Population genetics of Philotheca sporadica (Rutaceae) to advise an offset translocation program

Abstract

Philotheca sporadica (Rutaceae) is a vulnerable species restricted to a small geographic area, with very few populations protected in reserves. Environmental impact surveys identified some populations that will be impacted by gas pipeline construction. This study aimed to determine the genetic diversity of P. sporadica to advise an offset planting program. P. sporadica was found to have high population genetic diversity but all populations were genetically similar except two isolated genetically depauperate populations. Genetic diversity decreased with decreasing population size and increasing population isolation. Impacted populations were significant for the species viability, being among the largest and most genetically diverse, although a high percentage of populations were reproductively active and not inbred. A congeneric species P. difformis ssp. difformis that grows in the nearby vicinity was shown to be genetically distinct but some evidence of hybridisation was found suggesting that offset populations should not be located near known populations of this species to prevent further hybridisation.