摘要:

SummaryIn both folk taxonomy and science, the idea of species is based on the observation that phenotypic variation is discrete and not continuous. The definition of the species category, the “what,” must therefore be restricted to these empirically demonstrable facts. To avoid circularity, concepts about the biological nature of species, the “whys,” must be kept separate from the criteria by which individual species are circumscribed. Such ideas are models and can only be judged in terms of their capacity to bring observations into a meaningful context. The Biological Species Concept (BSC), the Evolutionary Species Concept (EvSC) and the Ecological Species Concept (EcSC) are models, not definitions. The BSC has its principal flaw in its inability to deal with uniparentally reproducing organisms. It fails to identify the driving force of speciation. It therefore fails to predict diversity and to explain why different species have different reproductive strategies. The EvSC fails to explain why different lineages are phenetically different. It fails, therefore, to explain why species arise, and why there are differences in diversity and reproductive strategies. The EcSC has the potential to make a direct connection between environment and phenetic variation patterns. It provides a useful conceptual framework for experimentation and observation at the interface between taxonomy and ecology and has the potential to explain on a universal basis variation in diversity and reproductive patterns. In some taxonomically difficult cases it also sheds light on the nature of variation patterns and might therefore help in taxonomic judgment where the BSC is conceptually inapplicable and the EvSC fails to provide useful concepts.

ISSN:0040-0262    

DOI:10.2307/1223084

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryIn preparation for continued phenetic and cladistic studies of taxonomic relationships of Centrospermae, 16 families are recognized in the order, and putative autapomorphies are designated for each where known, in order to support their monophyletic status. Polyphyly in Phytolaccaceae s.l. and paraphyly in Caryophyllaceae, Chenopodiaceae, and Portulacaceae are discussed. Pollen and floral characters used in an early study are revised and recoded. Recent molecular data bearing on centrosperm phylogeny are summarized.

ISSN:0040-0262    

DOI:10.2307/1223085

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

RésuméChez Engler, bien que cela ne soit pas explicite dans le texte, l'expression “affinités naturelles” réfère a une notion de relation phylogénétique. Il fait une distinction nette entre série génétique et série morphologique. Mais il n'a pas été jusqu'à dire, comme le feront les auteurs contemporains, que ces deux types de série peuvent être contradictoires. Engler se demande comment déterminer les affinités naturelles des organismes. Ce problème touche deux aspects fondamentaux de la systématique: la similarité entre les groupes et la détermination du niveau évolutif des caractères. D'après lui, l'étude de l'ontogenèse demeure le meilleur moyen pour connaître les affinités naturelles des organismes. Outre l'ontogenèse, c'est l'anatomie qui permet de déceler avec le plus de certitude les affinités taxonomiques. Pour déterminer le sens des séries morphologiques ou progressions, Engler se base sur le critère de complexité. De plus, il résout le problème de l'évolution en mosaïque des caractères, en prenant en considération les niveaux initiaux à l'intérieur des taxons.Un des points importants qui ressort de cette analyse est la distinction faite par Engler entre classification et phylogénie. Cependant, pour lui, les séries morphologiques sont équivalentes à des séries phylogénétiques.La différence fondamentale entre les principes systématiques de Engler et ceux des auteurs contemporains réside dans la reconnaissance par le premier de taxons polyphylétiques. Le système de Engler n'est donc pas strictement phylogénétique, si l'on entend par là la représentation exacte d'une phylogénie qu'on connaîtrait. Il n'a pas cherché à construire un système basé uniquement sur la phylogénie. Son système s'appuie sur des séries morphologiques déterminées à partir de principes qui relèvent souvent d'idées étrangères à la phylogénie, comme le principe de perfectionnement. Chez Engler c'est la classification qui semble conduire à la phylogénie et non l'inverse.Dans l'analyse de plusieurs séries évolutives (type de fleur, nombre de verticilles staminaux, nombre de téguments), il utilise le concept de phylogénie dans le sens des auteurs modernes; il parle de formes phylogénétiquement plus anciennes. Sauf la reconnaissance de groupes polyphylétiques, le système de Engler possède tous les éléments de la taxonomie évolutive décrits par Stevens (1986). Même si le système et les principes de Engler ne répondent pas aux critères de la systématique cladistique, nous pouvons qualifier son système de phylogénétique, si l'on entend par là un système représentant une généalogie des plantes.SummaryFor Engler, even if it is not explicit in his texts, the use of the expression “natural affinities” refers to a notion of phylogenetic relationships. In his reasoning, Engler makes a clear distinction between genetic series and morphological series. However, he did not go as far as to conclude, as have contemporary authors, that these two types of series can be contradictory. Engler asked himself how to determine the natural affinities of organisms. This problem concerns two fundamental aspects of systematics: the similarity between groups and the evolutionary level of characters. For him, the study of ontogenesis is the best means to discover the natural affinities between organisms. Beyond ontogenesis, it is the study of anatomy which allows us to determine with a high level of certitude the taxonomic affinities. To determine the direction of morphological series or progressions, Engler used the criterion of complexity. He solved the problem of mosaic evolution of characters, by considering the initial levels inside the taxa.One of the important points which comes out of this analysis is the distinction made by Engler between classification and phylogeny. Even so, for Engler, morphological series are equivalent to phylogenetic series.The fundamental difference between the systematic principles of Engler and those of contemporary authors is the recognition of Engler of polyphyletic taxa. The Englerian system is therefore not really phylogenetic, if we understand this concept to mean the exact representation of a phylogeny which is already known. He did not attempt to construct a system based only on phylogeny. His system is based on morphological series determined from principles which have no relationship with phylogeny, such as the principle of perfection. For Engler, it is the classification that seems to lead to the phylogeny, not the contrary.In the analysis of many evolutionary series (type of flower, number of staminal whorls, number of integuments) he used the concept of phylogeny in the sense of modern authors. Except for the acceptance of polyphyletic groups, the system of Engler has all the elements of the evolutionary taxonomy described by Stevens (1986). Even if the system and principles of Engler do not correspond to the criteria of cladistic systematics, we can nevertheless qualify his system as phylogenetic, if we understand this to mean a system representing a genealogy of plants.

