Chong, Caroline , Waycott, Michelle , Edwards, Will .
Survival strategies of the tropical riparian paperbark tree: an ecological genetic perspective.
Riparian woody plants face multiple ecological challenges to survival throughout their lifetime, including variable drought and flood disturbances. Understanding how plant biological strategies and ecosystem processes interact is central to ongoing efforts to understand the functioning and dynamics of riparian ecosystems.
Disturbance-prone tropical river catchments provide an ideal, but little explored landscape to investigate functional relationships between environmental variability and plant traits for survival. For instance, the long-lived paperbark tree, Melaleuca leucadendra (Myrtaceae), dominates the high-stress river bed environment in northern Australian rivers that experience extreme hydrologic variability, yet little is known of its ecological strategies for persistence.
We used a multi-faceted research framework (experimental ecology, molecular genetic and phylogenetic approaches) to investigate the ecological structure of this model taxon across multiple biological and spatial scales. First, our results from spatial genetic structure analysis at the individual-plant scale are consistent with the hypothesis that resprouting is a prevalent growth strategy in this taxon. In mature trees, stem clonality combined with high genotypic diversity indicate that multi-stemmed growth directly influences the spatial structure of individuals, and may confer morphological survival advantages against physical disturbance. We also found unexpectedly high resprouting ability from the earliest seedling stage that is not related to species seed size or growth rate, providing supporting evidence that resprouting as a functional trait is acquired early and maintained throughout the lifetime. Second, we detected differences in plant genotypic structure that relate strongly to differences in site hydrological signature (predicted flood return levels). In contrast, patterns of genetic relatedness were highly diverse. This suggests neighbourhood and population structure are more strongly influenced by vectors of gene flow at large spatial scales. Third, our analysis of species phylogenetic relationships via molecular sequencing techniques indicates that Melaleuca leucadendra represents a multi-species group of taxonomically defined, but ecologically congruent riparian taxa.
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1 - James Cook University, Australian Centre for Tropical Freshwater Research and School of Tropical Biology, Townsville, Queensland, 4811, Australia
2 - James Cook University, School of Tropical Biology, Townsville, Queensland, 4811, Australia
3 - James Cook University, School of Tropical Biology, Cairns, Queensland, 4878, Australia
spatial genetic structure
Presentation Type: Oral Paper:Papers for Sections
Location: Lake Ontario/Hilton
Date: Monday, July 9th, 2007
Time: 1:00 PM