ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1990.tb00504.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Much recent literature focuses on whether ontogenetic information can be used as a direct criterion for determining the polarity of character trasformations in systematic analysis. This paper reviews the relevant literature and concludes that the ontogenetic criterion is dependent on parsimony rather than the sequence observed during ontogeny. It is not, therefore, based on the discredited arguments of recapitulation. From the perspective of phyologenetic systematics the ontogenetic criterion is a valid means of polarizing character transformations that represents a special case of a broader methodology involving parsimony. The alternative perspective perspective of patttern cladistics holds that polarity should be contained within the data and not imposed upon it. Thus, ontogeny is not required to polarize characters, but ontogenetic information can generate unequivocal character interpretations in terms of the relative generality of related attributes, and in the sense that absence precedes presence. Furthermore, ontogeny is central to systematics, providing empirical evidence of character transformation, information on the whole life cycle and an escape from systematics being teleologically related to phylogenetic inference and the theory of evolution.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1990.tb00505.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The evolution of development required few new features not already present in the eukaryotic cell, as exemplified by the cell cycle. Moreover, the protozoa possess many features of spatial organization and regulation present in metazoan embryos.The earliest multicellular organism could have been reproduced by a stem cell mechanism or by fission, the latter requiring cell‐to‐cell interactions that may have favoured cell‐interactions and regulation. Regeneration can be considered as a meta‐phenomenon related to asexual reproduction and retention of embryonic characters. The origin of embryonic structures like the gastrula may be accounted for in terms of Haeckel's ‘Gastrea’ theory. Mechanisms based on selection at the level of cell lineage are rejected.It is not clear what selective forces act on development itself, as distinct from the requirement for reliably producing a functional orgainsm. There is, for example, a major problem why gastrulation should be so variable in related animals. Selection for rate of development in relation to energy utilization may play a role. If many variants are neutral this may facilitate the evolution of novelty.In general terms there is a requirement for a continuity principle for the evolution of each form in development. Most groups pass through a phylotypic stage with considerable diversity befor

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1990.tb00506.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Waddington's epigenetic landscape illustrates such characteristic features of development as homeorhesis and the existence of alternative developmental pathways. Simply recongnizing that these are typical allows us to make inferences about evolution, for example that macroevolution is often a different process from microevolution. We can account for the origin of these properties by assuming that many processes in development can be modelled by non‐linear differential equatiions. The assumption then leads to two further predictions: that multiple speciation may be relatively common and that phenocopying is likely to occur in one direction onl

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1990.tb00507.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The considerable constraints that can be imposed on the evolution of primary metabolic pathways are apparent in the carbon pathway of photosynthesis in plants. Here, the unfortunate dual nature of the key enzyme, rubisco, to act as both a carboxylase and an oxygenase has led to a variety of adaptations in higher plants to maintain the efficiency of photosynthesis as a response to climatic stress.Constraints on secondary metabolism are less apparent, although evolution can proceed by both loss of enzymic ability (as in the shikimate pathway) and by gain (as in the mevalonate pathway). One evolutionary trend in angiosperms is towards more highly toxic allelochemicals to provide protection from herbivory or microbial attack. One constraint on alkaloid evolution is the concomitant need to develop a metabolic pathway to recycle the nitrogen for other purposes. In the terpenoid series of compounds, there is a correlation between increasing oxygenation of a carbon skeleton and increasing toxicity. However, increasing oxygenation, especially peroxide formation, may produce a compound too unstable to act effectively against predators. In the evolution of blue flower colour, the synthesis of delphinidin 3‐glucoside is only the first step in the production of a stable pigment complex capable of providing intensein vivocolouration. In the coevolution of plants and animals, some insects (e.g. the Monarch butterfly) have developed the ability to sequester and store plant toxins to avoid the cost of synthesis but here again there are clear constraints on the processes involve

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1990.tb00508.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Among the flowering plants flowers are relatively closed systems of a considerable complexity and therefore more suitable for comparative developmental studies than other organs. They work with a few kinds of structural elements that occur in variable or fixed numbers and are arranged in patterns more or less constrained by developmental conditions. Diversity of floral structure occurs at different levels, with emphasis either on number and arrangement or on synorganization and form of the structural elements. The first level is shown here with examples of several representatives of the primitive subclasses Magnoliidae and Hamamelididae, the second with Asclepiadaceae representing the most advanced subclass of dicotyledons Asteridae. Although early ontogenetic patterns are fairly constant among larger groups, especially the sequence of initiation and position of the different classes of structural elements, there is no strict stability in any of the parameters studied.

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1990.tb00509.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

In the history of biology, the term ‘evolution’ has carried a dual meaning, viz. ontogeny (the unfolding of the germ) versus phylogeny (descent with modification). A problem in modern biology is the question of whether it is ontogeny which creates phylogeny, or whether it is phylogeny which moulds ontogeny. The paper explores the relationship of ontogeny to phylogeny in the context of ‘pattern cladism’. The conclusion is that the analysis of ontogeny provides a direct method for classification (‘a way forward for systematics’), which is a logical prerequisite for a phylogenetic interpretation of ontogenetic sequences (‘a way backward for phylogeny’). The ontogenetic process of growth, subdivision and differentiation is related to the ‘morphogenetic tree theory’ on the basis of Von Baer's “laws of individual development”. This conceptual relation shows that ontogeny creates phylogeny in an upward direction within the morphogenetic tree, whereas phylogeny (by means of natural selection) moulds ontogeny in a downward direction. A conflict originates with the conventions of Linnaean classification if ontogenetic divergence is proposed as a causal agent in the origin of higher taxa. It is proposed to solve this conflict by viewing individual organisms (or reproductive communities) not as constituents, but as represe

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1990.tb00510.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

ISSN:0024-4066    

DOI:10.1111/j.1095-8312.1990.tb00511.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY