1. |
INTRODUCTION |
|
TAXON,
Volume 19,
Issue 2,
2019,
Page 137-139
F. Ehrendorfer,
Preview
|
PDF (153KB)
|
|
ISSN:0040-0262
DOI:10.1002/j.1996-8175.1970.tb02994.x
出版商:Wiley
年代:2019
数据来源: WILEY
|
2. |
PROVOCATION OF BIOSYSTEMATICS |
|
TAXON,
Volume 19,
Issue 2,
2019,
Page 140-145
H. Merxmüller,
Preview
|
PDF (384KB)
|
|
摘要:
SummaryA breach exists between the biosystematists, who deal with evolutionary processes, and the more classical ‘conservative’ taxonomists, who deal with the endproducts. While dealing with processes, the problem of a generalized species concept (referring in fact to the end products) is hardly relevant to the study of biosystematics. Biosystematics can be successful only when it overcomes the gaps between its approaches “at the cross‐roads” to genetics and to systematics; biosystematics can thus become a true integral part of general systematics.
ISSN:0040-0262
DOI:10.2307/1217944
出版商:Wiley
年代:2019
数据来源: WILEY
|
3. |
BIOSYSTEMATICS AND EVOLUTIONARY NOISE |
|
TAXON,
Volume 19,
Issue 2,
2019,
Page 146-151
W. H. Wagner,
Preview
|
PDF (407KB)
|
|
摘要:
SummaryThe main pillars of plant evolution are the populations of normal species — diploid, sexual, and outbreeding. These basic stocks represent the diversity which has resulted from millions of years of phylogenetie change. Hybrids have occasionally appeared, but most have been sterile or ill‐adapted. Polyploids, apomicts, inbreeders, and hybrids arc common today and we have no reason to believe that they did not occur even among early land plants. The fact, however, that normal species with normal life cycles still prevail today strongly indicates that such plants have always been responsible for the primary thrust of evolution. A kind of evolutionary noise is produced through the repeated origin of populations with deleteriously modified life cycles in which the advantages of diploidy, sexuality, outbreeding, and species purity are counteracted or cancelled. Such deviations persist for longer or shorter periods while the normal parental stock continues to evolve.
ISSN:0040-0262
DOI:10.2307/1217945
出版商:Wiley
年代:2019
数据来源: WILEY
|
4. |
BIOSYSTEMATICS ALIVE? — A DISCUSSION |
|
TAXON,
Volume 19,
Issue 2,
2019,
Page 152-153
L. A. S. Johnson,
Preview
|
PDF (120KB)
|
|
摘要:
SummarySystematics in a broader sense, relating work in genetics, cytology, pollination, phytoehemistry and autecology to the study of evolutionary diversity is very much alive. The need for the term biosystematies to describe this activity has nearly disappeared.
ISSN:0040-0262
DOI:10.2307/1217946
出版商:Wiley
年代:2019
数据来源: WILEY
|
5. |
HYBRIDIZATION AND THE EVOLUTION OF PLANTS |
|
TAXON,
Volume 19,
Issue 2,
2019,
Page 154-160
H. N. Barber,
Preview
|
PDF (505KB)
|
|
摘要:
SummaryPolyploidy — both auto‐ and allo — may have dominated the short term evolution of plants because it increases “biochemical versatility” at the primary enzyme level. It actually creates new enzymes with different properties which may extend the range of environments in which normal and successful development may occur.. The new enzymes arise by oligomerisation of related polypeptides produced by related (homoeologous) genes (“hybrid” enzymes).Further study of polyploids may help us understand more about the control of development of the phenotype. There is evidence that the concentration of different isoenzymes changes with the development of tissues. Whether this denotes a causal connection between differentiation and enzyme production, we do not know. But the presence of isoenzymes generated by polyploidy may have allowed such controls to be made more refined and delicate and, thus, helped in ecological success. The determination of the actual amino‐acid sequences of such enzymes may, in the future, perhaps contribute to a further understanding of the role of enzyme hybridization for biochemical versatility as a factor in evolution.
ISSN:0040-0262
DOI:10.2307/1217947
出版商:Wiley
年代:2019
数据来源: WILEY
|
6. |
HYBRIDIZATION IN THE EVOLUTION OF BATRACHIUM |
|
TAXON,
Volume 19,
Issue 2,
2019,
Page 161-166
C. D. K. Cook,
Preview
|
PDF (423KB)
|
|
摘要:
SummaryThree groups of species can be distinguished inRanunculussubgenusBatrachiumwith respect to their leaf form. The first group of species produce only entire leaves and are primarily terrestrial. The second group produce only dissected leaves and all species are submerged aquatics. The third group is heterophyllous and the species produce both entire and divided leaves. The heterophyllous species are adapted to fluctuating water levels. The control of heterophylly is complex. When heterophyllous species are crossed the F1offspring are unstable in leaf form, but in the Fa stable, non‐heterophyllous segregants are found which in one jump may be preadapted to terrestrial or submerged conditions. Suchdecreasedepigenctic versatility in hybrids may be important in the evolution of higher plants.
ISSN:0040-0262
DOI:10.2307/1217948
出版商:Wiley
年代:2019
数据来源: WILEY
|
7. |
HYBRIDIZATION AND EVOLUTION — A DISCUSSION |
|
TAXON,
Volume 19,
Issue 2,
2019,
Page 167-171
Donald A. Levin,
Preview
|
PDF (343KB)
|
|
摘要:
SummaryThe interaction of divergent genomes as seen in the expression and stability of molecular, physiological and morphological characters may have a profound effect on the fitness of hybrids and bring forward new variations on which selection may act. The evolutionary implications of developmental interactions should prove to be a most rewarding area of inquiry for biosystematists.
ISSN:0040-0262
DOI:10.2307/1217949
出版商:Wiley
年代:2019
数据来源: WILEY
|
8. |
CHROMOSOME CHANGES IN PLANT EVOLUTION |
|
TAXON,
Volume 19,
Issue 2,
2019,
Page 172-179
Keith Jones,
Preview
|
PDF (589KB)
|
|
摘要:
SummaryWhen attempts are made to use chromosome characters as independent indicators of the direction of evolution there are few upon which we can depend. On the other hand, if we adopt the synthetic approach and view the chromosome in conjunction with all other characters of organisms then we can indeed determine with greater certainty patterns and pathways of evolution. This is not to equate the chromosome with the other aspects of our plants for we know that chromosomes can inform in ways which neither genes nor phenotypes can, but we require to know not only the way in which genes are assembled and controlled in their inheritance but also their nature as expressed in the chemical and structural phenotypes. We do stand at a cross‐road in the application of chromosome studies in plant biosystematics. We have arrived here not because we have been misled by the chromosomes but rather for the reason that they have been so frequently misused and misunderstood.
ISSN:0040-0262
DOI:10.2307/1217950
出版商:Wiley
年代:2019
数据来源: WILEY
|
9. |
EXTREME INSTABILITY OF CHROMOSOME NUMBER IN CLAYTONIA VIRGINICA |
|
TAXON,
Volume 19,
Issue 2,
2019,
Page 180-182
Walter H. Lewis,
Preview
|
PDF (220KB)
|
|
摘要:
SummaryClaytonia virginicaL. has two morphological races and some fifty chromosomal cytotypes. Even though apparently unique this complexity may prove to be of more general importance in the future. Simplicity and the most obvious may not always be Nature's way. InC. virginicagrowth and development, cytoecology and evolution are in juxtaposition, interacting and awaiting understanding. — The term biosystematics is now redundant because it has served its purpose to stress the importance of populational studies and cytogenetics for systematics.
ISSN:0040-0262
DOI:10.2307/1217951
出版商:Wiley
年代:2019
数据来源: WILEY
|
10. |
CHROMOSOME CHANGES — A DISCUSSION |
|
TAXON,
Volume 19,
Issue 2,
2019,
Page 183-184
Ben W. Smith,
Preview
|
PDF (145KB)
|
|
摘要:
SummaryEvolutionary studies, one of the main aims of “biosystematics” frequently do not provide the practical information required for classification. A truly phyletic classification is probably unattainable in view of the sheer numbers of organisms systematists have to deal with. Chromosomal changes, however, are often of importance as characters in more conventional taxonomy. The evolutionary direction of the changes is mostly difficult to assess.
ISSN:0040-0262
DOI:10.2307/1217952
出版商:Wiley
年代:2019
数据来源: WILEY
|