scholarly journals Small females prefer small males: size assortative mating in Aedes aegypti mosquitoes

2018 ◽  
Author(s):  
Ashley G. Callahan ◽  
Perran A. Ross ◽  
Ary A. Hoffmann
Keyword(s):  
Aedes Aegypti ◽  
Mating Success ◽  
Cytoplasmic Incompatibility ◽  
Size Range ◽  
Invasion Success ◽  
Disease Suppression ◽  
Small Field ◽  
Factors Influencing ◽  
Wide Range ◽  
Narrow Size Range

AbstractWith Aedes aegypti mosquitoes now being released in field programs aimed at disease suppression, there is interest in identifying factors influencing the mating and invasion success of released mosquitoes. One factor that can increase release success is size: released males may benefit competitively from being larger than their field counterparts. However, there could be a risk in releasing only large males if small field females avoid these males and instead prefer small males. Here we investigate this risk by evaluating mating success for mosquitoes differing in size. We measured mating success indirectly by coupling size with Wolbachia-infected or uninfected mosquitoes and scoring cytoplasmic incompatibility as a way of estimating relative mating success. Large females showed no evidence of a mating preference, whereas small males were relatively more successful than large males when mating with small females, exhibiting an advantage of around 20-25%. Because field females typically encompass a wide range of sizes while laboratory reared (and released) males typically fall into a narrow size range of large mosquitoes, these patterns can influence the success of release programs which rely on cytoplasmic incompatibility to suppress populations and initiate replacement invasions. Releases could include some small males generated under low food or crowded conditions to counter this issue, although this would need to be weighed against issues associated with costs of producing males of various size classes.

scholarly journals A decade of stability for wMel Wolbachia in natural Aedes aegypti populations

2021 ◽  
Author(s):  
Perran A Ross ◽  
Katie L Robinson ◽  
Qiong Yang ◽  
Ashley G Callahan ◽  
Thomas L Schmidt ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Cytoplasmic Incompatibility ◽  
Near Field ◽  
Virus Transmission ◽  
Host Density ◽  
Disease Suppression ◽  
Genomic Changes ◽  
Laboratory Populations ◽  
Wolbachia Genome

Mosquitoes carrying Wolbachia endosymbionts are being released in many countries for arbovirus control. The wMel strain of Wolbachia blocks Aedes-borne virus transmission and can spread throughout mosquito populations by inducing cytoplasmic incompatibility. Aedes aegypti mosquitoes carrying wMel were first released into the field in Cairns, Australia, over a decade ago, and with wider releases have resulted in the near elimination of local dengue transmission. The long-term stability of Wolbachia effects is critical for ongoing disease suppression, requiring tracking of phenotypic and genomic changes in Wolbachia infections following releases. We used a combination of field surveys, phenotypic assessments, and Wolbachia genome sequencing to show that wMel has remained stable in its effects for up to a decade in Australian Ae. aegypti populations. Phenotypic comparisons of wMel-infected and uninfected mosquitoes from near-field and long-term laboratory populations suggest limited changes in the effects of wMel on mosquito fitness. Treating mosquitoes with antibiotics used to cure the wMel infection had limited effects on fitness in the next generation, supporting the use of tetracycline for generating uninfected mosquitoes without off-target effects. wMel has a temporally stable within-host density and continues to induce complete cytoplasmic incompatibility. A comparison of wMel genomes from pre-release (2010) and nine years post-release (2020) populations show few genomic differences and little divergence between release locations, consistent with the lack of phenotypic changes. These results indicate that releases of Wolbachia-infected mosquitoes for population replacement are likely to be effective for many years, but ongoing monitoring remains important to track potential evolutionary changes.

