Associated evolution of bipedality and cursoriality among Triassic archosaurs: a phylogenetically controlled evaluation

Paleobiology ◽  
2012 ◽  
Vol 38 (3) ◽  
pp. 474-485 ◽  
Author(s):  
Tai Kubo ◽  
Mugino O. Kubo
Keyword(s):  
Comparative Analysis ◽  
Relative Length ◽  
Independent Contrasts ◽  
Avian Flight ◽  
Phylogenetically Independent Contrasts ◽  
Controlled Evaluation

Bipedalism evolved more than twice among archosaurs, and it is a characteristic of basal dinosaurs and a prerequisite for avian flight. Nevertheless, the reasons for the evolution of bipedalism among archosaurs have barely been investigated. Comparative analysis using phylogenetically independent contrasts showed a significant correlation between bipedality (relative length of forelimb) and cursoriality (relative length of metatarsal III) among Triassic archosaurs. This result indicates that, among Triassic archosaurs, bipeds could run faster than quadrupeds. Bipedalism is probably an adaptation for cursoriality among archosaurs, which may explain why bipedalism evolved convergently in the crocodilian and bird lineages. This result also indicates that the means of acquiring cursoriality may differ between archosaurs and mammals.

scholarly journals Long-legged bees make adaptive leaps: linking adaptation to coevolution in a plant–pollinator network

2017 ◽  
Vol 284 (1862) ◽  
pp. 20171707 ◽  
Author(s):  
Anton Pauw ◽  
Belinda Kahnt ◽  
Michael Kuhlmann ◽  
Denis Michez ◽  
Graham A. Montgomery ◽  
...  
Keyword(s):  
Plant Species ◽  
Evolutionary Divergence ◽  
Large Network ◽  
Independent Contrasts ◽  
Leg Length ◽  
Phylogenetically Independent Contrasts ◽  
Explained Variance ◽  
Spur Length ◽  
Plant Pollinator ◽  
Selective Environment

Adaptation is evolution in response to natural selection. Hence, an adaptation is expected to originate simultaneously with the acquisition of a particular selective environment. Here we test whether long legs evolve in oil-collecting Rediviva bees when they come under selection by long-spurred, oil-secreting flowers. To quantify the selective environment, we drew a large network of the interactions between Rediviva species and oil-secreting plant species. The selective environment of each bee species was summarized as the average spur length of the interacting plant species weighted by interaction frequency. Using phylogenetically independent contrasts, we calculated divergence in selective environment and evolutionary divergence in leg length between sister species (and sister clades) of Rediviva . We found that change in the selective environment explained 80% of evolutionary change in leg length, with change in body size contributing an additional 6% of uniquely explained variance. The result is one of four proposed steps in testing for plant–pollinator coevolution.

scholarly journals Nonlinear relationships and phylogenetically independent contrasts

2004 ◽  
Vol 17 (3) ◽  
pp. 709-715 ◽  
Author(s):  
S. Quader ◽  
K. Isvaran ◽  
R. E. Hale ◽  
B. G. Miner ◽  
N. E. Seavy
Keyword(s):  
Independent Contrasts ◽  
Nonlinear Relationships ◽  
Phylogenetically Independent Contrasts

scholarly journals Comparative Analysis of Karyotypes of Two Cryptic Species of Pelobatid Frogs (Amphibia, Anura) of Ukraine

2014 ◽  
Vol 48 (6) ◽  
pp. 511-520 ◽  
Author(s):  
N. N Suryadnaya
Keyword(s):  
Comparative Analysis ◽  
Cryptic Species ◽  
Chromosome Pair ◽  
Morphological Analysis ◽  
Relative Length ◽  
Diagnostic Features ◽  
Pelobates Fuscus ◽  
Comparative Morphological Analysis ◽  
Absolute Length ◽  
Secondary Constrictions

Abstract The paper first describes in detail the karyotype of Pelobates vespertinus (Pallas, 1771) in comparison with the karyotype of Pelobates fuscus (Laurenti, 1768). Comparative morphological analysis of chromosomes has shown that these two cryptic species have a symmetrical karyotype consisting of two-armed chromosomes. It has been established that their chromosome sets consist of 7 pairs of large chromosomes and 6 pairs of small ones. The species diff er by the position of the centromere in the chromosomes of the 10th and 11th pairs. The 10th pair of P. fuscus is metacentrics, the 11th pair is submetacentric; the 10th pair of P. vespertinus is submetacentric, and the 11th one is metacentrics. Secondary constrictions are on the short arms of the 7th chromosome pair. The chromosomal formula for both species is 4 meta-(m) + 7 submeta-(sm) + 2 subtelocentrics (st), 2n = 26, N.F. = 52. Absolute length of all the chromosomes in the karyotype of P. fuscus is somewhat larger than that one in the karyotype of P. vespertinus. The parameters of relative length are equivalent on average, but they diff er in individual chromosomes. On the background of established chromosomal differences between the cryptic species, reliable diagnostic features have not been identified.

