Investment in attending to cues and the evolution of amplifiers.

Signals and cues are extensively used in social interactions across diverse communication systems. Here, we extend an existing theoretical framework to explore investment by emitters and perceivers in the fidelity with which cues and signals associated with the former are detected by the latter. Traits of the emitter that improve cue or signal fidelity without adding information are termed 'amplifiers'. We assume that each party can invest in improving fidelity but that it is increasingly costly the more fidelity is improved. Our model predicts that evolution of amplifier traits of a pre-existing cue occurs over a broader range of circumstances than evolution of signalling in situations where the emitter offered no pre-existing cue to the perceiver. It further predicts that the greater the intrinsic informational value of a cue, the more likely it is that the perceiver (and not the emitter) will invest in the fidelity of detecting that cue. A consequence of this predicted asymmetry is that true communication with reciprocal adaptations in emitters and perceivers to improve signal fidelity is likely to occur predominantly for traits of intermediate reliability. The corollary is that uncertainty of the perceiver will then be a key feature of communication. Uncertainty can arise because perceivers misinterpret signals or do not perceive them correctly, but here we argue that uncertainty is more fundamentally at the root of communication because traits that are intrinsically highly informative will induce only the perceiver and not the emitter to invest in improved fidelity of perception of that trait.

Evaluating the Impact of Performance Improvement Initiatives on Transplant Center Reporting Compliance and Patient Follow-Up After Living Kidney Donation.

With the changing demographics of the living donor population and increased regulatory oversight, it is important that transplant centers report outcomes accurately. The aim of our retrospective cohort study of 312 living donors who underwent nephrectomy between 2008 and 2013 was to evaluate the impact of living donor program performance improvement initiatives on: (i) transplant center program reporting compliance; (ii) patient compliance with postdonation follow-up and its associated factors; and (iii) overall financial costs to the transplant center. The effect of the initiatives (donation eras 2008-2010 and 2011-2013) on compliance at key reporting points (6 months, 1 year, 2 years) was analyzed using correlation coefficients, χ(2) and Fisher's exact tests. Multivariable logistic regression models tested the initiatives' effect on the likelihood of patient follow-up. The initiatives were associated with significant improvement in form reporting compliance (r ≥ 0.862, p ≤ 0.027; 1 and 2 year Fisher's Exact p ≤ 0.002) and patient follow-up (χ(2) p ≤ 0.009) with acceptable transplant center costs. Multivariable analyses demonstrated that donation era was consistently and significantly (p < 0.001) associated with increased likelihood of postdonation patient follow-up. Institution of performance improvement initiatives with dedicated program resources is financially feasible and leads to more accurate and complete form reporting and improved patient follow-up after nephrectomy.

Linking signal fidelity and the efficiency costs of communication.

The handicap principle has been the overarching framework to explain the evolution and maintenance of communication. Yet, it is becoming apparent that strategic costs of signalling are not the only mechanism maintaining signal honesty. Rather, the fidelity of detecting signals can itself be strongly selected. Specifically, we argue that the fidelity of many signals will be constrained by the investment in signal generation and reception by the signaller and perceiver, respectively. Here, we model how investments in signal fidelity influence the emergence and stability of communication using a simple theoretical framework. The predictions of the model indicate that high-cost communication can be stable whereas low-cost intermediates are generally selected against. This dichotomy suggests that the most parsimonious route to the evolution of communication is for initial investment in communicative traits to be driven by noncommunicative functions. Such cues can appeal to pre-existing perceptual biases and thereby stimulate signal evolution. We predict that signal evolution will vary between systems in ways that can be linked to the economics of communication to the two parties involved.

Reproductive success depends on the quality of helpers in the endangered, cooperative El Oro parakeet (Pyrrhura orcesi).

In cooperative species, helping behaviour and reproductive success can be correlated, but understanding this correlation is often impaired by the difficulty to correctly infer causation. While helpers can incur costs by participating in brood care, it is yet unclear if their help depends on their individual quality. We address these questions in the previously unknown cooperative breeding system of the endangered El Oro parakeet (Pyrrhura orcesi). Specifically, we ask (i) whether breeders benefit directly from helpers by an enhanced reproductive success and if so, (ii) whether the amount of this potential benefit is regulated by the quality of contributing group members. Groups consist of a dominant breeding pair accompanied by helpers, but cooperation is not obligate. Microsatellite heterozygosity was used to assess individual quality; its suitability as indicator of quality was reflected in the positive relationship between offspring heterozygosity and recruitment into the population. The reproductive success of breeding pairs depended on helper (genetic) quality and the number of helpers. This relationship occurred on two different levels: clutch size and fledging success, indicating (i) that females profit from high-quality helpers and probably adjust clutch size accordingly and (ii) that the helpers increase fledging success. Congruently, we found that offspring body condition is positively affected by helper quality, which is most probably explained by the increased feeding rates when helpers are present. We suggest a causal link between cooperation and reproductive success in this frugivorous, endangered parakeet. Further, helper (genetic) quality can be a relevant factor for determining reproductive fitness in cooperative species, particularly in small and bottlenecked populations.

Selection on quantitative colour variation in Centaurea cyanus: the role of the pollinator's visual system.

Even though the importance of selection for trait evolution is well established, we still lack a functional understanding of the mechanisms underlying phenotypic selection. Because animals necessarily use their sensory system to perceive phenotypic traits, the model of sensory bias assumes that sensory systems are the main determinant of signal evolution. Yet, it has remained poorly known how sensory systems contribute to shaping the fitness surface of selected individuals. In a greenhouse experiment, we quantified the strength and direction of selection on floral coloration in a population of cornflowers exposed to bumblebees as unique pollinators during 4 days. We detected significant selection on the chromatic and achromatic (brightness) components of floral coloration. We then studied whether these patterns of selection are explicable by accounting for the visual system of the pollinators. Using data on bumblebee colour vision, we first showed that bumblebees should discriminate among quantitative colour variants. The observed selection was then compared to the selection predicted by psychophysical models of bumblebee colour vision. The achromatic but not the chromatic channel of the bumblebee's visual system could explain the observed pattern of selection. These results highlight that (i) pollinators can select quantitative variation in floral coloration and could thus account for a gradual evolution of flower coloration, and (ii) stimulation of the visual system represents, at least partly, a functional mechanism potentially explaining pollinators' selection on floral colour variants.

Resolving current disagreements and ambiguities in the terminology of animal communication.

Communication is central to most interactions between organisms. There is currently considerable controversy about the evolution, function and even about the most basic definition of communication. The controversy is linked to definitional ambiguities and disagreements. Here we discuss how some recent disagreements can be resolved and offer a clear set of definitions. Central to our approach is a definition of communication as being a trade between one organism (the informer) and another (the perceiver). The informer exerts influence on the perceiver through the communication process, and the perceiver experiences a change in its informational state (that is, gains information) as a consequence of detecting the communication. We define both influence and information explicitly and delineate between signalling, deceptive communication, and situations where perceivers respond to cues rather than signals. We demonstrate how our definitions allow resolution of conflicts arising in recent publications on the definitions on communication and related terms.

Colour, design and reward: phenotypic integration of fleshy fruit displays.

The functional or structural linkage among traits [phenotypic integration (PI)] within complex structures can constrain the evolutionary response of individual traits. To analyse whether frugivores with distinct sensory ecology have shaped the patterns of fruit diversification differently, we compared PI values of fleshy fruits that are consumed by birds and mammals. We used phylogenetic comparative analyses of PI among 13 morphological, nutritional and visual fruit traits from 111 Mediterranean plant species. Results showed that morphological traits had higher PI values than nutritional and colour traits. Visual and nutritional traits show positive phylogenetic covariance, while negative covariation occurs between fruits size and nutrients. Importantly, fruits consumed by birds were relatively more integrated than fruits consumed partly or solely by mammals. Hence, we show that major groups of mutualistic frugivores can shape the covariance among some fruit traits differently and thereby influence fruit diversification.

