Effects Of Asynchrony Research Articles

Plankton Community Stability and Its Relationship with Phytoplankton Species Richness in Lake Nansihu, China

The relationship between biodiversity and ecosystem functioning is a central issue in ecology. The insurance hypothesis suggests that biodiversity could improve community productivity and reduce the temporal variability of main ecosystem processes. In the present study, we used a plankton community that was investigated from 2011 to 2014 in Lake Nansihu to test this hypothesis and explore the mechanisms involved. As a result, 138 phytoplankton and 76 zooplankton species were identified in the lake, and their biomasses showed apparent seasonal variations. The average temporal stability index of zooplankton taxa was significantly higher than that of phytoplankton. Complex relationships were observed between the species richness and temporal stability of different phytoplankton taxa: a unimodal relationship for both Cyanophyta and Bacillariophyta; a strong concave relationship for Euglenophyta; and no apparent relationship for both Chlorophyta and total phytoplankton. These relationships were primarily controlled by the portfolio effect; while the effects of overyielding and species asynchrony were relatively weak. Phytoplankton species richness had a significant positive influence on the temporal stability indices of protozoa, Rotifera and total zooplankton, while its influence on Cladocera and copepods was not significant. The dominant mechanisms were found to be ‘trophic overyielding’ and a weak ‘trophic portfolio effect’; however, ‘trophic species asynchrony’ played a minor role. These results demonstrated that the effects of diversity on community stability can be complex in natural ecosystems. In addition, the diversity of phytoplankton not only influenced its own temporal stability, but also affected the stability of zooplankton through trophic interactions.

Effect of temporal asynchrony on children’s detection performance in a random-frequency, multi-tonal masking task

This study examined the degree to which children can use temporal onset/offset asynchronies to improve performance in a random-frequency, multi-tonal masking task. Normal-hearing school-age children (5-10 years) and adults were tested in two experiments. In Experiment 1, masked thresholds were measured in a 3IFC adaptive procedure. A 1000-Hz pure-tone signal was presented with a random-frequency, 4-tone masker played at 60 dB SPL. Onset/offset asynchrony was manipulated across conditions by fixing the signal duration at 200 ms and examining performance for masker durations of 200, 280, and 400 ms. The signal, when present, was temporally centered in the masker, resulting in asynchronies of 0, 40 and 100 ms. In Experiment 2, asynchrony was manipulated by holding masker duration constant and varying signal duration to be 200, 320, or 400 ms. Preliminary results suggest that children can use temporal onset/offset asynchrony to segregate a fixed-frequency signal tone from a tonal masker. Potential development...

Where is the beat?

The ability to find the beat in a sequence of auditory events may be linked to the ability to learn vocal communication, raising the question of how beat structure in speech events relates to that in other event sequences. We conducted a series of entrainment experiments designed to compare spoken syllable repetition with tapping. Producing taps to a periodic string of auditorily-presented spoken /pa/ syllables resulted in the tap falling between the release burst for the /p/ and the onset of voicing for the vowel. This is consistent with participants intending to align their taps with the vowel onsets but exhibiting the well-documented Negative Mean Asynchrony (NMA) effect, such that the taps precede their “target.” The finding of alignment with the voicing onset is reminiscent of a large body of work on the P-center in repeated spoken syllables. In contrast, producing repeated utterances of the syllable /pa/ to an auditorily-presented click train resulted in coincident occurrence of the release burst with the click, putting the voicing onset after the stimulus (inconsistent with a voicing-onset target with associated NMA). These findings indicate that the location of the beat may differ across tasks involving speech perception and various types of speech production.

Phenological asynchrony between host plant and gypsy moth reduces insect gut microbiota and susceptibility to Bacillus thuringiensis.

