Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Older Female Fish Prefer Imperfect Male Mates

17.11.2005


There’s hope for the less-than-perfect male – if you’re a swordtail fish, that is. As the size and age of female swordtail fish increase, so does the preference for males with asymmetrical markings, according to a new Ohio University study.

Molly Morris, associate professor of biological sciences, and colleagues found that older female swordtails spent more time with asymmetrically striped males than symmetrical males when offered a choice.

These findings are the first to contradict previous studies showing that females tend to prefer males with symmetrical markings, which in this case are black bars on each side of the body. Scientists have suggested that symmetrical markings are a sign of genetic fitness.



The new study provides evidence that visual cues are not the only thing driving mate selection, however. The findings also suggest that “females may not have the same mating preferences throughout their lives,” Morris said.

Funded by the National Science Foundation and the Research Challenge Program at Ohio University, the paper has been published online in Biology Letters and will appear in next month’s print edition.

Morris’ findings raise the question of whether there may be a change in mating preference over time in other species as well. In a current study on human attraction, for example, the average age of the females and males tested for preference for symmetrical faces was only 20.3 years and 19.5 years, she said.

The swordtail fish used in the latest research are two species of Mexican fish, Xiphophorus cortezi and Xiphophorus malinche. Because the genetic makeup of these fish is well known, researchers often use them to examine genetic causes of behavior.
To conduct the study, Morris and colleagues exposed females of both species to video animations of male fish, one with an equal number of bar markings on each side of the body, and one with an unequal number of bars on each side.

The animations simultaneously were projected on opposite sides of a tank, and researchers measured the time the female spent with each animation. While younger and smaller females still showed a preference for the symmetrical male, older and larger females increasingly preferred the asymmetrical male.

In previous research conducted elsewhere, females were shown to prefer symmetrical over asymmetrical males when presented with a choice. Scientists suggested that symmetrical figures have more redundant information, which makes for a more powerful, easy-to-remember stimulus. Females also may be likely to choose symmetrical males because they are better able to deal with environmental stresses and could pass on that resilience to offspring.

Another explanation would be that the visual system “develops an internal prototype of an object that is based on an average of all the male fish [the females] have seen,” Morris said. “Therefore, any fish they see that is closest to this prototype is preferred.” The same phenomenon has been suggested to explain attraction in other animals, including humans.

As their lives progress, however, female swordtails may encounter more asymmetrical than symmetrical males, and so begin to prefer the pattern to which they have become accustomed in their environment, she said.

Further research based on this study might examine whether the experience of mating draws older females to asymmetrical males, or whether there is a genetic factor, activated at a certain age or size, that makes larger females select more asymmetrically striped males.

The asymmetrical barring pattern is likely a result of environmental stresses experienced before birth, Morris explained. Some males have the genetic makeup to deal with these stresses and still develop a symmetrical pattern, while others survive the stress but show marks of the struggle. A population with a large amount of asymmetrical individuals may have been subject to a lot of environmental stress, such as pollution.

Co-authors of the study were post-doctoral fellow Oscar Rios-Cardenas and undergraduate student Mary Scarlett Tudor, both of Ohio University.

Andrea Gibson | EurekAlert!
Further information:
http://www.ohio.edu

More articles from Life Sciences:

nachricht Closing the carbon loop
08.12.2016 | University of Pittsburgh

nachricht Newly discovered bacteria-binding protein in the intestine
08.12.2016 | University of Gothenburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

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,...

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

Closing the carbon loop

08.12.2016 | Life Sciences

Applicability of dynamic facilitation theory to binary hard disk systems

08.12.2016 | Physics and Astronomy

Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D

08.12.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>