Sourcing Seed for Acacia acinacea, a Key Revegetation Species in South Eastern Australia

Abstract

Intensive large-scale revegetation programs are a major activity in degraded landscapes. The collection and deployment of seed for revegetation is primarily based on local seed sources to preclude concerns associated with local adaptation as well as outbreeding depression in small remnant populations. For most species however, little is known about the levels of genetic diversity being sourced and deployed, or even of the levels of adaptively significant variation present across the species range. Acacia acinacea (Gold Dust wattle) is a key revegetation species widely distributed across south eastern Australia. Levels of variation in terms of morphology, fitness, ploidy level and AFLPs were assessed using seed lots from 35 populations across the Murray Darling Basin in south eastern Australia. Multivariate analysis indicated that three of the populations were misidentified while the remaining populations were differentiated into three groups. One of these groups (Bendigo) was highly geographically localised and tetraploid while the other two (Group1 and Group2) were both diploid with overlapping distributions. Fitness differences were also evident among these three groups while AFLPs indicated that they were genetically differentiated and that lower levels of diversity were captured from some populations. A major finding of this study was that no one technique was able to fully describe the variation present in A. acinacea and seed sourcing guidelines based on any single approach could have resulted in erroneous decisions being made. Information generated from this study has been used to refine seed sourcing guidelines.