The phenological synchrony between the emergence of overwintering herbivorous insects and the budding of host plants is considered a crucial factor in the population dynamics of herbivores. However, the mechanisms driving the interactions between the host plant, herbivores, and their pathogens are often obscure. In the current study, an artificially induced phenological asynchrony was used to investigate how the asynchrony between silver birch Betula pendula and gypsy moth Lymantria dispar affects the immunity of the insect to bacteria, its susceptibility to the entomopathogenic bacteria Bacillus thuringiensis, and the diversity in its midgut microbiota. The lysozyme‐like activity in both the midgut and hemolymph plasma and the nonspecific esterase activity and antimicrobial peptide gene expression in the midgut were studied in both noninfected and B. thuringiensis‐infected larvae. Our results provide the first evidence that phenologically asynchronous larvae are less susceptible to B. thuringiensis infection than phenologically synchronous larvae, and our results show that these effects are related to the high basic levels and B. thuringiensis‐induced levels of lysozyme‐like activities. Moreover, a 16S rRNA analysis revealed that dramatic decreases in the diversity of the larval gut bacterial consortia occurred under the effect of asynchrony. Larvae infected with B. thuringiensis presented decreased microbiota diversity if the larvae were reared synchronously with the host plant but not if they were reared asynchronously. Our study demonstrates the significant effect of phenological asynchrony on innate immunity‐mediated interactions between herbivores and entomopathogenic bacteria and highlights the role of nonpathogenic gut bacteria in these interactions.

Sustained wakefulness and visual attention: moderation by chronotype

IntroductionAttentional networks are sensitive to sleep deprivation and increased time awake. However, existing evidence is inconsistent and may be accounted for by differences in chronotype or time-of-day. We examined the effects of sustained wakefulness over a normal “socially constrained” day (following 18 h of sustained wakefulness), following a night of normal sleep, on visual attention as a function of chronotype.MethodsTwenty-six good sleepers (mean age 25.58; SD 4.26; 54 % male) completed the Attention Network Test (ANT) at two time points (baseline at 8 am; following 18-h sustained wakefulness at 2 am). The ANT provided mean reaction times (RTs), error rates, and the efficiency of three attentional networks—alerting, orienting, and executive control/conflict. The Morningness–Eveningness Questionnaire measured chronotype.ResultsMean RTs were longer at time 2 compared to time 1 for those with increasing eveningness; the opposite was true for morningness. However, those with increasing morningness exhibited longer RT and made more errors, on incongruent trials at time 2 relative to those with increasing eveningness. There were no significant main effects of time or chronotype (or interactions) on attentional network scores.ConclusionSustained wakefulness produced differential effects on visual attention as a function of chronotype. Whilst overall our results point to an asynchrony effect, this effect was moderated by flanker type. Participants with increasing eveningness outperformed those with increasing morningness on incongruent trials at time 2. The preservation of executive control in evening-types following sustained wakefulness is likely driven by differences in circadian phase between chronotypes across the day.

Monitoring patient-ventilator asynchrony.

This article describes and discusses the importance of monitoring patient-ventilator asynchrony, and the advantages and limitations of the specific techniques available at the bedside to evaluate it. Signals provided by esophageal catheters (pressure or electromyogram) are the most reliable and accurate instruments to detect asynchronies. Esophageal signals (providing electrical activity of the diaphragm or/and esophageal pressure) have allowed the recent description of reverse triggering, a new kind of asynchrony, in which mechanical insufflation repeatedly triggers diaphragmatic contractions. However, the use of esophageal catheters is not widespread, and data on the prevalence and consequences of asynchronies are still scarce. The development of software solutions that continuously and automatically record breathing waveforms from the ventilator recording is emerging. Using this technology, recent data support the fact that asynchronies are frequent and may be negatively associated with outcome. The prevalence and consequences of asynchronies may be largely underestimated because of a frequent lack of monitoring. Dedicated software solutions that continuously and automatically detect asynchronies may allow both clinical research and clinical applications aimed at determining the effects of asynchronies and minimizing their incidence among critically ill patients.

The Effects of Odor Quality and Temporal Asynchrony on Modulation of Taste Intensity by Retronasal Odor.

