Longer study length, standardized sampling techniques, and broader geographic scope leads to higher likelihood of detecting stable abundance patterns in long term black-legged tick studies

Background

Understanding how study design and monitoring strategies shape inference within, and synthesis across, studies is critical across biological disciplines. Many biological and field studies are short term and limited in scope. Monitoring studies are critical for informing public health about potential vectors of concern, such as Ixodes scapularis (black-legged ticks). Black-legged ticks are a taxon of ecological and human health concern due to their status as primary vectors of Borrelia burgdorferi, the bacteria that transmits Lyme disease. However, variation in black-legged tick monitoring, and gaps in data, are currently considered major barriers to understanding population trends and in turn, predicting Lyme disease risk. To understand how variable methodology in black-legged tick studies may influence which population patterns researchers find, we conducted a data synthesis experiment.

Materials and Methods

We searched for publicly available black-legged tick abundance dataset that had at least 9 years of data, using keywords about ticks in internet search engines, literature databases, data repositories and public health websites. Our analysis included 289 datasets from seven surveys from locations in the US, ranging in length from 9 to 24 years. We used a moving window analysis, a non-random resampling approach, to investigate the temporal stability of black-legged tick population trajectories across the US. We then used t-tests to assess differences in stability time across different study parameters.

Results

All of our sampled datasets required 4 or more years to reach stability. We also found several study factors can have an impact on the likelihood of a study reaching stability and of data leading to misleading results if the study does not reach stability. Specifically, datasets collected via dragging reached stability significantly faster than data collected via opportunistic sampling. Datasets that sampled larva reached stability significantly later than those that sampled adults or nymphs. Additionally, datasets collected at the broadest spatial scale (county) reached stability fastest.

Conclusion

We used 289 datasets from seven long term black-legged tick studies to conduct a non-random data resampling experiment, revealing that sampling design does shape inferences in black-legged tick population trajectories and how many years it takes to find stable patterns. Specifically, our results show the importance of study length, sampling technique, life stage, and geographic scope in understanding black-legged tick populations, in the absence of standardized surveillance methods. Current public health efforts based on existing black-legged tick datasets must take monitoring study parameters into account, to better understand if and how to use monitoring data to inform decisioning. We also advocate that potential future forecasting initiatives consider these parameters when projecting future black-legged tick population trends.

Geographic and taxonomic trends of rising biological invasion costs

Invasive alien species (IAS) are a growing global ecological problem. Reports on the socio-economic impacts of biological invasions are accumulating, but our understanding of temporal trends across regions and taxa remains scarce. Accordingly, we investigated temporal trends in the economic cost of IAS and cost-reporting literature using the InvaCost database and meta-regression modelling approaches. Overall, we found that both the cost reporting literature and monetary costs increased significantly over time at the global scale, but costs increased faster than reports. Differences in global trends suggest that cost literature has accumulated most rapidly in North America and Oceania, while monetary costs have exhibited the steepest increase in Oceania, followed by Europe, Africa and North America. Moreover, the costs for certain taxonomic groups were more prominent than others and the distribution also differed spatially, reflecting a potential lack of generality in cost-causing taxa and disparate patterns of cost reporting. With regard to global trends within the Animalia and Plantae kingdoms, costs for flatworms, mammals, flowering and vascular plants significantly increased. Our results highlight significantly increasing research interest and monetary impacts of biological invasions globally, but uncover key regional differences driven by variability in reporting of costs across countries and taxa. Our findings also suggest that regions which previously had lower research effort (e.g., Africa) exhibit rapidly increasing costs, comparable to regions historically at the forefront of invasion research. While these increases may be driven by specific countries within regions, we illustrate that even after accounting for research effort (cost reporting), costs of biological invasions are rising.

On the relationship between baseline corticosterone levels and annual survival of the thorn-tailed rayadito

Baseline concentrations of glucocorticoids (i.e., cortisol and/or corticosterone) can moderately increase with the degree of energy demands that an individual faces. This could be a mechanism based on which glucocorticods (GCs) can mediate life history trade-offs, and therefore fitness. The 'cort-fitness hypothesis' predicts a negative relationship between GCs and fitness, meanwhile the 'cort-adaptation hypothesis' predicts the opposite pattern. Field studies on the relation between baseline GCs and survival rate have shown mixed results, supporting both positive and negative effect. These ambiguous results could be partially consequence of the short time frame in that most of the studies are carried on. In this study, we tested the predictions of the 'cort-fitness hypothesis' and 'cort-adaptation hypothesis' by using long-term data (eight-year of capture-mark-recapture) of Thorn-tailed Rayadito (Aphrastura spinicauda) in two populations at different latitudes. We assessed whether survival varied as a function of Cort levels and whether it varied in a linear (positive: 'cort-adaptation hypothesis' or negative: 'cort-fitness hypothesis') or curvilinear way. The two populations in our study had different baseline Cort levels, then we evaluated whether the association between baseline Cort and survival probability varied between them. In the high latitude population (i.e., lower baseline Cort levels), we observed a marginally quadratic relationship that is consistent with the cort-fitness hypothesis. In contrast, in the low altitude population we did not find this relation. Our findings suggests that the association between baseline Cort and survival probability is context-dependent, and highlights the importance of comparing different populations and the use of long-term data.

Curve progression 25 years after bracing for adolescent idiopathic scoliosis: long term comparative results between two matched groups of 18 versus 23 hours daily bracing

Background

Scoliotic curves do not necessarily stop progressing at skeletal maturity. The factors that influence curve behavior following bracing are not fully determined. Our objectives were to evaluate the loss of the scoliotic curve correction in a cohort of patients treated with bracing during adolescence and to compare the outcomes of 18 versus 23 h of bracing at a mean of 25 years post brace removal.

Methods

Seventy-seven patients, who were successfully treated for Adolescent Idiopathic Scoliosis with Βoston brace, were re-evaluated 25 years after the end of their treatment. Patients were further divided in 2 matched groups; those wearing the brace for 23 h and those not wearing the brace at school-time, limiting the application of the brace to 18 h. The mean scoliotic curve was compared between groups before, during, just after bracing and 25 years post bracing. Validated in patients’ native language forms of Short Form 36 and Oswestry Disability Index questionnaires were used to compare the quality of life between groups 25 years post bracing.

Results

The mean age of the cohort was 40.4 (±3.2) years. They underwent long term follow up at a mean of 25.16 (±2.69) years after brace removal. The mean cohort scoliotic curve increased by 3.9 (±6.69) at 25 years since brace removal. There was however no significant difference in the mean Cobb angle of the cohort between pre brace and long term follow up period (p = 0.307).

The 18 and 23 h application groups were comparable according to demographics and several bracing and scoliotic curve parameters. There was no significant difference in the mean curve magnitude between 18 and 23 h application groups at brace removal (p = 0.512) and at 25 years follow-up (p = 0.878). There was also no significant difference in the mean score of Quality of Life questionnaires between groups at long term follow up.

Conclusion

Scoliotic curves do not necessarily stop progressing after bracing. Bracing is effective treatment method with good long term results in appropriate patients. Since compliance was not objectively measured, we don’t feel confident to give any indication about everyday dosage.