Search results for "phylogenetic"

Genetic and aromatic diversity of the Burgundy truffle

2013

Truffles are ectomycorrhizal Ascomycota fungi belonging to the Tuberaceae family and more specifically to the Tuber genus. More than thirty Tuber species are currently described in Europe. In this thesis, we specifically focused on the Tuber aestivum-uncinatum model. This truffle is commonly called "Burgundy Truffle" and has a gastronomic and cultural interest.The first part of this thesis focused on the taxonomic status of the Burgundy truffle (Tuber uncinatum). For this, we used a multi-marker approach combining several genetic markers commonly used at the interspecific scale. Our analyses showed that the two taxa, Tuber aestivum (summer truffle) and Tuber uncinatum are conspecific.In the…

The never-ending story of geologically ancient DNA: was the model plantArabidopsisthe source of Miocene Dominican amber?

2013

Studies characterizing geologically ancient DNA in plants are rare, and all have reportedly obtained plastid DNA sequences from Miocene fossils in a remarkable state of preservation. Recently, a group made the extraordinary claim of having amplified a geologically ancient Miocene plastid DNA fragment (the rbcL gene) from Dominican amber nuggets, and the organismal source of this DNA was identified as Hymenaea protera (Fabaceae), the plant that produced the fossilized Dominican amber. Assuming that the Miocene sequence is error-free, reanalysis of the sequence indicates it is probably a technical artifact or an rbcL pseudogene. Furthermore, BLAST similarity searches and phylogenetic analyses…

Gladius-bearing coleoids from the Upper Cretaceous Lebanese Lagerstätten: diversity, morphology, and phylogenetic implications.

2017

AbstractGladius-bearing coleoids are rare in the fossil record. For the Cretaceous period, these cephalopods are mainly recorded in a few Lagerstätten in Lebanon (Haqel, Hajoula, En Nammoura, and Sahel Aalma). Here, we study 16 specimens of gladius-bearing coleoids from these Upper Cretaceous Lebanese Lagerstätten to investigate their taxonomic diversity. Besides two species that were already reported (Dorateuthis syriacaandGlyphiteuthis libanotica), one new species is identified in the Cenomanian site of Hajoula:Rachiteuthis acutalin. sp., as well as another form ofGlyphiteuthisfrom En Nammoura. Several studied specimens exhibit well-preserved soft-part characters. Among them, we document …

Gene arrangement phylogeny of the E element in Drosophila species of the Obscura group

1993

Split decomposition A technique to analyze viral evolution

1993

A clustering technique allowing a restricted amount of overlapping and based on an abstract theory of coherent decompositions of finite metrics is used to analyze the evolution of foot-and-mouth disease viruses. The emerging picture is compatible with the existence of viral populations with a quasispecies structure and illustrates various forms of evolution of this virus family. In addition, it allows the correlation of these forms with geographic occurrence.

Ecdysteroid titres in a tenebrionid beetle, Zophobas atratus: effects of grouping and isolation.

1997

Metamorphosis in Zophobas atratus is dependent on isolation: when kept in grouped conditions, larvae undergo numerous supernumerary moults, growing in size, without pupating. This beetle thus represents an interesting model for the analysis of possible differences in the endocrine regulation of normal vs. supernumerary larval moults. In this study, the ecdysteroid titres have been analysed in this species, using enzyme immunoassay. The hormonal variations of larvae undergoing normal or supernumerary larval cycles were particularly examined, in either grouped or isolated conditions. Normal larval cycles presented very similar ecdysteroid variations in grouped as well as isolated conditions, …

Testing alternative vicariance scenarios in Western Mediterranean discoglossid frogs

2004

Dated molecular phylogenies are often used to interpret evolutionary history with respect to paleogeographic events. Where more than one interpretation is possible, it is desirable but difficult to assess the alternatives in an objective manner. The present work demonstrates a formalized method for testing molecular clock calibrations and biogeographic scenarios based on them. We assessed the plausibility of several previously published biogeographic hypotheses, using the frog genera Alytes, Discoglossus, and Bombina as model groups. Our data set comprised ca. 900bp of partial mitochondrial 16S and 12S rRNA gene sequences (both genes evolved in a clock-like manner across genera) from nearly…

A geographical pattern ofAntirrhinum(Scrophulariaceae) speciation since the Pliocene based on plastid and nuclear DNA polymorphisms

2009

Aim To infer phylogenetic relationships among Antirrhinum species and to reconstruct the historical distribution of observed sequence polymorphism through estimates of haplotype clades and lineage divergence. Location Antirrhinum is distributed primarily throughout the western Mediterranean, with 22 of 25 species in the Iberian Peninsula. Methods Plastid (83 trnS-trnG and 83 trnK-matK) and nuclear (87 ITS) sequences were obtained from 96 individuals representing 24 of the 25 Antirrhinum species. Sequences were analysed using maximum parsimony, Bayesian inference and statistical parsimony networking. Molecular clock estimates were obtained for plastid trnK-matK sequences using the penalized …

CONSTRUCTING, BOOTSTRAPPING, AND COMPARING MORPHOMETRIC AND PHYLOGENETIC TREES: A CASE STUDY OF NEW WORLD MONKEYS (PLATYRRHINI, PRIMATES)

2005

Morphometric data sets are often phenetically analyzed by using various kinds of spatial, metric, or nonmetric multivariate analyses. Such methods produce results that are difficult to compare directly with molecular or morphological phylogenetic hypotheses, which are usually expressed by using nonspatial tree representations. Therefore, it is useful in a comparative approach to analyze, and above all to visualize, morphometric pairwise relationships as tree structures. For this purpose, several additive or ultrametric methods exist, which often return different topologies for the same data set. Objective criteria are thus needed to identify the tree-building algorithm (or algorithm family)…

Investigating the origin of parthenogenesis and ploidy level in Dahlica fennicella (Lepidoptera: Psychidae)

2013

The theories for the predominance of sexual reproduction predict that parthenogens should have no long-term evolutionary potential due to the lack of genetic recombination, despite short term advantages. Although parthenogenesis is rare among high order animals, true parthenogens can be found in various taxa. The intriguing question of the proliferation and persistence of parthenogenetic species needs investigation. An ideal species for such research is a parthenogenetic mont Dahlica fennicella that appears to be as equally successful as other coexisting sexual species. We investigated whether high ploidy level of D. fennnicella is due to hybridization between closely related sexual species…