Grevillea caleyi is an endangered, fire-sensitive and self-compatible shrub that has been severely affected by recent habitat fragmentation. Small population size appears to have a negative impact on plant fecundity, plant survivorship, the mating system, and pollinator visitation in G. caleyi. These effects, as well as the random processes that occur in small populations, render small remnants of formerly more extensive G. caleyi populations vulnerable to genetic problems such as the loss of genetic diversity and increased inbreeding, which may in turn cause reduced population viability. However, G. caleyi possesses a longlived soil-stored seed bank that, theoretically, might buffer some of these genetic changes by storing genetic diversity from previous generations. In this study, I investigated whether the seed bank of G. caleyi possesses genetic characteristics that may allow it to slow the rate of genetic changes in populations that have suffered various effects of habitat fragmentation.

I used seven microsatellite loci to genotype both the adult plants at three G. caleyi populations, and also the seedlings that emerged following fire. One population, DF, was of moderate size (several hundred plants), while two (RA and JJM) had very small pre-fire adult populations (5 and 14 adults) but over 100 post-fire seedlings. DF had no genetic diversity among the adults or seedlings, which were genetically identical for the markers I used, indicating historical isolation and/or the effects of past population bottlenecks. At the other two populations, post-fire seedlings had similar allele frequencies to pre-fire adults but greater genetic diversity, as indicated by the percent of loci that were polymorphic and the levels of heterozygosity. In addition, the seed bank contained 20%(RA) and 12.5%(JJM) more alleles than were found among the adults. Parentage analyses revealed that, for some seedlings, neither parent was found among the pre-fire adults.