Data/hora: 13/06/2024 23:20:25

Provedor de dados: | 17
País: | United Kingdom
Título: | The hypothesis of basic phenotype modules
Autores: | Thomas von Zelewsky.
Data: | 2010-01-28
Ano: | 2010
Palavras-chave: | Developmental Biology; Evolutionary Biology.
Resumo: | The evolutionary events that allowed the rapid occurrence of metazoa are still enigmatic. The presumably oldest metazoan fossils are microscopic and occur just above 635 Ma, at the beginning of the Ediacaran period. Upon condition that the lack of macrofossils in the lower Ediacaran strata is real, the assumption of a sudden appearance of already complex, but still small animals that flourished during the first half of the Ediacaran is a reasonable option. Consequently, the emergence of the first macrofossils with metazoan affinity in mid Ediacaran strata would indicate a second leap in animal evolution. Here, these apparent leaps are explained in terms of a new concept of evolvability that is based on well definable developmental modules: A system based on blast cell-induced cell division modules has paved the way for rapid evolution to small multicellular animals. The second module, an ancestral form of segments, allowed the construction of a new sort of metameric body plans that appeared some tenth of million years later and at a larger scale. Based on this new model of basic radiations, the lower Ediacaran strata are predicted to contain a sequence of exotic embryos that is followed by an explosion of small metazoan diversity. The upper Ediacaran biota are interpreted as representatives of an evolutionary succession that culminated in a maximally evolvable and segmented ancestor with an already complex archetype body plan. Then, around the Ediacaran-Cambrian boundary branching of most modern animal phyla would have taken place, with extensive secondary simplifications in many groups. This radically new hypothesis allows the formulation of clear predictions that are in agreement with available fossils and geochemical data from that period, however, it calls for a precise and chronologically well-definable sequence of Ediacaran events that can only be confirmed through future investigations.
Tipo: | Manuscript

Identificador:

http://precedings.nature.com/documents/4189/version/1

oai:nature.com:10101/npre.2010.4189.1

http://hdl.handle.net/10101/npre.2010.4189.1

Fonte: | Nature Precedings
Fonte: | Creative Commons Attribution 3.0 License