摘要:

Abstract—18S ribosomal RNA sequences from 11 echinoderms are analysed using parsimony to investigate phylogenetic relationships. Their estimated divergence limes range from less than 20 Ma to more than 550 Ma before present. Phylogenies based on 18S rRNA sequence data are compared with well‐established morphological phylogenies to discover at what evolutionary distance the two approaches start to produce incongruent results. Three regions of the 18S rRNA molecule are analysed separately and together, and paired and unpaired sites are also treated separately and combined.Results show that a parsimony analysis of sequence data produces reliable results only when taxa have diverged more recently than about 100 Ma. At greater evolutionary distances (up to 250 Ma), paired nucleotides produce more reliable results than unpaired, while paired and unpaired data combined produce intermediate results. All trees within about 1% of the most parsimonious solution ought to be accepted. Transversions give results almost as reliable as paired regions though there were relatively few informative sites. The relationships of echinoderm classes, which diverged 450–550 Ma ago, are unresolved by 18S rRNA

ISSN:0748-3007    

DOI:10.1111/j.1096-0031.1989.tb00567.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract—A cladistic analysis of the “green ash” eucalypts, informal subgenus “Monocalyptus”, is presented‐ As a first step, ordination methods of principal coordinates analysis and multidimensional scaling delineated some terminal taxa. The cladistic analysis, applying parsimony methods to the unweighted data set, yielded 25 equally parsimonious trees, each with a consistency index of 0.57.Farris' successive approximations approach to character weighting produced one tree with a consistency index of 0.74.An informal classification of the group, superseriesEucalyptus, is based on that cladogram. The biogeographic history of superseriesEucalyptusis interpreted from the cladogram as having been caused by lour vicariant events in southeastern Australia, in combination with a suite of ecological features that overlie the biogeographic a

ISSN:0748-3007    

DOI:10.1111/j.1096-0031.1989.tb00568.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract—Algorithms to reconstruct character evolution on polytomous cladograms or phylogenetic trees have to date interpreted each polytomy literally, as if it were an event of multiple speciation, with multiple daughter species descending independently from a mother species, thus requiring any similarities shared by only some of these daughters to be accounted for by convergence. These algorithms are not appropriate when the polytomy is interpreted in the usual way, namely as representing uncertainty in the cladogram's resolution. New algorithms for both ordered and unordered characters are presented to reconstruct character evolution under the uncertain‐resolution interpretation of polytomies. These algorithms allow the cladogram to resolve itself so as to be favourable for the character whose evolution is being reconstructed. Because different characters may have different favourable resolutions, it is not possible in general to use these algorithms to determine the total parsimony of a polytomous cladogram (the number of evolutionary steps required over all characters by the cladogram), for which the only adequate approach is to find a most parsimonious dichotomous resolution of the cladog

ISSN:0748-3007    

DOI:10.1111/j.1096-0031.1989.tb00569.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract—A cladistic analysis of the endemic South American family Tristiridae was performed using 29 characters from external morphology and the genitalia. Polarity of characters was based on the outgroup comparison method. One most parsimonious cladogram of 54 steps was obtained, from which a classification of the family Tristiridae was constructed. The analysis of phylogenetic relationships showed that the different kinds of characters define taxa at different levels in the cladogram. Those mostly from the phallic complex define suprageneric taxa while those from external morphology characterize genera. It is hypothesized that in Tristiridae differentiation of the phallic complex preceded differentiation of external morphology and that characters from the phallic complex arc less conservative than those from the external morpholog

ISSN:0748-3007    

DOI:10.1111/j.1096-0031.1989.tb00570.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Abstract—It is common practice to attempt to find the minimum length tree (also known as the Wagner tree) for a given data matrix on a group of OTUs (taxa). However, little study has been made of the pattern of frequency distributions when the lengths of all possible networks (unrooted trees) are taken into consideration. A published real data matrix with eight OTUs was compared with randomly generated data, when the former showed a much larger variance and very marked skewness. A number of published data matrices with a larger number of OTUs were studied by random selection of 10240 out of the possible trees: these were compared with 32 randomly generated data sets with 13 OTUs, using the same program. An algorithm has been found for calculation of the expected mean, variance and skewness for random binary data with up to 13 OTUs, based on the number of characters representing each type of partition of the OTUs. The calculation requires listing of the possible topologies and their relative weighting, which are tabulate

ISSN:0748-3007    

DOI:10.1111/j.1096-0031.1989.tb00571.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0748-3007    

DOI:10.1111/j.1096-0031.1989.tb00572.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0748-3007    

DOI:10.1111/j.1096-0031.1989.tb00573.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Book reviewed in this article:Fauna of Australia. Volume 1A. General Articles.Australian Government Publishing Service. 1987.Phylogenetic Relationships of the Lizard Families. Essays Commemorating Charles L. Camp.—R. Estes and G. Pregill (eds). 198

ISSN:0748-3007    

DOI:10.1111/j.1096-0031.1989.tb00574.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY