SGER: Geometric Morphometrics-Based Visualization and Analysis of Morphological Integration: A New Look at Bivalve Evolution

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SGER: Geometric Morphometric-based Visualization and Analysis of Morphological Integration: A New Look at Bivalve EvolutionPeter D. RoopnarineEAR-0313560ABSTRACTThe proposed research is a novel approach to morphological integration, a long-standing interest in morphological studies. Morphological integration is a measure of the relationships among morphological characters at the level of the organism. Patterns of morphological integration are descriptions of how the phenotype of a monophyletic group of organisms is actually assembled from recognized characters. Variation of patterns within a monophyletic clade is therefore representative of adaptive histories, as well as phylogenetic and functional constraints. The present study proposes to develop a new method for the derivation and analysis of patterns of morphological integration within a very diverse and geologically old clade of bivalved molluscs, the superfamily Veneroidea. Viewing patterns of morphological integration within a clade, and over geological time, will allow this study to address an important paleobiological concept, namely the precise role of phenotypic construction in morphological constraint, adaptive radiation, and phylogenetic diversification. This proposal is novel because integration patterns will be derived from geometric morphometrics-based analyses, which will allow direct visualization on the phenotypes of the study organisms. The analyses will also encompass the longest interval of geologic time yet considered for a study of integration, approximately 80 million years. Furthermore, it is proposed that these patterns be analyzed in the recent frameworks of network theory and the mathematics of complexity because: 1) Patterns of morphological integration are true networks of relationships among regions of the organism's morphology, and 2) Network theory has been applied recently to both the very lowest levels of the biological hierarchy, such as genomic organization and gene function , and the highest levels, such as trophic food webs. Patterns of morphological integration at the level of species and monophyletic clades represent a critical link between these two ends of the hierarchy.