scholarly journals Asexual parasites and their extraordinary host ranges

2019 ◽  
Vol 59 (6) ◽  
pp. 1463-1484 ◽  
Author(s):  
Amanda K Gibson
Keyword(s):  
Host Range ◽  
Niche Breadth ◽  
Positive Association ◽  
Scale Insects ◽  
Evolution Of Sex ◽  
Ecological Specialization ◽  
Geographic Parthenogenesis ◽  
Link Theory ◽  
First Pass ◽  
Large Host

Abstract In diverse parasite taxa, from scale insects to root-knot nematodes, asexual lineages have exceptionally large host ranges, larger than those of their sexual relatives. Phylogenetic comparative studies of parasite taxa indicate that increases in host range and geographic range increase the probability of establishment of asexual lineages. At first pass, this convergence of traits appears counter-intuitive: intimate, antagonistic association with an enormous range of host taxa correlates with asexual reproduction, which should limit genetic variation within populations. Why would narrow host ranges favor sexual parasites and large host ranges favor asexual parasites? To take on this problem I link theory on ecological specialization to the two predominant hypotheses for the evolution of sex. I argue that both hypotheses predict a positive association between host range and the probability of invasion of asexual parasites, mediated either by variation in population size or in the strength of antagonistic coevolution. I also review hypotheses on colonization and the evolution of niche breadth in asexual lineages. I emphasize parasite taxa, with their diversity of reproductive modes and ecological strategies, as valuable assets in the hunt for solutions to the classic problems of the evolution of sex and geographic parthenogenesis.

A New Sharpshooter Threatens Both Crops and Ornamentals

2000 ◽  
Vol 1 (1) ◽  
pp. 4 ◽  
Author(s):  
Matthew J. Blua ◽  
Phil A. Phillips ◽  
Richard A. Redak
Keyword(s):  
Host Range ◽  
Potential Distribution ◽  
Xylella Fastidiosa ◽  
New Disease ◽  
Leaf Scorch ◽  
Economic Problems ◽  
The Future ◽  
Different Strains ◽  
Large Host ◽  
Almond Leaf Scorch

The glassy-winged sharpshooter (Homalodisca coagulate), an insect that has recently invaded California, and the smoke tree sharpshooter (Homalodisca lacerta) are creating serious new economic problems in both agricultural and ornamental plantings. The greatest threats surround their ability to spread the plantpathogenic bacterium Xylella fastidiosa, which induces Pierce's disease in grapevines, almond leaf scorch disease, and a new disease known as oleander leaf scorch. Because of the potential distribution and large host range of the glassywinged sharpshooter, other diseases caused by different strains of X. fastidiosa may have an even greater impact on the state's agricultural and ornamental landscape industries in the future. Posted 27 June 2000.

scholarly journals Jack-of-all-trades paradigm meets long-term data: generalist herbivores are more widespread and locally less abundant

2020 ◽  
Author(s):  
C. Sudta ◽  
D.M. Salcido ◽  
M.L. Forister ◽  
T. Walla ◽  
S. Villamarín-Cortez ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Negative Relationship ◽  
Positive Association ◽  
Interspecific Variation ◽  
Diet Breadth ◽  
Ecological Specialization ◽  
Dietary Specialization ◽  
Mixed Support ◽  
Term Data

AbstractSome of the most common ecological interactions are between plants and herbivorous insects, and these relationships are central to the study of ecological specialization. We address established assumptions about the positive association between local abundance and dietary specialization using a 17-year dataset on the caterpillars of Ecuador. Our long-term data include standardized plot-based samples as well as general, regional collections, allowing for investigations across spatial scales and using different indices of abundance for 1917 morphospecies of Lepidoptera from 33 families. We find that specialists are locally more abundant than generalists, consistent with a key component of the “jack of all trades, master of none” hypothesis, which has otherwise received poor to mixed support from previous studies that have mostly involved fewer species and shorter time series. Generalists achieve greater prevalence across the landscape, and we find some evidence for geographic variation in the abundance-diet breadth relationship, in particular among elevational bands. Interspecific variation in abundance also had a negative relationship with diet breadth, with specialists having more variable abundances across species. The fact that more specialized species can be both rare and common highlights the ecological complexity of specialization.

Flaviviruses excluding dengue

2020 ◽  
pp. 830-845
Author(s):  
Shannan Lee Rossi ◽  
Nikos Vasilakis
Keyword(s):  
Japanese Encephalitis Virus ◽  
Host Range ◽  
Yellow Fever ◽  
Japanese Encephalitis ◽  
Human Infection ◽  
Virus Species ◽  
Human Pathogens ◽  
West Nile ◽  
The Family ◽  
Large Host

The family Flaviviridae currently consists of four recognized genera: Flavivirus, Pestivirus, Hepacivirus, and Pegivirus. Although members of the family have a large host range that includes both vertebrates and invertebrates, only members of the genus Flavivirus are known as arboviruses, vectored either by mosquitoes or ticks. The remaining genera in the family are exclusively found in mammals, and their diversity has greatly expanded with recent virus discoveries. The genus Flavivirus comprises 92 virus species, of which over 40 can cause human infection. Many of these include important human pathogens such as Zika, dengue, yellow fever, West Nile, and Japanese encephalitis virus.

Ecological release in lizard endoparasites from the Atlantic Forest, northeast of the Neotropical Region

Parasitology ◽  
2020 ◽  
Vol 147 (4) ◽  
pp. 491-500
Author(s):  
Adonias A. Martins Teixeira ◽  
Pablo Riul ◽  
Samuel Vieira Brito ◽  
João A. Araujo-Filho ◽  
Diêgo Alves Teles ◽  
...  
Keyword(s):  
Host Range ◽  
Host Specificity ◽  
Atlantic Forest ◽  
Positive Relationship ◽  
Niche Breadth ◽  
Neotropical Region ◽  
Parasite Abundance ◽  
Ecological Release ◽  
Parasite Richness

AbstractWe compared lizard endoparasite assemblages between the Atlantic Forest and naturally isolated forest enclaves to test the ecological release hypothesis, which predicts that host specificity should be lower (large niche breadth) and parasite abundance should be greater for parasites from isolated forest enclaves (poor assemblages) than for parasites from the coastal Atlantic Forest (rich assemblages). Parasite richness per specimen showed no difference between the isolated and non-isolated areas. Parasite abundance did not differ between the isolated and non-isolated areas but showed a positive relationship with parasite richness considering all areas (isolated and non-isolated). Furthermore, host specificity was positively related to parasite richness. Considering that host specificity is inversely proportional to the host range infected by a parasite, our results indicate that in assemblages with greater parasite richness, parasites tend to infect a smaller range of hosts than do those in simple assemblages. In summary, our study partially supports the ecological release hypothesis: in assemblages with greater parasite richness, lizard parasites from Atlantic Forest are able to increase their parasite abundance (per host), possibly through facilitated infection; however, the amplitude of infected hosts only expands in poor assemblages (lower parasite richness).

Two species of whitefly and six species of scale insect (Hemiptera: Aleyrodidae and Coccoidea), new for Antigua, Lesser Antilles

2018 ◽  
Vol 154 (1) ◽  
pp. 53-59
Author(s):  
Chris Malumphy
Keyword(s):  
Host Range ◽  
Geographical Distribution ◽  
Scale Insect ◽  
Economic Importance ◽  
Scale Insects ◽  
Lesser Antilles ◽  
The Caribbean ◽  
First Time

Two species of whitefly and six species of scale insect are recorded for the first time from the island of Antigua, Antigua and Barbuda, Lesser Antilles, Caribbean: Aleyrodidae – Dialeurodes schefflerae Hodges & Dooley and Minutaleyrodes minuta (Singh); Coccidae – Milviscutulus mangiferae (Green); Conchaspididae – Conchaspis angraeci Cockerell; Diaspididae – Duplachionaspis divergens (Green), Mycetaspis personata (Comstock), Parlatoria proteus (Curtis); and Pseudococcidae – Ferrisia dasylirii (Cockerell). The geographical distribution, host range and economic importance of each of the whiteflies and scale insects are summarised. Three of these species, D. schefflerae, M. minuta and D. divergens are native to Asia and have been spreading in the Caribbean in recent years, most probably with plant trade.

scholarly journals Scale insect host ranges are broader in the tropics

2015 ◽  
Vol 11 (12) ◽  
pp. 20150924 ◽  
Author(s):  
Nate B. Hardy ◽  
Daniel A. Peterson ◽  
Benjamin B. Normark
Keyword(s):  
Host Range ◽  
General Pattern ◽  
Ecological Factors ◽  
Plant Species Richness ◽  
Scale Insect ◽  
Scale Insects ◽  
Explanatory Factors ◽  
Trade Offs ◽  
Host Plant Specificity ◽  
The Tropics

