Concordancia entre las ecuaciones de estimación del filtrado glomerular y el aclaramiento de creatinina en orina de 4horas en pacientes críticos con trauma grave / Concordance between glomerular filtration rate estimation equations and 4-hour urinary creatinine clearance in critically ill patients with severe trauma

Antecedentes y objetivo: Cada vez hay más estudios que evidencian que las ecuaciones utilizadas para conocer la tasa de filtrado glomerular estimada (TFGe) no son adecuadas para los pacientes críticos en los que se producen continuas variaciones del filtrado glomerular (FG). El método más práctico para aproximarse al estudio del FG es el cálculo del aclaramiento de creatinina (ClCr) en periodos de recogida de orina variables. El objetivo del estudio fue observar el comportamiento de las ecuaciones empleadas para estimar el filtrado glomerular cuando se aplican a la subpoblación de pacientes críticos ingresados por trauma grave y comparar el ClCr en orina recogida en un periodo de 4horas (ClCr-4h). Material y métodos: Estudio observacional que incluye pacientes ingresados por trauma grave. Se calculó el ClCr-4h y se determinó la TFGe mediante las ecuaciones de Cockcroft-Gault, Jelliffe modificada, MDRD, t-MDRD y CKD-EPI. Los resultados se expresan referidos a superficie corporal (ml/min/1,73m2). Los análisis se realizaron con el software estadístico R versión 4.0.4. Resultados: Se incluyeron 85 pacientes. La edad mediana de los pacientes fue de 51años; 68 pacientes fueron varones (78,82%). El ClCr-4h ajustado a superficie corporal (ClCr-4h ml/min/1,73m2) medio fue de 84,5ml/min/1,73m2. Hallamos correlación estadísticamente significativa de ClCr-4h/1,73m2 con la TFGe por t-MDRD. Para ClCr-4h/1,73m2 mayores de 130ml/min/m2 la ecuación de Cockcroft-Gault identifica a los pacientes correctamente de una forma estadísticamente significativa. Conclusiones: El cálculo de ClCr en el entorno de UCI proporciona datos fiables del FG, no siendo adecuado el uso de ecuaciones estimativas.(AU)

Background and objective: There is a growing body of evidence that the equations used to estimate the glomerular filtration rate (GFR) are not suitable in critically ill patients, a population whose GFR fluctuates continuously. Glomerular filtration is usually estimated by measuring urine creatinine clearance (CrCl) at various time points. The aim of our study was to evaluate the performance of the most widely used GFR calculators in the subpopulation of critically ill patients admitted for severe trauma, and to compare the results against determinations of CrCl in urine collected over a 4-hour period (4h-CrCl). Material and methods: Observational study in patients hospitalized for severe trauma. We measured the 4h-CrCl and estimated GFR using the Cockcroft-Gault, modified Jelliffe, MDRD, t-MDRD, and CKD-EPI equations, adjusting the results for body surface area (BSA) (ml/min/1.73m2). Data were analysed using R version 4.0.4. Results: A total of 85 patients were included. Median age was 51years, and 68 were men (78.82%). The mean BSA-adjusted 4h-CrCl (4h-ClCr/1.73m2) was 84.5ml/min/1.73m2. We found that GFR estimated using the t-MDRD equation correlated significantly with 4h-CrCl/1.73m2. The Cockcroft-Gault equation correlated significantly with 4h-CrCl/1.73m2 when GFR was greater than 130ml/min/m2. Conclusions: In ICU patients, glomerular filtration can be reliably estimated by determining urine CrCl, but GFR calculators are not accurate in this population.(AU)

Concordance between glomerular filtration rate estimation equations and 4-hour urinary creatinine clearance in critically ill patients with severe trauma.

