摘要:

SummaryA method is described for the rapid and accurate collection of descriptive taxonomic data for use in computer applications to taxonomy by using a computer driven display. Considerable savings of time and labour were achieved when the method was applied to descriptions of the microspecies ofRubus fruticosus.

ISSN:0040-0262    

DOI:10.2307/1219154

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryUsing the six diploid species ofClarkiacsection Myxocarpaas exemplifying rapidly‐evolved, chromosomally‐based reproductive isolates, the temporal relationships of adaptive and reproductive divergence are examined. Unlike the more familiar pattern, in which adaptive divergence is greater at the interspecific level than at the intraspecific level, two of the species consist of subspecies which have adaptively diverged to a greater extent than has anyMyxocarpaspecies from its putative progenitor. This indicates that the tempo and degree of adaptive change are relatively independent of the establishment of reproductive isolation, and indeed that the establishment of reproductive isolation by rapid chromosomal reorganization may not be coincidental with much change in adaptive level. Evidence bearing on the tempo of adaptive change prior to, during, and subsequent to the evolution of chromosomal isolates is examined. It is speculated that increased adaptation may frequently evolve prior to the establishment of chromosomal reorganization, because chromosomal isolates usually evolve from populations which have survived for a period of time in an especially stressful environment. Occasionally, less‐adapted chromosomal isolates, generated through genetic drift, may temporarily compete succesfully against a better‐adapted progenitor because of the competitive exclusion which occurs between intersterile populations which readily form F1hybrids. However, such isolates probably do not survive unless subsequent improvement in adaptation occurs.

ISSN:0040-0262    

DOI:10.2307/1219155

出版商:Wiley    

年代:2019

数据来源: WILEY

ISSN:0040-0262    

DOI:10.1002/j.1996-8175.1972.tb00249.x

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryThe problem of producing a classification from data gathered on specimens has two main components: first the information about the specimens must be structured as characters and character states in such a way that it carries the most information about the taxonomic structure of the objects under study, the mathematical ‘noise’ being eliminated as much as possible. Then this information must be handled in such a way that a hierarchical partitioning of the objects, called classification, is derived.This paper presents computer‐aided methods for the accomplishment of these steps. These methods were worked out to be both mathematically and biologically sound. The character analysis method (called CHARANAL) uses information theory to measure the amount of information common to pairs of characters, and derives from it various measures for the comparison of characters. The clustering technique presented here (entitled GRAPH), on the other hand, is based upon graph theory, and is intended to represent the thought process of the ‘classical’ taxonomist. For each method are given a general explanation, a detailed explanation of the mathematics involved, an example, and a section on interpretation of results.

ISSN:0040-0262    

DOI:10.2307/1219157

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryTwo recently proposed measures of the dissimilarity between classifications of a group of organisms are shown to be only pseudometrics when applied to nondichotomous classifications. Modifications of these measures are introduced and proved to have the properties of a true metric.

ISSN:0040-0262    

DOI:10.2307/1219158

出版商:Wiley    

年代:2019

数据来源: WILEY

ISSN:0040-0262    

DOI:10.1002/j.1996-8175.1972.tb00252.x

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryThe use of chemical characteristics in plant taxonomy is briefly surveyed. Some types of numerical treatment of variation in chromatographically separated substances are discussed. The usefulness of such methods is shown to be more restricted than is often claimed. The use of certain index values to illustrate differences between taxa or affinities between them is criticized from a biological point of view. An alternative possibility of the use of variation in chromatographically obtained data is suggested. A modified analysis of variance makes it possible to study population structures and genetical systems within one taxon at a time. Variation arising from irregularities in chromatographical separation, chance, etc., can also be estimated by this method.

ISSN:0040-0262    

DOI:10.2307/1219160

出版商:Wiley    

年代:2019

数据来源: WILEY

ISSN:0040-0262    

DOI:10.1002/j.1996-8175.1972.tb00254.x

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryAn account is given of the organisation of a data bank, associated with a small herbarium, consisting of an in clear card file and an in code computer file. The system is being used in the preparation of floras for Antarctic regions, phytogeographical investigations and the planning of future field work. The data bank is comparatively inexpensive to initiate and run and an estimate is provided of growth in size relative to manpower.

ISSN:0040-0262    

DOI:10.2307/1219162

出版商:Wiley    

年代:2019

数据来源: WILEY

ISSN:0040-0262    

DOI:10.1002/j.1996-8175.1972.tb00256.x

出版商:Wiley    

年代:2019

数据来源: WILEY