Breaking down the components of the competition-colonization trade-off: New insights into its role in diverse systems.

Performance trade-offs between competition and colonization can be an important mechanism facilitating regional coexistence of competitors. However, empirical evidence for this trade-off is mixed, raising questions about the extent to which it shapes diverse ecological communities. Here, we outline a framework that can be used to improve empirical tests of the competition-colonization trade-off. We argue that tests of the competition-colonization trade-off have been diverted into unproductive paths when dispersal mode and/or competition type have been inadequately defined. To generate comparative predictions of associations between dispersal and competitive performance, we develop a conceptual trait-based framework that clarifies how dispersal mode and type of competitor shape this trade-off at the stage of dispersal and establishment in a variety of systems. Our framework suggests that competition-colonization trade-offs may be less common for passively dispersing organisms when competitive dominants are those best able to withstand resource depletion (competitive response), and for active dispersers when traits for dispersal performance are positively associated with resource pre-emption (competitive effect). The framework presented here is designed to provide common ground for researchers working in different systems in order to prompt more effective assessment of this performance trade-off and its role in shaping community structure. By delineating key system properties that mediate the trade-off between competitive and colonization performance and their relationship to individual-level traits, researchers in disparate systems can structure their predictions about this trade-off more effectively and compare across systems more clearly.

Phenotype-by-environment interactions influence dispersal.

Numerous studies have demonstrated that dispersal is dependent on both disperser phenotype and the local environment. However, there is substantial variability in the observed strength and direction of phenotype- and environment-dependent dispersal. This has been hypothesized to be the result of interactive effects among the multiple phenotypic and environmental factors that influence dispersal. Here, our goal was to test the hypothesis that these interactions are responsible for generating variation in dispersal behaviour. We achieved these goals by conducting a large, 2-year, mark-release-recapture study of the backswimmer Notonecta undulata in an array of 36 semi-natural ponds. We measured the effects of multiple phenotypic (sex and body size) and environmental (population density and sex ratio) factors, on both dispersal probability and dispersal distance. We found support for the hypothesis that interactive effects influence dispersal and produce variability in phenotype- and environment-dependent dispersal: dispersal probability was dependent on the three-way interaction between sex, body mass and population density. Small males displayed strong, positive density dependence in their dispersal behaviour, while large males and females overall did not respond strongly to density. Small notonectids, regardless of sex, were more likely to disperse, but this effect was strongest at high population densities. Finally, the distance dispersed by backswimmers was a negative function of population density, a pattern which we hypothesize could be related to: (a) individuals from high and low density patches having different dispersal strategies, or (b) the effect of density on dispersal capacity. These results suggest that phenotype-by-environment interactions strongly influence dispersal. Since phenotype- and environment-dependent dispersal has different consequences for ecological and evolutionary dynamics (e.g. metapopulation persistence and local adaptation) than random dispersal, interactive effects may have wide-reaching impacts on populations and communities. We therefore argue that more investment should be made into estimating the effects of multiple, interacting factors on dispersal and determining whether similar interactive effects are acting across systems.

Novel habitats for biodiversity? A systematic review and meta-analysis of freshwater biodiversity in stormwater management ponds.

Stormwater ponds are increasingly becoming a dominant pond type in cities experiencing urban sprawl. These human-made ponds are designed primarily to control flooding issues associated with increased impervious surface in cities and serve to retain sediment and contaminants before flowing to urban downstream waterways. Along with these important functions, constructed ponds including stormwater ponds may be critical in urban freshwater conservation because they often represent some of the few remaining lentic environments (still water; e.g. ponds, wetlands, lakes) in many cities. We currently lack a clear understanding of the role that stormwater ponds play in serving as habitat for freshwater biodiversity. Here, we examined whether stormwater ponds support freshwater biodiversity in cities by reviewing the empirical literature on biotic community responses in urban stormwater ponds across a range of taxonomic groups. We conducted a meta-analysis on empirical papers that quantitatively examined differences in taxonomic richness between stormwater ponds and reference ponds (n = 11 papers, 22 effects). We also examined a broader set of 58 papers to qualitatively synthesize studies on stormwater pond communities and assess various indicators of habitat quality in stormwater ponds. In the studies examined, heterogeneity exists in the habitat quality of stormwater ponds and increased pollutant loads are often reported. However, the results highlight that stormwater ponds tend to contain alpha diversity comparable to reference ponds, and that overall, a range of ecologically important wildlife make use of and inhabit urban stormwater ponds. We find that stormwater ponds can often support communities with broad compositions of taxa, including those that are sensitive or vulnerable to environmental change. We compile recommendations provided within the studies in order to improve our understanding of the management of urban stormwater ponds for biodiversity conservation.

Evaluation of prototype risk prediction tools for clinicians and people living with type 2 diabetes in North West London using the think aloud method.

The prevalence of type 2 diabetes in North West London (NWL) is relatively high compared to other parts of the United Kingdom with outcomes suboptimal. This presents a need for more effective strategies to identify people living with type 2 diabetes who need additional support. An emerging subset of web-based interventions for diabetes self-management and population management has used artificial intelligence and machine learning models to stratify the risk of complications from diabetes and identify patients in need of immediate support. In this study, two prototype risk prediction tools on the MyWay Diabetes and MyWay Clinical platforms were evaluated with six clinicians and six people living with type 2 diabetes in NWL using the think aloud method. The results of the sessions with people living with type 2 diabetes showed that the concept of the tool was intuitive, however, more instruction on how to correctly use the risk prediction tool would be valuable. The feedback from the sessions with clinicians was that the data presented in the tool aligned with the key diabetes targets in NWL, and that this would be useful for identifying and inviting patients to the practice who are overdue for tests and at risk of complications. The findings of the evaluation have been used to support the development of the prototype risk predictions tools. This study demonstrates the value of conducting usability testing on web-based interventions designed to support the targeted management of type 2 diabetes in local communities.

Expression of Oct-6, a POU III domain transcription factor, in schizophrenia.

OBJECTIVE: Oct-6, a POU-III domain transcription factor, is expressed in embryonic stem cells and Schwann cells and in neuronal subpopulations during early mammalian development, but its relevance to disorders of cerebral development in humans is untested. This study evaluated the expression of Oct-6 in schizophrenia, a disorder that has been linked with neurodevelopmental abnormalities. METHOD: Immunohistochemistry was used to examine Oct-6 expression in the temporal lobe in postmortem tissue from 10 subjects with schizophrenia and 10 matched comparison subjects. Western blot analysis was used to study Oct-6 expression in the frontal and temporal cortex in tissue from an additional three schizophrenic and three matched comparison subjects and in the frontal lobe only in tissue from an additional 10 schizophrenic and 10 matched comparison subjects. RESULTS: Extensive Oct-6 immunoreactivity was present in the temporal lobe in all 10 schizophrenic subjects, while very little or no expression was found in the comparison subjects. In schizophrenic subjects, Oct-6 immunoreactivity was found in a subset of cells in the pyramidal cell layer of the hippocampus and in the granule cell layer of the dentate gyrus. Oct-6 staining was predominantly localized in the cytoplasm. Western blot analysis confirmed the presence of Oct-6 in the frontal and temporal cortex in schizophrenic subjects but not in comparison subjects. CONCLUSIONS: The presence of Oct-6 expression in the schizophrenic subjects but not in the comparison subjects suggests that Oct-6 may provide a marker for the neuropathology associated with schizophrenia. Further, it may provide a clue to the neurodevelopmental basis of the disease and could be a reliable means to examine the developmental brain abnormalities described in this disorder.

Gender and age related expression of Oct-6--a POU III domain transcription factor, in the adult mouse brain.

Oct-6 is a POU III domain transcription factor whose primary role is thought to be developmental. It is expressed in embryonic stem cells, Schwann cells, and in neuronal subpopulations during telencephalic development. Its best characterised role is in Schwann cells where it is thought to regulate myelin specific gene expression. Expression of Oct-6 was recently discovered in neurons in post-mortem human schizophrenic specimens while being undetectable in matched controls. This study of human tissue contrasted in a number of regards with earlier studies of rodent brain, and questioned what we can consider to be normal adult expression of this gene. In this study, we have investigated Oct-6 expression via in situ hybridisation and Western blot analysis in normal adult female mice of different ages. We show that both RNA and protein levels of Oct-6 expression are highly sustained in the adult and aging cerebellum, whereas they are attenuated in the telencephalon by PW30 (postnatal week 30). These observations suggest that Oct-6 expression takes place in a sex and age dependent way.

Oct-6 transcription factor.

A variety of neurological disorders may have their origin during development of the central nervous system. Defects consistent with abnormal brain development have been reported in schizophrenia. These include faulty neuronal migration,altered spatial neuronal distribution, and the absence of significant gliosis. These abnormalities in the adult are allocated to developmental processes and thus indicate a developmental basis for schizophrenia. Our way toward understanding schizophrenia pathology has been to consider the genes that regulate normal brain development. One such family of genes is the POU family of homeobox transcription factors. This chapter reviews POU domain proteins, focusing on the POU III domain gene, Oct-6, along with its potential relevance to schizophrenia.