BACKGROUND AND OBJECTIVE: There is a growing body of evidence that the equations used to estimate the glomerular filtration rate (GFR) are not suitable in critically ill patients, a population whose GFR fluctuates continuously. Glomerular filtration is usually estimated by measuring urine creatinine clearance (CrCl) at various time points. The aim of our study was to evaluate the performance of the most widely used GFR calculators in the subpopulation of critically ill patients admitted for severe trauma, and to compare the results against determinations of CrCl in urine collected over a 4-h period (4h-CrCl). MATERIAL AND METHODS: Observational study in patients hospitalized for severe trauma. We measured the 4h-CrCl and estimated GFR using the Cockcroft-Gault, modified Jelliffe, MDRD, t-MDRD, and CKD-EPI equations, adjusting the results for body surface area (BSA) (ml/min/1.73m2). Data were analysed using R version 4.0.4. RESULTS: A total of 85 patients were included. Median age was 51 years, and 68 were men (78.82%). The mean BSA-adjusted 4h-CrCl (4h-ClCr/1.73m2) was 84.5 ml/min/1.73m2. We found that GFR estimated using the t-MDRD equation correlated significantly with 4h-CrCl/1.73m2. The Cockcroft-Gault equation correlated significantly with 4h-CrCl/1.73m2 when GFR was greater than 130ml/min/m2. CONCLUSIONS: In ICU patients, glomerular filtration can be reliably estimated by determining urine CrCl, but GFR calculators are not accurate in this population.

Posterior reversible encephalopathy syndrome in critical COVID-19 patients: Report of 2 cases.

Posterior reversible encephalopathy syndrome is an acute neurological disorder characterized by variable symptoms and radiological images characteristic of vasogenic parietal-occipital edema. It is associated with clinical conditions such as high blood pressure, infection/sepsis, or cytotoxic/immunosuppressive drugs, among others. It is characterized pathophysiologically by endothelial damage with breakdown of blood-brain barrier, cerebral hypoperfusion, and vasogenic edema. The cases are presented on 2 critical COVID-19 patients who were admitted to pneumonia requiring mechanical ventilation and who, after removing sedation, developed acute and reversible neurological symptoms consisting of epilepsy and encephalopathy, associated with hyperintense subcortical lesions on brain magnetic resonance imaging compatible with posterior reversible encephalopathy syndrome. SARS-CoV-2 coronavirus would activate an inflammatory response that would damage brain endothelium. It could be triggered by cytokine release, as well as by direct viral injury, given that endothelium expresses ACE2 receptors. It could explain the possible association between posterior reversible encephalopathy syndrome and COVID-19.

Síndrome de encefalopatía posterior reversible en pacientes críticos COVID-19: reporte de 2 casos / Posterior reversible encephalopathy syndrome in critical COVID-19 patients: Report of 2 cases

El síndrome de encefalopatía posterior reversible es un trastorno neurológico agudo caracterizado por una sintomatología variable e imágenes radiológicas características de edema vasogénico parietooccipital. Está asociado a condiciones clínicas como hipertensión arterial, infección/sepsis o fármacos citotóxicos/inmunosupresores, entre otros. Se caracteriza fisiopatológicamente por daño endotelial con rotura de la barrera hematoencefálica, hipoperfusión cerebral y edema vasogénico. Presentamos 2 casos de pacientes críticos COVID-19 que ingresaron por neumonía con necesidad de ventilación mecánica y que tras retirar la sedación desarrollaron clínica neurológica aguda y reversible consistente en epilepsia y encefalopatía, asociada a lesiones subcorticales hiperintensas en la resonancia magnética cerebral compatibles con síndrome de encefalopatía posterior reversible. El coronavirus SARS-CoV-2 activaría una respuesta inflamatoria que produciría daño en el endotelio cerebral. Este último podría ser desencadenado por la liberación de citocinas, así como por una lesión viral directa, dado que el endotelio expresa receptores ACE2. Esto podría explicar la posible asociación entre el síndrome de encefalopatía posterior reversible y la COVID-19.(AU)

Posterior reversible encephalopathy syndrome is an acute neurological disorder characterized by variable symptoms and radiological images characteristic of vasogenic parietal-occipital edema. It is associated with clinical conditions such as high blood pressure, infection/sepsis, or cytotoxic/immunosuppressive drugs, among others. It is characterized pathophysiologically by endothelial damage with breakdown of blood-brain barrier, cerebral hypoperfusion, and vasogenic edema. The cases are presented on 2 critical COVID-19 patients who were admitted to pneumonia requiring mechanical ventilation and who, after removing sedation, developed acute and reversible neurological symptoms consisting of epilepsy and encephalopathy, associated with hyperintense subcortical lesions on brain magnetic resonance imaging compatible with posterior reversible encephalopathy syndrome. SARS-CoV-2 coronavirus would activate an inflammatory response that would damage brain endothelium. It could be triggered by cytokine release, as well as by direct viral injury, given that endothelium expresses ACE2 receptors. It could explain the possible association between posterior reversible encephalopathy syndrome and COVID-19.(AU)

[Posterior reversible encephalopathy syndrome in critical COVID-19 patients: Report of 2 cases]. / Síndrome de encefalopatía posterior reversible en pacientes críticos COVID-19: reporte de 2 casos.

Posterior reversible encephalopathy syndrome is an acute neurological disorder characterized by variable symptoms and radiological images characteristic of vasogenic parietal-occipital edema. It is associated with clinical conditions such as high blood pressure, infection/sepsis, or cytotoxic/immunosuppressive drugs, among others. It is characterized pathophysiologically by endothelial damage with breakdown of blood-brain barrier, cerebral hypoperfusion, and vasogenic edema.The cases are presented on 2 critical COVID-19 patients who were admitted to pneumonia requiring mechanical ventilation and who, after removing sedation, developed acute and reversible neurological symptoms consisting of epilepsy and encephalopathy, associated with hyperintense subcortical lesions on brain magnetic resonance imaging compatible with posterior reversible encephalopathy syndrome.SARS-CoV-2 coronavirus would activate an inflammatory response that would damage brain endothelium. It could be triggered by cytokine release, as well as by direct viral injury, given that endothelium expresses ACE2 receptors. It could explain the possible association between posterior reversible encephalopathy syndrome and COVID-19.

Ectoparasite Activity During Incubation Increases Microbial Growth on Avian Eggs.

While direct detrimental effects of parasites on hosts are relatively well documented, other more subtle but potentially important effects of parasitism are yet unexplored. Biological activity of ectoparasites, apart from skin injuries and blood-feeding, often results in blood remains, or parasite faeces that accumulate and modify the host environment. In this way, ectoparasite activities and remains may increase nutrient availability that may favour colonization and growth of microorganisms including potential pathogens. Here, by the experimental addition of hematophagous flies (Carnus hemapterus, a common ectoparasite of birds) to nests of spotless starlings Sturnus unicolor during incubation, we explore this possible side effect of parasitism which has rarely, if ever, been investigated. Results show that faeces and blood remains from parasitic flies on spotless starling eggshells at the end of incubation were more abundant in experimental than in control nests. Moreover, eggshell bacterial loads of different groups of cultivable bacteria including potential pathogens, as well as species richness of bacteria in terms of Operational Taxonomic Units (OTUs), were also higher in experimental nests. Finally, we also found evidence of a link between eggshell bacterial loads and increased embryo mortality, which provides indirect support for a bacterial-mediated negative effect of ectoparasitism on host offspring. Trans-shell bacterial infection might be one of the main causes of embryo death and, consequently, this hitherto unnoticed indirect effect of ectoparasitism might be widespread in nature and could affect our understanding of ecology and evolution of host-parasite interactions.

Life history, immunity, Peto's paradox and tumours in birds.

Cancer and tumours may evolve in response to life-history trade-offs between growth and duration of development on one hand, and between growth and maintenance of immune function on the other. Here, we tested whether (i) bird species with slow developmental rates for their body size experience low incidence of tumours because slow development allows for detection of rapid proliferation of cell lineages. We also test whether (ii) species with stronger immune response during development are more efficient at detecting tumour cells and hence suffer lower incidence of tumours. Finally, we tested Peto's paradox, that there is a positive relationship between tumour incidence and body mass. We used information on developmental rates and body mass from the literature and of tumour incidence (8468 birds) and size of the bursa of Fabricius for 7659 birds brought to a taxidermist in Denmark. We found evidence of the expected negative relationship between incidence of tumours and developmental rates and immunity after controlling for the positive association between tumour incidence and body size. These results suggest that evolution has modified the incidence of tumours in response to life history and that Peto's paradox may be explained by covariation between body mass, developmental rates and immunity.

Telomere dynamics in parasitic great spotted cuckoos and their magpie hosts.