The specificity of the interactions between plants and their consumers varies considerably. The evolutionary and ecological factors underlying this variation are unclear. Several potential explanatory factors vary with latitude, for example plant species richness and the intensity of herbivory. Here, we use comparative phylogenetic methods to test the effect of latitude on host range in scale insects. We find that, on average, scale insects that occur in lower latitudes are more polyphagous. This result is at odds with the general pattern of greater host-plant specificity of insects in the tropics. We propose that this disparity reflects a high cost for host specificity in scale insects, stemming from unusual aspects of scale insect life history, for example, passive wind-driven dispersal. More broadly, the strong evidence for pervasive effects of geography on host range across insect groups stands in stark contrast to the weak evidence for constraints on host range due to genetic trade-offs.

scholarly journals Intraspecific Competition and the Promotion of Ecological Specialization

2021 ◽  
Author(s):  
Abdel H. Halloway ◽  
Joel S. Brown
Keyword(s):  
Resource Use ◽  
Intraspecific Competition ◽  
Niche Breadth ◽  
Evolutionary Model ◽  
Ecological Specialization ◽  
Secondary Resources ◽  
Cast Doubt ◽  
The Face ◽  
Game Theoretic ◽  
Diversification Hypothesis

AbstractThe evolution of ecological specialization can be summed up in a single question: why would a species evolve a more-restricted niche space? Various hypotheses have been developed to explain the promotion or suppression of ecological specialization. One hypothesis, competitive diversification, states that increased intraspecific competition will cause a population to broaden its niche breadth. With individuals alike in resource use preference, more individuals reduce the availability of preferred resources and should grant higher fitness to those that use secondary resources. However, recent studies cast doubt on this hypothesis with increased intraspecific competition reducing niche breadth in some systems. We present a game-theoretic evolutionary model showing greater ecological specialization with intraspecific competition under specific conditions. This is in contrast to the competitive diversification hypothesis. Our analysis reveals that specialization can offer a competitive advantage. Largely, when facing weak competition, more specialized individuals are able to acquire more of the preferred resources without greatly sacrificing secondary resources and therefore gain higher fitness. Only when competition is too great for an individual to significantly affect resource use will intraspecific competition lead to an increased niche breadth. Other conditions, such as a low diversity of resources and a low penalty to specialization, help promote ecological specialization in the face of intraspecific competition. Through this work, we have been able to discover a previously unseen role that intraspecific competition plays in the evolution of ecological specialization.

scholarly journals High rates of evolution preceded shifts to sex-biased gene expression in Leucadendron, the most sexually dimorphic angiosperms

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Mathias Scharmann ◽  
Anthony G Rebelo ◽  
John R Pannell
Keyword(s):  
Gene Expression ◽  
Sexual Dimorphism ◽  
Positive Association ◽  
Leaf Size ◽  
Sex Bias ◽  
Evolution Of Sex ◽  
Rates Of Evolution ◽  
Expression Evolution ◽  
Species Specific ◽  
And Shifts

Differences between males and females are usually more subtle in dioecious plants than animals, but strong sexual dimorphism has evolved convergently in the South African Cape plant genus Leucadendron. Such sexual dimorphism in leaf size is expected largely to be due to differential gene expression between the sexes. We compared patterns of gene expression in leaves among ten Leucadendron species across the genus. Surprisingly, we found no positive association between sexual dimorphism in morphology and the number or the percentage of sex-biased genes. Sex bias in most sex-biased genes evolved recently and was species-specific. We compared rates of evolutionary change in expression for genes that were sex-biased in one species but unbiased in others and found that sex-biased genes evolved faster in expression than un-biased genes. This greater rate of expression evolution of sex-biased genes, also documented in animals, might suggest the possible role of sexual selection in the evolution of gene expression. However, our comparative analysis clearly indicates that the more rapid rate of expression evolution of sex-biased genes predated the origin of bias, and shifts towards bias were depleted in signatures of adaptation. Our results are thus more consistent with the view that sex bias is simply freer to evolve in genes less subject to constraints in expression level.

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