A review of methods for analysing insect structures - the role of morphology in the age of phylogenomics

Abstract

Techniques currently used in insect morphology are outlined briefly. Scanning electron microscopy (SEM) and microphotography are used mainly for documenting external features, the former providing more information on tiny surface structures and the latter on coloration, transparency and degree of sclerotization. A broad spectrum of methods is now available for anatomical studies: histological serial sections, confocal laser scanning microscopy (CLSM), light-sheet fluorescence microscopy (LSFM), serial block-face scanning electron microscopy (SBFSEM), dual beam scanning electron microscopy (FIB-SEM), nuclear magnetic resonance imaging (NMRI), and μ-computed tomography (micro-CT). The use of SBFSEM and FIB-SEM is restricted to extremely small samples. NMRI is used mainly in in vivo studies. Micro-computed tomography, in combination with computer-based reconstruction, has greatly accelerated the acquisition of high quality data in a phylogenetic context. Morphology will continue to play a vital role in phylogenetic and evolutionary investigations. It provides independent data for checking the plausibility of molecular phylogenies and is the only source of information for placing extinct taxa. It is the necessary basis for reconstructing character evolution on the phenotypic level and for developing complex evolutionary scenarios. Computer-based anatomical ontologies are an additional future perspective of morphological work.