Although little is known on the impact of environment on telomere length dynamics, it has been suggested to be affected by stress, lifestyle and/or life-history strategies of animals. We here compared telomere dynamics in erythrocytes of hatchlings and fledglings of the brood parasite great spotted cuckoos (Clamator glandarius) and of magpies (Pica pica), their main host in Europe. In magpie chicks, telomere length decreased from hatching to fledging, whereas no significant change in telomere length of great spotted cuckoo chicks was found. Moreover, we found interspecific differences in the association between laying date and telomere shortening. Interspecific differences in telomere shortening were interpreted as a consequence of differences in lifestyle and life-history characteristics of magpies and great spotted cuckoos. In comparison with magpies, cuckoos experience reduced sibling competition and higher access to resources and, consequently, lower stressful environmental conditions during the nestling phase. These characteristics also explain the associations between telomere attrition and environmental conditions (i.e. laying date) for magpies and the absence of association for great spotted cuckoos. These results therefore fit expectations on telomere dynamics derived from interspecific differences in lifestyle and life history of brood parasites and their bird hosts.

Recognizing odd smells and ejection of brood parasitic eggs. An experimental test in magpies of a novel defensive trait against brood parasitism.

One of the most important defensive host traits against brood parasitism is the detection and ejection of parasitic eggs from their nests. Here, we explore the possible role of olfaction in this defensive behaviour. We performed egg-recognition tests in magpie Pica pica nests with model eggs resembling those of parasitic great spotted cuckoos Clamator glandarius. In one of the experiment, experimental model eggs were exposed to strong or moderate smell of tobacco smoke, whereas those of a third group (control) were cleaned with disinfecting wipes and kept in boxes containing odourless cotton. Results showed that model eggs with strong tobacco scent were more frequently ejected compared with control ones. In another experiment, models were smeared with scents from cloacal wash from magpies (control), cloacal wash or uropygial secretions from cuckoos, or human scents. This experiment resulted in a statistically significant effect of treatment in unparasitized magpie nests in which control model eggs handled by humans were more often rejected. These results provide the first evidence that hosts of brood parasites use their olfactory ability to detect and eject foreign eggs from their nests. These findings may have important consequences for handling procedures of experimental eggs used in egg-recognition tests, in addition to our understanding of interactions between brood parasites and their hosts.

Host-parasite relationship between colonial terns and bacteria is modified by a mutualism with a plant with antibacterial defenses.

Predator-prey and host-parasite interactions and mutualisms are common and may have profound effects on ecosystems. Here we analyze the parasitic and mutualistic associations between three groups of organisms: the plant Artemisia maritima, bacteria, and a colonial seabird (the sandwich tern Sterna sandvicensis) that breeds in dense colonies covered in feces produced by both adults and chicks. A disproportionately large fraction of colonies of the sandwich tern in Denmark were located in patches covered by A. maritima. This association was specific for the densely colonial sandwich tern, but was not present for four other sympatric species of terns that breed in much less dense colonies. A. maritima reduced the abundance of pathogenic Staphylococcus on chicken eggshells in a field experiment. Recruitment by sandwich terns breeding in patches of A. maritima was 18 % higher than for sandwich terns breeding in the absence of A. maritima. A. maritima benefitted from the association with sandwich terns due to the supply of nutrients from feces and uneaten food lost by young. These findings are consistent with sandwich terns exploiting the association with A. maritima and its antimicrobial properties to improve their reproductive success, while sandwich terns and A. maritima are involved in a mutualistic interaction.

The evolution of size of the uropygial gland: mutualistic feather mites and uropygial secretion reduce bacterial loads of eggshells and hatching failures of European birds.

Potentially, pathogenic bacteria are one of the main infective agents against which a battery of chemical and physical barriers has evolved in animals. Among these are the secretions by the exocrine uropygial gland in birds. The antimicrobial properties of uropygial secretions may prevent colonization and growth of microorganisms on feathers, skin and eggshells. However, uropygial gland secretions also favour the proliferation of feather mites that feed on secretions and microorganisms living on feathers that would otherwise reach eggshells during incubation if not consumed by feather mites. Therefore, at the interspecific level, uropygial gland size (as an index of volume of uropygial secretion) should be positively related to eggshell bacterial load (i.e. the risk of egg infection), whereas eggshell bacterial loads may be negatively related to abundance of feather mites eating bacteria. Here, we explore these previously untested predictions in a comparative framework using information on eggshell bacterial loads, uropygial gland size, diversity and abundance of feather mites and hatching success of 22 species of birds. The size of the uropygial gland was positively related to eggshell bacterial loads (mesophilic bacteria and Enterobacteriaceae), and bird species with higher diversity and abundance of feather mites harboured lower bacterial density on their eggshells (Enterococcus and Staphylococcus), in accordance with the hypothesis. Importantly, eggshell bacterial loads of mesophilic bacteria, Enterococcus and Enterobacteriaceae were negatively associated with hatching success, allowing us to interpret these interspecific relationships in a functional scenario, where both uropygial glands and mutualistic feather mites independently reduce the negative effects of pathogenic bacteria on avian fitness.

