摘要:

The environment and history of this 19 485 km2tropical and subtropical savanna national park are described. The growth in awareness of the problems posed by alien organisms is documented: protected since 1898 and proclaimed as a national park in 1926, the first major policy decisions and control programmes for introduced species were initiated in the 1950s. Eight introduced pathogenic micro-organisms, 113 higher plants, two molluscs, one ant, one fish, one bird and two mammals have become ‘invasive’ in the Park. Only the micro-organisms and seven of the higher plants (comprising three floating aquatic macrophytes, one tree, one shrub, one cactus and one herb) are considered to have serious ecological impacts on the Park. The control programmes that have been carried out are described: seven of 25 invasive species of trees and shrubs and three of 88 plant species of other growth forms have been eliminated. With current technology, control is considered feasible for a further 13 and one species respectively. Intentional and accidental introduction by man and water-borne dispersal into the Park down the major influent rivers are all of major importance. Infestations of introduced plants are negligible in the frequently fired savanna vegetation while the rivers, riverbeds and riverine fringe have heavy infestations. Fire and ungulate herbivory are considered important factors limiting plant invasions. Control of certain introduced plant species along these rivers has proven to be difficult if not impossible, and the growth in the allocation of manpower and funds to these control programmes is documented. The importance of devising effective control strategies for these water-dispersed species is stressed.

ISSN:0035-919X    

DOI:10.1080/00359198809520128

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0035-919X    

DOI:10.1080/00359198809520129

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0035-919X    

DOI:10.1080/00359198809520130

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0035-919X    

DOI:10.1080/00359198809520131

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0035-919X    

DOI:10.1080/00359198809520132

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

This paper explores the use of genotypic data derived by protein electrophoresis in taxonomic and phylogenetic research. Variation in the electrophoretic mobilities of proteins can be used as a measure of nucleotide sequence variation in nuclear DNA. The resulting Mendelian data are useful for identifying morphologically cryptic species and for inferring phylogenetic relationships among congeneric species or closely related genera. Two methods, phenetics and cladistics, can be used to make phylogenetic inferences. In the phenetic approach, genetic distances are calculated between all possible pairs of taxa and a clustering algorithm is used to produce a tree-like phenogram. Cladistic methods, on the other hand, attempt to identify phylogenies on the basis of shared derived character states. Electrophoretic data can be used cladistically on the basis of: (1) tissue distributions of gene expression, (2) the occurrence of tandem or genomic gene duplications, (3) the ability of multimeric proteins to form heteropolymers between duplicated proteins, (4) alleles as characters, and (5) loci as characters and alleles as states. We illustrate the use of some of these methods to infer phylogenetic relationships among the taxa of two gastropod genera,BulliaandBurnupena.In comparison with other molecular techniques, protein electrophoresis is a relatively inexpensive, ‘low-technology’ method that does not require sophisticated equipment and has a large potential for solving taxonomic problems in southern Africa.

ISSN:0035-919X    

DOI:10.1080/00359198809520133

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0035-919X    

DOI:10.1080/00359198809520134

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The so-called molecules vs morphology ‘controversy’ currently plaguing phylogenetic systematics is discussed within a historical and philosophical context. It is concluded that the controversy is an artifact of flawed philosophy, improper project design and incorrect methods of data analysis, and that the controversy is sustained primarily by conflict of personalities. Moreover, the controversy may be resolved simply by closer collaboration between morphologists and molecular biologists, and by the use of philosophically sound phylogenetic methods (i.e. cladistics), founded on consilience and parsimony, and by the standardized use of mathematically correct analytical procedures.

ISSN:0035-919X    

DOI:10.1080/00359198809520135

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0035-919X    

DOI:10.1080/00359198809520136

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0035-919X    

DOI:10.1080/00359198809520137

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor