FSD 2010 - Hardesty

5th International Symposium-Workshop on Frugivores and Seed Dispersal (1985-2010)

Britta Denise Hardesty

CSIRO, Sustainable Ecosystems, PO Box 780 Atherton Qld 4883, Australia
email : denise.hardesty-at-csiro.au

Activities

My interest in forest community structure and regeneration has resulted in applying molecular markers to understand the dispersal and recruitment process, and the relative contribution of gene movement via both pollen and seeds. Recently I’ve been looking at dispersal in intact and fragmented systems and using molecular markers to trace invasion pathways for weedy species invading in tropical forest communities.

Abstract

**In a new landscape: dispersal ecology and genetics of Miconia invasion in Australia**

by Britta Denise Hardesty and David Westcott

Sustainable Ecosystems, CSIRO

Biological invasions have been identified as a key threatening process with significant negative impacts for global biodiversity. To better understand the process of plant invasion and spread for woody weeds in Australia’s rainforests, we ask how individuals and species move across the landscape and whether genetic bottlenecks constrain invasive potential in three related Melastomes, Miconia calvescens, M. nervosa and M. racemosa. All three species are actively being eradicated, and while they have similar growth forms, fruit presentation and occur in similar habitats, the nature of their invasions differs. M. calvescens is present at more than 30 sites across the Wet Tropics, whereas M. nervosa and M. racemosa are each known from a single location. Even though these weedy Melastomes were only recently introduced to Australia, they are well dispersed within their novel environments (up to 1-2 km). Hence, native frugivores are effectively providing dispersal services. Genetic diversity is lower in M. calvescens and M. racemosa than that observed in M. nervosa, which is consistent with few founding individuals (or closely related individuals) being responsible for introduction in those populations. In contrast, the M. nervosa population was likely founded by more individuals or from multiple sources that were less closely related. Interestingly, multiple introductions of M. calvescens have not resulted in increased genetic diversity; and the more genetically diverse M. nervosa has, at least to date, failed to demonstrate the level of invasiveness characterised by M. calvescens.

References

Hardesty, BD. Molecular marker application in invasive species ecology. 2008. in ‘Population Genetics Research Progress’ Ed. V.T. Koven, Nova Publishers, USA.

Hardesty, BD, SP Hubbell, and E Bermingham 2006. Genetic evidence of frequent long distance recruitment in a vertebrate dispersed Neotropical tree. Ecology Letters, 9: 516-525.

Muller-Landau, HC and BD Hardesty 2005. Seed dispersal of woody plants in tropical forests: Concepts, Examples, and Future Directions. pp 267-309 in ‘Biotic Interactions in the Tropics’. Eds. D Burslem, MA Pinard, and S Hartley. Cambridge University Press, Cambridge.

Hardesty, BD, CW Dick, A Kremer, SP Hubbell and E Bermingham 2005. Spatial genetic structure of Simarouba amara Aubl. (Simaroubaceae), a dioecious, animal-dispersed Neotropical tree, on Barro Colorado Island, Panama. Heredity 95: 290-297.

Former FSD presentations:

Hardesty, BD 2007. How far do offspring recruit from parent plants? A molecular approach to understanding effective dispersal. pp 277-299 in ‘Seed dispersal: theory and its application in a changing world’ AJ Dennis, EW Schupp RJ Green, and DA Westcott (eds). CAB International, Wallingford, UK.

Hardesty, BD, and VT Parker, 2002. Community seed rain patterns and a comparison to adult community structure in a West African tropical forest. Plant Ecology 164: 49-64.