Was the ancestral angiosperm flower whorled throughout?статья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 28 марта 2018 г.
Аннотация:Inferring directions of character transformations during angiosperm evolution is a long-term goal of systematic botany. A recent study by Sauquet et al. (2017) constitutes a keystone in investigating the evolution of floral characters in angiosperms. For the first time, it uses model-based approaches to infer transformations of 27 characters across time-calibrated molecular phylogenetic trees covering most angiosperm families. According to one of the reconstructions considered most plausible by Sauquet et al. (2017) and subsequently widely reproduced, the ancestral flower possessed a whorled perianth and a whorled androecium but a spiral gynoecium, a hypothesis that contradicts traditional ideas of ancestrally spiral flowers. The angiosperm-wide data set of Sauquet et al. (2017) is re-examined with respect to the occurrence of transformations from spiral to whorled and from whorled to spiral phyllotaxis at the points of transition from perianth to androecium and from androecium to gynoecium. We found no convincing example of a switch from whorled to spiral phyllotaxis (or vice versa) at the transition from androecium to gynoecium. Changes of phyllotaxis at the transition from perianth to androecium are rare, but can occur in both directions. 'Developmental parsimony' indicates that the ancestral flower is unlikely to have experienced the non-essential complication of a transition from whorled androecium to spiral gynoecium, and that this conservatism represents a strong developmental constraint. We suggest that the ancestral flower was either entirely spiral or entirely whorled; if whorled, it is possible that flowers with unidirectional acropetal prepatterning of organs are derived within angiosperms.