DATE2024.11.18 #Press Releases
Discovery of vertebral count patterns across animal species:
- Mammals exhibit constant sums, birds prioritize balance -
Summary of Presentation
A research team led by Dr. Rory T. Cerbus (Research Scientist, Laboratory for Developmental Epigenetics) and Dr. Kyogo Kawaguchi (Team Leader, RIKEN Hakubi Research Team for Non-equilibrium Living Matter Physics, RIKEN Center for Biosystems Dynamics Research; Associate Professor, Institute for Physics of Intelligence, Graduate School of Science, The University of Tokyo) and Dr. Ichiro Hiratani (Team Leader, Laboratory for Developmental Epigenetics), at the RIKEN Center for Biosystems Dynamics Research, has discovered previously unknown evolutionary constraints on the diversity of vertebral counts
in mammals and birds. This was achieved through a comprehensive analysis of vertebral count patterns in tetrapods (four-limbed animals).
These findings contribute to our understanding of the mechanisms driving morphological evolution in animals and hold potential for applications in species classification and evolutionary lineage determination.
The common rule that mammals, from humans to giraffes, possess seven neck vertebrae is well-known. Such morphological constraints are acquired during evolution and are thought to be partially regulated by the actions of genes such as Hox genes, which specify the development of different body segments. However, the presence of other constraints in tetrapods beyond mammals had not been systematically investigated.
In this study, by referencing records and specimen collections from museums both within and outside Japan, the researchers investigated the vertebral counts of hundreds of tetrapod species spanning four classes: amphibians, reptiles, birds, and mammals, and analyzed the patterns observed in these numbers.
The results revealed a “constant sum constraint” in mammals, where the total number of vertebrae in adjacent regions remains almost constant even when the number of vertebrae within individual regions changes.
In birds, they observed a “balance constraint”, where the number of vertebrae is balanced between the anterior and posterior sections along the body axis. Furthermore, the presence of a balance constraint in birds suggests the possibility that it was acquired during the evolutionary transition from dinosaurs to birds in association with flight capability.
Figure: Vertebral count patterns revealed through data collection and phylogenetic analysis
Related link: RIKEN Center for Biosystems Dynamics Research (BDR)
Journal
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Journal name Proceedings of the National Academy of Sciences (PNAS)Title of paper