The Hungarian Agendas Project

2019 ◽  
pp. 105-113
Author(s):  
Zsolt Boda ◽  
Miklós Sebők
Keyword(s):  
Public Opinion ◽  
Comparative Analysis ◽  
Political Development ◽  
Relative Length ◽  
Hungarian Academy ◽  
Added Value ◽  
Policy Agendas ◽  
Academy Of Sciences ◽  
Public Opinion Polls ◽  
Opinion Polls

The chapter presents the Hungarian Comparative Agendas Project. It delineates its origins at the Centre for Social Sciences, Hungarian Academy of Sciences and situates it in the context of Hungarian political science. The project developed numerous databases, including those on budgets, laws, decrees, parliamentary speeches, newspaper articles, and public opinion polls. Due to the post-communist political development of Hungary our country project shows some specificities vis-à-vis more established projects. First, the codebook includes a few country-specific minor topic codes (such as those related to post-communist restitution) that are directly linked in to the comparative codebook (therefore our results remain fully comparable). Second, one added value of some of our datasets is their relative length which—in some cases—covers multiple centuries as well as various political regimes, including non-democratic ones. This allows for not only cross-country comparative analysis but also for comparing policy agendas in different regimes.

Freshwater-to-marine transitions may explain the evolution of herbivory in the subgenus Mollienesia (genus Poecilia, mollies and guppies)

2019 ◽  
Vol 127 (4) ◽  
pp. 742-761 ◽  
Author(s):  
Jessica L Sanchez ◽  
Heather D Bracken-Grissom ◽  
Joel C Trexler
Keyword(s):  
Independent Contrasts ◽  
Diversification Rates ◽  
Ecosystem Boundaries ◽  
Evolutionary Diversification ◽  
Dietary Preferences ◽  
Phylogenetically Independent Contrasts ◽  
Habitat Transition ◽  
Saline Habitats

Abstract The ability of organisms to cross ecosystem boundaries is an important catalyst of evolutionary diversification. The genus Poecilia (mollies and guppies) is an excellent system for studying ecosystem transitions because species display a range of salinity and dietary preferences, with herbivory concentrated in the subgenus Mollienesia. We reconstructed ancestral habitats and diets across a phylogeny of the genus Poecilia, evaluated diversification rates and used phylogenetically independent contrasts to determine whether diet evolved in response to habitat transition in this group. The results suggest that ancestors of subgenus Mollienesia were exclusively herbivorous, whereas ancestral diets of other Poecilia included animals. We found that transitions across euryhaline boundaries occurred at least once in this group, probably after the divergence of the subgenus Mollienesia. Furthermore, increased salinity affiliation explained 24% of the decrease in animals in the gut, and jaw morphology was associated with the percentage of animals in the gut, but not with the percentage of species occupying saline habitats. These findings suggest that in the genus Poecilia, herbivory evolved in association with transitions from fresh to euryhaline habitats, and jaw morphology evolved in response to the appearance of herbivory. These results provide a rare example of increased diet diversification associated with the transition from freshwater to euryhaline habitats.

ÉTUDE BIOMÉTRIQUE DU CARYOTYPE DE LA BRUCHE DU HARICOT (ACANTHOSCELIDES OBTECTUS, COLÉOPTÈRES, BRUCHIDAE)

1982 ◽  
Vol 24 (6) ◽  
pp. 687-692 ◽  
Author(s):  
P. Garaud ◽  
P. Lecher
Keyword(s):  
Comparative Analysis ◽  
Diploid Number ◽  
Relative Length ◽  
Graphic Representation ◽  
Acanthoscelides Obtectus ◽  
European Strain ◽  
Bean Beetle ◽  
Two Parameters

The karyotype of a European strain of the bean beetle, Acanthoscelides obtectus, has been made using biometrical methods with two parameters: arm ratio and relative length; each chromosome is defined by two values. Graphic representation of all chromosomes gave well scattered points. This method allowed us to determine the diploid number (2n = 20), sex mechanism (XY/XX) and the establishment of a definite karyotype. This study is part of an ongoing comparative analysis of strains from various geographical origins.[Translated by the journal]

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