The experiments had 2 main goals: 1) to add to the sparse literature on how retronasal aromas interact with bitter tastes, and 2) to determine whether modulation of taste intensity by aroma depends on temporal contiguity, as one might expect if flavor interactions depend on cross-modal binding (similar to object perception in other modalities). An olfactometer-gustometer allowed independent oral presentation of odorized air and liquid samples. First, using simultaneous presentation of odors and tastes (Experiments 1a-d) we found that a "sweet-smelling" aroma enhanced the rated sweetness of sucrose and decreased the rated bitterness of sucrose octaacetate (SOA), and that a "bitter-smelling" aroma enhanced the bitterness of SOA and decreased the sweetness of sucrose. Thus, with respect to effects on taste intensity, sweet and bitter aromas mimicked mixture-interactions between sweet and bitter tastes under current conditions. Next (Experiment 2), both odors were again paired with both tastes, with a parametric manipulation of odor onset. Odor presentation ranged from before taste delivery to after taste delivery. Enhancement of taste intensity was greatest with simultaneous onset, and greatly attenuated with offsets of 1s. These results are consistent with the idea that enhancement of taste by retronasal aroma depends on a temporal binding window like many other cross-modal interactions. The effects of temporal offsets on suppression of taste were inconclusive. These findings are discussed within the context of past work on odor-taste interactions.

Assisted mechanical ventilation: the future is now!

Assisted ventilation is a highly complex process that requires an intimate interaction between the ventilator and the patient. The complexity of this form of ventilation is frequently underappreciated by the bedside clinician. In assisted mechanical ventilation, regardless of the specific mode, the ventilator’s gas delivery pattern and the patient’s breathing pattern must match near perfectly or asynchrony between the patient and the ventilator occurs. Asynchrony can be categorized into four general types: flow asynchrony; trigger asynchrony; cycle asynchrony; and mode asynchrony. In an article recently published in BMC Anesthesiology, Hodane et al. have demonstrated reduced asynchrony during assisted ventilation with Neurally Adjusted Ventilatory Assist (NAVA) as compared to pressure support ventilation (PSV). These findings add to the growing volume of data indicating that modes of ventilation that provide proportional assistance to ventilation – e.g., NAVA and Proportional Assist Ventilation (PAV) – markedly reduce asynchrony. As it becomes more accepted that the respiratory center of the patient in most circumstances is the most appropriate determinant of ventilatory pattern and as the negative outcome effects of patient-ventilator asynchrony become ever more recognized, we can expect NAVA and PAV to become the preferred modes of assisted ventilation!

Intrusion-Tolerant Broadcast and Agreement Abstractions in the Presence of Byzantine Processes

A process commits a Byzantine failure when its behavior does not comply with the algorithm it is assumed to execute. Considering asynchronous message-passing systems, this paper presents distributed abstractions, and associated algorithms, that allow non-faulty processes to correctly cooperate, despite the uncertainty created by the net effect of asynchrony and Byzantine failures. These abstractions are broadcast abstractions (namely, no-duplicity broadcast, reliable broadcast, and validated broadcast), and agreement abstraction (namely, consensus). While no-duplicity broadcast and reliable broadcast are well-known one-to-all communication abstractions, validated broadcast is a new all-to-all communication abstraction designed to address agreement problems. After having introduced these abstractions, the paper presents an algorithm implementing validated broadcast on top of reliable broadcast. Then the paper presents two consensus algorithms, which are reductions of multivalued consensus to binary consensus. The first one is a generic algorithm, that can be instantiated with unreliable broadcast or no-duplicity broadcast, while the second is a consensus algorithm based on validated broadcast. Finally, a third algorithm is presented that solves the binary consensus problem. This algorithm is a randomized algorithm based on validated broadcast and a common coin. The presentation of all the abstractions and their algorithms is done incrementally.

Asynchrony between Host Plant and Insects-Defoliator within a Tritrophic System: The Role of Herbivore Innate Immunity.