Hydraulic segmentation does not protect stems from acute water loss during fire

2021 ◽  
Author(s):  
William A Hoffmann ◽  
Amanda C Rodrigues ◽  
Nicholas Uncles ◽  
Lorenzo Rossi
Keyword(s):  
Water Uptake ◽  
Water Loss ◽  
High Water ◽  
Fire Plume ◽  
Magnolia Grandiflora ◽  
Hydraulic Failure ◽  
Factors Influencing ◽  
Wide Range ◽  
Transport Path ◽  
Measured Water

Abstract The heat plume associated with fire has been hypothesized to cause sufficient water loss from trees to induce embolism and hydraulic failure. However, it is unclear whether the water transport path remains sufficiently intact during scorching or burning of foliage to sustain high water loss. We measured water uptake by branches of Magnolia grandiflora while exposing them to a range of fire intensities, and examined factors influencing continued water uptake after fire. Burning caused a 22-fold mean increase in water uptake, with greatest rates of water loss observed at burn intensities that caused complete consumption of leaves. Such rapid uptake is possible only with steep gradients in water potential, which would likely result in substantial cavitation of xylem and loss of conductivity in intact stems. Water uptake continued after burning was complete, and was greatest following burn intensities that killed leaves but did not consume them. This post-fire uptake was mostly driven by rehydration of the remaining tissues, rather than evaporation from the tissues. Our results indicate that the fire-plume hypothesis can be expanded to include a wide range of burning conditions experienced by plants. High rates of water loss are sustained during burning, even when leaves are killed or completely consumed.

scholarly journals Male competition and the evolution of mating and life-history traits in experimental populations of Aedes aegypti

2019 ◽  
Vol 286 (1904) ◽  
pp. 20190591 ◽  
Author(s):  
Alima Qureshi ◽  
Andrew Aldersley ◽  
Brian Hollis ◽  
Alongkot Ponlawat ◽  
Lauren J. Cator
Keyword(s):  
Life History ◽  
Aedes Aegypti ◽  
Mating Success ◽  
Life History Traits ◽  
Male Competition ◽  
Male Mating ◽  
Male Mating Success ◽  
Reproductive Control ◽  
Evolutionary Response ◽  
Mating Conditions

Aedes aegypti is an important disease vector and a major target of reproductive control efforts. We manipulated the opportunity for sexual selection in populations of Ae . aegypti by controlling the number of males competing for a single female. Populations exposed to higher levels of male competition rapidly evolved higher male competitive mating success relative to populations evolved in the absence of competition, with an evolutionary response visible after only five generations. We also detected correlated evolution in other important mating and life-history traits, such as acoustic signalling, fecundity and body size. Our results indicate that there is ample segregating variation for determinants of male mating competitiveness in wild populations and that increased male mating success trades-off with other important life-history traits. The mating conditions imposed on laboratory-reared mosquitoes are likely a significant determinant of male mating success in populations destined for release.

scholarly journals Stem photosynthesis: new evidence highlights the contribution of phenotypic plasticity to the invasion success of Mikania micrantha

2020 ◽  
Author(s):  
Jin Zheng ◽  
Tai-Jie Zhang ◽  
Bo-Hui Li ◽  
Wei-Jie Liang ◽  
Qi-Lei Zhang ◽  
...  
Keyword(s):  
Phenotypic Plasticity ◽  
Plant Species ◽  
Invasive Plant ◽  
Stem Elongation ◽  
Invasion Success ◽  
Invasive Plant Species ◽  
Alien Plant ◽  
Mikania Micrantha ◽  
Stem Photosynthesis ◽  
Wide Range

Phenotypic plasticity affords invasive plant species the ability to colonize a wide range of habitats, but physiological plasticity of their stems is seldom recognized. Investigation of the stem plasticity of invasive plant species could lead to a better understanding of their invasiveness. We performed a pot experiment involving defoliation treatments and an isolated culture experiment to determine whether the invasive species Mikania micrantha exhibits greater plasticity in the stems than do three native species that co-occur in southern China and then explored the mechanism underlying the modification of its stem photosynthesis. Our results showed that the stems of M. micrantha exhibited higher plasticity in terms of either net or gross photosynthesis in response to the defoliation treatment. These effects were positively related to an increased stem elongation rate. The enhancement of stem photosynthesis in M. micrantha resulted from the comprehensive action involving increases in the Chl a/b ratio, D1 protein and stomatal aperture, changes in chloroplast morphology and a decrease in anthocyanins. Increased plasticity of stem photosynthesis may improve the survival of M. micrantha under harsh conditions and allow it to rapidly recover from defoliation injuries. Our results highlight that phenotypic plasticity promotes the invasion success of alien plant invaders.

scholarly journals A systematic review of provider-and system-level factors influencing the delivery of cardiac rehabilitation for heart failure

