A biosystematic study of Castilleja crista-galli (Scrophulariaceae): An allopolyploid origin reexamined

Castilleja crista-galli is confined to northwest Wyoming, south-central Mon tana, and central Idaho and displays morphological attributes typical of th e ornithophilous Indian-paintbrushes. We examined its putative allopolyploi d origin with molecular, morphological, and cytological analyses. In analys es of restriction site mutations of the chloroplast genome, we found that n one of the seventeen species of Castilleja examined was characterized by a unique haplotype or set of haplotypes. Rather, geographically isolated spec ies are polymorphic for similar arrays of haplotypes. Moreover, we found no nuclear ribosomal DNA repeat types that characterized species; polymorphis ms in nuclear ribosomal DNA repeats were distributed both among individuals and among repeat units of single individuals. Morphometric analyses reveal ed morphological discontinuities among species, including C. crista-galli, but cladistic analyses of morphological characters failed to reveal synapom orphies for most taxa. Thus, morphological and molecular data were uninform ative regarding the hybrid origin of C. crista-galli. Results of cytologica l analyses do not support allopolyploid origin. We detected diploid and tet raploid populations of C, crista-galli, previously known as just an octoplo id. We retain the specific status of C. crista-galli under a morphological species concept. We also suggest that the species of Castilleja included in this study may have radiated recently and rapidly, maintaining ancestral p olymorphism.