Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Are females glamorous because males are?

05.11.2015

The higher ornamentation of males is usually explained by sexual selection. However, there are also many highly ornamented females.

Scientists from the Max Planck Institute for Ornithology and colleagues quantified plumage colour of almost 6000 species of passerine birds and found that selection acts on the ornamentation of both sexes, even in opposite direction.


Male Olive-backed Sunbird (Cinnyris jugularis). This species is found from southern China to the Philippines and from Malaysia to northeastern Australia.

Kaspar Delhey


Pair of White-winged fairywren (Malurus leucopterus) from Australia.

Kaspar Delhey

Strong sexual selection on males led to an increase in their plumage colouration, but also to a more pronounced reduction in female ornamentation. The researchers found colourful females predominantly in larger species, in species living in the tropics and in cooperatively breeding species.

Sperm is small and cheap and eggs are large and expensive – this fact of life is the reason why females invest more in their offspring than males, and why males have to compete and females can be choosy.

Ornamental traits such as plumage colour may signal a male’s competitiveness or attractiveness to the opposite sex, and therefore ornamented males will enjoy higher reproductive success. Sexual selection will thus lead to increased male ornamentation.

But how then can it be explained that females of many species are also highly ornamented? A widely held view is that female ornamentation is a side-effect of selection on males. Under strong sexual selection, males should become more ornamented, and because females inherit the same genes, they will become more ornamented as well.

However, often both sexes compete for resources such as food and territories, and plumage ornamentation could be advantageous in this competition for females as well. Birds are ideal to study this: they show extraordinary variation in plumage colouration in both sexes, with males being more colourful than females, with both sexes looking alike or with females being the more colourful sex.

To answer the question of which selective forces act on plumage colouration in males and females, a team of researchers from the Max Planck Institute for Ornithology in Seewiesen together with colleagues in New Zealand, Canada, and Australia quantified plumage colour of males and females in almost 6000 species of passerine birds, listed in the “Handbook of the birds of the World”.

The scientists found the colour elaboration of males being highly correlated with that of females, suggesting that there are limitations to independent evolution of plumage ornamentation in each sex. However, contrary to the expectation, strong sexual selection on males – which led to increased colouration – had an antagonistic and stronger effect on females.

“Strong sexual selection leads to larger differences in ornamentation between the sexes, but the most obvious is not that males become more colourful, but that females becoming duller” summarizes Mihai Valcu.

The scientists also found that larger species and species that live in the tropics are more colourful, and this is true in both sexes. Being large reduces predation risk and hence being colourful may be less “costly” in those species. In the tropics, resource competition is typically higher, and therefore it may be more important to signal quality via increased ornamentation.

Overall, interspecific variation in plumage colour can be better explained in females than in males: females are more colourful in monogamous species and in cooperatively breeding species, where the competition among females over mating opportunities is higher.

“Our study shows that plumage ornamentation of females is not simply a by-product of the ornamentation in males”, says Bart Kempenaers, director in Seewiesen. In fact, it seems that females are highly ornamented when they also benefit from signalling their quality or competitiveness, either because it plays a role in mate choice, or via competition among females.

Weitere Informationen:

http://www.mpg.de/9711615/birds-plumage-colouration
http://DOI: 10.1038/nature15509

Dr. Sabine Spehn | Max-Planck-Institut für Ornithologie

Further reports about: Max Planck Institute Max-Planck-Institut breeding female females plumage species tropics

More articles from Life Sciences:

nachricht Unique genome architectures after fertilisation in single-cell embryos
30.03.2017 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH

nachricht Transport of molecular motors into cilia
28.03.2017 | Aarhus University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

'On-off switch' brings researchers a step closer to potential HIV vaccine

30.03.2017 | Health and Medicine

Penn studies find promise for innovations in liquid biopsies

30.03.2017 | Health and Medicine

An LED-based device for imaging radiation induced skin damage

30.03.2017 | Medical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>