineering and Applied Sciences (SEAS).

"Charles Darwin, observing orchids, recognized that the extraordinarily long nectar spur on the Angraecum must have evolved in concert with the equally long tongue of the moth that pollinated it, but the exact mechanism for this kind of adaptation has been a matter of speculation."

For more than 60 years, biologists have assumed that the length of columbine spurs was achieved primarily by cell proliferation. The new research reveals that proliferation plays almost no role at all in creating the vast diversity of Aquilegia species currently seen.

In fact, 99 percent of the variation in spur length can be attributed to changes in cell shape—specifically, changing round cells into long ones.

The researchers made more than 13,000 measurements to count the number of cells along the spur, as well as the area and degree of elongation of each cell.

They found that cell division ceases early in the development of the spur—when it is about 5 millimeters long. At that point, the general pattern for the spur has been established, and all species of columbine petals look the same. From that point on, the cells elongate to varying extents, creating diverse spur lengths across species.

"The controlled elongation of cells within the petal spurs was a critical evolutionary innovation for Aquilegia, a genus that is considered to be a textbook example of adaptive radiation," says co-lead author Joshua Puzey, a graduate student in Harvard's Department of Organismic and Evolutionary Biology (OEB).

The researchers confirmed their results through mathematical analysis and modeling, and through in vivo experiments to disrupt cellular structure. The next step will be to examine several major hormone pathways and cytoskeletal elements that are known to influence cell elongation and developmental timing.

"We want to understand the genes that are responsible for both the initial evolution of nectar spurs and their subsequent diversification," says co-principal investigator Elena Kramer, Professor of OEB at Harvard.

It is clear, she says, that the starting point for the spur is likely to have already been present in the last common ancestor of all the columbine species.

"Now that we understand the real developmental basis for the first appearance and diversification of spurs, we can make much more informed guesses about what genes contributed to the process," Kramer adds.

"Fundamentally, these studies will help us answer questions about the genetic basis for speciation and how developmental processes evolve."

Columbines show promise as a model organism for the study of evolution in plants because they have experienced such a rapid adaptive radiation within the past 3 million years.

"The fact that this occurred quite recently is incredibly useful," says Kramer, "because it means that the species are still very similar to each other at the genetic level."

Once researchers have identified the molecular signals that drive elongation in the spurs, the hope is that they will be able to recognize and understand speciation at all levels, from genes to populations.

"Aquilegia serve as a nice example of how environmental selective pressures may drive extreme morphologies—as here the flower and pollinator strive for an exclusive relationship," adds co-principal investigator L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics at SEAS and Professor of OEB and Physics at Harvard.

"Given that we can now manipulate spur length using externally applied drugs, our study even raises the possibility of artificially tuning that process and studying the results from an ecological perspective."

The research was supported by the MacArthur Foundation, the Wyss Institute for Biologically Inspired Engineering at Harvard, The Kavli Institute for Bionano Science and Technology at Harvard, the National Science Foundation (NSF), and the NSF-supported Materials Research Science and Engineering Center at Harvard.

UCSB faculty member Scott A. Hodges served as co-author for the research.

Caroline Perry | EurekAlert!
Further information:
http://www.seas.harvard.edu

More articles from Life Sciences:

nachricht How brains surrender to sleep
23.06.2017 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht A new technique isolates neuronal activity during memory consolidation
22.06.2017 | Spanish National Research Council (CSIC)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>