Prevalence, diversity, and interaction patterns of avian haemosporidians in a four-year study of blackcaps in a migratory divide.

Migratory birds contribute to the movement of avian parasites between distant locations, thereby influencing parasite distribution and ecology. Here we analyse the prevalence, diversity and interaction patterns of Haemosporida parasites infecting Blackcap (Sylvia atricapilla) populations in a recently established migratory divide of southwestern Germany across 4 years. We hypothesize that the temporal and spatial isolation provided by 2 sympatric Blackcap breeding populations (migratory divide) might modify ecological interactions and thus create differences in the structure of the parasite community according to migratory route. We used a fragment of the mitochondrial DNA cytochrome b gene to determine haemosporidian haplotypes. We detected an overall infection prevalence of 70.3% (348 out of 495 blackcaps sampled from 2006 to 2009), and prevalence rates were significantly different among years and seasons. We observed a total of 27 parasite haplotypes infecting blackcaps, from them 6 new rare Haemoproteus haplotypes were found in 2 mixed infections. H. parabelopolskyi haplotypes SYAT01 (35.7%) and SYAT02 (20.8%) comprised most of the infections. An association analysis suggests that SYAT01 and SYAT02 are interacting negatively, implying that they are either competing directly for host resources, or indirectly by eliciting a cross-immune response. Molecular data show no clear difference between the parasite communities infecting blackcaps with different migratory routes, despite some temporal and spatial isolation between the two sympatric blackcap populations.

Signal convergence in fruits: a result of selection by frugivores?

The Dispersal Syndrome hypothesis remains contentious, stating that apparently nonrandom associations of fruit characteristics result from selection by seed dispersers. We examine a key assumption under this hypothesis, i.e. that fruit traits can be used as reliable signals by frugivores. We first test this assumption by looking at whether fruit colour allows birds and primates to distinguish between fruits commonly dispersed by birds or primates. Second, we test whether the colours of fruits dispersed by primates are more contrasting to primates than the colours of bird-dispersed fruits, expected if fruit colour is an adaptation to facilitate the detection by seed dispersers. Third, we test whether fruit colour has converged in unrelated plant species dispersed by similar frugivores. We use vision models based on peak sensitivities of birds' and primates' cone cells. We base our analyses on the visual systems of two types of birds (violet and ultraviolet based) and three types of primates (trichromatic primates from the Old and the New Worlds, and a dichromatic New World monkey). Using a Discriminant Function Analysis, we find that all frugivore groups can reliably discriminate between bird- and primate-dispersed fruits. Fruit colour can be a reliable signal to different seed dispersers. However, the colours of primate-dispersed fruits are less contrasting to primates than those of bird-dispersed fruits. Fruit colour convergence in unrelated plants is independent of phylogeny and can be better explained by disperser type, which supports the hypothesis that frugivores are important in fruit evolution. We discuss adaptive and nonadaptive hypotheses that can potentially explain the pattern we found.

Dietary flavonoids enhance conspicuousness of a melanin-based trait in male blackcaps but not of the female homologous trait or of sexually monochromatic traits.

Signalling theory predicts that signals should fulfil three fundamental requirements: high detectability, discriminability and, most importantly, reliability. Melanins are the most common pigments in animals. Correlations between genotypic and phenotypic qualities of the sender and size and morph of melanin-based traits are known, but it is contentious whether melanin-based colouration may signal any quality. We examined the effect of supplementing blackcaps (Sylvia atricapilla) with flavonoids, potent plant antioxidants, on plumage colouration. We demonstrate that melanin-based colour can fulfil all requirements of signals of phenotypic condition. As predicted by sexual selection theory, flavonoid supplementation influenced only the sexually dichromatic black cap of males, whereas the female homologous trait and the sexually monochromatic back colouration remained unaffected. Using avian vision models we show that birds can estimate male flavonoid intake from colouration of males' black cap. Because flavonoid ingestion can increase immune responsiveness in blackcaps, melanin head colouration may signal environmentally determined immune condition.

