The costs and benefits of multiple mating in a mostly monandrous wasp

This is the final version of the article. Available from Wiley via the DOI in this record.The taxonomically widespread nature of polyandry remains a puzzle. Much of the empirical work regarding the costs and benefitsof multiple mating to females has, for obvious reasons, relied on species that are already highly polyandrous. However, thismakes it difficult to separate the processes that maintain the current level of polyandry from the processes that facilitate itsexpression and initiated its evolution. Here we consider the costs and benefits of polyandry in Nasonia vitripennis, a speciesof parasitoid wasp that is “mostly monandrous” in the wild, but which evolves polyandry under laboratory culture conditions.In a series of six experiments, we show that females gain a direct fecundity and longevity benefit from mating multiply withvirgin males. Conversely, mating multiply with previously mated males actually results in a fecundity cost. Sexual harassment mayalso represent a significant cost of reproduction. Harassment was, however, only costly during oviposition, resulting in reducedfecundity, longevity, and disrupted sex allocation. Our results show that ecological changes, in our case associated with differencesin the local mating structure in the laboratory can alter the costs and benefits of mating and harassment and potentially lead toshifts in mating patterns.RAB is supported by a NERC DTG studentship

Polyandry is context dependent but not convenient in a mostly monandrous wasp.

This is the final version of the article. Available from Elsevier via the DOI in this record.Research over the past two decades suggests that polyandry is almost ubiquitous in nature. In some cases, females can gain direct and indirect (genetic) fitness benefits from mating with multiple males. However, when females accept superfluous matings without gaining any clear benefit, polyandry has been interpreted as a strategy to mitigate the costs of resisting or avoiding matings, a situation known as convenience polyandry. When females mate out of ‘convenience’ the mating rate is expected to be plastic, since females should mate at a higher rate when the costs of resistance or avoidance are high, for instance when males occur in high densities and/or around resources required by females such as oviposition sites. Here we show that remating in Nasonia vitripennis, a species of wasp that is largely monandrous in the wild but that evolves polyandry under laboratory culture, is dependent upon the availability of hosts for oviposition and upon male density. We found that females mated at a higher rate when male density was high but only if a suitable oviposition substrate was available. Outwardly this seems suggestive of convenience polyandry. However, females that remated under these conditions did not gain more time to oviposit than females that resisted superfluous matings. The results of this study highlight the importance of comprehensively assessing the costs and benefits of mating before attributing the observed behaviour to convenience polyandry. Furthermore, these results add to the growing body of evidence that the ecological context under which sexual interactions occur is critical to the economics of mating.R.A.B. is supported by a NERC DTG studentshi

Beyond sex allocation: the role of mating systems in sexual selection in parasitoid wasps

Despite the diverse array of mating systems and life histories which characterise the parasitic Hymenoptera,sexual selection and sexual conict in this taxon have been somewhat overlooked. For instance, parasitoidmating systems have typically been studied in terms of how mating structure affects sex allocation. In thepast decade, however, some studies have sought to address sexual selection in the parasitoid wasps moreexplicitly and found that, despite the lack of obvious secondary sexual traits, sexual selection has the potentialto shape a range of aspects of parasitoid reproductive behaviour and ecology. Moreover, various characteristicsfundamental to the parasitoid way of life may provide innovative new ways to investigate different processesof sexual selection. The overall aim of this review therefore is to re-examine parasitoid biology with sexualselection in mind, for both parasitoid biologists and also researchers interested in sexual selection and theevolution of mating systems more generally. We will consider aspects of particular relevance that have alreadybeen well studied including local mating structure, sex allocation and sperm depletion. We go on to review whatwe already know about sexual selection in the parasitoid wasps and highlight areas which may prove fruitfulfor further investigation. In particular, sperm depletion and the costs of inbreeding under chromosomal sexdetermination provide novel opportunities for testing the role of direct and indirect benets for the evolutionof mate choice

The evolution of parental care strategies in subsocial wasps

This is the final version. Available from the publisher via the DOI in this record.Code accessibility Code used for this study will be archived on Dryad digital repository on acceptance.Data accessibility All data will be archived on Dryad digital repository on acceptance.Insect parental care strategies are particularly diverse, and prolonged association between parents and offspring may be a key precursor to the evolution of complex social traits. Macroevolutionary patterns remain obscure, however, due to the few rigorous phylogenetic analyses. The subsocial sphecid wasps are a useful group in which to study parental care because of the diverse range of strategies they exhibit. These strategies range from placing a single prey item in a pre-existing cavity to mass provisioning a pre-built nest, through to complex progressive provisioning where a female feeds larvae in different nests simultaneously as they grow. We show that this diversity stems from multiple independent transitions between states. The strategies we focus on were previously thought of in terms of a stepping-stone model in which complexity increases during evolution, ending with progressive provisioning which is a likely precursor to eusociality. We find that evolution has not always followed this model: reverse transitions are common, and the ancestral state is the most flexible rather than the simplest strategy. Progressive provisioning has evolved several times independently, but transitions away from it appear rare. We discuss the possibility that ancestral plasticity has played a role in the evolution of extended parental care

The response of perennial and temporary headwater stream invertebrate communities to hydrological extremes

The headwaters of karst rivers experience considerable hydrological variability, including spates and streambed drying. Extreme summer flooding on the River Lathkill (Derbyshire, UK) provided the opportunity to examine the invertebrate community response to unseasonal spate flows, flow recession and, at temporary sites, streambed drying. Invertebrates were sampled at sites with differing flow permanence regimes during and after the spates. Following streambed drying at temporary sites, dewatered surface sediments were investigated as a refugium for aquatic invertebrates. Experimental rehydration of these dewatered sediments was conducted to promote development of desiccation-tolerant life stages. At perennial sites, spate flows reduced invertebrate abundance and diversity, whilst at temporary sites, flow reactivation facilitated rapid colonisation of the surface channel by a limited number of invertebrate taxa. Following streambed drying, 38 taxa were recorded from the dewatered and rehydrated sediments, with Oligochaeta being the most abundant taxon and Chironomidae (Diptera) the most diverse. Experimental rehydration of dewatered sediments revealed the presence of additional taxa, including Stenophylax sp. (Trichoptera: Limnephilidae) and Nemoura sp. (Plecoptera: Nemouridae). The influence of flow permanence on invertebrate community composition was apparent despite the aseasonal high-magnitude flood events

Relevance of large litter bag burial for the study of leaf breakdown in the hyporheic zone

Particulate organic matter is the major source of energy for most low-order streams, but a large part of this litter is buried within bed sediment during floods and thus become poorly available for benthic food webs. The fate of this buried litter is little studied. In most cases, measures of breakdown rates consist of burying a known mass of litter within the stream sediment and following its breakdown over time. We tested this method using large litter bags (15 x 15 cm) and two field experiments. First, we used litter large bags filled with Alnus glutinosa leaves (buried at 20 cm depth with a shovel) in six stations within different land-use contexts and with different sediment grain sizes. Breakdown rates were surprisingly high (0.0011–0.0188 day-1) and neither correlate with most of the physico-chemical characteristics measured in the interstitial habitats nor with the land-use around the stream. In contrast, the rates were negatively correlated with a decrease in oxygen concentrations between surface and buried bags and positively correlated with both the percentage of coarse particles (20–40 mm) in the sediment and benthic macro-invertebrate richness. These results suggest that the vertical exchanges with surface water in the hyporheic zone play a crucial role in litter breakdown. Second, an experimental modification of local sediment (removing fine particles with a shovel to increase vertical exchanges) highlighted the influence of grain size on water and oxygen exchanges, but had no effect on hyporheic breakdown rates. Burying large litter bags within sediments may thus not be a relevant method, especially in clogged conditions, due to changes induced through the burial process in the vertical connectivity between surface and interstitial habitats that modify organic matter processing

Explanations for less small fibre neuropathy in South Asian versus European people with type 2 diabetes mellitus in the UK.

Low foot ulcer risk in South Asian, compared with European, people with type 2 diabetes in the UK has been attributed to their lower levels of neuropathy. We have undertaken a detailed study of corneal nerve morphology and neuropathy risk factors, to establish the basis of preserved small nerve fibre function in South Asians versus Europeans.In a cross-sectional, population-based study, age- and sex-matched South Asians (n=77) and Europeans (n=78) with type 2 diabetes underwent neuropathy assessment using corneal confocal microscopy, symptoms, signs, quantitative sensory testing, electrophysiology and autonomic function testing. Multivariable linear regression analyses determined factors accounting for ethnic differences in small fibre damage. -adjusted ethnic difference in corneal nerve fibre length (P=0.032) were pack-years smoked (P=0.13), BMI (P=0.062) and triglyceride levels (P=0.062).South Asians have better preserved small nerve fibre integrity than equivalent Europeans; furthermore, classic, modifiable risk factors for coronary heart disease are the main contributors to these ethnic differences. We suggest that improved autonomic neurogenic control of cutaneous blood flow in Asians may contribute to their protection against foot ulcers

Direct observations of the effect of fine sediment deposition on the vertical movement of Gammarus pulex (Amphipoda: Gammaridae) during substratum drying

