Geometric Geometric morphometrics morphometrics as a as a useful tool for visualising and useful tool for visualising and analysing deformities in fish analysing deformities in fish D. Adriaens D. Adriaens 1 1 , Y. Verhaegen , Y. Verhaegen 1 1 , T. De Wolf , T. De Wolf 2 2 , P. , P. Dhert Dhert 3 3 & P. Sorgeloos & P. Sorgeloos 4 4 1 Evolutionary Morphology of Vertebrates (UGent, Belgium) 2 Maricoltura Rosignano Solvay (Italy) 3 INVE Technologies (Dendermonde, Belgium) 4 Artemia Reference Centre (UGent, Belgium) [email protected]
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Geometric morphometrics as a useful tool for visualising and ......Geometric morphometrics as a useful tool for visualising and analysing deformities in fish D. Adriaens1, Y. Verhaegen,
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Geometric Geometric morphometricsmorphometrics as a as a useful tool for visualising and useful tool for visualising and analysing deformities in fishanalysing deformities in fish
D. AdriaensD. Adriaens11, Y. Verhaegen, Y. Verhaegen11, T. De Wolf, T. De Wolf22, P. , P. DhertDhert33 & P. Sorgeloos& P. Sorgeloos44
March 11 2005March 11 2005 Workshop "Deformities in Fish Larvae"Workshop "Deformities in Fish Larvae" 3/223/22
Traditional “morphometrics”Traditional “morphometrics”•• Length measurementsLength measurements
–– advantagesadvantages•• easy to measureeasy to measure•• easy to analyseeasy to analyse
–– PCA, DFA, ...PCA, DFA, ...
–– disadvantagesdisadvantages•• size variables, not shape variablessize variables, not shape variables•• unsufficient model of shapeunsufficient model of shape
ab
a=a’b=b’
a’
b’
‘shapes’ are equal
March 11 2005March 11 2005 Workshop "Deformities in Fish Larvae"Workshop "Deformities in Fish Larvae" 4/224/22
Traditional “morphometrics”Traditional “morphometrics”•• Length ratiosLength ratios
–– left left -- #9#9•• strongly deoperculatedstrongly deoperculated
right
left
March 11 2005March 11 2005 Workshop "Deformities in Fish Larvae"Workshop "Deformities in Fish Larvae" 22/2222/22
ConclusionsConclusions•• Use of geometric morphometricsUse of geometric morphometrics
–– more solid shape descriptorsmore solid shape descriptors–– more correct standardisation (GPA)more correct standardisation (GPA)–– statistical analyses applicablestatistical analyses applicable–– visualisation of shape variationvisualisation of shape variation
•• Deformations in Deformations in Sparus aurataSparus aurata–– geometric morphometrics very usefulgeometric morphometrics very useful–– ‘shape‘shape--gap’ between normal and deoperculatedgap’ between normal and deoperculated–– withinwithin--group variation not size relatedgroup variation not size related–– extreme leftextreme left--right asymmetryright asymmetry