Search results for "Convergent evolution"

2015

Bacterial endosymbiosis is an important evolutionary process in insects, which can harbor both obligate and facultative symbionts. The evolution of these symbionts is driven by evolutionary convergence, and they exhibit among the tiniest genomes in prokaryotes. The large host spectrum of facultative symbionts and the high diversity of strategies they use to infect new hosts probably impact the evolution of their genome and explain why they undergo less severe genomic erosion than obligate symbionts. Candidatus Hamiltonella defensa is suitable for the investigation of the genomic evolution of facultative symbionts because the bacteria are engaged in specific relationships in two clades of in…

SARS-CoV-2 genome surveillance in Mainz, Germany, reveals convergent origin of the N501Y spike mutation in a hospital setting

2021

AbstractWhile establishing a regional SARS-Cov-2 variant surveillance by genome sequencing, we have identified three infected individuals in a clinical setting (two long-term hospitalized patients and a nurse) that shared the spike N501Y mutation within a genotype background distinct from the current viral variants of concern. We suggest that the adaptive N501Y mutation, known to increase SARS-CoV-2 transmissibility, arose by convergent evolution around December in Mainz, Germany. Hospitalized patients with a compromised immune system may be a potential source of novel viral variants, which calls for monitoring viral evolution by genome sequencing in clinical settings.

The founder principle, founder selection, and evolutionary divergence and convergence in natural populations of Philaenus

2009

Parts of the archipelago of the Baltic Sea are rising above the water level at a steady, slow rate. Plant species appear on the emerging islands in a definite order, and an early stage and a late stage can be distinguished in the development of meadows on the islands. In 1969–1973 four populations of Philaenus spumarius living in meadows at the early stage had widely different frequencies of the alleles determining colour polymorphism. In the same years three Philaenus populations living on islands with meadows at the late stage had closely similar allele frequencies. The differences between the Philaenus populations in the early stage meadows are ascribed partly to the founder principle an…

Evolution of alternative male morphotypes in oxyurid nematodes: a case of convergence?

2014

Male dimorphism has been reported across different taxa and is usually expressed as the coexistence of a larger morph with exaggerated male traits and a smaller one with reduced traits. The evolution and maintenance of male dimorphism are still poorly understood for several of the species in which it has been observed. Here, we analyse male dimorphism in several species of reptile parasitic nematodes of the genus Spauligodon, in which a major male morph (exaggerated morph), which presents the traditional male morphological traits reported for this taxon, coexists with a minor morph with reduced morphological traits (i.e. reduced genital papillae) resembling more closely the males of the sis…

Evidence for Positive Selection in the Capsid Protein-Coding Region of the Foot-and-Mouth Disease Virus (FMDV) Subjected to Experimental Passage Regi…

2001

We present sequence data from two genomic regions of foot-and-mouth disease virus (FMDV) subjected to several experimental passage regimens. Maximum-likelihood estimates of the nonsynonymous-to-synonymous rate ratio parameter (dN/dS) suggested the action of positive selection on some antigenic sites of the FMDV capsid during some experimental passages. These antigenic sites showed an accumulation of convergent amino acid replacements during massive serial cytolytic passages and also in persistent infections of FMDV in cell culture. This accumulation was most significant at the antigenic site A (the G-H loop of capsid VP1), which includes an Arg-Gly-Asp (RGD) cellular recognition motif. Our …