How population dynamics shape the functional response in a one-predator-two-prey system

The type III functional response has historically been associated with switching predators; when there is a choice of prey the predator favors the more abundant prey type. Although this functional response has been found in experiments where both prey densities are manipulated, in real world studies the type II functional response is more commonly found. In modeling, the type III functional response is often used in systems where the second prey type is, implicitly, assumed to be constant. Here we define a functional response that takes into account both prey densities. This causes the functional response to show both type II and type III behavior, dependent on the interaction between the two prey densities. If we take into account population dynamics, we find a type II functional response in most cases, because predation regulates the relative prey densities. This explains why type III functional responses are found in experiments where both prey densities are manipulated, but type II functional responses occur when the feedback of population dynamics on the functional response is important. Furthermore, the results show that switching can have a stabilizing or destabilizing effect and can even lead to predator extinction.     

Plant defense, growth, and habitat: a comparative assessment of constitutive and induced resistance

The growth rate (GR) hypothesis relates the evolution of plant defense to resource availability and predicts that plants that have evolved in abiotically stressful environments grow inherently more slowly and are more constitutively resistant to herbivory than plants from more productive habitats. Stress-adapted plants are also predicted to have reduced inducibility, but this prediction has not been previously tested. To evaluate this hypothesis, I compared the growth of nine species of herbaceous plants from Missouri glade habitats to congeners from more productive non-glade habitats. I also conducted bioassays using larvae of the generalist herbivore Spodoptera exigua to estimate constitutive and inducible resistance in these congeners. Glade congeners tended to grow more slowly and have higher constitutive resistance and lower inducibility than non-glade species. However, none of these comparisons was statistically significant due to the conflicting response of one congeneric pair (Salvia azurea and S. lyrata). Analyses without this genus were consistent with the GR hypothesis, as were analyses that categorized congeners by relative growth rate. These results highlight the complexity in searching for factors that determine plant growth rates and resistance traits across multiple genera and support the hypothesis that both constitutive and induced resistance may be influenced by selection on traits that alter plant growth rates. Future studies should attempt to determine whether variation in inducibility is better explained by habitat or relative plant growth rates.     

Dental fluorosis associated with drinking water from hot springs in Choma district in southern province,Zambia

This study was conducted to investigate the high incidence of mottled teeth among residents of an area with hot springs in the Choma District of the Southern Province of Zambia. A survey involving 128 pupils was conducted at a Basic School to collect data on pupil’s backgrounds and their main sources of drinking water between birth and age 7. A dental specialist examined the pupils’ teeth and samples of drinking water were collected from locations where the majority of the pupils lived. It was analysed for fluorides and other drinking water quality parameters. Results of the survey showed a highly significant (P < 0.001) association between pupils’ main sources of drinking water between birth and age 7 and the incidence of discoloured teeth. All (100%) pupils who drank water from hot springs before age 7 had moderate to severe fluorosis, while the majority (96.7%) of the pupils who drank water from other sources had no dental fluorosis. Fluoride concentrations ranged from 5.95 to 10.09 mg/l in water from hot springs, and from 0.03 to 0.6 mg/l in water from other sources. Fluoride levels in water from hot spring water samples exceeded the 1.5 mg/l WHO guideline value for drinking water, while those in water from other sources were significantly (P < 0.05) lower than this. We conclude that the high prevalence of mottled teeth among residents of the study area is a case of endemic dental fluorosis associated with drinking water from hot springs containing high concentrations of fluoride.     

New genetic markers to identify European resistant abalone to vibriosis revealed by high-resolution melting analysis,a sensitive and fast approach

Increasing temperature of seawater is often associated with increased exposure incidence of disease in field and in aquaculture populations. Numerous episodic mass mortalities of the abalone Haliotis tuberculata have been observed along the northern Brittany coast of France caused by a complex interaction between the host, pathogen and environmental factors. Here, we evaluated the potential of high-resolution melting (HRM) analysis for mutation genotyping and development of genetic markers for resistance to vibriosis in the gastropod species H. tuberculata. Small amplicon assays were developed and revealed genetic polymorphism between surviving and susceptible abalone obtained after two successive infections of aquaculture families in controlled conditions. Together with specific COI haplotypes, we identified particular genotypes in nascent polypeptide-associated complex subunit alpha and ferritin genes linked to the susceptibility or resistance of abalone to vibriosis. Selection of genitors based on these genes may increase the proportion in offspring of resistant individuals of more than 76 %. Finally, HRM assays constitute a very efficient genotyping tool to validate the genetic markers on a representative number of individuals of wild populations and thus identify future resistant genitors for aquaculture or conservation purposes.     

Critically evaluating best management practices for preventing freshwater turtle extinctions

Ex situ conservation tools, such as captive breeding for reintroduction, are considered a last resort to recover threatened or endangered species, but they may also help reduce anthropogenic threats where it is difficult or impossible to address them directly. Headstarting, or captive rearing of eggs or neonate animals for subsequent release into the wild, is controversial because it treats only a symptom of a larger conservation problem; however, it may provide a mechanism to address multiple threats, particularly near population centers. We conducted a population viability analysis of Australia's most widespread freshwater turtle, Chelodina longicollis, to determine the effect of adult roadkill (death by collision with motor vehicles), which is increasing, and reduced recruitment through nest predation from introduced European red foxes (Vulpes vulpes). We also modeled management scenarios to test the effectiveness of headstarting, fox management, and measures to reduce mortality on roads. Only scenarios with headstarting from source populations eliminated all risks of extinction and allowed population growth. Small increases in adult mortality (2%) had the greatest effect on population growth and extinction risk. Where threats simultaneously affected other life‐history stages (e.g., recruitment), eliminating harvest pressures on adult females alone did not eliminate the risk of population extinction. In our models, one source population could supply enough hatchlings annually to supplement 25 other similar‐sized populations such that extinction was avoided. Based on our results, we believe headstarting should be a primary tool for managing freshwater turtles for which threats affect multiple life‐history stages. We advocate the creation of source populations for managing freshwater turtles that are greatly threatened at multiple life‐history stages, such as depredation of eggs by invasive species and adult mortality via roadkill.     

Occurrence of pharmaceutical and personal care products in Cau River,Vietnam

Environmental Science and Pollution Research - This study evaluated the occurrence of PPCPs in Cau River (Vietnam). Surface water and sediment samples were collected to determine PPCP...     

International Society for Prenatal Diagnosis 2022 debate 3—Fetal genome sequencing should be offered to all pregnant patients

Prenatal trio exome sequencing (ES) has become integrated into the care for pregnant women when the fetus has structural anomalies. Details regarding optimizing indications for prenatal exome sequencing, its detection rates with different categories of fetal anomalies, and principles of interpretation of pathogenicity of sequence variants are still under investigation. However, there is now growing consensus about its benefits for finding the cause of fetal structural anomalies. What is not established, is whether exome or genome sequencing (GS) has a place in the care of all pregnant women. This report is a summary of the debate on this topic at the 26th International Conference on Prenatal Diagnosis and Therapy. Both expert debaters considered the advantages and disadvantages. Advantages include the ability to diagnose serious childhood conditions without a prenatally observable phenotype, which creates the potential of early treatments. Disadvantages include difficulties with variant classification, counseling complexities, healthcare cost, and the burden on healthcare systems and families, in particular with the discovery of adult-onset disorders or variants of uncertain significance. Although both debaters weighed the balance of these conflicting arguments differently, they agreed that more research is needed to further explore the clinical utility and ethical aspects of GS for all pregnant women.