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Abstract Detail



Morphospaces, Morphometrics, and Phylogenetics

Savriama, Yoland [1].

Statistical shape analysis of complex symmetry in botany.

Symmetry is a pervasive feature in organismal structures and bilateral symmetry in particular has been extensively studied in a plethora of biological contexts. For instance, studies of left-right asymmetries have created a widely popular and extremely active field of research under the banner of fluctuating asymmetry that is traditionally used as an estimate of developmental instability. These studies have opened new ways to understand the developmental bases of phenotypic variation and have also shed new light on the patterns of modularity and morphological integration.
The powerful and advanced methods of geometric morphometrics have been already used to precisely quantify symmetric variation and asymmetry in bilaterally symmetric organisms. However, bilateral symmetry is not the only type of symmetry in organismal shape. For instance, the arrangement of flower petals often shows complex symmetry and plays a key role in the development and evolution of flowers; the disposition of leaves along the shoot of plants exhibit translational symmetry (or serial homology); and algae as well as diatoms are symmetric with respect to two perpendicular axes of bilateral symmetry.
Here, I review a landmark based geometric morphometric method that allows the shape and size analysis of symmetry and asymmetry in plants. This method explicitly takes symmetry into account and separates out a component of symmetric variation (e.g. variation among flowers) from components of asymmetry (e.g. variation within flowers). This framework combines the mathematical theory of symmetry groups with the methods of geometric morphometrics and can be used for the shape analysis of any type of symmetric structure. Therefore, it provides a complete and general approach for morphological analyses of symmetric variation and asymmetry in plants. I illustrate this new framework by analyzing symmetry and allometric growth in Micrasterias rotata (Zygnemophyceae, Viridiplantae) cells; the role of symmetry in corolla shape variation of a wild population of flowers (Erysimum mediohispanicum, Brassicaceae); and the relationship between symmetry and CYC-like floral gene expressions and their role in the ontogeny of the capitulum inflorescence in Dipsacaceae (Knautia arvensis and Scabiosa columbaria).


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1 - Institute of Biotechology, Developmental biology, P.O.Box 56 , Viikinkaari 9, Helsinki, 00014, Finland

Keywords:
radial flower symmetry
bilateral flower symmetry
fluctuating asymmetry
developmental instability
natural selection
diatoms
algae
Procrustes superimposition
directional asymmetry
Procrustes ANOVA
PCA.

Presentation Type: Symposium Presentation
Session: SY06
Location: Salon 10/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 2:15 PM
Number: SY06003
Abstract ID:394
Candidate for Awards:None


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