Reexamining Waddington: Canalization and new mutations are not required for the evolution of genetic assimilation

Over 65 years ago, Waddington demonstrated ancestrally phenotypically plastic traits can evolve to become constitutive, a process he termed genetic assimilation. Genetic assimilation evolves rapidly, assumed to be in large part due to segregating genetic variation only expressed in rare/novel environments, but otherwise phenotypically cryptic. Despite previous work suggesting a substantial role of cryptic genetic variation contributing to the evolution of genetic assimilation, some have argued for a prominent role for new mutations of large effect concurrent with selection. Interestingly, Waddington was less concerned by the relative contribution of CGV or new variants, but aimed to test the role of canalization, an evolved form of robustness. While canalization has been extensively studied, its role in the evolution of genetic assimilation is disputed, in part because explicit tests of evolved robustness are lacking. To address these questions, we recreated Waddington's selection experiments on an environmentally sensitive change in Drosophila wing morphology (crossvein development), using many independently evolved replicate lineages. Using these, we show that 1) a polygenic CGV, but not new variants of large effect are largely responsible for the evolved response demonstrated using both genomic and genetic approaches. 2) Using both environmental manipulations and mutagenesis of the evolved lineages that there is no evidence for evolved changes in canalization contributing to genetic assimilation. Finally, we demonstrate that 3) CGV has potentially pleiotropic and fitness consequences in natural populations and may not be entirely cryptic.

Sustainable Ecosystem Management

Ecosystems are part of human wellbeing and their sustainable management is essential for the survival of the human race and biodiversity. This chapter explores the concept of sustainable ecosystem management (SEM), its principles, elements, faces, and implementation. SEM is defined as environmentally sensitive, ecosystem-based, and eco-regional based. Its successful implementation is therefore complex due to the different priorities of stakeholders, the scope of ecosystems, some of which are transboundary, and the ever-changing nature of these areas amidst environmental uncertainties. These aspects are vulnerable to political changes and reconciling them is difficult. This chapter proposes a five-step implementation plan on SEM that is pegged on adaptive management and holistic consideration of ecological resources. Using documented case studies, SEM is a proposed solution to ecosystem challenges of modern-day amidst hindrances of rising resource demand, population increase, and climate variability.

Evaluation of Desertification Severity in El-Farafra Oasis, Western Desert of Egypt: Application of Modified MEDALUS Approach Using Wind Erosion Index and Factor Analysis

Desertification is a serious threat to human survival and to ecosystems, especially to inland desert oases. An assessment of desertification severity is essential to ensure national sustainable development for agricultural and land expansion processes in this region. In this study, Index of Land Susceptibility to Wind Erosion (ILSWE) was integrated with a Modified Mediterranean Desertification and Land Use (MEDALUS) method and factor analysis (FA) to develop a GIS-based model for mapping desertification severity. The model was then applied to 987.77 km2 in the El- Farafra Oasis, located in the Western Desert of Egypt, as a case study. Climate and field survey data together with remote sensing images were used to generate five quality indices (soil, climate, vegetation, land management and wind erosion). Based on the FA, a weighted value was assigned to each index. Five thematic layers representing the indices were created within the GIS environment and overlaid using the weighted sum model. The developed model showed that 59% of the total area was identified as high-critical and 38% as medium-critical. The results of an environmentally sensitive area index suggested by the original MEDALUS model indicated similar results: 18.37% of the total area was classified as high-critical and 78.73% as medium-critical. However, the sensitivity analysis indicated that weights derived from FA resulted in better performance of the developed spatial model than that derived from the original MEDALUS method. The proposed model would be a suitable tool for monitoring vulnerable zones, and could be a starting point for sustainable agricultural development in inland oases.

Gene by environment interaction mouse model reveals a functional role for 5-hydroxymethylcytosine in neurodevelopmental disorders

Mouse knockouts of Cntnap2 exhibit altered neurodevelopmental behavior, deficits in striatal GABAergic signaling and a genome-wide disruption of an environmentally sensitive DNA methylation modification (5-hydroxymethylcytosine, 5hmC) in the orthologs of a significant number of genes implicated in human neurodevelopmental disorders. We tested adult Cntnap2 heterozygous mice (Cntnap2+/-, lacking behavioral or neuropathological abnormalities) subjected to a prenatal stress and found that prenatally stressed Cntnap2+/- female mice showed repetitive behaviors and altered sociability, similar to the homozygote phenotype. Genomic profiling revealed disruptions in hippocampal and striatal 5hmC levels that were correlated to altered transcript levels of genes linked to these phenotypes (e.g., Reln, Dst, Trio, and Epha5). Chromatin-immunoprecipitation coupled with high-throughput sequencing and hippocampal nuclear lysate pull-down data indicated that 5hmC abundance alters the binding of the transcription factor CLOCK in the promoters of these genes (e.g., Palld, Gigyf1, and Fry), providing a mechanistic role for 5hmC in gene regulation. Together, these data support gene by environment hypotheses for the origins of mental illness and provide a means to identify the elusive factors contributing to complex human diseases.

Environmental policy stringency and comparative advantage of environmental sensitive goods: a study of textile exports in G20 countries

PurposeTextile, listed as one of the highly environmentally sensitive goods, its trade is susceptible to be influenced by the implementation of stringent environmental policies. This paper aims to investigate the long-run relationship between revealed comparative advantage (RCA) and Environmental Policy Stringency Index (EPSI) for textile exports of G20 countries in panel data setup.Design/methodology/approachApart from trend analysis, the authors have employed Pedroni and Westerlund panel cointegration method and fully modified ordinary least square (FMOLS) method to study the long-run relationship between RCA and EPSI in presence of cross-sectional dependence.FindingsA strong link between trade and environmental stringency is observed for textile in the present study. For G20 countries, slight evidence of the Pollution Haven Hypothesis has also been witnessed in the study. Correspondingly, the results reveal the presence of long-run association between the variables under study, implying that stringent environmental policies reduce RCA for some countries, whereas some countries witness the Porter hypothesis.Research limitations/implicationsThe results imply that policy formulation should not aim at limiting the efforts of connecting RCA to environmental stringency but to set trade policies in a wider framework, considering environmental concerns, as these are inseparable subjects. However, this study also provides relevant real-world implications that can support further research.Practical implicationsThe present study has important implications for textile exporters such as green innovations. The Porter hypothesis can be a beneficial tool for G20 exporters in enhancing their export performance, especially for the ones dealing in environmentally sensitive goods. This study offers relevant policy implications and provides directions for future research on global trade and environment nexus.Originality/valueThis study deals in a debatable area of research that evaluates the interlinkages between environmental stringency and global trade flows in the G20 countries. An important observation of the study is the asymmetrical nature of policy stringency across different countries and its impact on trade. The unavailability of updated data is the limitation of the present study.