The effects of asynchrony in the phenology of spring-feeding insect-defoliators and their host plants on insects’ fitness, as well as the importance of this effect for the population dynamics of outbreaking species of insects, is a widespread and well-documented phenomenon. However, the spreading of this phenomenon through the food chain, and especially those mechanisms operating this spreading, are still unclear. In this paper, we study the effect of seasonally declined leafquality (estimated in terms of phenolics and nitrogen content) on herbivore fitness, immune parameters and resistance against pathogen by using the silver birch Betula pendula—gypsy moth Lymantria dispar—nucleopolyhedrovirus as the tritrophic system. We show that a phenological mismatch induced by the delay in the emergence of gypsy moth larvae and following feeding on mature leaves has negative effects on the female pupal weight, on the rate of larval development and on the activity of phenoloxidase in the plasma of haemolymph. In addition, the larval susceptibility to exogenous nucleopolyhydrovirus infection as well as covert virus activation were both enhanced due to the phenological mismatch. The observed effects of phenological mismatch on insect-baculovirus interaction may partially explain the strong and fast fluctuations in the population dynamics of the gypsy moth that is often observed in the studied part of the defoliator area. This study also reveals some indirect mechanisms of effect related to host plant quality, which operate through the insect innate immune status and affect resistance to both exogenous and endogenous virus.

The effects of cell asynchrony on gene expression levels: analysis and application to Plasmodium falciparum.

To investigate the intraerythrocytic developmental cycle of Plasmodium falciparum, time-series gene expression data is commonly measured of infected red blood cells. However, the observed data are usually blurred due to cell asynchrony during experiments. In this paper, the effect of cell asynchrony is investigated by conducting numerical experiments. The simulation results suggest that cell asynchrony has varying effects on different intrinsic expression patterns. Specifically, the intrinsic patterns with high expression around the late life stage are more likely to be affected by cell asynchrony. It is also investigated how the effect of cell asynchrony depends on the experimental conditions. From this analysis, the burst rate r% in infection period and the standard deviation σ of growth rate are identified to have a strong impact on the blurring due to cell asynchrony. Consequently, it is important to measure these two parameters during biological experiments in order to deblur time-series gene expression data.

Adults with dyslexia can use cues to orient and constrain attention but have a smaller and weaker attention spotlight

We report results from two experiments assessing distribution of attention and cue use in adults with dyslexia (AwD) and in a group of typically reading controls. Experiment 1 showed normal effects of cueing in AwD, with faster responses when probes were presented within a cued area and normal effects of eccentricity and stimulus onset asynchrony (SOA). In addition, AwD showed stronger benefits of a longer SOA when they had to move attention farther, and stronger effects of inclusion on the left, suggesting that cueing is particularly important in more difficult conditions. Experiment 2 tested the use of cues in a texture detection task involving a wider range of eccentricities and a shorter SOA. In this paradigm, focused attention at the central location is actually detrimental and cueing further reduces performance. Thus, if AwD have a more distributed attention, they should show a reduced performance drop at central locations and, if they do not use cues, they should show less negative effects of cueing. In contrast, AwD showed a larger drop and a positive effect of cueing. These results are better accounted for by a smaller and weaker spotlight of attention. Performance does not decrease at central locations because the attentional spotlight is already deployed with maximum intensity, which cannot be further enhanced at central locations. Instead, use of cueing helps to focus limited resources. Cues orient attention to the right area without enhancing it to the point where this is detrimental for texture detection. Implications for reading are discussed.

The effect of onset asynchrony in audio-visual speech and the Uncanny Valley in virtual characters

This study investigates if the Uncanny Valley phenomenon is increased for realistic, human-like characters with an asynchrony of lip movement during speech. An experiment was conducted in which 113 participants rated, a human and a realistic, talking-head, human-like, virtual character over a range of onset asynchronies for both perceived familiarity and human-likeness. The results show that virtual characters were regarded as more uncanny (less familiar and human-like) than humans and that increasing levels of asynchrony increased perception of uncanniness. Interestingly, participants were more sensitive to the uncanny in characters when the audio stream preceded the visual stream than with asynchronous footage where the video stream preceded the audio stream. This paper considers possible psychological explanations as to why the magnitude and direction of an asynchrony of speech dictates magnitude of perceived uncanniness and the implications of this in character design.