A2 to B Blood Type Incompatible Deceased Donor Kidney Transplantation in a Recipient Infected with the Human Immunodeficiency Virus: A Case Report.

BACKGROUND: With the introduction of the Kidney Allocation System in the United States in December 2014, transplant centers can list eligible B blood type recipients for A2 organ offers. There have been no prior reports of ABO incompatible A2 to B deceased donor kidney transplantation in human immunodeficiency virus-positive (HIV+) recipients to guide clinicians on enrolling or performing A2 to B transplantations in HIV+ candidates. We are the first to report a case of A2 to B deceased donor kidney transplantation in an HIV+ recipient with good intermediate-term results. METHODS AND RESULTS: We describe an HIV+ 39-year-old African American man with end-stage renal disease who underwent A2 to B blood type incompatible deceased donor kidney transplantation. Prior to transplantation, he had an undetectable HIV viral load. The patient was unsensitized, with his most recent anti-A titer data being 1:2 IgG and 1:32 IgG/IgM. Induction therapy of basiliximab and methylprednisolone was followed by a postoperative regimen of plasma exchange, intravenous immunoglobulin, and rituximab with maintenance on tacrolimus, mycophenolate mofetil, and prednisone. He had delayed graft function without rejection on allograft biopsy. Nadir serum creatinine was 2.0 mg/dL. He continued to have an undetectable viral load on the same antiretroviral therapy adjusted for renal function. CONCLUSIONS: To our knowledge, this is the first report of A2 to B deceased donor kidney transplantation in an HIV+ recipient with good intermediate-term results, suggesting that A2 donor kidneys may be considered for transplantation into HIV+ B-blood type wait list candidates.

Calcineurin inhibitor avoidance versus steroid avoidance following kidney transplantation: Postoperative complications.

This study compared early postoperative complications in kidney transplant recipients treated with either a sirolimus-based calcineurin inhibitor (CNI)-free regimen or a tacrolimus-based steroid-free regimen. We used a single-center, prospective, sequential but nonrandomized study design. Consecutive recipients of primary cadaveric or non-HLA identical kidney transplant recipients received either a CNI-free regimen, consisting of sirolimus 5 mg daily beginning postoperative day 3, mycophenolate mofetil 1 gm twice a day, and methylprednisolone 500 mg intraoperatively, then prednisone 30 mg daily tapered to 10 mg daily at 3 months, or a prednisone-free regimen, consisting of methylprednisolone 500 mg, 250 mg, and 125 mg from days 0 to 2, then no further steroids, tacrolimus 0.075 mg/kg twice a day, and mycophenolate mofetil 1 g twice a day. All patients received thymoglobulin induction 6 mg/kg total dose. Outcome measures were patient and graft survival, BPAR, surgical and wound complications, viral infections and posttransplant diabetes mellitus (PTDM). Both groups had excellent early outcomes with no significant difference in patient or graft survival, early renal function, BPAR, surgical or wound complications, or viral infections between the two groups. Patients in the sirolimus-based CNI-free group had a significantly higher incidence of PTDM and a trend toward more discontinuation due to drug toxicity. Whether either regimen improves long-term outcomes awaits longer follow-up.

Short-term results under three different immunosuppressive regimens at one center.

We examined short-term outcomes and posttransplant medical complications under three different immunosuppressive regimens at a single center. The study design was a randomized, prospective, open-label trial comparing a calcineurin inhibitor-free (CNI) protocol to standard triple therapy with tacrolimus, prednisone, and mycophenolate mofetil. They were also compared to a concurrent but nonrandomized third cohort treated with a prednisone-free protocol. All three groups had excellent early outcomes with no significant difference in patient or graft survival or biopsy-proven acute rejection. Serum creatinine was significantly lower in the CNI-free recipients. Lipid panels and posttransplant diabetes mellitus were significantly lower in the prednisone-free patients. Prednisone-free kidney transplant recipients have improved early glucose metabolism and hyperlipidemia compared to CNI-free or standard triple therapy recipients with comparable rejection and graft survival rates.