James Cook University

Regeneration dynamics in a disturbance-prone landscape: population genetics and ecology of tropical riparian Melaleuca

Overview | Research Aims | Research Strategies | Supervisors |

Overview

Australian dry land river systems are uniquely complex environments characterised by extreme physical, biological and hydrologic variability. An outstanding challenge of tropical riparian research is to understand the ecology of native vegetation, and the functional role physical processes may play in driving species population dynamics and persistence. The extant lack of such ecological knowledge is a critical consideration in the development of riparian conservation and management strategies.

Melaleuca (the paperbark)is a conspicuous native element of the tropical riparian environment, yet little is known of its basic ecology. The ‘broad-leaved’ M. leucadendra group dominates the ecologically challenging, flood-prone zone of riverbanks and is therefore a model taxon to investigate relationships between environmental variability and biological functioning.

Through this research project, I aim to gain insight into the regeneration ecology of M. leucadendra and, in particular, an understanding of how interaction between physical, ecological and genetic processes may govern population demographics and functioning in this riparian dominant species.

Research aims

My specific research aims include:

• Investigation of vegetative (clonal) growth: spatial structuring and extent of genetic individuals
• Identification of population structure, size and connectivity: spatial genetic patterns of variation at local (river reach) to regional (catchment and inter-catchment) spatial scales
• Investigation of interactive processes: evaluate influence of geographic distance, location in river network (upstream to downstream), hydrologic potential (stream order), physical site characteristics, and biological parameters (plant life stage) on detected patterns of genetic and population structuring
• Understanding of species regeneration strategies: ecological investigations of seed bank dynamics and seedling resilience to disturbance
• Elucidation of species relationships: potential extent of outcrossing and hybridisation in the species group.

Research strategies

The rising field of molecular genetics provides a powerful means to address key paradigms of population ecology and gene flow - including seed dispersal, population connectivity and environmental adaptations - in an evolutionary context. In particular, application of hypervariable markers such as microsatellites, in concert with basic biological data and novel statistical frameworks, is facilitating new insight into processes underlying plant spatial distributions from local to landscape scales.

I aim to utilise this emergent field of research and integrate genetic, ecological and spatial information to identify population demographic processes in riparian Melaleuca . My research strategy thus incorporates three key approaches:

• Genetic: Use extant microsatellite markers to genotype individual leaf samples, and spatial autocorrelation analyses to identify spatial genetic patterns of variability
• Ecological: Conduct seed bank and seedling cropping experiments for insight into biological recruitment strategies
• Statistical: Conduct multivariate analyses of genetic, ecological and spatial data sets; perform and compare range of current spatial analyses (e.g. Bayesian methods), and consequent ecological interpretations of spatial genetic and biological patterns.

Supervisors

Dr Michelle Waycott, JCU
Will Edwards, JCU
Professor Richard Pearson, JCU
Gethin Morgan (EPA, Qld)