Cytogeometric Constraints in Tetrahymena Evolution: Contractile Vacuole Pore Positions in Nineteen Species of the Tetrahymena pyriformis Complex

Publisher Website
Google Scholar
Abstract
The position of the contractile vacuole pores [CVP], relative to the stomatogenic ciliary row, is a critical cytogeometrical parameter and a stable species characteristic in the T. pyriformis complex [T. hyperangularis, Syngen 14, Syngen 15, T. cosmopolitanis, T. americanis, T. lwoffi, Syngen 13, T. tropicalis; Syngen 5, T. furgasoni, T. australis, T. capricornis, T. pigmentosa, T. elliotti, T. canadensis, T. pyriformis, T. borealis, T. thermophila and Phenoset D]. The total variability within the complex is surprisingly small in view of the very large molecular diversities among the species. The extension of studies on this cytogeometric measure to 19 spp. shows how contrained the organismic design really is. One species has a mean CVP position of 19.6% of the cell''s circumference to the right of the stomatogenic meridian. At the other extreme 1 sp. has a mean position of 29.8%. Eleven species in the center of the range have a mean CVP position between 23.8-24.7%. The CVP position is of limited taxonomic utility because of its constraint within these narrow limits. The functional significance of the CVP placement is not known, nor are the selective forces essential to its preservation.

This publication has 2 references indexed in Scilit: