14 research outputs found
Patterns of co-speciation and host switching in primate malaria parasites
<p>Abstract</p> <p>Background</p> <p>The evolutionary history of many parasites is dependent on the evolution of their hosts, leading to an association between host and parasite phylogenies. However, frequent host switches across broad phylogenetic distances may weaken this close evolutionary link, especially when vectors are involved in parasites transmission, as is the case for malaria pathogens. Several studies suggested that the evolution of the primate-infective malaria lineages may be constrained by the phylogenetic relationships of their hosts, and that lateral switches between distantly related hosts may have been occurred. However, no systematic analysis has been quantified the degree of phylogenetic association between primates and their malaria parasites.</p> <p>Methods</p> <p>Here phylogenetic approaches have been used to discriminate statistically between events due to co-divergence, duplication, extinction and host switches that can potentially cause historical association between <it>Plasmodium </it>parasites and their primate hosts. A Bayesian reconstruction of parasite phylogeny based on genetic information for six genes served as basis for the analyses, which could account for uncertainties about the evolutionary hypotheses of malaria parasites.</p> <p>Results</p> <p>Related lineages of primate-infective <it>Plasmodium </it>tend to infect hosts within the same taxonomic family. Different analyses testing for congruence between host and parasite phylogenies unanimously revealed a significant association between the corresponding evolutionary trees. The most important factor that resulted in this association was host switching, but depending on the parasite phylogeny considered, co-speciation and duplication may have also played some additional role. Sorting seemed to be a relatively infrequent event, and can occur only under extreme co-evolutionary scenarios. The concordance between host and parasite phylogenies is heterogeneous: while the evolution of some malaria pathogens is strongly dependent on the phylogenetic history of their primate hosts, the congruent evolution is less emphasized for other parasite lineages (e.g. for human malaria parasites). Estimation of ancestral states of host use along the phylogenetic tree of parasites revealed that lateral transfers across distantly related hosts were likely to occur in several cases. Parasites cannot infect all available hosts, and they should preferentially infect hosts that provide a similar environment for reproduction. Marginally significant evidence suggested that there might be a consistent variation within host ranges in terms of physiology.</p> <p>Conclusion</p> <p>The evolution of primate malarias is constrained by the phylogenetic associations of their hosts. Some parasites can preserve a great flexibility to infect hosts across a large phylogenetic distance, thus host switching can be an important factor in mediating host ranges observed in nature. Due to this inherent flexibility and the potential exposure to various vectors, the emergence of new malaria disease in primates including humans cannot be predicted from the phylogeny of parasites.</p
Genetic diversity and host alternation of the egg parasitoid Oencyrtus pityocampae between the pine processionary moth and caper bug
Research ArticleThe increased use of molecular tools for species identification in recent decades revealed
that each of many apparently generalist parasitoids are actually a complex of morphologically
similar congeners, most of which have a rather narrow host range. Ooencyrtus pityocampae
(OP), an important egg parasitoid of the pine processionary moth (PPM), is
considered a generalist parasitoid. OP emerges from PPM eggs after winter hibernation,
mainly in spring and early summer, long before the eggs of the next PPM generation occurs.
The occurrence of OP in eggs of the variegated caper bug (CB) Stenozygum coloratum in
spring and summer suggests that OP populations alternate seasonally between PPM and
CB. However, the identity of OP population on CB eggs seemed uncertain; unlike OP-PPM
populations, the former displayed apparently high male/female ratios and lack of attraction
to the PPM sex pheromone. We studied the molecular identities of the two populations
since the morphological identification of the genus Ooencyrtus, and OP in particular, is difficult.
Sequencing of COI and ITS2 DNA fragments and AFLP analysis of individuals from
both hosts revealed no apparent differences between the OP-PPM and the OP-CB populations
for both the Israeli and the Turkish OPs, which therefore supported the possibility of
host alternation. Sequencing data extended our knowledge of the genetic structure of OP
populations in the Mediterranean area, and revealed clear separation between East and
West Mediterranean populations. The overall level of genetic diversity was rather small,
with the Israeli population much less diverse than all others; possible explanations for this
finding are discussed. The findings support the possibility of utilizing the CB and other hosts
for enhancing biological control of the PPMinfo:eu-repo/semantics/publishedVersio
Análise filogenética em espécies de lippia spp. (verbenaceae) da Cadeia do Espinhaço - MG com o uso de caracteres moleculares.
Misguided phylogenetic comparisons using DGGE excised bands may contaminate public sequence databases
Controversy surrounding bacterial phylogenies has become one of the most important challenges for microbial ecology. Comparative analyses with nucleotide databases and phylogenetic reconstruction of the amplified 16S rRNA genes from DGGE (Denaturing Gradient Gel Electrophoresis) excised bands have been used by several researchers for the identification of organisms in complex samples. Here, we individually analyzed DGGE-excised 16S rRNA gene bands from 10 certified bacterial strains of different species, and demonstrated that this kind of approach can deliver erroneous outcomes to researchers, besides causing/emphasizing errors in public databases
Nuclear mitochondrial DNA: an Achilles’ heel of molecular systematics, phylogenetics, and phylogeographic studies of stingless bees
International audienceMitochondrial-like DNA (numt) has been found in a variety of insect species. In this work, our objective was to create a phylogeographic hypothesis of Melipona capixaba based on the complete COI sequence. However, several inconsistencies were found, such as 1-2-bp-long indels and a stop codon within the putative amino acid sequences. This led us to infer that M. capixaba has numts. A phylogenetic analysis which included COI sequences of several species of Melipona Illiger, 1806 revealed that numts are also common among other species of the genus. Based on our results, we have proposed a checklist to help to identify the most conspicuous numts; however, it does not ensure that all numts will be identified, since not all numts present explicit signals. Therefore, we recommend taking the maximum care in phylogeographic and phylogenetic analysis within Melipona as well as Hymenoptera, since several evidences of numts were found within this order
Systematics of Spiny Predatory Katydids (Tettigoniidae: Listroscelidinae) from the Brazilian Atlantic Forest Based on Morphology and Molecular Data
<div><p>Listroscelidinae (Orthoptera: Tettigoniidae) are insectivorous Pantropical katydids whose taxonomy presents a long history of controversy, with several genera incertae sedis. This work focused on species occurring in the Brazilian Atlantic Forest, one of the world's most threatened biomes. We examined material deposited in scientific collections and visited 15 conservation units from Rio de Janeiro to southern Bahia between November 2011 and January 2012, catching 104 specimens from 10 conservation units. Based on morphological and molecular data we redefined Listroscelidini, adding a new tribe, new genus and eight new species to the subfamily. Using morphological analysis, we redescribed and added new geographic records for six species, synonymized two species and built a provisional identification key for the Atlantic Forest Listroscelidinae. Molecular results suggest two new species and a new genus to be described, possibly by the fission of the genus <i>Hamayulus</i>. We also proposed a 500 bp region in the final portion of the COI to be used as a molecular barcode. Our data suggest that the Atlantic Forest Listroscelidinae are seriously endangered, because they occur in highly preserved forest remnants, show high rates of endemism and have a narrow geographic distribution. Based on our results, we suggest future collection efforts must take into account the molecular barcode data to accelerate species recognition.</p></div
Phylogeny, biogeography and divergence times in Passiflora (Passifloraceae)
As part of a long-term investigation on the evolution of Passiflora L., we investigated the divergence ages of the genus and diversification of its subgenera, relating them with biogeographical and/or historical events, and other characteristics of this taxon. The main aim of the present work was to evaluate the biogeographic distribution of this genus to better understand its evolutionary history. This is the first time that representatives from South American and Old World Passifloraceae genera have been studied as a group comprising a total of 106 widely distributed species, with representative samples of the four suggested subgenera. Seven DNA regions were studied, comprising 7,431 nucleotides from plastidial, mitochondrial and nuclear genomes. Divergence time estimates were obtained by using a Bayesian Markov Chain Monte Carlo method and a random local clock model for each partition. Three major subgenera have been shown to be monophyletic and here we are proposing to include another subgenus in the Passiflora infrageneric classification. In general, divergence among the four subgenera in Passiflora is very ancient, ranging from ~32 to ~38 Mya, and Passifloraceae seems to follow a biogeographic scenario proposed for several plant groups, originating in Africa, crossing to Europe/Asia and arriving in the New World by way of land bridges. Our results indicated that Passiflora ancestors arrived in Central America and diversified quickly from there, with many long distance dispersion events