Reappraising speciation in fossil gastropods
|February 5, 2013||Posted by David Tyler under Intelligent Design|
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.