Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Female Birds – Acting Just Like the Guys – Become Sexual Show Offs in Cooperative Breeding Species

10.12.2009
Female birds in species that breed in groups can find themselves under pressure to sexually show off and evolve the same kinds of embellishments – like fanciful tail feathers or chest-puffing courtship dances - as males, according to new research in the latest issue of Nature (Dec. 10, 2009).

"We've known it happens with females in some specialized cases, but it's probably more widespread than we ever realized before," said Irby Lovette, the Fuller Director of Evolutionary Biology at the Cornell Lab of Ornithology and co-author of the Nature study published with Dustin Rubenstein, Cornell Ph.D. ’06, of Columbia University.

The researchers found compelling evidence for why sexual selection sometimes acts with equal strength on both females and males. Sexual selection is strongest in situations where not every individual gets a chance to reproduce – as when rams butt heads over access to a flock of ewes.

Called reproductive skew, this pattern tends to be common in males. Females of most species generally invest more in producing and nurturing young and tend to have more steady reproductive success.

Rubenstein and Lovette reasoned that if sexual selection were to operate on females, it would likely be in situations where females had to compete for mates. They found such scenarios among more than a dozen species of cooperatively breeding starlings in Africa.

In these systems, family groups raise young jointly, helping one or more breeding pairs with feeding and protecting against predators.

With only a limited number of breeding pairs, many of the females don't get to nest each year. On the other hand, unpaired males still have chances to father young through infidelity with one of the breeding females. Competition to be chosen as a mate is somewhat relaxed for males but intensified for females.

To test whether females show evidence of sexual selection on the same traits that males have used to compete for mates, Rubenstein and Lovette compared the 17 species of cooperatively breeding starlings in Africa with the continent's 28 species of typical pair-breeding starlings. They also used DNA samples to reconstruct the African starlings' evolutionary history, confirming that cooperative breeding had developed independently several times within the family.

After measuring more than 1,600 museum specimens of all 45 species, the researchers report that males and females of cooperatively breeding species were substantially more similar to each other – closer in size and with similar plumage – than males and females of pair-breeding species.

The result paints two different pictures of evolution: Among pair-breeders, sexual selection on males makes the sexes look increasingly different; in cooperative breeders, competition among females leads to them evolving the same showy traits as males.

The finding that reproductive skew dictates how sexual selection acts could apply to nearly any species that breeds in groups, the researchers believe.

"This goes beyond starlings," Rubenstein said. "Any species that lives with relatives might be expected to show similar patterns. This type of complex social behavior is not only common in birds, but also many mammals – including humans – and insects."

The research was supported by the National Science Foundation and the Miller Institute for Basic Research in Science at the University of California-Berkeley.

Blaine Friedlander | Newswise Science News
Further information:
http://www.cornell.edu

More articles from Life Sciences:

nachricht A novel socio-ecological approach helps identifying suitable wolf habitats
17.02.2017 | Universität Zürich

nachricht New, ultra-flexible probes form reliable, scar-free integration with the brain
16.02.2017 | University of Texas at Austin

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>