Temporal resource partitioning mitigates interspecific competition and promotes coexistence among insect parasites.

A key to understanding life's great diversity is discerning how competing organisms divide limiting resources to coexist in diverse communities. While temporal resource partitioning has long been hypothesized to reduce the negative effects of interspecific competition, empirical evidence suggests that time may not often be an axis along which animal species routinely subdivide resources. Here, we present evidence to the contrary in the world's most biodiverse group of animals: insect parasites (parasitoids). Specifically, we conducted a meta-analysis of 64 studies from 41 publications to determine if temporal resource partitioning via variation in the timing of a key life-history trait, egg deposition (oviposition), mitigates interspecific competition between species pairs sharing the same insect host. When competing species were manipulated to oviposit at (or near) the same time in or on a single host in the laboratory, competition was common, and one species was typically inherently superior (i.e. survived to adulthood a greater proportion of the time). In most cases, however, the inferior competitor could gain a survivorship advantage by ovipositing earlier (or in a smaller number of cases later) into shared hosts. Moreover, this positive (or in a few cases negative) priority advantage gained by the inferior competitor increased as the interval between oviposition times became greater. The results from manipulative experiments were also correlated with patterns of life-history timing and demography in nature: the more inherently competitively inferior a species was in the laboratory, the greater the interval between oviposition times of taxa in co-occurring populations. Additionally, the larger the interval between oviposition times of competing taxa, the more abundant the inferior species was in populations where competitors were known to coexist. Overall, our findings suggest that temporal resource partitioning via variation in oviposition timing may help to facilitate species coexistence and structures diverse insect communities by altering demographic measures of species success. We argue that the lack of evidence for a more prominent role of temporal resource partitioning in promoting species coexistence may reflect taxonomic differences, with a bias towards larger-sized animals. For smaller species like parasitic insects that are specialized to attack one or a group of closely related hosts, have short adult lifespans and discrete generation times, compete directly for limited resources in small, closed arenas and have life histories constrained by host phenology, temporal resource subdivision via variation in life history may play a critical role in allowing species to coexist by alleviating the negative effects of interspecific competition.

Pulmonary Artery Wedge Pressure Respiratory Variation Increases With Sodium Nitroprusside Vasodilator Challenge.

BACKGROUND: The physiologic factors leading to pulmonary arterial wedge pressure respiratory variation (PAWPvar) are underexplored. We hypothesized that PAWPvar is associated with baseline PAWP and would predict response to sodium nitroprusside (SNP). METHODS AND RESULTS: We performed a retrospective study of right heart catheterization studies in 51 subjects with SNP challenge at our institution from 2012 to 2019. PAWPvar was defined as expiratory minus inspiratory PAWP. Baseline %PAWPvar was inversely correlated with baseline PAWP (R = -0.5). SNP administration led to increased %PAWPvar (+27%, P < .01). Subjects with low baseline PAWPvar (less than the median) had an increase in PAWPvar with SNP (3 ± 4 mm Hg), whereas those with a high baseline PAWPvar (greater than the median) did not (-0.6 ± 4 mm Hg, P = .003). Those who had a greater than the median PAWPvar increase with SNP had greater cardiac output augmentation compared with those who had less than a median increase in PAWPvar (1.7 ± 1.5 L/min vs 0.9 ± 0.7 L/min, P = .02). An increasing PAWPvar after SNP was associated with significant discrepancy in the number of subjects achieving transplant-acceptable pulmonary vascular resistance (<2.5 Wood units) when calculated by expiratory versus mean PAWP (37 vs 27 subjects, 20% discrepancy rate). Subjects with a higher PAWPvar after SNP were more likely to demonstrate discrepant transplant-acceptable pulmonary vascular resistance calculations comparing expiratory versus mean PAWP than those with lower PAWPvar post-SNP (47% vs 13%, odds ratio 5.5, P = .03). CONCLUSIONS: Our findings indicate that PAWPvar is a meaningful physiologic parameter that is influenced by the compliance of the left heart/pulmonary vascular system and its relative preload and afterload states.

Patient perception of obesity versus physician documentation of obesity: A quality improvement study.

As the prevalence of obesity increases, the prevalence of associated comorbid diseases, obesity-related mortality rates and healthcare costs rise concordantly. Two main factors that hinder efforts to treat obesity include a lack of recognition by patients and documentation by physicians. This study evaluates the relationship between patient perception of obese weight and physician documentation of obesity. This quality improvement observational study surveyed patients of an academic internal medicine clinic on their perception of obesity. Responses were compared to longitudinal physician documentation of obesity and body mass index (BMI). A total of 59.9% of patients with obesity perceived their weight as obese. While 33.7% of patients with a BMI of 30 to 34.9 kg/m2 perceived themselves as having obesity, 71.4% of patients with a BMI of 45 to 49.9 kg/m2 perceived themselves as having obesity. A total of 42.4% of patients with obesity had physician documentation of obesity in the last year. While 25% of patients with a BMI of 30 to 34.9 kg/m2 had physician documentation of obesity, 85.7% of patients with a BMI of 45 to 49.9 kg/m2 had physician documentation of obesity. For patients with a BMI ≥50 kg/m2 , 52.9% perceived their weight to be obese and 76.5% had physician documentation of obesity in the last year. Both patient perception and physician documentation of obesity were significantly less than the prevalence of obesity. Patient perception of obesity and provider documentation of obesity increased as BMI increased until a BMI ≥50 kg/m2 . Both patients and providers must improve recognition of this disease.