scholarly journals Nonadaptive Radiation: Pervasive diet specialization by drift in scale insects?

2016 ◽  
Author(s):  
Nate B Hardy ◽  
Daniel A Peterson ◽  
Benjamin B Normark
Keyword(s):  
Host Specificity ◽  
Phylogenetic Analyses ◽  
Negative Relationship ◽  
Diet Breadth ◽  
Scale Insects ◽  
Host Specialization ◽  
Herbivorous Insects ◽  
Strong Positive Relationship ◽  
Adaptive Processes ◽  
Source Populations

AbstractAt least half of metazoan species are herbivorous insects. Why are they so diverse? Most herbivorous insects feed on few plant species, and adaptive host specialization is often invoked to explain their diversification. Nevertheless, it is possible that the narrow host ranges of many herbivorous insects are non-adaptive. Here, we test predictions of this hypothesis with comparative phylogenetic analyses of scale insects, a group for which there appears to be few host-use tradeoffs that would select against polyphagy, and for which passive wind-dispersal should make host specificity costly. We infer a strong positive relationship between host range and diversification rate, and a marked asymmetry in cladogenetic changes in diet breadth. These results are consonant with a system of pervasive non-adaptive host specialization in which small, drift-and extinction-prone populations are frequently isolated from persistent and polyphagous source populations. They also contrast with the negative relationship between diet breadth and taxonomic diversification that has been estimated in butterflies, a disparity which likely stems from differences in the average costs and benefits of host specificity and generalism in scale insects vs. butterflies. Our results indicate the potential for non-adaptive processes to be important to diet-breadth evolution and taxonomic diversification across herbivorous insects.

scholarly journals Physical Modeling of Landward Scour Due to Tsunami Bore Overtopping Seawall

2018 ◽  
Vol 203 ◽  
pp. 01003
Author(s):  
Raidan Maqtan ◽  
Badronnisa Yusuf ◽  
Saiful Bahri Hamzah
Keyword(s):  
Froude Number ◽  
Laboratory Experiments ◽  
Negative Relationship ◽  
Structural Performance ◽  
Flow Depth ◽  
Initial Water ◽  
Field Surveys ◽  
Strong Positive Relationship ◽  
Strong Negative Relationship ◽  
Wave Forms

many of the post tsunami field surveys which conducted by researchers revealed that, the failure due to scour at the landward toe of the seawall due to overtopping of tsunami wave forms one of the important types of coastal defence structures failure and constitutes one of the biggest threats to their structural performance. This study was intended to investigates the scour profile induced by tsunami bores at the landward toe of the vertical seawall and to discuss the effects of the parameters; tide level, incident bore Froude number Fb, incident bore height Hb, overtopping flow Froude number Fo, and overtopping flow depth Ho on the maximum scour depth induced at the landward toe of the seawall. A set of laboratory experiments were conducted at National Hydraulic Research Institute of Malaysia (NAHRIM) with the tichnique of dam break to generate the bore like tsunami. The experiments showed that the initial water level upstream of the seawall has a significant effect on the scour profile and there is a strong negative relationship exists with Froude number of the incident bore and a strong positive relationship exists with Froude number of the overtopping flow depth above the crest of the seawall.

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.

What We Don't Know About Diet-Breadth Evolution in Herbivorous Insects

2020 ◽  
Vol 51 (1) ◽  
pp. 103-122 ◽  
Author(s):  
Nate B. Hardy ◽  
Chloe Kaczvinsky ◽  
Gwendolyn Bird ◽  
Benjamin B. Normark
Keyword(s):  
Plant Species ◽  
Population Genetic ◽  
Genetic Architecture ◽  
Diet Breadth ◽  
Herbivorous Insects ◽  
Herbivorous Insect ◽  
Insect Diversity ◽  
Major Question ◽  
Genetic Environment ◽  
Species Ecology

Half a million species of herbivorous insects have been described. Most of them are diet specialists, using only a few plant species as hosts. Biologists suspect that their specificity is key to their diversity. But why do herbivorous insects tend to be diet specialists? In this review, we catalog a broad range of explanations. We review the evidence for each and suggest lines of research to obtain the evidence we lack. We then draw attention to a second major question, namely how changes in diet breadth affect the rest of a species’ biology. In particular, we know little about how changes in diet breadth feed back on genetic architecture, the population genetic environment, and other aspects of a species’ ecology. Knowing more about how generalists and specialists differ should go a long way toward sorting out potential explanations of specificity, and yield a deeper understanding of herbivorous insect diversity.

HOST SPECIFICITY IN PISSODES STROBI (COLEOPTERA: CURCULIONIDAE): ROLES OF GEOGRAPHY, GENETICS, AND BEHAVIOR

2000 ◽  
Vol 132 (6) ◽  
pp. 811-823 ◽  
Author(s):  
Thomas W. Phillips ◽  
Gerald N. Lanier
Keyword(s):  
New York ◽  
British Columbia ◽  
Host Specificity ◽  
Sitka Spruce ◽  
Picea Sitchensis ◽  
Host Specialization ◽  
Pinus Monticola ◽  
White Pine ◽  
Eastern White Pine ◽  
Pissodes Strobi

AbstractHost specificity of Pissodes strobi (Peck) from different geographic regions and genetic divergence of local host-associated weevil populations were studied in a series of experiments. Pacific coast P. strobi reared from Sitka spruce, Picea sitchensis (Bong.) Carr (Pinaceae), were unable to successfully colonize either eastern white pine, Pinus strobus L. (Pinaceae), or western white pine, Pinus monticola Dougl. ex D. Don., in a forced-infestation study on interplanted trees in New York. Reproductively mature field-collected P. strobi from British Columbia did not oviposit on eastern white pine in New York, but field-collected New York weevils successfully reproduced in Sitka spruce leaders in British Columbia. Unacceptability of eastern white pine for western P. strobi was shown to be under genetic control, rather than influenced by prior host experience on Sitka spruce. Pissodes strobi originating from Sitka spruce but reared one generation in the laboratory on the exotic Norway spruce, Picea abies (L.) Karst., were also unable to utilize eastern white pine as a host in a forced-infestation experiment in the field. Population genetic studies using allozyme electrophoresis found that P. strobi populations occurring on different host species within 2 km of each other had significant differences in allele frequencies in three out of four cases. These results suggest that P. strobi can exist as small breeding populations that can facilitate host specialization. Applied research on host resistance against P. strobi could target mechanisms that prevent western P. strobi from utilizing nonhosts such as eastern and western white pines.

Antecedents of Online Game Dependency

2010 ◽  
Vol 21 (2) ◽  
pp. 69-99 ◽  
Author(s):  
Kaunchin Chen ◽  
Jengchung V. Chen ◽  
William H. Ross
Keyword(s):  
Predictive Models ◽  
Positive Relationship ◽  
Aesthetic Experience ◽  
Negative Relationship ◽  
Virtual Community ◽  
Online Games ◽  
Online Game ◽  
Massively Multiplayer Online Game ◽  
Mediating Factors ◽  
Strong Positive Relationship

Massively Multiplayer Online Game (MMOG) dependency has been widely studied but research results suggest inconclusive antecedent causes. This study proposes and empirically tests three predictive models of MMOG dependency using a survey of online gaming participants. It finds multimedia realism for social interaction serves as an original antecedent factor affecting other mediating factors to cause MMOG dependency. These mediating factors derive from Uses and Gratifications theory and include: (1) participation in a virtual community, (2) diversion from everyday life, and (3) a pleasant aesthetic experience. Of these, participation in a virtual community has a strong positive relationship with MMOG dependency, and aesthetics has a modest negative relationship. Moderator analyses suggest neither gender nor “frequency of game playing” are significant but experience playing online games is a significant moderating factor of MMOG dependency.

scholarly journals Identification and Quantification of Polymyxa graminis f. sp. temperata and P. graminis f. sp. tepida on Barley and Wheat

Plant Disease ◽  
2007 ◽  
Vol 91 (7) ◽  
pp. 857-864 ◽  
Author(s):  
C. Vaïanopoulos ◽  
C. Bragard ◽  
V. Moreau ◽  
H. Maraite ◽  
A. Legrève
Keyword(s):  
Host Specificity ◽  
Dna Sequences ◽  
Fragment Length Polymorphism ◽  
Rflp Analysis ◽  
Host Specialization ◽  
Molecular Tools ◽  
Chain Reaction ◽  
Polymyxa Graminis ◽  
Real Time Quantitative Pcr ◽  
Polymerase Chain

Polymyxa graminis f. sp. temperata and P. graminis f. sp. tepida are distinguished on the basis of their specific ribosomal DNA sequences. In order to evaluate whether or not host specialization is associated with the special form, the occurrence of infection of both forms on barley and wheat was studied. P. graminis inocula were obtained from soils collected in Belgium and France. Their ribotypes were characterized using molecular tools specific to P. graminis f. sp. temperata or P. graminis f. sp. tepida such as restriction fragment length polymorphism (RFLP) analysis of polymerase chain reaction (PCR)-amplified rDNA, nested and multiplex PCR. Both special forms were found in each country and coexisted in some soils. The host specificity of P. graminis special forms for barley and wheat was studied from two soils collected at Gembloux (Belgium) and Chambon-sur-Cisse (France), each infested by bymo- and furoviruses. P. graminis f. sp. temperata is more frequent on barley and P. graminis f. sp. tepida on wheat. Furthermore, the quantification of each form on barley and wheat by two separated real-time quantitative PCR assays confirms the observations on the vector specialization. These results suggest a certain but not exclusive host specificity of P. graminis special forms.

Benefits of fidelity: does host specialization impact nematode parasite life history and fecundity?

Parasitology ◽  
2013 ◽  
Vol 140 (5) ◽  
pp. 587-597 ◽  
Author(s):  
J. KOPRIVNIKAR ◽  
H. S. RANDHAWA
Keyword(s):  
Life History ◽  
Host Specificity ◽  
Egg Size ◽  
Host Specialization ◽  
Published Data ◽  
Female Size ◽  
Patent Period ◽  
Trade Offs ◽  
Evolutionary Level ◽  
Host Parasite

SUMMARYThe range of hosts used by a parasite is influenced by macro-evolutionary processes (host switching, host–parasite co-evolution), as well as ‘encounter filters’ and ‘compatibility filters’ at the micro-evolutionary level driven by host/parasite ecology and physiology. Host specialization is hypothesized to result in trade-offs with aspects of parasite life history (e.g. reproductive output), but these have not been well studied. We used previously published data to create models examining general relationships among host specificity and important aspects of life history and reproduction for nematodes parasitizing animals. Our results indicate no general trade-off between host specificity and the average pre-patent period (time to first reproduction), female size, egg size, or fecundity of these nematodes. However, female size was positively related to egg size, fecundity, and pre-patent period. Host compatibility may thus not be the primary determinant of specificity in these parasitic nematodes if there are few apparent trade-offs with reproduction, but rather, the encounter opportunities for new host species at the micro-evolutionary level, and other processes at the macro-evolutionary level (i.e. phylogeny). Because host specificity is recognized as a key factor determining the spread of parasitic diseases understanding factors limiting host use are essential to predict future changes in parasite range and occurrence.

Haemogregarines from western Palaearctic freshwater turtles (generaEmys, Mauremys) are conspecific withHaemogregarina stepanowiDanilewsky, 1885

Parasitology ◽  
2013 ◽  
Vol 141 (4) ◽  
pp. 522-530 ◽  
Author(s):  
NELA DVOŘÁKOVÁ ◽  
JANA KVIČEROVÁ ◽  
IVO PAPOUŠEK ◽  
HOSSEIN JAVANBAKHT ◽  
GHOULEM TIAR ◽  
...  
Keyword(s):  
Host Specificity ◽  
18S Rdna ◽  
Phylogenetic Analyses ◽  
Wide Distribution ◽  
Freshwater Turtles ◽  
Turtle Species ◽  
Rdna Sequences ◽  
Mauremys Leprosa ◽  
18S Rdna Sequences ◽  
Western Palaearctic

SUMMARYThe majority ofHaemogregarinaspecies have been based on the morphology of their erythrocytic stages and supposed strict host specificity. The quantity of species with a limited number of overlapping diagnostic traits has led to a considerable mess in haemogregarine taxonomy and significant synonymy. We analysed host specificity, intra- and interspecific variability, evolutionary relationships, and the distribution of the type species of the genusHaemogregarina–H. stepanowi.The morphology of blood stages and 18S rDNA sequences of this haemogregarine from four western Palaearctic hard-shelled freshwater turtles (Emys orbicularis, Mauremys caspica, Mauremys leprosaandMauremys rivulata) were compared withHaemogregarina balli. Additional sequences of 18S rDNA ofHaemogregarina-like isolates collected from three species of African hinged terrapins (genusPelusios) were used to enlarge the dataset for phylogenetic analyses. Thirteen sequences (1085 bp) ofHaemogregarinarepresenting all four western Palaearctic turtle species were identical, corresponding toH. stepanowi, which is closely related to the Nearctic speciesH. balli. In our analyses,Haemogregarinaspp. constituted a monophyletic clade sister to the genusHepatozoon. Haemogregarina stepanowipossesses a wide distribution range from the Maghreb, through Europe, Turkey and the Middle East to Iran. We consider that the genusHaemogregarinahas a low host specificity crossing the family level of its vertebrate hosts and that its distribution is likely to be linked to the vector and definitive host – the leech.

