Stone Loach

E.U. cave fish “evolved super-fast”, according to articles in New Scientist, Science (AAAS) News and ScienceDaily 3 April 2017 and Current Biology doi: 10.1016/j.cub.2017.02.048.

Scientists and cave explorers in Germany have found the first known European cave fish – small fish belonging to the genus Barbatula, also known as stone loaches, in the Danube–Aach underground karst waterway system. The fish are smaller than surface dwelling loaches, and have features typically found in other cave fish: pale skin lacking pigment and scales, and small eyes. They have larger nostrils and longer whisker-like barbels on the front of their heads than surface fish. These features are all considered to be adaptations for living in the dark.

Until the fish was discovered two years ago it had been assumed that fish had been unable to colonise European cave systems because they were blocked by Ice Age glaciers. Jasminca Behrmann-Godel of University of Konstanz, Germany explained: “The cave fish was found surprisingly far in the north, in Southern Germany. This is spectacular as it was believed before that the Pleistocene glaciations had prevented fish from colonizing subterranean habitats so far north”.

According to Arne Nolte from the University of Oldenburg, “It was only when the glaciers retreated that the system first became a suitable habitat for fish”. The researchers also reported the fish are “genetically isolated from populations in surface habitats and exhibit reduced genetic variability”.

The scientists were surprised at how short a time it took these cave fish to evolve. Jasminca Behrmann-Godel commented: “Our first genetic studies, plus knowledge of the geological history of the region, suggest the cave loach population is amazingly young, certainly not older than 20,000 years”. Roi Holzman of Tel Aviv University, Israel, who studies cave fish, commented that knowing the speed of evolution for this fish “opens a window to see evolution in its relatively early stages, which is not common”. New Scientist, Science, ScienceDaily

Editorial Comment: Cave fish are commonly used as evidence for evolution, but loss of skin pigment, scales, eye structure and genetic variability are change but they are definitely not evolution, regardless of how fast they may have occurred.

The lack of genetic variability in cave fish certainly indicates they are the descendants of a few fish that found their way into the cave system and became isolated from their surface dwelling cousins in the rivers, so henceforth they could only breed with one another. As with all inbred populations, any genetic mutations are reinforced in each succeeding generation, and they accumulate rapidly in the descendants. Stone loaches are not long lived fish, only 3-5 years, and females spawn thousands of eggs each year. Therefore, it does not take a long time for mutations to accumulate if the cave fish have been breeding at the same rate. The fact that they are still alive, even if in a reduced state, is a good indicator they have not been there for 20,000 years.

The larger barbels and nostril sizes are not evolution either. Surface dwelling loaches have barbels and use them to forage for food on river bottoms. In a dark environment the fish would be more reliant on using the barbels and their sense of smell to find food, and fish with larger barbels and nostrils would be more likely to survive in a cave environment, and live to reproduce and pass on genes for these traits. This is definitely natural selection at work, but it is not, repeat not, evolution – Darwinian, Dawkinsian, or any sort of evolution.

The difference between a surface dwelling loach and a cave dwelling loach is best summarised as a loss of features (pigment, scales), plus degeneration (eyes) with selection of already existing variations (barbels and nostrils). These are real changes but none are evolution, and all can happen in way less than 4,000 years.

Evidence News vol. 17, No. 6
19 April 2017
Creation Research Australia

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