Conservation Genetics

, Volume 9, Issue 3, pp 515–529 | Cite as

Integrating population demography, genetics and self-incompatibility in a viability assessment of the Wee Jasper Grevillea (Grevillea iaspicula McGill., Proteaceae)

  • Susan E. Hoebee
  • Peter H. Thrall
  • Andrew G. Young
Research Article

Abstract

Grevillea iaspicula is an endangered shrub known from only eight small populations (<250 individuals) in south-eastern Australia. The species is threatened by combined ecological and genetic factors, e.g. land conversion, weed invasion, low recruitment and low gene flow among populations. The populations also show large variance in male fitness and limited mate availability which are thought to arise as a consequence of gametophytic self-incompatibility (GSI). This study has used an individual-based, spatially explicit simulation model to explore the interaction between GSI and mate limitation in this species, as well as its effect on long-term population viability. The model was parameterised with demographic and genetic data obtained from 2 years of population monitoring. Simulation results identified extremely low establishment rates as the most critical factor currently influencing the persistence of G. iaspicula populations and indicated that the extant populations are at serious risk of extinction in the near future unless this is altered by, at very least, an order of magnitude higher. SI was shown to affect the magnitude of variation in establishment but this effect was masked when establishment was critically low. Disassortative mating, owing to low allelic richness at the S-locus, had the negative demographic effect of restricting mating to relatively few compatible plants. Restricted mate availability imposed additional limitations to the viability of populations but, given a 20-fold increase in establishment rate, population fluctuations stabilised. The long-term viability of G. iaspicula is bleak without artificial augmentation of the populations but management planning must also consider genetic processes, including SI, to ensure such strategies optimise the benefits gained.

Keywords

Gametophytic self-incompatibility (GSI) Individual-based model 

Notes

Acknowledgements

Thanks to Elizabeth Gregory, Huibrecht and Alison Hoebee, Bernard Pfeil, Jane Pulford and Darren Shearer for their willing field assistance, and all property owners for access to the populations. Suggestions from anonymous reviewers greatly improved the manuscript. SEH was supported by a CSIRO Student Stipend during the term of this study.

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Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • Susan E. Hoebee
    • 1
    • 2
    • 3
  • Peter H. Thrall
    • 1
  • Andrew G. Young
    • 1
  1. 1.CSIRO Plant IndustryCanberraAustralia
  2. 2.School of Resources, Environment and SocietyAustralian National UniversityCanberraAustralia
  3. 3.School of BotanyUniversity of MelbourneParkvilleAustralia

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