Dear Ranjeev,
That's a difficult question and there is no simple answer to it. Shell sculpture (as well as shape) can be both ecophenotypic and genetically fixed, depending on the environmental conditions and the presence or absence of competition and predation pressure.
For instance, in the Gyraulus species flock in Miocene Lake Steinheim the evolution of shape and sculpture is considered to reflect partly speciation and partly ecophenotypic variation (see Rasser 2013; attached).
In recent Melanopsis species of the Mediterranean, sculpture and shape are highly variable within single species, which makes species identification based on the shell alone sometimes almost impossible. Apparently, most of the morphological variability seems to be ecophenotypic (e.g. Glaubrecht 1993; Heller & Sivan 2002; attached).
For another example, I suggest you also see Glaubrecht & Köhler (2004 and references therein; attached).
In summary, shell carination CAN indeed be a result of ecophenotypic plasticity but the difficult task is to prove it!
Best wishes,
thomas
Dear Ranjeev,
That's a difficult question and there is no simple answer to it. Shell sculpture (as well as shape) can be both ecophenotypic and genetically fixed, depending on the environmental conditions and the presence or absence of competition and predation pressure.
For instance, in the Gyraulus species flock in Miocene Lake Steinheim the evolution of shape and sculpture is considered to reflect partly speciation and partly ecophenotypic variation (see Rasser 2013; attached).
In recent Melanopsis species of the Mediterranean, sculpture and shape are highly variable within single species, which makes species identification based on the shell alone sometimes almost impossible. Apparently, most of the morphological variability seems to be ecophenotypic (e.g. Glaubrecht 1993; Heller & Sivan 2002; attached).
For another example, I suggest you also see Glaubrecht & Köhler (2004 and references therein; attached).
In summary, shell carination CAN indeed be a result of ecophenotypic plasticity but the difficult task is to prove it!
Best wishes,
thomas
Thank you Dr. Neubauer and thank you very much for the papers. It is very intriguing to understand the evolution and adaptive roles of these shell structures
Heller_Sivan_2002_Melanopsis_Jordan_hybridi zation.pdf
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