ISSN:0748-3007    

DOI:10.1111/j.1096-0031.1995.tb00001.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract —Gondwanan biogeography, particularly the relationships between southern South America, New Zealand, Australia, New Guinea and New Caledonia, has been much studied.Nothofagusis often used as the “test taxon”, and many papers have been directed at usingNothofagusto explain Gondwanan biogeography. Cladistic biogeographers, working on plant material, have generally failed to find congruence among taxa expected from the southern Pacific disjunctions. New morphological and molecular data on the phytogeny ofNothofagushave re‐opened the issue, and we analysed these data to construct a new hypothesis of the biogeography of the genus. We assembled all plant taxa for which we could find reasonably robust phylogenetic hypotheses, and sought a parsimonious biogeographical pattern common to all. Two analyses, based on different assumptions, produced the same general areacladogram. We use the general area‐cladogram, in conjunction with the fossil record ofNothofagusto construct a historical scenario for the evolution of the genus. This scenario indicates extensive extinction, but also suggests that Australia has a more recent relationship to New Zealand than to southern South America. This is not congruent with the current geological theories, nor with the patterns evident from insect biogeography. We suggest that concordant dispersal is an unlikely explanation for this pattern, and propose that the solution might be found in alternative geological h

ISSN:0748-3007    

DOI:10.1111/j.1096-0031.1995.tb00002.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract —Randomization routines have quickly gained wide usage in phylogenetic systematies. Introduced a decade ago, the jackknife has rarely been applied in cladistic methodology. This data resampling technique was re‐investigated here as a means to discover the effect that taxon removal may have on the stability of the results obtained from parsimony analyses. This study shows that the removal of even a single taxon in an analysis can cause a solution of relatively few multiple equally parsimonious trees in an inclusive matrix to result in hundreds of equally parsimonious trees with the single removal of a taxon. On the other hand, removal of other taxa can stabilize the results to fewer trees. An index of clade stability, the Jackknife Monophyly Index (JMI) is developed which, like the bootstrap, applies a value to each clade according to its frequency of occurrence in jackknife pseudoreplicates. Unlike the bootstrap and earlier application of the jackknife, alternative suboptimal hypotheses are not forwarded by this method. Only those clades in the most parsimonious tree(s) are given JMI values. The behaviour of this index is investigated both in relation to a hypothetical and a real data set, as well as how it performs in comparison to the bootstrap. The JMI is found to not be influenced by uninformative characters or relative synapomorphy number, unlike the bootst

ISSN:0748-3007    

DOI:10.1111/j.1096-0031.1995.tb00003.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract —Goloboff recently introduced a method of character weighting that can be performed concomitantly with tree reconstruction. The basis for this method is his tree fitness measureF. The behaviour ofFis examined for a number of hypothetical and real data sets. It depends strongly on the value of the concavity constantk, and does not seem to be predictable. This makes it difficult to make general recommendations about the appropriate value ofkin specific cases. The basis forF, the number of extra steps taken by a character on a tree, does remain valuable as a basis for quality measures of trees, because it is independent of the number of states in the character, unlike the total number of steps and measures based on it such as CI and RC. Although no new measure is developed here, a number of requirements are formulated for an ideal tree quality measur

ISSN:0748-3007    

DOI:10.1111/j.1096-0031.1995.tb00004.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Abstract —In reconstructing the history of host‐parasite associations, it is necessary to consider several different processes, such as cospeciation and host switching, that may affect an association. A simple reconstruction method is to maximise the number of host‐parasite cospeciations. However, maximum cospeciation reconstruction may require the postulation of a large number of other kinds of events, such as parasite extinction or exclusion from certain hosts. A more sophisticated method associates each kind of event with a cost or weight which is inversely related to the likelihood of that kind of event occurring. I present a method of the latter type that distinguishes between two different processes: host tracking, of which cospeciation is a special case, and host switching. Given a relative weight for these two types of events, it is possible to convert the host phytogeny into a cost matrix, allowing for host switching, and use generalised‐parsimony algorithms to find minimum‐cost reconstructions of the history of the host‐parasite association. Different relative switch weights give different minimum‐cost reconstructions; the optimal switch weight can be found by maximising the fit between the tracking events and the parasite phytogeny, controlling for the number of postulated switches. As an empirical application of the method, data on an association between pocket gophers and their parasitic chewing lice were re‐examined. Although these data have been extensively analysed previously, the generalised parsimony approach throws new light on the history of

ISSN:0748-3007    

DOI:10.1111/j.1096-0031.1995.tb00005.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0748-3007    

DOI:10.1111/j.1096-0031.1995.tb00006.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0748-3007    

DOI:10.1111/j.1096-0031.1995.tb00007.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY