Sexual competition primes plants for extinction.

Like painted prostitutes posing in a red-light district window, plants use brightly-colored flowers to attract pollinators. Yet, for both plants and women, flashy trappings sometimes aren’t enough.

A study to be published in the January issue of Proceedings of the National Academy of Sciences suggests that just as it’s hard for a girl to catch a gent’s eye in a room full of beauties, in areas of high diversity, plant reproduction can be severely limited by competition. The resulting decrease in the reproductive rate increases a species’ risk of extinction.

The current study is a meta-analysis of over 1,000 studies, carried out around the world. In each case researchers added pollen to one group of plants and then compared seed production to plants who had not received supplemental pollen. If the addition of pollen resulted in more seeds, the plant was pollen-limited—it was not getting enough pollen to reproduce at its optimum rate. If the pollen addition had no result, then the plant’s reproductive rate was not limited by access to pollinators.

“The idea is that if everything is fine for the flowers, and they’re getting all the pollen that they need, then you adding pollen should do nothing, because the pollinators are doing a fine job.” said author Tiffany Knight, an assistant professor of biology at the Department of Biology at Washington University in St. Louis.

The research found the most intense pollen limitation in areas with high species diversity. They say the limitation is likely due to interspecies competition.

“Some studies, especially those conducted in areas with low species richness, actually showed very little pollen limitation,” said Jana Vamosi, a postdoc at the University of Calgary, the lead author of the study. “However, as you get closer to areas that are biodiversity hotspots, such as tropical rainforests, the effect of pollen limitation is extremely high.”

Pollen limitation in high-diversity environments may be the result of recent changes to those environments, Vamosi explained. Biodiversity hotspots—like tropical areas—are frequently subject to habitat loss and fragmentation. As a result, it is likely that these environments have experienced a reduction in the number of pollinators, as well as declines in pollinator diversity.

If pollen limitation is due to recent environmental changes, it may be a harbinger of plant extinctions. If so, “there is going to be a real trickle-down effect in ecosystem function,” Vamosi said. “Ecosystems are going to start to deteriorate.”

Yet, Vamosi explained, the correlation she and her colleagues observed between pollen limitation and diversity may not be a recent phenomenon. Rather, pollen limitation may be a characteristic of high-diversity environments, regardless of outside intrusion and fragmentation. 

“[The presence of] a lot of species creates competition for pollinators, which decreases the amount by which plant species reproduce,” said Vamosi. “So they then evolve to specialize in pollinators.”

Aside from targeting specific pollinators, plants have developed an arsenal of adaptations to maximize their chances of reproduction. They can reduce their need for fickle pollinators with self-compatible breeding systems—in which both male and female gametes are produced by the same plant—or by reproducing asexually. In addition, they can reduce competition for pollinators by changing the time of day that they flower.

As in the animal kingdom, plants that adapt to increased competition stay alive, while those who stand still perish. Vamosi put it best: “Biodiversity begets biodiversity.”

Originally published January 24, 2006


Share this Stumbleupon Reddit Email + More


  • Ideas

    I Tried Almost Everything Else

    John Rinn, snowboarder, skateboarder, and “genomic origamist,” on why we should dumpster-dive in our genomes and the inspiration of a middle-distance runner.

  • Ideas

    Going, Going, Gone

    The second most common element in the universe is increasingly rare on Earth—except, for now, in America.

  • Ideas

    Earth-like Planets Aren’t Rare

    Renowned planetary scientist James Kasting on the odds of finding another Earth-like planet and the power of science fiction.

The Seed Salon

Video: conversations with leading scientists and thinkers on fundamental issues and ideas at the edge of science and culture.

Are We Beyond the Two Cultures?

Video: Seed revisits the questions C.P. Snow raised about science and the humanities 50 years by asking six great thinkers, Where are we now?

Saved by Science

Audio slideshow: Justine Cooper's large-format photographs of the collections behind the walls of the American Museum of Natural History.

The Universe in 2009

In 2009, we are celebrating curiosity and creativity with a dynamic look at the very best ideas that give us reason for optimism.

Revolutionary Minds
The Interpreters

In this installment of Revolutionary Minds, five people who use the new tools of science to educate, illuminate, and engage.

The Seed Design Series

Leading scientists, designers, and architects on ideas like the personal genome, brain visualization, generative architecture, and collective design.

The Seed State of Science

Seed examines the radical changes within science itself by assessing the evolving role of scientists and the shifting dimensions of scientific practice.

A Place for Science

On the trail of the haunts, homes, and posts of knowledge, from the laboratory to the field.


Witness the science. Stunning photographic portfolios from the pages of Seed magazine.

SEEDMAGAZINE.COM by Seed Media Group. ©2005-2015 Seed Media Group LLC. All Rights Reserved.

Sites by Seed Media Group: Seed Media Group | ScienceBlogs | Research Blogging | SEEDMAGAZINE.COM