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 Amputees can learn to control a robotic arm with their minds
28.11.2017 | University of Chicago Medical Center

nachricht The importance of biodiversity in forests could increase due to climate change
17.11.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

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: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Long-lived storage of a photonic qubit for worldwide teleportation

12.12.2017 | Physics and Astronomy

Multi-year submarine-canyon study challenges textbook theories about turbidity currents

12.12.2017 | Earth Sciences

Electromagnetic water cloak eliminates drag and wake

12.12.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>