Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

From Obscurity to Dominance: Tracking the Rapid Evolutionary Rise of Ray-Finned Fish

23.07.2013
Mass extinctions, like lotteries, result in a multitude of losers and a few lucky winners.

This is the story of one of the winners, a small, shell-crushing predatory fish called Fouldenia, which first appears in the fossil record a mere 11 million years after an extinction that wiped out more than 90 percent of the planet's vertebrate species.

The extinction that ended the Devonian Era 359 million years ago created opportunities quickly exploited by a formerly rare and unremarkable group of fish that went on to become—in terms of the sheer number of species—the most successful vertebrates (backboned animals) on the planet today: the ray-finned fish.

A University of Michigan evolutionary biologist and a colleague have shown that the previously known but misclassified Fouldenia was the first recorded shell-crushing ray-finned fish. This long-extinct fish, and a handful of its relatives, demonstrate that in the immediate aftermath of the end-Devonian extinction, ray-finned fish had already acquired a diversity of forms that gave them an evolutionary edge, enabling them to fill the ecological vacuum left by the demise of most major fish groups.

"This event 359 million years ago is called the Hangenberg extinction, and it nearly wiped out vertebrate life, which at the time was limited to the water," said Lauren Sallan, an assistant professor in the U-M Department of Ecology and Evolutionary Biology. "The ray-finned fish come to the fore after that event. They not only recover from this extinction, but they go from being a few minor lineages to dominating all the oceans."

Sallan and Michael Coates of the University of Chicago also were able to identify juveniles of Fouldenia, a rare find that allowed them to show that the body shape of these fish changed dramatically as they developed. The relatives of Fouldenia, shell-crushers all, apparently took advantage of this developmental quirk to produce new forms. This diverse band of survivors spread worldwide and persisted for nearly 100 million years.

A study by Sallan and Coates was published online July 22 in the Zoological Journal of the Linnean Society.

"These early, post-Devonian ray-finned fish provide the first glimpse of what is to come: an evolutionary profusion of body forms, fin shapes, and extraordinary jaws and teeth. The ray-finned fish really do exemplify Darwin's comment about 'endless forms most beautiful and wonderful,'" Coates said.

There are around 30,000 species of ray-finned fish today, comprising nearly 99 percent of all fish species. Think of the word "fish" and the image that pops into your mind will likely be a ray-finned fish, members of a ubiquitous class that includes everything from tuna to trout, catfish to cod, swordfish to sunfish, perch to piranha, goldfish to goby.

After re-evaluating fossils from sites in Scotland dating to 348 million years ago, Sallan and Coates concluded that Fouldenia and its relative Styracopterus, which previous researchers had classified as the same species, are in fact separate genera. A genus is the category of biological classification between the family and the species.

Sallan and Coates determined that Fouldenia had massive tooth plates on its upper and lower jaws, suitable for preying on hard-shelled animals. It resembled modern-day jacks, which include the Japanese amberjack, or yellowtail, familiar to sushi lovers. Styracopterus was an early mimic of modern deep-bodied fish such as the angelfish. Both of these primeval fish were less than 10 inches long.

"Those Scottish fossil beds have four or five known genera of ray-finned fish in them. They all look completely different, and they all do completely different things," Sallan said.

The same sites have also produced some of the earliest post-Devonian tetrapods, four-limbed creatures that included some of humanity's earliest relatives, filling a post-extinction lull in their diversity known as Romer's Gap.

New branches on the tree of life had sprouted, setting the stage for an explosive diversification of forms that evolutionary biologists call an adaptive radiation. These events often occur in response to new ecological opportunities—when habitats are unoccupied by competitors, for example. That's what happened when a much later extinction killed off the dinosaurs and allowed mammals to take over those reptiles' ecological roles.

Something similar happened to ray-finned fish, which have fins supported by long, bony rods arranged in a ray pattern. Before the extinction, fish were dominated by two groups: the armor-plated, predatory placoderms and the lobe-finned fish, whose fins are borne on a fleshy, scaly stalk extending from the body.

Placoderms were eliminated by the end-Devonian extinction, and most of the lobe-finned fish perished as well, though survivors live on today in the lungfish and the coelacanth. In addition to a few ray-finned fish, some sharks and tetrapods survived the Hangenberg event. Tetrapods later crawled ashore and evolved into amphibians, reptiles, birds and mammals.

Other survivors of the Hangenberg event included sea urchins, sea lilies and shelled invertebrates called brachiopods. With most other predators now out of the picture, early sharks and ray-finned fish like Fouldenia used their crushing jaws to dine on these spiny, stalked and hard-shelled creatures.

"Because the ecosystem's been decimated, the only thing left to prey on are shelly animals," Sallan said. "So in this vacuum left by the mass extinction event, a bunch of different animals are going into these vacated niches and taking over those jobs."

The Hangenberg event was the final blow in a series of mass extinctions that ended the Devonian, which is often called the Age of Fish. The Hangenberg extinction is associated with a warming period when sea levels rose and the amount of oxygen in the water plummeted, followed by a cooling period that spread glaciers as far as the tropics.

Study: http://onlinelibrary.wiley.com/doi/10.1111/zoj.12054/abstract

Lauren Sallan: www.lsa.umich.edu/eeb/directory/faculty/lsallan/default.asp

Jim Erickson | EurekAlert!
Further information:
http://www.umich.edu

More articles from Life Sciences:

nachricht Researchers develop eco-friendly, 4-in-1 catalyst
25.04.2017 | Brown University

nachricht Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017
25.04.2017 | Laser Zentrum Hannover e.V.

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

NASA's Fermi catches gamma-ray flashes from tropical storms

25.04.2017 | Physics and Astronomy

Researchers invent process to make sustainable rubber, plastics

25.04.2017 | Materials Sciences

Transfecting cells gently – the LZH presents a GNOME prototype at the Labvolution 2017

25.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>