A possible mechanism for the attainment of out-of-phase periodic dynamics in two chaotic subpopulations coupled at low dispersal rate.

Much research in metapopulation dynamics has concentrated on identifying factors that affect coherence in spatially structured systems. In this regard, conditions for the attainment of out-of-phase dynamics have received considerable attention, due to the stabilizing effect of asynchrony on global dynamics. At low to moderate rates of dispersal, two coupled subpopulations with intrinsically chaotic dynamics tend to go out-of-phase with one another and also become periodic in their dynamics. The onset of out-of-phase dynamics and periodicity typically coincide. Here, we propose a possible mechanism for the onset of out-of-phase dynamics, and also the stabilization of chaos to periodicity, in two coupled subpopulations with intrinsically chaotic dynamics. We suggest that the onset of out-of-phase dynamics is due to the propensity of chaotic subpopulations governed by a steep, single-humped one-dimensional population growth model to repeatedly reach low subpopulation sizes that are close to a value Nt = A (A ≠ equilibrium population size, K) for which Nt( + 1) = K. Subpopulations with very similar low sizes, but on opposite sides of A, will become out-of-phase in the next generation, as they will end up at sizes on opposite sides of K, resulting in positive growth for one subpopulation and negative growth for the other. The key to the stabilization of out-of-phase periodic dynamics in this mechanism is the net effect of dispersal placing upper and lower bounds to subpopulation size in the two coupled subpopulations, once they have become out-of-phase. We tested various components of this proposed mechanism by simulations using the Ricker model, and the results of the simulations are consistent with predictions from the hypothesized mechanism. Similar results were also obtained using the logistic and Hassell models, and with the Ricker model incorporating the possibility of extinction, suggesting that the proposed mechanism could be key to the attainment and maintenance of out-of-phase periodicity in two-patch metapopulations where each patch has local dynamics governed by a single-humped population growth model.

112 EFFECT OF ASYNCHRONOUS EMBRYO TRANSFER ON GLUCOSE TRANSPORTER EXPRESSION IN EQUINE TROPHECTODERM

Equine pregnancy is characterised by an unusually long pre-implantation period (40 days) during which the conceptus is entirely dependent on uterine secretions for nutrient provision; although glucose is an important nutrient during development post-blastocyst formation, little is known about its transport into the early horse conceptus. Equine embryos are also known to tolerate an unusually large degree of uterine asynchrony following embryo transfer (ET). However, negative asynchrony (recipient behind the donor) of more than 5 days markedly retards conceptus growth and development, and thereby offers a unique tool for studying the effect of the uterine environment on early development. In a preliminary study, we detected abundant mRNA expression for the facilitative glucose transporters (SLC2As) 1–3, 5, 8 and 10 and sodium-glucose co-transporter (SLC5A)11 in Day 14 to 28 equine conceptus membranes. In the current study, we evaluated the effect of uterine asynchrony on trophectodermal glucose transporter expression. Day 8 horse embryos were transferred to recipient mares that ovulated on the same day (synchronous; n = 10) or 5 days after (asynchronous; n = 10) the donor mare. The conceptuses were collected 6 or 11 days after ET (Day 14 or 19 of embryo development: n = 5 per group). Trophectodermal mRNA expression for glucose transporters was evaluated by RT-qPCR, and the effects of asynchronous ET and stage of pregnancy were analysed by two-way ANOVA followed by independent-samples t-tests. Gene expression for SLC2A3 and 8 was stable over time and treatment. Expression of SLC2A1 and SLC5A11 decreased between Days 14 and 19 in synchronous pregnancies only (P < 0.05). SLC2A2 expression increased markedly on Day 19 in synchronous (P < 0.01) but not asynchronous pregnancies (P < 0.05). SLC2A5 expression was lower in the asynchronous group on Day 14, but increased beyond expression levels in synchronous pregnancies by Day 19 (P < 0.05). In summary, expression of SLC2A1 and 3, the major placental glucose transporters, was not affected by asynchronous ET. The marked up-regulation of SLC2A2 expression between Days 14 and 19 of synchronous but not asynchronous pregnancy suggests a stage-specific function, whereas the increase in SLC2A5 at Day 19 after asynchronous ET could be a compensatory response to growth retardation. This study was funded by EpiHealthNet (Project number 317146).

