On the consistency of the plurality rule consensus function for molecular sequences

1994 ◽  
Vol 11 (2) ◽  
pp. 233-249 ◽  
Author(s):  
William H. E. Day ◽  
F. R. McMorris
Keyword(s):  
Plurality Rule ◽  
Consensus Function ◽  
Molecular Sequences

scholarly journals The asymptotic plurality rule for molecular sequences

1996 ◽  
Vol 23 (3) ◽  
pp. 27-42 ◽  
Author(s):  
W.H.E. Day ◽  
E. Kubicka ◽  
G. Kubicki ◽  
F.R. McMorris
Keyword(s):  
Plurality Rule ◽  
Molecular Sequences

Was Duverger Correct? Single-Member District Election Outcomes in Fifty-three Countries

2012 ◽  
Vol 43 (1) ◽  
pp. 201-220 ◽  
Author(s):  
Matthew M. Singer
Keyword(s):  
Institutional Arrangements ◽  
District Level ◽  
Party Competition ◽  
Plurality Rule ◽  
Third Place ◽  
Institutional Rules ◽  
Large Numbers ◽  
Level Data ◽  
Number Of Parties ◽  
Duverger's Law

In districts where only one seat is contested, the electoral formula (plurality or majority) should be a major determinant of the number of parties that receive votes. Specifically, plurality rule should generate two-party competition while other institutional arrangements should generate electoral fragmentation. Yet tests of these propositions using district-level data have focused on a limited number of cases; they rarely contrast different electoral systems and have reached mixed conclusions. This study analyses district-level data from 6,745 single-member district election contests from 53 democratic countries to test the evidence for Duverger's Law and Hypothesis. Double-ballot majoritarian systems have large numbers of candidates, as predicted, but while the average outcome under plurality rule is generally consistent with two-party competition, it is not perfectly so. The two largest parties typically dominate the districts (generally receiving more than 90 per cent of the vote), and there is very little support for parties finishing fourth or worse. Yet third-place parties do not completely disappear, and ethnic divisions shape party fragmentation levels, even under plurality rule. Finally, institutional rules that generate multiparty systems elsewhere in the country increase electoral fragmentation in single-member plurality districts.

Consensus sequences based on plurality rule

1992 ◽  
Vol 54 (6) ◽  
pp. 1057-1068 ◽  
Author(s):  
W DAY ◽  
F MCMORRIS
Keyword(s):  
Plurality Rule ◽  
Consensus Sequences

A combined morphological and molecular phylogeny for sea urchins (Echinoidea: Echinodermata)

1995 ◽  
Vol 347 (1320) ◽  
pp. 213-234 ◽  
Keyword(s):  
Data Base ◽  
Sequence Data ◽  
Phylogenetic Analyses ◽  
Total Evidence ◽  
Morphological Data ◽  
Rrna Genes ◽  
Rrna Gene ◽  
Molecular Sequences ◽  
Higher Taxa ◽  
Stem Group

Phylogenedc reladonships of higher taxa of echinoids have been invesdgated using a 163 character morphological data base and molecular sequences from large and small subunit (LSU and SSU) ribosomal RNA (rRNA) genes. The complete ssu rRNA gene has been sequenced for 21 taxa, with representatives from nine of the 14 extant orders of Echinoidea. Partial LSU sequences, representing the first 400 base pairs (b.p.) from the 5' end were also sequenced for three taxa to complement an existing data base of ten taxa. The two molecular sequences provided a total of 371 variable sites, of which 143 were phylogenetically informative (compared to 145 phylogenetically informative sites from morphological data). Morphological, LSU and SSU data have been analysed separately and together. Morphological and ssu sequence data generate topologies that are not significantly in conflict (under Templeton’s test), but the strong signal pairing arbaciids with clypeasteroids in the LSU derived tree marks the LSU sequence data as anomalous for this taxon. A ‘ total evidence’ approach derived a tree very similar in topology to that derived from morphological data. Rooted on the stem group echinoid Archaeocidaris , our total evidence tree suggested relationships of higher taxa as follows: Gidaroida Phormosomatidae Echinothuriidae Diadematidae Spatangoida Clypeasteroida, Cassiduloida Calycina, Arbacioida Stomopneustidae Glyphocidaridae Temnopleuridae Echinometridae Echinidae, Strongylocentridae. Phylogenetic analyses run both with and without key fossil taxa yielded slightly different topologies. It is important to include fossil taxa in a phylogenetic analysis where there are long stem-group branches or where the crown group is highly derived.

Morphological and molecular identification of Octopoda (Mollusca: Cephalopoda) paralarvae from the southern Gulf of Mexico

2021 ◽  
Author(s):  
Mariana L Santana-Cisneros ◽  
Rossanna Rodríguez-Canul ◽  
Jesús Alejandro Zamora-Briseño ◽  
Monica Améndola-Pimenta ◽  
Roxana De Silva-Dávila ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
First Record ◽  
Coi Gene ◽  
Octopus Vulgaris ◽  
Type I ◽  
Molecular Sequences ◽  
Molecular Approaches ◽  
Morphological Criteria ◽  
Southern Gulf Of Mexico ◽  
Genetic Sequences

Paralarvae (PL) are crucial to understanding the life cycle and population dynamics of cephalopods. Misidentification of species with similar morphology is a problem that hampers understanding of cephalopod composition and distribution. In this study, we used morphological and molecular approaches to carry out a comprehensive identification of Octopoda PL that inhabit two main areas (Tamaulipas and Yucatán) in the southern Gulf of Mexico (GoM). A total of 189 paralarvae were identified using morphological criteria. Of these, 52 PL were analyzed molecularly by sequencing the mitochondrial cytochrome c oxidase subunit I (COI) gene. We identified four species and five morphotypes. The molecular tools corroborated three of four species, while the molecular sequences of three out of four morphotypes indicated that they belong to three different species. All the genetic sequences had high similarities (99.3%–100%) with previous records. One species and one morphotype could not be sequenced because of unsatisfactory fixation; one morphotype remained as such after the molecular analysis. An identification tree was constructed for the species identified with the molecular approach. The species found off the Yucatán platform were Octopus vulgaris Type I, Octopus americanus, Macrotritopus defilippi, Amphioctopus burryi, A. cf. burryi, Octopus sp., and Callistoctopus furvus. The species identified off the Tamaulipas coast were Octopus insularis and M. defilippi. Paralarvae of O. vulgaris Type I and M. defilippi were the most abundant during 2016–2017. This study provides the first record of Octopoda PL in the southern GoM, including morphological descriptions and molecular sequences of the analyzed taxa.

scholarly journals A new method for inferring timetrees from temporally sampled molecular sequences

2020 ◽  
Vol 16 (1) ◽  
pp. e1007046 ◽  
Author(s):  
Sayaka Miura ◽  
Koichiro Tamura ◽  
Qiqing Tao ◽  
Louise A. Huuki ◽  
Sergei L. Kosakovsky Pond ◽  
...  
Keyword(s):  
New Method ◽  
Molecular Sequences
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