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Paulina Daw ◽  
Thomas M. Withers ◽  
Jet J. C. S. Veldhuijzen van Zanten ◽  
Alexander Harrison ◽  
Colin J. Greaves
Keyword(s):  
Heart Failure ◽  
Systematic Review ◽  
Cardiac Rehabilitation ◽  
Thematic Analysis ◽  
System Level ◽  
Future Research ◽  
Heart Failure Patients ◽  
Barriers And Enablers ◽  
Factors Influencing ◽  
Wide Range

Abstract Background There is a longstanding research-to-practice gap in the delivery of cardiac rehabilitation for patients with heart failure. Despite adequate evidence confirming that comprehensive cardiac rehabilitation can improve quality of life and decrease morbidity and mortality in heart failure patients, only a fraction of eligible patients receives it. Many studies and reviews have identified patient-level barriers that might contribute to this disparity, yet little is known about provider- and system-level influences. Methods A systematic review using narrative synthesis. The aims of the systematic review were to a) determine provider- and system-level barriers and enablers that affect the delivery of cardiac rehabilitation for heart failure and b) juxtapose identified barriers with possible solutions reported in the literature. A comprehensive search strategy was applied to the MEDLINE, Embase, PsycINFO, CINAHL Plus, EThoS and ProQuest databases. Articles were included if they were empirical, peer-reviewed, conducted in any setting, using any study design and describing factors influencing the delivery of cardiac rehabilitation for heart failure patients. Data were synthesised using inductive thematic analysis and a triangulation protocol to identify convergence/contradiction between different data sources. Results Seven eligible studies were identified. Thematic analysis identified nine overarching categories of barriers and enablers which were classified into 24 and 26 themes respectively. The most prevalent categories were ‘the organisation of healthcare system’, ‘the organisation of cardiac rehabilitation programmes’, ‘healthcare professional’ factors and ‘guidelines’. The most frequent themes included ‘lack of resources: time, staff, facilities and equipment’ and ‘professional’s knowledge, awareness and attitude’. Conclusions Our systematic review identified a wide range of provider- and system-level barriers impacting the delivery of cardiac rehabilitation for heart failure, along with a range of potential solutions. This information may be useful for healthcare professionals to deliver, plan or commission cardiac rehabilitation services, as well as future research.

Investigation of Factors Influencing the Formation of Tungstate-Based Inorganic-Organic Hybrid Nanobelts/Nanotubes

2007 ◽  
Vol 352 ◽  
pp. 85-88 ◽  
Author(s):  
De Liang Chen ◽  
Yoshiyuki Sugahara
Keyword(s):  
Reaction Rate ◽  
Molar Ratio ◽  
Long Range Order ◽  
Interlayer Water ◽  
Organic Hybrid ◽  
Lamellar Structures ◽  
Factors Influencing ◽  
Wide Range ◽  
Formation Behavior ◽  
Apparent Diameter

Tungstate-based inorganic−organic hybrid nanobelts/nanotubes were synthesized in a system of H2W2O7·xH2O/n-octylamine/heptane (n-octylamine:H2W2O7·xH2O molar ratio: 30), and the effects of the volume ratios of heptane to n-octylamine and the amounts of interlayer water in H2W2O7·xH2O on the formation behavior of the hybrids were investigated. The belt/tubelike hybrids obtained were 10–20 +m in length and 200–500 nm in apparent diameter. Large volume ratios of heptane to n-octylamine not only enhanced the degree of the long-range order of the lamellar structures in the hybrids, but they also improved the morphologic uniformity of the hybrids. The existence of interlayer water in H2W2O7·xH2O was indispensable to the formation of tungstate-based inorganic−organic hybrid nanobelts/nanotubes. The amounts of interlayer water in H2W2O7·xH2O varied over a wide range (x, from 0.85 to 4.1), had a neglectable effect on the morphology of the tungstate-based nanophase hybrids, but exerted a remarkable influence on the rate of the reaction of H2W2O7·xH2O with n-octylamine in the heptane solvent. The larger the amount of interlayer water, the more rapid the reaction rate.

