摘要:

SummaryPhylogenetic systematics in the sense of W. Hennig has exerted a great influence on systematic zoology. Among botanists, however, it has been overlooked and the present paper is intended as a brief summary of the principles, results, and advantages of its application in botanical systematics.In phylogenetic reconstruction monophyletic groups are established by the use of the unique, derived features inherited by the members from the immediate ancestor of the group. Since species splitting has been mainly dichotomous, the search for sister species or sister groups is the main procedure in phylogenetic reconstruction. The effects of multiple splitting of species, parallelism, and reticulate evolution are also discussed.In traditional, “natural” or “evolutionary” classification the degree of similarity is a main criterion for relationship. Since similarity depends on both primitive and derived characters, the groups established will often be paraphyletic; some of the descendants of the common ancestor will nor be included in such a group. Paraphyletic groups have no reality in nature and their use in evolutionary and biogeographic discussion is a major obstacle to progress. In a strictly phylogenetic classification all taxa must be monophyletic and all sister groups given equal rank. If these principles are followed, the classification will reflect nature's own hierarchy and its groups will be directly useful in all branches of causal biology.The effects of phylogenetic classification on different levels are demonstrated by two examples. Takhtajan's angiosperm system is discussed and it is shown that the traditional division of the angiosperms into the two classes Magnoliatae (dicotyledons) and Liliatae (monocotyledons) will have to be abandoned, since Magnoliatae is paraphyletic. On the genus level it is shown that if one wishes to maintain a number of specialized genera within the Capparidaceae‐Cleomoideae, the genusCleomebecomes paraphyletic. As long as the phylogeny of the whole group is not worked out, the only solution is to include the specialized segregates within the genusCleome.Similar examples could be found anywhere in contemporary botanical classification.

ISSN:0040-0262    

DOI:10.2307/1220367

出版商:Wiley    

年代:2019

数据来源: WILEY

ISSN:0040-0262    

DOI:10.1002/j.1996-8175.1978.tb04247.x

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryThe family Ulmaceae is most often treated as a single family with two subfamilies: The Ulmeae (Ulmoideae) and Celteae (Celtidoideae) or, more recently, as two separate families: the Ulmaceae and the Celtidaceae (sensu Grudzinskaya). A flavonoid survey of 80 species of Ulmaceae shows that each of the 19 genera is characterized by the production of flavonols (Ulmoid) or glycoflavones (Celtoid), but not both. Further, the arrangement of genera based on this flavonoid dichotomy is remarkably compatible with the generic assignments in Grudzinskaya's bifamilial concept of the Ulmaceae. The only exceptions areAmpelocera, Aphananthe, andGironniera(in part), which are normally considered Celtoid but possess Ulmoid (flavonols) chemistry. However, recent anatomical and morphological studies of these three genera indicate that their relationship to the Celtoid line may not be as direct as has been supposed, a point also suggested by the flavonoid chemistry.

ISSN:0040-0262    

DOI:10.2307/1220369

出版商:Wiley    

年代:2019

数据来源: WILEY

ISSN:0040-0262    

DOI:10.2307/1220370

出版商:Wiley    

年代:2019

数据来源: WILEY

ISSN:0040-0262    

DOI:10.1002/j.1996-8175.1978.tb04250.x

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryBaum (1977) suggests that improved ordinations may be found by first powering the dissimilarity matrix. Although transformations of dissimilarity are always worth considering, this note shows that improvements in fit can be misleadingly optimistic when the powering method is used.

ISSN:0040-0262    

DOI:10.2307/1220373

出版商:Wiley    

年代:2019

数据来源: WILEY

ISSN:0040-0262    

DOI:10.1002/j.1996-8175.1978.tb04252.x

出版商:Wiley    

年代:2019

数据来源: WILEY

ISSN:0040-0262    

DOI:10.2307/1220375

出版商:Wiley    

年代:2019

数据来源: WILEY

ISSN:0040-0262    

DOI:10.1002/j.1996-8175.1978.tb04254.x

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryThe differences between maize and annual teosinte are so numerous that individuals of the two species are never confused, and hybrids and backcrosses are easily distinguished. Mexican and Central American teosintes are similar, but differences in the male and female inflorescences, as well as cytogenetic and geographical separation, allow them to be delimited as two species ofZeaLinnaeus (1753) (Gramineae).

ISSN:0040-0262    

DOI:10.2307/1220377

出版商:Wiley    

年代:2019

数据来源: WILEY