Ecological niche models (ENMs),which are created by linking species’ occurrence data with environmental envelopes, are popular tools to answer fundamental questions in ecology and evolution. Often, due to data availability, ENMs must rely on museum and herbarium data (or PO data). As with any other type of model, ENMs’ performance will depend on the specific model conditions such as model assumptions, data points quality and quantity and covariates availability. Moreover, due to the lack of species’ absence information, ENMs utilizing PO data should face additional caveats. The two main problems are; sampling bias and difficulty in the estimation of species occurrence probability. This thesis aims to address some unresolved issues in the ENM-PO field by using different datasets and conditions. Whether it is possible to accurately predict species occurrence probability, when working with presence only data, is the main question of the first part of this study. Specifically, I compared two ENMs (i.e. Maxlike & MaxEnt) using a generous set of Acacia species. A strong relationship between quantity of data and Maxlike model performance was described, and further implications were discussed. The consequences of using these methods to predict areas of distribution, rank covariates and forecast climate scenarios were analyzed using the freshwater turtle Emydura Macquarii as a case study. Although, similarities among methods were evident when ranking covariates and predicting E. macquarii distribution. Predictions over time were particularly heterogeneous among models, which prevents users from applying these methods in an interchangeable manner. The second part of the thesis moves beyond ENM methodologies, using ENMs to evaluate phylogenetic niche conservatism (PNC) in Australia grasses, thereby tackling the question of whether environmental niches are conserved among related species. Novel approaches were developed to evaluate niche conservatism, and more importantly, a relationship among niche conservatism and phylogenetic clustering was identified. Specifically, Panicoidea clade presented a tendency towards niche shifts. Theoretical and practical implications were discussed.
|Date of Award||2017|
|Supervisor||Bernd Gruber (Supervisor) & Arthur Georges (Supervisor)|
Ecological niche modelling using presence only (PO) data : an evaluation of methods and applications
Lopez Aldana, M. A. (Author). 2017
Student thesis: Doctoral Thesis