The Origin of Phenotypic Plasticity in Stylopoma, North American Paleontological Convention

Bryozoans colonies grow by asexual propagation of members (“zooids”) within a colony. Previous studies of the cheilostome bryozoan Stylopoma have shown that there is a wide range of morphological variation of zooids within in a colony. This pattern limits the amount of evolution that occurs within a colony, since phenotypic changes don’t accumulate. But different Stylopoma species are morphometrically distinct, showing that even though these same attributes cannot evolve within colonies, they can and have evolved across different species. Therefore, the pattern of evolution within colonies must be screened off from the pattern of evolution between species. To study this evolutionary process, I test the idea that the degree of plasticity of morphology within a colony is evolving rather than individual phenotypes of zooids within in a colony. Using Stylopoma colonies bred in a common garden breeding experiment, I measure the heritability of phenotypic plasticity between colonies.