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Reappraising speciation in fossil gastropods


It is often said that the timescales for evolution are too long to allow speciation to be studied experimentally. Consequently, researchers look to the fossil record to provide the evidence base. However, this also has its limitations. With fossils, molecular analyses are not possible because soft tissues decay rapidly. Furthermore, the drivers of speciation are often a matter of speculation. Nevertheless, by selecting a depositional environment that provides a sequence of stratigraphical horizons that allow analysis of environmental factors, some informative studies are possible.

“Long-lived lakes are virtually predetermined for these studies, because of their duration and relative stability, being therefore often called ‘islands of evolution’. Many studies have proven this fact repeatedly, including the papers on the impressive morphological developments in the Middle Miocene Lake Steinheim planorbids, the Neogene Aegean freshwater gastropods, or the Recent Lake Tanganyika gastropods.” (page 117)

The research considered in this blog has gathered data from Lake Pannon. In the past, this covered parts of eastern Austria, Hungary, Slovakia, Croatia, Serbia, and western Romania. At its maximum, it covered 290,000 km2; it lasted from the Late Miocene to the Early Pliocene. A stratigraphy has been developed and its diverse fauna logged. The research paper considers the changing fortunes of the gastropod genus Melanopsis over successive stages of the lake’s chronological development.

The published work is discussed in this blog and it is suggested that observations are better explained using the concept of phenotypic plasticity, with no evidence for the origin of any novel genetic material or biological information. For more, go here.

What a huge lake! Sounds like it was a leftover from a huge flood or something. tjguy
The biggest limitation is that biological evidence can not be gathered by fossils. The only way to compare is to know the fossils in each deposition strata are indeed separated by the time needed. This is all from geology and not biology. There is no biological evidence for evolution. Its all presumed upon a geological presumption of segregated serious time lags. If the fossils were only separated by months in their deposition then they would be living at the same time and no evolution need apply. I disagree with this thread. Even if true in evidence for/against evolution it still would not be biological evidence. There is no biological evidence in comparing fossils. There is only geological claims for these fossils being years apart and then biologists wax heavy on evolution or lack of it. Fossils are only data points. The connections are not fossilized. No connection then no evidence for connection. These lakes are only as stable as these non biological lake guys say. IN this case YEC trumps ID on the realness of biological evidence and how its unrelated to observing fossils. Robert Byers
Thanks Dr. Tyler,, a few related footnotes: "...but Natural Selection reduces genetic information and we know this from all the Genetic Population studies that we have..." Maciej Marian Giertych - Population Geneticist - member of the European Parliament - EXPELLED EXPELLED - Natural Selection And Genetic Mutations - video http://www.metacafe.com/watch/4036840 Fantasy Island: Evolutionary Weirdness Does Not Favor Islands - July 2010 Excerpt: “We concluded that the evolution of body sizes is as random with respect to ‘isolation’ as on the rest of the planet,” he said. “This means that you can expect to find the same sort of patterns on islands and on the mainland.” http://www.creationsafaris.com/crev201007.htm#20100708b Amazing Insects Defy Evolution – October 2010 Excerpt: India spent tens of millions of years as an island before colliding with Asia. Yet the fossil record contains no evidence that unique species evolved on the subcontinent during this time, http://www.creationsafaris.com/crev201010.htm#20101026a Allopatric Speciation Tested in Martinique Cornelius Hunter - February 2012 Excerpt: In spite of evolutionary expectations the different lizard populations, which had been separated for six to eight millions years, had no difficulty interbreeding as one species. The so-called allopatric speciation never happened. Undaunted as ever, evolutionist now call for “ecological speciation,” which didn’t occur either but it has the virtue that it can’t be falsified. http://darwins-god.blogspot.com/2012/02/allopatric-speciation-tested-in.html African cichlid fish: a model system in adaptive radiation research: "The African cichlid fish radiations are the most diverse extant animal radiations and provide a unique system to test predictions of speciation and adaptive radiation theory(of evolution).----(surprising implication of the study?)---- the propensity to radiate was significantly higher in lineages whose precursors emerged from more ancient adaptive radiations than in other lineages" http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=16846905 What is Speciation? (Cichlids) - July 2012 - podcast http://intelligentdesign.podomatic.com/entry/2012-07-16T00_41_12-07_00 "The closest science has come to observing and recording actual speciation in animals is the work of Theodosius Dobzhansky in Drosophilia paulistorium fruit flies. But even here, only reproductive isolation, not a new species, appeared." from page 32 "Acquiring Genomes" Lynn Margulis. bornagain77

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