Visualizing morphometric differences between geographic populations
Abstract
Morphometric analyses of variation as a method to distinguish between differing geographic populations is a widespread method that works particularly well for patchy occurrences. However, when investigated species have a seemingly continuous distribution area, the analysis of their geographic variation is confronted with some difficulties. The majority of morphometric methods require a pre-grouping either for data presentation or for the calculations (e.g. discriminant function analysis, canonical variates analysis), which is generally based on independent information, e.g. differences in coloration, or hypotheses of geographic barriers like rivers or mountains. This a priori grouping is necessarily more or less arbitrary and can easily lead to false negative results, when differing groups are (partially) lumped together and/or separated. Here we present an interactive visualization system which enables a better supported grouping based on the morphometric data.
At the heart of our system are iconic information visualization techniques which are capable to display all attributes of a specimen at once in a graphical manner. The idea is that overlaying these icons on a geographic map makes differences between single specimens or whole populations apparent in their spatial context. To facilitate rapid direct quantification of attributes as well as qualitative comparison of attribute differences between different regions, our system provides two icon types which exhibit adequate perceptual qualities for those tasks. The underlying attribute set can be changed interactively in our system. Furthermore a spatial grouping can be applied which eases the investigation of large datasets by visualizing group representatives instead of individuals.
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Bibtex
@MISC{hermann-2010-starvis-poster, author = {Schunke, Anja C. and Hermann, Max and Klein, Reinhard}, title = {Visualizing morphometric differences between geographic populations}, year = {2010}, month = jul, howpublished = {Poster presentation at 9th Int. Congress of Vertebrate Morphology in Punta del Este, Uruguay}, abstract = {Morphometric analyses of variation as a method to distinguish between differing geographic populations is a widespread method that works particularly well for patchy occurrences. However, when investigated species have a seemingly continuous distribution area, the analysis of their geographic variation is confronted with some difficulties. The majority of morphometric methods require a pre-grouping either for data presentation or for the calculations (e.g. discriminant function analysis, canonical variates analysis), which is generally based on independent information, e.g. differences in coloration, or hypotheses of geographic barriers like rivers or mountains. This a priori grouping is necessarily more or less arbitrary and can easily lead to false negative results, when differing groups are (partially) lumped together and/or separated. Here we present an interactive visualization system which enables a better supported grouping based on the morphometric data. At the heart of our system are iconic information visualization techniques which are capable to display all attributes of a specimen at once in a graphical manner. The idea is that overlaying these icons on a geographic map makes differences between single specimens or whole populations apparent in their spatial context. To facilitate rapid direct quantification of attributes as well as qualitative comparison of attribute differences between different regions, our system provides two icon types which exhibit adequate perceptual qualities for those tasks. The underlying attribute set can be changed interactively in our system. Furthermore a spatial grouping can be applied which eases the investigation of large datasets by visualizing group representatives instead of individuals.} }