scholarly journals Five-Minute Awake Snoring Test for Determining CPAP Pressures (Five-Minute CPAP Test): A Pilot Study

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Macario Camacho ◽  
Chad M. Ruoff ◽  
Makoto Kawai ◽  
Rahul Modi ◽  
Jabri Arbee ◽  
...  
Keyword(s):  
Pilot Study ◽  
Positive Relationship ◽  
Water Pressure ◽  
Negative Relationship ◽  
Case Series ◽  
Apnea Hypopnea Index ◽  
Nasal Cpap ◽  
Strong Positive Relationship ◽  
Bedside Test ◽  
Obstructive Sleep

Objective. To develop a quick, simple, bedside test for determining continuous positive airway pressures (CPAP) for obstructive sleep apnea (OSA) patients.Study Design. Prospective case series at a tertiary medical center.Methods. The Five-Minute Awake Snoring Test for Determining CPAP (Five-Minute CPAP Test) was developed and tested. Patients wear a soft-gel nasal triangle mask while holding a tongue depressor with the wide section (1.75 cm) between the teeth. Fixed pressure nasal CPAP is applied while the patient simulates snoring at 4 centimeters of water pressure. The pressure is incrementally titrated up and then down to determine the lowest pressure at which the patient cannot snore (Quiet Pressure).Results. Overall, thirty-eight patients participated. All could simulate snoring. Correlation coefficients were statistically significant between Quiet Pressures and body mass index (rs=0.60[strong positive relationship],p=0.0088), apnea-hypopnea index (rs=0.49[moderate positive relationship],p=0.039), lowest oxygen saturation (rs=-0.47[moderate negative relationship],p=0.048), and oxygen desaturation index (rs=0.62[strong positive relationship],p=0.0057).Conclusion. This pilot study introduces a new concept, which is the final product of over one year of exploration, development, and testing. Five-Minute CPAP Test is a quick, inexpensive, and safe bedside test based on supine awake simulated snoring with nasal CPAP.

scholarly journals Diet shifts of Rhizoprionodon terraenovae from the southern Gulf of Mexico: possible scenario by temperature changes

2020 ◽  
Vol 48 (3) ◽  
pp. 406-420
Author(s):  
Javier E. Viana-Morayta ◽  
Yassir E. Torres-Rojas ◽  
Jaime Camalich-Carpizo
Keyword(s):  
Body Size ◽  
Gulf Of Mexico ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Trophic Level ◽  
Negative Relationship ◽  
Diet Breadth ◽  
Sea Surface ◽  
Rhizoprionodon Terraenovae ◽  
Southern Gulf Of Mexico

The current study examined the stomach contents of the Atlantic sharpnose shark (Rhizoprionodon terraenovae) in the southern Gulf of Mexico during 2015 to understand the relationship between diet and changes in sea surface temperature (SST). Prey-specific index of relative importance (%PSIRI), diet breadth (Bi), trophic level (TrL), and trophic overlap (PERMANOVA) were calculated between sexes, body size, and climatic seasons (dry, rainy and winter storm). The lowest temperature recorded in the area was during February (23.9°C), and the highest was during August (29.1°C). A total of 124 stomachs were analyzed, with 54.84% containing food. The trophic spectrum was composed of 32 identified prey, with demersal fish (Haemulon plumierii; %PSIRI = 22.82) and pelagic fish (Sardinella aurita; %PSIRI = 12.83) being the most important. According to the diet breadth (Bi = 0.002), Costello's graph, and trophic level (TrL = 4.2), R. terraenovae is a specialist tertiary consumer. PERMANOVA indicated significant trophic differences between sexes (F = 32.22; P < 0.05), body size (F = 13.68; P < 0.05), and among climatic seasons (F = 23.86; P < 0.05). Spearman's correlation indicated a negative relationship between the diversity of prey consumed by R. terraenovae and sea surface temperature (r = -0.75; P < 0.05). Therefore, diet for R. terraenovae is associated with SST, allowing for the development of possible scenarios related to climatic phenomena like climate change.

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