Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Darkness Stifles Reproduction of Surface-Dwelling Fish

11.05.2011
There’s a reason to be afraid of the dark.

Fish accustomed to living near the light of the water’s surface become proverbial “fish out of water” when they move to dark environments like those found in caves, according to a study from North Carolina State University.

In research published this week in Biology Letters, a Royal Society scientific journal, NC State post-doctoral researcher Rüdiger Riesch and colleagues found that Atlantic molly females from regular surface streams have a difficult time adjusting to cavelike conditions. Surface female fish had trouble reproducing in the dark conditions, study results show. In addition, many surface-dwelling females introduced to dark conditions – surprisingly, according to the researchers – suffered from high incidents of stress-induced bacterial columnaris disease, or “fin rot,” which causes patchy lesions on the bodies of the fish.

“Permanent darkness severely hampers reproduction in surface-dwelling females,” Riesch says. “But this study also shows that the successful colonization of a subterranean habitat must have been a rare event for Atlantic mollies.”

The study was designed to provide an answer to why Atlantic mollies – their scientific name is Poecilia mexicana – living close to each other in and near a cave in southern Mexico can evolve in different ways. These population differences are normally attributed to geographic separation – like mountain ridges or some other physical barrier – but no physical barrier exists in or around the cave where these Atlantic mollies live.

In the study, the researchers placed some Atlantic mollies in cavelike total darkness while others received a “normal day” of 12 hours of light and 12 hours of darkness.

Most of the cave-dwelling fish of either sex as well as male surface-dwelling fish performed well in both light and darkness. Surface-dwelling females, however, did not breed well or maintain good health in the darkness.

One explanation for the results, Riesch says, has to do with the amount of resources fish have available for reproduction. A fish that has evolved in light has difficulties navigating and finding food in darkness, resulting in reproductive failure.

“Light and dark can completely disrupt life and reproduction for certain fish, and specific key adaptations are necessary to survive in caves,” Riesch says. “This study may be one answer to why fish of the same species living side by side can be so different.”

The research was funded by the National Science Foundation.

- kulikowski -

“Speciation in caves: experimental evidence that permanent darkness promotes reproductive isolation”

Authors: Rüdiger Riesch, North Carolina State University; Martin Plath, J.W. Goethe University; Ingo Schlupp, University of Oklahoma

Published: Online May 10, 2011, in Biology Letters

Abstract: Divergent selection through biotic factors like predation or parasitism can promote reproductive isolation even in the absence of geographical barriers. On the other hand, evidence for a role of adaptation to abiotic factors during ecological speciation in animals is scant. In particular, the role played by perpetual darkness in establishing reproductive isolation in cave animals (troglobites) remains elusive. We focused on two reproductively isolated ecotypes (surface- and cave-dwelling) of the widespread livebearer Poecilia mexicana, and raised offspring of wild-caught females to sexual maturity in a 12-month common-garden experiment. Fish were reared in light or darkness combined with high- or low-food conditions. Females, but not males, of the surface ecotype suffered from almost complete reproductive failure in darkness, especially in the low-food treatment. Furthermore, surface fish suffered from a significantly higher rate of spontaneous, stress-related infection with bacterial columnaris disease. This experimental evidence for strong selection by permanent darkness on non-adapted surface-dwelling animals adds depth to our understanding of the selective forces establishing and maintaining reproductive isolation in cave faunas.

Rudiger Riesch | EurekAlert!
Further information:
http://www.ncsu.edu

More articles from Life Sciences:

nachricht The balancing act: An enzyme that links endocytosis to membrane recycling
07.12.2016 | National Centre for Biological Sciences

nachricht Transforming plant cells from generalists to specialists
07.12.2016 | Duke 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: 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

NTU scientists build new ultrasound device using 3-D printing technology

07.12.2016 | Health and Medicine

The balancing act: An enzyme that links endocytosis to membrane recycling

07.12.2016 | Life Sciences

How to turn white fat brown

07.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>