Animals evolved from unicellular predecessors, differentiating into thirty or forty distinct anatomical plans. At the point when and how these outlines emerged has been the focus of debate.
To shed light on this, scientists at the University of Bristol compiled the presence and absence of thousands of features from all living animal groups. Doing this, they were able to create a ‘shape space’ for animal body plans, quantifying their similarities and differences.
They found that basic transformative change was not constrained to an early burst of developmental experimentation. Animal designs have kept on evolving to the present day – not progressively as Darwin anticipated – but rather in fits and starts, ramblingly through their developmental history.
The results highlight the patterns and pathways in which animal body plans evolved.
Co-author Bradley Deline, from the University of West Georgia (USA) said, “Our results are important in that they highlight the patterns and pathways in which animal body plans evolved. Moreover, major expansions in animal form following the Cambrian aligns with other major ecological transitions, such as the exploration of land.”
“Many of the animals we are familiar with today are objectively bizarre compared with the Cambrian weird wonders. Frankly, butterflies and birds are stranger than anything swimming in the ancient sea.”
Dr Mark Puttick from the University of Bath’s Department of Biology said, “One of the problems we had is that our study is mostly based on living species and we needed to include fossils. We solved the problem through a combination of analyzing the fossils and using computer models of evolution.”
Co-authors James Clark from Bristol’s School of Earth Sciences said, “The fossils plot intermediate of their living relatives in shape space. This means that the distinctiveness of living groups is a consequence of the extinction of their evolutionary intermediates. Therefore, animals appear different because of their history rather than unpreserved jumps in anatomy.”
Co-author Jenny Greenwood said, “We did this by collecting data on the different genomes, proteins, and regulatory genes, that living animal groups possess. The differences in anatomical designs correlate with regulatory gene sets, but not the type or diversity of proteins. This indicates that it is the evolution of genetic regulation of embryology that precipitated the evolution of animal biodiversity.”
Co-author Kevin Peterson from Dartmouth College (USA), added: “Our study confirms the view that continued gene regulatory construction was a key to animal evolution.”
Scientists reported this research in the journal Proceedings of the National Academy of Sciences USA.