Contextual Influences on Science Teachers' TPACK Levels

2015 ◽  
pp. 307-333 ◽  
Author(s):  
Kofi Acheaw Owusu ◽  
Lindsey Conner ◽  
Chris Astall
Keyword(s):  
Case Studies ◽  
Science Teachers ◽  
Teaching And Learning ◽  
Contextual Influences ◽  
Learning Context ◽  
Pedagogical Content ◽  
Factors Influencing ◽  
Use Of Technology ◽  
Wide Range ◽  
Technology In Instruction

The contextual factors influencing teachers' use of technology as well as teachers' Technological Pedagogical Content Knowledge (TPACK) levels were investigated through multiple embedded case studies of five science teachers who were regular users of technology in their teaching. The case studies reported in this chapter revealed that teachers used technology to support inquiry learning through a wide range of ways in lower levels of high school but mostly to clarify concepts and theories for senior level students. This chapter identified that teachers demonstrated different TPACK levels of expertise and engagement in the use of technology when transferring different types of knowledge from one teaching and learning context to another and for addressing differences amongst learners. The context of assessment driven teaching influences science teachers' TPACK for integrating technology in instruction. The chapter noted that having teachers actively evaluate the effectiveness of the technology on students' learning may help increase teachers' TPACK levels.

Contextual Influences on Science Teachers' TPACK Levels

2018 ◽  
pp. 448-475
Author(s):  
Kofi Acheaw Owusu ◽  
Lindsey Conner ◽  
Chris Astall
Keyword(s):  
Case Studies ◽  
Science Teachers ◽  
Teaching And Learning ◽  
Contextual Influences ◽  
Learning Context ◽  
Pedagogical Content ◽  
Factors Influencing ◽  
Use Of Technology ◽  
Wide Range ◽  
Technology In Instruction

The contextual factors influencing teachers' use of technology as well as teachers' Technological Pedagogical Content Knowledge (TPACK) levels were investigated through multiple embedded case studies of five science teachers who were regular users of technology in their teaching. The case studies reported in this chapter revealed that teachers used technology to support inquiry learning through a wide range of ways in lower levels of high school but mostly to clarify concepts and theories for senior level students. This chapter identified that teachers demonstrated different TPACK levels of expertise and engagement in the use of technology when transferring different types of knowledge from one teaching and learning context to another and for addressing differences amongst learners. The context of assessment driven teaching influences science teachers' TPACK for integrating technology in instruction. The chapter noted that having teachers actively evaluate the effectiveness of the technology on students' learning may help increase teachers' TPACK levels.

scholarly journals Mating Competitiveness of Transgenic Aedes aegypti (Diptera: Culicidae) Males Against Wild-Type Males Reared Under Simulated Field Conditions

2020 ◽  
Vol 57 (6) ◽  
pp. 1775-1781
Author(s):  
David S Kang ◽  
Joanne M Cunningham ◽  
Diane D Lovin ◽  
Dave D Chadee ◽  
David W Severson
Keyword(s):  
Aedes Aegypti ◽  
Environmental Stress ◽  
Environmental Conditions ◽  
Mating Success ◽  
Genetically Modified ◽  
Field Isolate ◽  
Larval Density ◽  
Laboratory Strain ◽  
Adult Mosquito ◽  
Male Mating

Abstract Efforts directed at genetic modification of mosquitoes for population control or replacement are highly dependent on the initial mating success of transgenic male mosquitoes following their release into natural populations. Adult mosquito phenotypes are influenced by the environmental conditions experienced as larvae. Semifield studies conducted to date have not taken that under consideration when testing male mating fitness, and have compared mating success of males reared under identical environmental conditions. We performed pairwise mating challenges between males from a genetically modified laboratory strain (BF2) versus males from a recent Trinidad field isolate of Aedes aegypti (L.), a major vector of multiple arboviruses. We utilized larval density and nutrition to simulate environmental stress experienced by the Trinidad males and females. Our results indicated that environmental stress during larval development negatively influenced the competitiveness and reproductive success of males from the Trinidad population when paired with optimum reared BF2 males. Small (0.027 m3) and large (0.216 m3) trials were conducted wherein stressed or optimum Trinidad males competed with optimum BF2 males for mating with stressed Trinidad females. When competing with stress reared Trinidad males, optimum reared BF2 males were predominant in matings with stress reared Trinidad females, and large proportions of these females mated with males of both strains. When competing with optimum reared Trinidad males, no difference in mating success was observed between them and BF2 males, and frequencies of multiple matings were low. Our results indicate that future mating competition studies should incorporate appropriate environmental conditions when designing mating fitness trials of genetically modified males.

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