Evolution of sexual dichromatism in relation to nesting habits in European passerines: a test of Wallace's hypothesis.

Wallace proposed in 1868 that natural rather than sexual selection could explain the striking differences in avian plumage dichromatism. Thus, he predicted that nesting habits, through their association with nest predation, could drive changes in sexual dichromatism by enabling females in cavity nesters to become as conspicuous as males, whereas Darwin (1871, The Descent of Man and Selection in Relation to Sex, John Murray, London) argued that sexual selection was the sole explanation for dichromatism. Sexual dichromatism is currently used as indicating the strength of sexual selection, and therefore testing Wallace's claim with modern phylogentically controlled methodologies is of prime interest for comparing the roles of natural and sexual selection in affecting the evolution of avian coloration. Here, we have related information on nest attendance, sexual dichromatism and nesting habits (open and cavity nesting) to male and female plumage conspicuousness in European passerines. Nest incubation attendance does not explain male or female plumage conspicuousness but nest type does. Moreover, although females of monochromatic and cavity nesting species are more conspicuous than females of other species, males of monochromatic and open nesting species are those with more cryptic plumage. Finally, analyses of character evolution suggest that changes in nesting habits influence the probability of changes in both dichromatism and plumage conspicuousness of males but do not significantly affect those in females. These results strongly suggest a role of nesting habits in the evolution of plumage conspicuousness of males, and a role for sexual selection also in females, both factors affecting the evolution of sexual dichromatism. We discuss our findings in relation to the debate that Darwin and Wallace maintained more than one century ago on the importance of natural and sexual selection in driving the evolution of plumage conspicuousness and sexual dichromatism in birds, and conclude that our results partly support the evolutionary scenarios envisaged by both extraordinary scientists.

Goshawk prey have more bacteria than non-prey.

1. Predators often prey on individuals that are sick or otherwise weakened. Although previous studies have shown higher abundance of parasites in prey, whether prey have elevated loads of micro-organisms remains to be determined. 2. We quantified the abundance of bacteria and fungi on feathers of woodpigeons Columba palumbus L., jays Garrulus glandarius L. and blackbirds Turdus merula L. that either fell prey to goshawks Accipiter gentilis L. or were not depredated. 3. We found an almost three-fold increase in bacterial load of prey compared with non-prey, while there was no significant difference between prey and non-prey in level of fungal infection of the plumage. 4. The results were not confounded by differences in size or mass of feathers, date of collection of feathers, or date of analysis of feathers for micro-organisms. 5. These findings suggest a previously unknown contribution of bacteria to risk of predation, with important implications for behaviour, population ecology and community ecology.

Migratory divides and their consequences for dispersal, population size and parasite-host interactions.

Populations of migratory birds differ in their direction of migration with neighbouring populations often migrating in divergent directions separated by migratory divides. A total of 26% of 103 passerine bird species in Europe had migratory divides that were located disproportionately often along a longitudinal gradient in Central Europe, consistent with the assumption of a Quaternary glacial origin of such divides in the Iberian and Balkan peninsulas followed by recolonization. Given that studies have shown significant genetic differentiation and reduced gene flow across migratory divides, we hypothesized that an absence of migratory divides would result in elevated rates of gene flow and hence a reduced level of local adaptation. In a comparative study, species with migratory divides had larger population sizes and population densities and longer dispersal distances than species without migratory divides. Species with migratory divides tended to be habitat generalists. Bird species with migratory divides had higher richness of blood parasites and higher growth rates of Staphylococcus on their eggs during the incubation period. There was weaker cell-mediated immunity in adults and stronger cell lysis in species with migratory divides. These findings may suggest that migratory divides constitute barriers to dispersal with consequences for ecology and evolution of distributions, population sizes, habitats and parasite-host interactions. They also suggest that migratory divides may play a role in local adaptation in host-parasite interactions.

Evolution of tolerance by magpies to brood parasitism by great spotted cuckoos.