Asynchrony of seasons: genetic differentiation associated with geographic variation in climatic seasonality and reproductive phenology.

Many organisms exhibit distinct breeding seasons tracking food availability. If conspecific populations inhabit areas that experience different temporal cycles in food availability spurred by variation in precipitation regimes, then they should display asynchronous breeding seasons. Thus, such populations might exhibit a temporal barrier to gene flow, which may potentially promote genetic differentiation. We test a central prediction of this hypothesis, namely, that individuals living in areas with more asynchronous precipitation regimes should be more genetically differentiated than individuals living in areas with more similar precipitation regimes. Using mitochondrial DNA sequences, climatic data, and geographical/ecological distances between individuals of 57 New World bird species mostly from the tropics, we examined the effect of asynchronous precipitation (a proxy for asynchronous resource availability) on genetic differentiation. We found evidence for a positive and significant cross-species effect of precipitation asynchrony on genetic distance after accounting for geographical/ecological distances, suggesting that current climatic conditions may play a role in population differentiation. Spatial asynchrony in climate may thus drive evolutionary divergence in the absence of overt geographic barriers to gene flow; this mechanism contrasts with those invoked by most models of biotic diversification emphasizing physical or ecological changes to the landscape as drivers of divergence.

How topography induces reproductive asynchrony and alters gypsy moth invasion dynamics.

Reproductive asynchrony, a temporal mismatch in reproductive maturation between an individual and potential mates, may contribute to mate-finding failure and Allee effects that influence the establishment and spread of invasive species. Variation in elevation is likely to promote variability in maturation times for species with temperature-dependent development, but it is not known how strongly this influences reproductive asynchrony or the population growth of invasive species. We examined whether spatial variation in reproductive asynchrony, due to differences in elevation and local heterogeneity in elevation (hilliness), can explain spatial heterogeneity in the population growth rate of the gypsy moth, Lymantria dispar (L.), along its invasion front in Virginia and West Virginia, USA. We used a spatially explicit model of the effects of reproductive asynchrony on mating success to develop predictions of the influences of elevation and elevational heterogeneity on local population growth rates. Population growth rates declined with increased elevation and more modestly with increased elevational heterogeneity. As in earlier work, we found a positive relationship between the population growth rate and the number of introduced egg masses, indicating a demographic Allee effect. At high elevations and high heterogeneity in elevation, the population growth rate was lowest and the density at which the population tended to replace itself (i.e. the Allee threshold) was highest. An analysis of 22years of field data also showed decreases in population growth rates with elevation and heterogeneity in elevation that were largely consistent with the model predictions. These results highlight how topographic characteristics can affect reproductive asynchrony and influence mate-finding Allee effects in an invading non-native insect population. Given the dependence of developmental rates on temperature in poikilotherms, topographic effects on reproductive success could potentially be important to the population dynamics of many organisms.

The effects of cell asynchrony on time-series data: an analysis on gene expression level of Plasmodium falciparum.

