Does Species Range and Rarity Affect Population Genetics? A Case Study of Four Graptophyllum Species from Queensland,Australia

There are four species of Graptophyllum (Acanthaceae) in Australia which span a gradient in rarity and conservation status from the most endangered, Graptophyllum reticulatum (endangered), to G. ilicifolium (vulnerable), to G. excelsum (rare), to the least endangered G. spinigerum (widespread). Graptophyllum reticulatum and G. ilicifolium are each only known from three locations. All species were found to have quite high levels of genetic diversity (H_e, A, A_p, P) and there was no significant difference among species in genetic diversity ( P > 0.05), thus, genetic diversity was unrelated to conservation status or species geographic range. All species had high allelic fixation values ( F  ), indicating that populations were effectively inbred regardless of conservation status and geographic range. The genetic diversity among populations (F_ST) was not related to rarity and contrasted among the most restricted species, where diversity among populations was twice as high among G. reticulatum populations (F_ST, 0.22) compared with among G. ilicifolium populations (F_ST, 0.11).