Hosts may use two different strategies to ameliorate negative effects of a given parasite burden: resistance or tolerance. Although both resistance and tolerance of parasitism should evolve as a consequence of selection pressures owing to parasitism, the study of evolutionary patterns of tolerance has traditionally been neglected by animal biologists. Here, we explore geographical covariation between tolerance of magpies (Pica pica) and brood parasitism by the great spotted cuckoo (Clamator glandarius) in nine different sympatric populations. We estimated tolerance as the slope of the regression of number of magpie fledglings (i.e. host fitness) on number of cuckoo eggs laid in non-depredated nests (which broadly equals parasite burden). We also estimated prevalence of parasitism and level of host resistance (i.e. rejection rates of mimetic model eggs) in these nine populations. In accordance with the hypothetical role of tolerance in the coevolutionary process between magpies and cuckoos we found geographical variation in tolerance estimates that positively covaried with prevalence of parasitism. Levels of resistance and tolerance were not associated, possibly suggesting the lack of a trade-off between the two kinds of defences against great spotted cuckoo parasitism for magpies. We discuss the results in the framework of a mosaic of coevolutionary interactions along the geographical distribution of magpies and great spotted cuckoos for which we found evidence that tolerance plays a major role.

Spatial heterogeneity in distribution and ecology of Western Palearctic birds.

Species vary in abundance and heterogeneity of spatial distribution, and the ecological and evolutionary consequences of such variability are poorly known. Evolutionary adaptation to heterogeneously distributed resources may arise from local adaptation with individuals of such locally adapted populations rarely dispersing long distances and hence having small populations and small overall ranges. We quantified mean population density and spatial heterogeneity in population density of 197 bird species across 12 similarly sized regions in the Western Palearctic. Variance in population density among regions differed significantly from a Poisson distribution, suggesting that random processes cannot explain the observed patterns. National estimates of means and variances in population density were positively correlated with continental estimates, suggesting that means and variances were maintained across spatial scales. We used Morisita's index of population abundance as an estimate of heterogeneity in distribution among regions to test a number of predictions. Heterogeneously distributed passerine bird species as reflected by Morisita's index had small populations, low population densities, and small breeding ranges. Their breeding populations had been consistently maintained at low levels for considerable periods of time, because the degree of genetic variation in a subsample of non-passerines and passerines was significantly negatively related to heterogeneity in distribution. Heterogeneously distributed passerine species were not more often habitat specialists than homogeneously distributed species. Furthermore, heterogeneously distributed passerine species had high annual adult survival rates but did not differ in annual fecundity from homogeneously distributed species. Heterogeneously distributed passerine species rarely colonized urban habitats. Finally, homogeneously distributed bird species were hosts to a greater diversity of blood parasite species than heterogeneously distributed species. In conclusion, small breeding ranges, population sizes, and population densities of heterogeneously distributed passerine bird species, combined with their low degree of genetic variability, and their inability to colonize urban areas may render such species particularly susceptible to human-influenced global climatic changes.

Nestling coloration is adjusted to parent visual performance in altricial birds irrespective of assumptions on vision system for Laniidae and owls, a reply to Renoult et al.

We have recently published support to the hypothesis that visual systems of parents could affect nestling detectability and, consequently, influences the evolution of nestling colour designs in altricial birds. We provided comparative evidence of an adjustment of nestling colour designs to the visual system of parents that we have found in a comparative study on 22 altricial bird species. In this issue, however, Renoult et al. (J. Evol. Biol., 2009) question some of the assumptions and statistical approaches in our study. Their argumentation relied on two major points: (1) an incorrect assignment of vision system to four out of 22 sampled species in our study; and (2) the use of an incorrect approach for phylogenetic correction of the predicted associations. Here, we discuss in detail re-assignation of vision systems in that study and propose alternative interpretation for current knowledge on spectrophotometric data of avian pigments. We reanalysed the data by using phylogenetic generalized least squares analyses that account for the alluded limitations of phylogenetically independent contrasts and, in accordance with the hypothesis, confirmed a significant influence of parental visual system on gape coloration. Our results proved to be robust to the assumptions on visual system evolution for Laniidae and nocturnal owls that Renoult et al. (J. Evol. Biol., 2009) study suggested may have flawed our early findings. Thus, the hypothesis that selection has resulted in increased detectability of nestling by adjusting gape coloration to parental visual systems is currently supported by our comparative data.