To investigate the intraerythrocytic cycle of Plasmodium falciparum, time-series gene expression data are measured of infected red blood cells. However, the observed data is blurred due to cell asynchrony during experiments. In this paper, the effects of cell asynchrony are investigated by conducting numerical experiments. The simulation results suggest that cell asynchrony has varying effects on different intrinsic expression patterns. Specifically, the intrinsic patterns with high expression around the late life stage are more likely to be affected by cell asynchrony. It is also investigated how the effects of cell asynchrony are influenced by the experimental conditions. Certain parameters are identified that have a strong effects on cell asynchrony, and these parameters should be measured during biological experiments in order to deblur time-series gene expression data.

Effects of clipping and fertilizing on the relationships between species diversity and ecosystem functioning and mechanisms of community stability in alpine meadow

Aims Recent theoretical and empirical work suggests that species diversity enhances the primary productivity and stability of communities. However, the relationships between the diversity of different species types (i.e., total species, response species, effect species and common species), the special function of ecosystems, and the potential mechanism driving stability remain unclear. Our objective is to address the question by comparing the diversity effect of these different types on aboveground net primary productivity (ANPP) and community stability. Methods Our experiment was conducted in alpine meadow at the Haibei Research Station of the Chinese Academy of Sciences from 2007 to 2011. We used a split-plot design with clipping treatment in the whole plot using three clipping levels (stubbled 1 cm, 3 cm and unclipped). Subplots were treated with fertilizer (urea7.5 g·m–2 ·a–1 + ammonium phosphate 1.8 g·m–2 ·a–1 and unfertilized) and watering (20.1 kg·m–2 ·a-1 and unwatered). Important findings We observed that the diversity of different species types affected ecosystem functioning differently. ANPP was mainly affected by the diversity of response species and effect species, whereas community stability was largely affected by that of common species. The maintenance of stability depended on increasing diversity in common species, and the potential mechanism was the portfolio effect. Both the over-yielding effect and asynchrony effect, however, had no influence on stabilizing the community. Clipping had enormous effects on the diversity of total species, whereas the changes in diversity of response species mainly connected with resource availability. Thus, clipping and fertilization had reverse effects on species diversity, ANPP and stability, i.e., the former increased both species diversity and stability and decreased ANPP, while the latter had opposite effects on them. Our results suggest that ANPP is driven by the diversity of a few effect species because they have a great influence on ANPP, while stability is driven by the diversity of a large number of common species because they can coexist stably in the community. The portfolio effect is the main mechanism of the diversity-stability relationship. The diversity effect of different species differs among each other; therefore, in terms of specific ecosystem functioning, we infer that "functional identity" of species in community is more important than diversity per se and it may be incorrect if we did not discriminate when defining the relationship between species diversity and ecosystem function in any situation.

The effects of embryo-uterine asynchrony on early embryonic development

Equine pregnancy has an extraordinary ability to tolerate embryo-uterine asynchrony. Indeed, while ruminant embryos will not survive negative asynchrony (i.e. the recipient ovulated after the donor) of more than 2 days [Lawson RAS,et.al, J Reprod Fertil, 1975;45:101-7], horse embryos will continue to develop in the uterus of a recipient that ovulated up to 7 days later [Wilsher S,et.al, Reproduction 2010;139:575-85.]. However, negative asynchrony of more than 4 days appears to compromise embryo development and survival and may therefore be a useful model to study embryo-maternal communication. This study examined the effects of negative uterine asynchrony on the development of equine embryos over a period of either 6 or 11 days. Embryos were recovered on day 8 after ovulation and transferred non-surgically to synchronous (day 8; donor-recipient difference 1⁄4 0 days) or asynchronous (day 3; donor-recipient difference 1⁄4 -5 days) recipient mares. The resulting conceptuses were recovered either 6 days later by uterine lavage or 11 days later using a video-endoscopically-guided net (n 1⁄4 5 per group in all cases). Prior to recovery, vesicle size was determined ultrasonographically; following recovery the embryonic disc and, for conceptuses recovered on day 11 post-ET, the embryo proper were identified, measured and staged in terms of primitive steak formation and indices of embryo development such as crown-rump length and somite