Electrophoretic and cytological evidence for genetic heterogeneity and the hybrid origin of Athyrium oblitescens [Ferns]

Athyrium oblitescens, a putative hybrid species, was examined electrophoretically and cytologically to clarify its origin. Allozyme data showed that A. oblitescens consisted of at least three allozyme types, designated Type C, Type O and Type W. Genotypic compositions of Type C and Type W suggested that they were derived from independent hybridizations between A. otophorum and A. clivicola and between A. otophorum and A. wardii, respectively. Contrary to previous reports of tetraploidy in A. oblitescens and its hypothesized parent species, cytological observation revealed that Type C and Type W were both hexaploids. Possible pathways for the origin of these hexaploids are proposed. Type O was not genetically distinct from A. otophorum by either electrophoretic or cytological analyses, and thus there was no evidence of hybrid origin.