Built-in billboards: Male bluefin killifish signal different things with different fins

October 20, 2014

CHAMPAIGN, Ill. -- They help fish swim, but fins also advertise a fish's social standing and health. In a new study, researchers report that for the male bluefin killifish (Lucania goodei), each colorful fin presents its own messages to other fish.

Researchers report their findings in the journal Behavioral Ecology.

They're called "bluefin" killifish, but the first thing University of Illinois animal biology professor Rebecca Fuller noticed while she was snorkeling in a Florida stream was the killifishes' differently colored fins. In addition to having reflective skin, the males sometimes had red, yellow and/or black markings on their anal, caudal (tail) and dorsal fins.

"In some of the males, the anal fin was yellow, and then some of them were red," she said. "And the field guide showed them as blue."

Some of the males had darker black markings on their anal fins than others, and some had bright yellow or orange tailfins.

Fuller immediately wanted to know what was driving the variation.

Previous studies suggested that melanin, the black pigment, is a badge of status among males; those with more prominent melanin markings tend to be more aggressive towards other males. In the new study, Fuller and her former graduate student Ashley Johnson, found that males with heavier melanin outlines on their anal fins dominated: They were more aggressive with other males - driving them off to gain exclusive access to females.

"Melanin is a signal to other males: 'I've been winning in the past and I'm doing well and get out of my way,'" Fuller said.

The red and yellow pigments on the anal fins and the yellow tints on the tailfins have different origins, the researchers found. Carotenoids color the tailfins, but another class of pigments, called pterins, tint the anal fins either yellow or red. Yellow and red pterins are tied to differences in a single gene, Fuller said.

Carotenoids (the same pigments that give carrots and apricots their color) are known antioxidants; they gobble up highly reactive ions or molecules that can damage cells and tissues. Because killifish obtain carotenoids only by eating, researchers hypothesize that a display of color derived from carotenoids signals to potential mates that they are gazing upon a particularly robust, well-fed individual.

In the new study, Fuller and Johnson discovered that richer carotenoid coloration on the tailfin was associated with better body condition, lower parasite infection and good spawning success. This suggests that females respond positively to the brightly pigmented tailfins of potential mates, Fuller said.

Much less is known about pterins, she said. They are associated with immune function and also have antioxidant characteristics, and so also may be a badge of health.

In the new study, the researchers found that the pterin and carotenoid color patterns were independent of one another: Carotenoids colored only the tailfin, while pterins appeared only on the anal fin. Brighter pterin coloration was associated with lower parasite infection and higher spawning success, the researchers found.

"We are finding that communication is complicated in nature and that animals have evolved ways to send different messages to different receivers," Fuller said. "In the case of bluefin killifish, multiple messages are being provided by three distinct pigments that are in three different areas of the body. Both females and males are getting these messages. Males are paying attention to the melanin, most likely, and females are paying attention to these more-colorful fins."
-end-
The National Science Foundation Division of Environmental Biology and the U. of I. provided funding for this study.

Editor's note: To reach Rebecca Fuller, call 217-328-2026; email rcfuller@illinois.edu

The paper, "The meaning of melanin, carotenoid, and pterin pigments in the bluefin killifish, Lucania goodei" is available online or from the U. of I. News Bureau.

University of Illinois at Urbana-Champaign

Related Carotenoids Articles from Brightsurf:

How boundaries become bridges in evolution
The mechanisms that make organisms locally fit and those responsible for change are distinct and occur sequentially in evolution.

How plants protect themselves from sun damage
MIT chemists have observed, for the first time, one of the possible mechanisms that have been proposed for how plants dissipate energy when they are exposed to excess sunlight.

Gene responsible for lutein esterification in bread wheat identified
Researchers have identified and confirmed the gene responsible for lutein esterification in bread wheat.

Meatballs might wreck the anti-cancer perks of tomato sauce
Some of the anti-cancer benefits of tomatoes, specifically those from a compound called lycopene, could disappear when they're eaten with iron-rich foods, according to a new study from The Ohio State University.

Cooking vegetables: healthier with extra virgin olive oil
Cooking vegetables in the sofrito (sauté) with extra virgin olive oil favours the absorption and release of bioactive compounds of its traditional ingredients (garlic, onion and tomato), according to the study published in the journal Molecules about the role of gastronomy in the health-improving effects of the Mediterranean Diet.

What the vibrant pigments of bird feathers can teach us about how evolution works
A UA team shows that evolution is driven by dependency on other species within ecological communities - testing a long-held idea of the UA's late, great George Gaylord Simpson.

New study uncovers how lutemax 2020 protects the eyes against blue light damage
Morristown, N.J., June 29, 2018 - In a new study published in Nutrients titled 'Lutein and Zeaxanthin Isomers Protect Against Light-induced Retinopathy via Decreasing Oxidative and Endoplasmic Reticulum Stress in BALB/cJ Mice', Lutemax 2020 supplementation was shown to protect photoreceptors against blue light damage by mitigating oxidative and endoplasmic reticulum stress -- a primary mechanism associated with photoreceptor damage and visual impairment.

Healthy diet may lower eye disease risk
An analysis of recent high-quality research reveals that diet may affect individuals' risks related to the development and progression of age-related macular degeneration (AMD).

Deep-freezing of orange juice can increase the absorption of beneficial compounds
The cold treatments have two opposite effects. On one hand, they cause the carotenoids to degrade (negative effect) and, on the other hand, they generate an increase in the bioaccessibility of the carotenoids (positive effect).

Tomatoes of the same quality as normal, but using only half the water
When reducing the water used to water cherry tomato crops by more than 50%, the product not only maintains its quality, both commercially and nutritionally, but it also even increases the level of carotenoids, compounds of great interest in the food-processing industry.

Read More: Carotenoids News and Carotenoids Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.