Role of host genetics and heat‐tolerant algal symbionts in sustaining populations of the endangered coral Orbicella faveolata in the Florida Keys with ocean warming

Identifying which factors lead to coral bleaching resistance is a priority given the global decline of coral reefs with ocean warming. During the second year of back‐to‐back bleaching events in the Florida Keys in 2014 and 2015, we characterized key environmental and biological factors associated with bleaching resilience in the threatened reef‐building coral Orbicella faveolata. Ten reefs (five inshore, five offshore, 179 corals total) were sampled during bleaching (September 2015) and recovery (May 2016). Corals were genotyped with 2bRAD and profiled for algal symbiont abundance and type. O. faveolata at the inshore sites, despite higher temperatures, demonstrated significantly higher bleaching resistance and better recovery compared to offshore. The thermotolerant Durusdinium trenchii (formerly Symbiondinium trenchii) was the dominant endosymbiont type region‐wide during initial (78.0% of corals sampled) and final (77.2%) sampling; >90% of the nonbleached corals were dominated by D. trenchii. 2bRAD host genotyping found no genetic structure among reefs, but inshore sites showed a high level of clonality. While none of the measured environmental parameters were correlated with bleaching, 71% of variation in bleaching resistance and 73% of variation in the proportion of D. trenchii was attributable to differences between genets, highlighting the leading role of genetics in shaping natural bleaching patterns. Notably, D. trenchii was rarely dominant in O. faveolata from the Florida Keys in previous studies, even during bleaching. The region‐wide high abundance of D. trenchii was likely driven by repeated bleaching associated with the two warmest years on record for the Florida Keys (2014 and 2015). On inshore reefs in the Upper Florida Keys, O. faveolata was most abundant, had the highest bleaching resistance, and contained the most corals dominated by D. trenchii, illustrating a causal link between heat tolerance and ecosystem resilience with global change.     

The effects of heterospecific mating frequency on the strength of cryptic reproductive barriers

Heterospecific mating frequency is critical to hybrid zone dynamics and can directly impact the strength of reproductive barriers and patterns of introgression. The effectiveness of post‐mating prezygotic (PMPZ) reproductive barriers, which include reduced fecundity via heterospecific matings and conspecific sperm precedence, may depend on the number, identity and order of mates. Studies of PMPZ barriers suggest that they may be important in many systems, but whether these barriers are effective at realistic heterospecific mating frequencies has not been tested. Here, we evaluate the strength of cryptic reproductive isolation in two leaf beetles (Chrysochus auratus and C. cobaltinus) in the context of a range of heterospecific mating frequencies observed in natural populations. We found both species benefited from multiple matings, but the benefits were greater in C. cobaltinus and extended to heterospecific matings. We found that PMPZ barriers greatly limited hybrid production by C. auratus females with moderate heterospecific mating frequencies, but that their effectiveness diminished at higher heterospecific mating frequencies. In contrast, there was no evidence for PMPZ barriers in C. cobaltinus females at any heterospecific mating frequency. We show that integrating realistic estimates of cryptic isolation with information on relative abundance and heterospecific mating frequency in the field substantially improves our understanding of the strong directional bias in F1 production previously documented in the Chrysochus hybrid zone. Our results demonstrate that heterospecific mating frequency is critical to understanding the impact of cryptic post‐copulatory barriers on hybrid zone structure and dynamics, and that future studies of such barriers should incorporate field‐relevant heterospecific mating frequencies.     

A pragmatic approach to understand peripheral artery lumen surface stiffness due to plaque heterogeneity

The goal of this study was to develop a pragmatic approach to build patient-specific models of the peripheral artery that are aware of plaque inhomogeneity. Patient-specific models using element-specific material definition (to understand the role of plaque composition) and homogeneous material definition (to understand the role of artery diameter and thickness) were automatically built from intravascular ultrasound images of three artery segments classified with low, average, and high calcification. The element-specific material models had average surface stiffness values of 0.0735, 0.0826, and 0.0973?MPa/mm, whereas the homogeneous material models had average surface stiffness values of 0.1392, 0.1276, and 0.1922?MPa/mm for low, average, and high calcification, respectively. Localization of peak lumen stiffness and differences in patient-specific average surface stiffness for homogeneous and element-specific models suggest the role of plaque composition on surface stiffness in addition to local arterial diameter and thickness.     

Connecting ecology to daily life: how students and teachers relate food webs to the food they eat

This study used sociocultural learning theory to better understand how middle and high school environmental science and biology students and pre- and in-service science teachers connect the daily life activity of eating to the food web model learned in school. We sought to understand how student and teacher perceptions of the environment and their experiences influenced their responses to interview questions regarding this topic. Findings, based on transcribed interviews with 54 study participants, indicate that three quarters of teachers and students were unable to connect the food they eat with ecosystem food webs. Even so, many respondents particularly those from elite public schools, did not demonstrate common food web misconceptions identified by other researchers, instead showing a sophisticated understanding of food web interactions. These findings indicate that even though participants were proficient in their school science understanding of food web interactions, they did not readily think about how their everyday out of school activities, like eating, relate to those interactions. This may be representative of a more general disconnect between formal ecology instruction and daily life activities. We provide several recommendations for how this disconnect can be remedied in our classrooms.     

Genomic,ecological, and morphological approaches to investigating species limits: A case study in modern taxonomy from Tropical Eastern Pacific surgeonfishes

A wide variety of species are distinguished by slight color variations. However, molecular analyses have repeatedly demonstrated that coloration does not always correspond to distinct evolutionary histories between closely related groups, suggesting that this trait is labile and can be misleading for species identification. In the present study, we analyze the evolutionary history of sister species of Prionurus surgeonfishes in the Tropical Eastern Pacific (TEP), which are distinguished by the presence or absence of dark spots on their body. We examined the species limits in this system using comparative specimen‐based approaches, a mitochondrial gene (COI), more than 800 nuclear loci (Ultraconserved Elements), and abiotic niche comparisons. The results indicate there is a complete overlap of meristic counts and morphometric measurements between the two species. Further, we detected multiple individuals with intermediate spotting patterns suggesting that coloration is not diagnostic. Mitochondrial data recovered a single main haplotype shared between the species and all locations resulting in a complete lack of structure (Φ_ST = 0). Genomic analyses also suggest low levels of genetic differentiation (F_ST = 0.013), and no alternatively fixed SNPs were detected between the two phenotypes. Furthermore, niche comparisons could not reject niche equivalency or similarity between the species. These results suggest that these two phenotypes are conspecific and widely distributed in the TEP. Here, we recognize Prionurus punctatus Gill 1862 as a junior subjective synonym of P. laticlavius (Valenciennes 1846). The underlying causes of phenotypic variation in this species are unknown. However, this system gives insight into general evolutionary dynamics within the TEP.     

The symptom‐specific efficacy of antidepressant medication vs. cognitive behavioral therapy in the treatment of depression: results from an individual patient data meta‐analysis

A recent individual patient data meta‐analysis showed that antidepressant medication is slightly more efficacious than cognitive behavioral therapy (CBT) in reducing overall depression severity in patients with a DSM‐defined depressive disorder. We used an update of that dataset, based on seventeen randomized clinical trials, to examine the comparative efficacy of antidepressant medication vs. CBT in more detail by focusing on individual depressive symptoms as assessed with the 17‐item Hamilton Rating Scale for Depression. Five symptoms (i.e., “depressed mood” , “feelings of guilt” , “suicidal thoughts” , “psychic anxiety” and “general somatic symptoms”) showed larger improvements in the medication compared to the CBT condition (effect sizes ranging from .13 to .16), whereas no differences were found for the twelve other symptoms. In addition, network estimation techniques revealed that all effects, except that on “depressed mood” , were direct and could not be explained by any of the other direct or indirect treatment effects. Exploratory analyses showed that information about the symptom‐specific efficacy could help in identifying those patients who, based on their pre‐treatment symptomatology, are likely to benefit more from antidepressant medication than from CBT (effect size of .30) versus those for whom both treatments are likely to be equally efficacious. Overall, our symptom‐oriented approach results in a more thorough evaluation of the efficacy of antidepressant medication over CBT and shows potential in “precision psychiatry” .     

Associations among spring-dependent aquatic assemblages and environmental and land use gradients in a Mojave Desert mountain range

In many arid landscapes, springs provide the only reliable source of water. Accordingly, both native species and human land uses, including diversion of water, livestock grazing, and recreation, tend to concentrate around springs and spring‐fed riparian areas. We examined whether species richness and composition of aquatic macroinvertebrates at 45 springs in the Spring Mountains, an isolated mountain range in the eastern Mojave Desert (Nevada, USA), could be predicted using readily measured environmental gradients and estimates of disturbance intensity. The Spring Mountains is a focus of regional conservation planning, and managers are charged with prioritizing its springs for conservation and rehabilitation. Our results suggested that species richness of aquatic macroinvertebrates in the Spring Mountains system may be greatest at intermediate levels of natural and human disturbance. Discharge and springbrook length appeared to be only weakly correlated with species richness, whereas neither elevation, nor water temperature, nor electrical conductance was significantly associated with species richness. Nestedness analyses demonstrated that species present in relatively depauperate locations tended to be subsets of the species present in locations that were richer in species, but that pattern did not appear to be driven by either disturbance intensity or by the environmental variables we measured. Disturbance intensity was not associated with the extent to which species presences and absences were predictable. Although our results should not be interpreted to mean that major environmental gradients and disturbance intensity have no effect on distributional patterns of aquatic invertebrates in the Spring Mountains, the ability of these variables to serve as predictors of species richness and composition may be relatively low. Springs and other wetlands in arid landscapes are characterized by isolation and unpredictable disturbances, and faunal responses to environmental gradients may tend to be individualistic and taxon‐specific.     

Under pressure: Short- and long-term response to predation varies in two populations of a live-bearing fish

The non-lethal effects of predation can significantly influence animal behavior and population composition. Research has often centered around prey response to predator exposure in the short term, but fewer studies have highlighted the effects of long-term predator exposures. In addition, studies of responses to predation risk are not always calibrated against the ecological history of predation risk in specific populations. We address these gaps by examining the effects of both long- and short-term predator exposure on the behavior of individuals from populations that have different ecological histories of predation risk. We exposed individuals from high-predation and low-predation populations of the live-bearing freshwater poeciliid, Heterandria formosa, to predators to assess changes in male reproductive behavior toward females. We also assessed longer-term reproductive responses by exposing male and female H. formosa to predators at a random time of day, every day, for 30 days. In the presence of a predator, in the short term, males changed the frequency of their behaviors and females varied in their concentration of cortisol, demonstrating immediate responses to the perceived risk. The magnitude of these changes was larger in the population without a long history of predator exposure. However, we found that males and females did not change their reproductive output when exposed to predators over longer periods of time, suggesting that individuals acclimatize to the level of predation risk they experience. These results also suggest that short-term variation in behavior or stress hormone responses should not be used as proxies for long-term responses or fitness effects. Future work should assess both short-term behavior and long-term responses while simultaneously considering the ecological history of populations.     

Pistacia integerrima alleviated Bisphenol A induced toxicity through Ubc13/p53 signalling

Molecular Biology Reports - Exposure to environmental toxicants such as Bisphenol A (BPA) has raised serious health issues globally particularly in developing countries. It is ubiquitously used in...