ISSN:0040-0262    

DOI:10.2307/1223086

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryThe dating of the Prodromus and its two first supplements in Tenore'sFlora Napolitanahas been re‐examined. The reconstruction of the fascicles of the first volume and the publication dates are assembled in a table.

ISSN:0040-0262    

DOI:10.2307/1223087

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryNineteen populations ofAllium schœnoprasumL., distributed throughout the region between Lévis (near Québec City) and western Newfoundland, Canada, were sampled for a study of morphological variation. These populations overlapped the eastern Canadian ranges of var.laurentianumFern. (an endemic taxon of eastern North America) and var.sibiricum(L.) Hartm. (a circumboreal taxon). Twenty morphological characters were measured on 20 plants from each population. Kruskal‐Wallis tests showed that (1) all the characters exhibited very significant differences between populations, and (2) 17 characters were different between habitats. Principal coordinate analyses, based on the 14 characters related more strongly to locality than to habitat, showed that similarity values were generally higher between populations from the same region. Using populations from both ends of the geographic gradient asa prioridefined groups, canonical discriminant and classification analyses indicated that the overall variation pattern ofA. schœnoprasumwas clinal on a longitudinal gradient. The proportion of plants per population classified in one or the other group changed gradually along that gradient, and longitude alone accounted for most of the variance in mean population discriminant scores. Populations from Newfoundland and the eastern part of the Gaspé Peninsula, corresponding to var.laurentianum, are different from native populations of the upper St. Lawrence estuary region (var.sibiricum), but the clinal variation between these two extremes casts doubts on the need of retaining var.laurentianumin future taxonomic treatments of that species. Present variation patterns ofA. schœnoprasumin eastern North America are interpreted as resulting from widespread introgression, following secondary contacts between two population systems that survived Wisconsin glaciation in refugia situated around the Gulf of St. Lawrence and in southern New England, respectively.

ISSN:0040-0262    

DOI:10.2307/1223088

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryThe genusLuciliopsis(Fig. 1), described by Weddell (1855) for the minute BolivianL.Gnaphaliinae (Asteraceae), and evidence for a transfer of this species toChaetantheraof the tribe Mutisieae is presented.

ISSN:0040-0262    

DOI:10.2307/1223089

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryThe Southeastern Regional Floral Information System (SERFIS), a multi‐institutional specimen‐based database, is being developed at the University of Alabama. At maturity, it will contain full label data for specimens housed in the nearly 120 herbaria of the southeastern United States. Specimen labels are photographed with still frame video cameras. Each label image is recorded digitally to disk on a microcomputer. These label images are viewed by trained data entry personnel and keyed into HERB, the SERFIS data management system. In the process of developing this regional database, institutional databases are being established at each participating herbarium to provide computerized collection management capabilities within each. The resultant SERFIS database is to be managed as a research resource for systematic and conservation investigations.

ISSN:0040-0262    

DOI:10.2307/1223090

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryData recently presented suggest no correlation exists between pollen exine sculpturing and self‐incompatibility systems in angiosperms is re‐examined. All the variation that permits rejection of the correlation resides among 27 taxa designated as having gametophytic self‐incompatibility. However, no empirical data have been published which support this designation. When these taxa are deleted and all the data are pooled there is a significant difference between exine perforations in sporophytic and gametophytic self‐incompatible plants at the 0.95 confidence interval.

ISSN:0040-0262    

DOI:10.2307/1223091

出版商:Wiley    

年代:2019

数据来源: WILEY

ISSN:0040-0262    

DOI:10.2307/1223092

出版商:Wiley    

年代:2019

数据来源: WILEY

ISSN:0040-0262    

DOI:10.2307/1223093

出版商:Wiley    

年代:2019

数据来源: WILEY