Benthic macroinvertebrates inhabit the streambed sediments of temporary streams during drying events. Fine sediment (< 2 mm in diameter) deposition and clogging of interstitial pathways reduces the connectivity between benthic and subsurface habitats, potentially inhibiting macroinvertebrate vertical movements. Direct observations within subsurface sediments are, however, inherently difficult. As a result, confirmation of macroinvertebrate vertical movement, and the effect of fine sediment, is limited. We used laboratory mesocosms containing transparent gravel sized particles (10–15 mm) to facilitate the direct observation and tracking of vertical movements by Gammarus pulex in response to water level reduction and sedimentation. Seven sediment treatments comprised two fine sediment fractions (small: 0.125–0.5 mm, coarse sand: 0.5–1 mm) deposited onto the surface of the substrate, and a control treatment where no fine sediment was applied. We found that G. pulex moved into the subsurface gravel sediments in response to drying, but their ability to remain submerged during water level reduction was impeded by fine sediment deposition. In particular deposition of the coarser sand fraction clogged the sediment surface, limiting vertical movements. Our results highlight the potential effect of sedimentation on G. pulex resistance to drying events in streams

Multifocal electroretinogram and Optical Coherence tomography spectral-domain in arc welding macular injury: a case report

<p>Abstract</p> <p>Background</p> <p>the purpose of this study was to report a binocular photic retinal injury induced by plasma arc welding and the follow-up after treatment with vitamin supplements for a month. In our study, we used different diagnostic tools such as fluorescein angiography (FA), optical coherence tomography (OCT) and multifocal electroretinogram (mfERG).</p> <p>Case presentation</p> <p>in the first visit after five days from arc welding injury in the left eye (LE) the visual acuity was 0.9 and 1.0 in the right eye (RE). FA was normal in both eyes. OCT in the left eye showed normal profile and normal reflectivity and one month later, a hyperreflectivity appeared in the external limiting membrane (ELM). The mfERG signal in the LE was 102.30 nV/deg2 five days after the injury and 112.62 nV/deg2 after one month and in the RE respectively 142.70 nV/deg2 and 159.46 nV/deg2.</p> <p>Conclusions</p> <p>in cases of retinal photo injury it is important for the ophthalmologist to evaluate tests such as OCT and the mfERG in the diagnosis and follow-up of the patient because the recovery of visual acuity cannot exclude the persistence of phototoxic damage charged to the complex inner-outer segment of photoreceptors.</p

Small-fibre neuropathy in men with type 1 diabetes and erectile dysfunction: a cross-sectional study

Aims/hypothesis: The aim of this study was to identify the contribution of small- and large-fibre neuropathy to erectile dysfunction in men with type 1 diabetes mellitus. Methods: A total of 70 participants (29 without and 41 with erectile dysfunction) with type 1 diabetes and 34 age-matched control participants underwent a comprehensive assessment of large- and small-fibre neuropathy. Results: The prevalence of erectile dysfunction in participants with type 1 diabetes was 58.6%. After adjusting for age, participants with type 1 diabetes and erectile dysfunction had a significantly higher score on the Neuropathy Symptom Profile (mean ± SEM 5.3 ± 0.9 vs 1.8 ± 1.2, p = 0.03), a higher vibration perception threshold (18.3 ± 1.9 vs 10.7 ± 2.4 V, p = 0.02), and a lower sural nerve amplitude (5.0 ± 1.1 vs 11.7 ± 1.5 mV, p = 0.002), peroneal nerve amplitude (2.1 ± 0.4 vs 4.7 ± 0.5 mV, p < 0.001) and peroneal nerve conduction velocity (34.8 ± 1.5 vs 41.9 ± 2.0 m/s, p = 0.01) compared with those without erectile dysfunction. There was also evidence of a marked small-fibre neuropathy with an impaired cold threshold (19.7 ± 1.4°C vs 27.3 ± 1.8°C, p = 0.003), warm threshold (42.9 ± 0.8°C vs 39.0 ± 0.9°C, p = 0.005) and heart rate variability (21.5 ± 3.1 vs 30.0 ± 3.7 beats/min, p = 0.001) and reduced intraepidermal nerve fibre density (2.8 ± 0.7 vs 5.9 ± 0.7/mm, p = 0.008), corneal nerve fibre density (12.6 ± 1.5 vs 23.9 ± 2.0/mm2, p < 0.001), corneal nerve branch density (12.7 ± 2.5 vs 31.6 ± 3.3/mm2, p < 0.001) and corneal nerve fibre length (8.3 ± 0.7 vs 14.5 ± 1.0 mm/mm2, p < 0.001) in participants with type 1 diabetes and erectile dysfunction. Erectile dysfunction correlated significantly with measures of both large- and small-fibre neuropathy. Conclusions/interpretation: Small-fibre neuropathy is prominent in patients with type 1 diabetes, and is associated with erectile dysfunction and can be objectively quantified using corneal confocal microscopy. This may allow the identification of patients who are less likely to respond to conventional therapies such as phosphodiesterase type 5 inhibitors