Evolution: a different view; convergence (Introduction)

by David Turell , Friday, May 01, 2015, 14:32 (3493 days ago) @ David Turell

Another example of convergence. Swim technique to reach high speed. Reminds me of the discussions we had about patterns of development. think about built-in design guides:-http://www.sciencedaily.com/releases/2015/04/150428151506.htm-"The ability to move one's body rapidly through water is a key to existence for many species on this blue planet of ours. The Persian carpet flatworm, the cuttlefish and the black ghost knifefish look nothing like each other -- their last common ancestor lived 550 million years ago, before the Cambrian period -- but a new study uses a combination of computer simulations, a robotic fish and video footage of real fish to show that all three aquatic creatures have evolved to swim with elongated fins using the same mechanical motion that optimizes their speed, helping to ensure their survival.-"These three animals are part of a very diverse group of aquatic animals -- both vertebrate and invertebrate -- that independently arrived at the same solution of how to use their fins to maximize speed. And, remarkably, this so-called "convergent" evolution happened at least eight times across three different phyla, or animal groups, supporting the belief that necessity played a larger role than chance in developing this trait. The findings could help scientists better understand evolution as well as help pave the way for highly agile underwater vehicles.-"In an article publishing April 28 in the Open Access journal PLOS Biology, the researchers from Northwestern University in Evanston Illinois describe how they studied 22 animals called median/paired fin swimmers, in a wide variety of shapes and sizes. Their elongated fins both undulate, or ripple, lengthwise and oscillate from side to side. For all these animals' fins, the team found that the length of one undulation during swimming divided by the mean amplitude of the sideways movement is always a ratio of around 20."