Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Evolution drives many plants and animals to be bigger, faster

08.03.2011
For the vast majority of plants and animals, the 'bigger is better' view of evolution may not be far off the mark, says a new broad-scale study of natural selection. Organisms with bigger bodies or faster growth rates tend to live longer, mate more and produce more offspring, whether they are deer or damselflies, the authors report.

Researchers working at the National Evolutionary Synthesis Center compiled and reviewed nearly 150 published estimates of natural selection, representing more than 100 species of birds, lizards, snakes, insects and plants. The results confirm that for most plants and animals, larger body size and earlier seasonal timing — such as earlier breeding, blooming or hatching —confer significant survival advantages.

"It's a very widespread pattern," said co-author Joel Kingsolver of the University of North Carolina at Chapel Hill.

What's puzzling, the authors say, is not why the 'bigger is better' model of evolution is so common, but why the 'Goldilocks' model is so rare: If organisms are supposedly well-adapted to their particular circumstances, then why is it so seldom the case that the individuals that survive and reproduce the best are the ones that are not too small, nor too big, but just right?

A classic example is human birth weight. Newborns of intermediate size are more likely to survive than newborns that are extremely large or extremely small. In lieu of driving organisms to be bigger and faster over time, the 'Goldilocks' model — also known as stabilizing selection — favors moderation, the authors explained. But for the vast majority of organismal traits, this pattern is the exception, not the rule. "Rarely is it the case that the individuals that survive and reproduce the best are the ones in the middle," Kingsolver said.

The result is puzzling because the conventional wisdom is that most creatures are well adapted to the environments in which they live. "When we look at nature, we see all these amazing ways species are well-adapted to their lifestyles and habitats," Kingsolver said. "Yet the organisms that are bigger, faster, still do the best in terms of survival and reproduction. Why aren't they already just the right size or speed, or pretty close to it?" he asked.

The authors explored three possible explanations. One possibility, they explained, is that evolving to be bigger, faster, or flashier comes at a cost. "A trait that's good for reproduction or fertility may be bad for survival — there may be a tradeoff," Kingsolver said. "In guppies, for example, brightly colored males have greater mating success, but they're also more likely to be eaten by predators," said co-author Sarah Diamond, currently a postdoctoral researcher at North Carolina State University.

Another possibility is that environments simply change from one season to the next, such that the traits that confer the greatest advantage change over time. "In Darwin's finches, for example, there are years where large-beaked birds have an advantage because large seeds are more abundant, and years where smaller-beaked birds do better because small seeds are more abundant," Diamond said.

A third possibility is that natural selection drives one trait in one direction, while simultaneously driving another, genetically correlated trait in the opposite direction. "For example it may be good for flying insects to evolve larger wings and smaller bodies for more efficient flight," Kingsolver said, "but if insects with larger wings also have larger bodies, they can't evolve both."

The third explanation frequently limits the evolution of body size, the authors found, but not traits related to timing, or body shape, or coloration. "Size is the one case where correlated selection is important," Kingsolver said.

The findings appear in the March 2011 issue of American Naturalist.

CITATION: Kingsolver, J. and S. Diamond (2011). "Phenotypic selection in natural populations: what limits directional selection?" American Naturalist 177(3): 346-357. doi:10.1086/658341.

Study data are available in the Dryad Digital Repository at http://datadryad.org/handle/10255/dryad.7997.

The National Evolutionary Synthesis Center (NESCent) is a nonprofit science center dedicated to cross-disciplinary research in evolution. Funded by the National Science Foundation, NESCent is jointly operated by Duke University, The University of North Carolina at Chapel Hill, and North Carolina State University. For more information about research and training opportunities at NESCent, visit www.nescent.org.

Robin Ann Smith | EurekAlert!
Further information:
http://www.nescent.org

More articles from Studies and Analyses:

nachricht Smart Data Transformation – Surfing the Big Wave
02.12.2016 | Fraunhofer-Institut für Angewandte Informationstechnik FIT

nachricht Climate change could outpace EPA Lake Champlain protections
18.11.2016 | University of Vermont

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>