Statistical method for testing the neutral mutation hypothesis by DNA polymorphism.

Systems linking people and nature, known as social-ecological systems, are increasingly understood as complex adaptive systems. Essential features of these complex adaptive systems – such as nonlinear feedbacks, strategic interactions, individual and spatial heterogeneity, and varying time scales – pose substantial challenges for modeling. However, ignoring these characteristics can distort our picture of how these systems work, causing policies to be less effective or even counterproductive. In this paper we present recent developments in modeling social-ecological systems, illustrate some of these challenges with examples related to coral reefs and grasslands, and identify the implications for economic and policy analysis.

Social-ecological systems as complex adaptive systems : modeling and policy implications

https://www.cell.com/trends/genetics/pdf/S0168-9525(08)00156-X.pdf

Sex chromosomes and speciation in Drosophila

The gene balance hypothesis states that the stoichiometry of members of multisubunit complexes affects the function of the whole because of the kinetics and mode of assembly Gene regulatory mechanisms also would be governed by these principles Here, we review the impact of this concept with regard to the effects on the genetics of quantitative traits, the fate of duplication of genes following polyploidization events or segmental duplication, the basis of aneuploid syndromes, the constraints on cis and trans variation in gene regulation and the potential involvement in hybrid incompatibilities

The Gene Balance Hypothesis: implications for gene regulation, quantitative traits and evolution

Dosage compensation is the crucial process that equalizes gene expression from the X chromosome between males (XY) and females (XX). In Drosophila, the male-specific lethal (MSL) ribonucleoprotein complex mediates dosage compensation by upregulating transcription from the single male X chromosome approximately twofold. A key challenge is to understand how the MSL complex distinguishes the X chromosome from autosomes. Recent studies suggest that this occurs through a multi-step targeting mechanism that involves DNA sequence elements and epigenetic marks associated with transcription. This review will discuss the relative contributions of sequence elements and transcriptional marks to the complete pattern of MSL complex binding.

/pdf/drosophila-dosage-compensation-a-complex-voyage-to-the-x-1cr1jymg9l.pdf

Drosophila dosage compensation: a complex voyage to the X chromosome.

In many taxa, males and females have unequal ratios of sex chromosomes to autosomes, which has resulted in the invention of diverse mechanisms to equilibrate gene expression between the sexes (dosage compensation). Failure to compensate for sex chromosome dosage results in male lethality in Drosophila. In Drosophila, a male-specific lethal (MSL) complex of proteins and noncoding RNAs binds to hundreds of sites on the single male X chromosome and up-regulates gene expression. Here we use population genetics of two closely related Drosophila species to show that adaptive evolution has occurred in all five protein-coding genes of the MSL complex. This positive selection is asymmetric between closely related species, with a very strong signature apparent in Drosophila melanogaster but not in Drosophila simulans. In particular, the MSL1 and MSL2 proteins have undergone dramatic positive selection in D. melanogaster, in domains previously shown to be responsible for their specific targeting to the X chromosome. This signature of positive selection at an essential protein-DNA interface of the complex is unexpected and suggests that X chromosomal MSL-binding DNA segments may themselves be changing rapidly. This highly asymmetric, rapid evolution of the MSL genes further suggests that misregulated dosage compensation may represent one of the underlying causes of male hybrid inviability in Drosophila, wherein the fate of hybrid males depends on which species' X chromosome is inherited.

Species-specific positive selection of the male-specific lethal complex that participates in dosage compensation in Drosophila.

The purpose of this research proposal was aimed at analyzing the existence of a significantly differential academic performance depending on the class modality: traditional face-to-face vs. remote face-to-face, in students of the psychology program, who were studying the subject of fundamentals of measurement and psychological evaluation in a higher education institution in the city of Barranquilla/Colombia. To achieve this objective, a study framed in the postpositivist paradigm was developed, based on quantitative, non-experimental, correlational, cross-sectional and field research. The sample consisted of 37 students, divided into two groups: Group 1 traditional face-to-face modality: 20 students and Group 2 remote face-to-face modality with an N of 17. For the analysis of the data, the t-test was applied, for independent samples, using the SPSS version 18 statistical package. The results allowed to establish the existence of a significantly higher academic performance that favors the group that studied the subject under the traditional face-to-face modality. Elements that could explain this superior performance under the traditional education format, have to do with low level of adaptability of those involved to this new way of developing the teaching-learning process, alteration and emotional management in the face of this new learning atmosphere, low experience and little preparation of students and the teacher to digital management and connection platforms for the development of classes from face-to-face remote, not having the right tools to be able to work effectively lowers the remote connection. 

Traditional Face-to-Face Educational Modality vs. Remote Face-to-Face: Its Impact on Academic Performance in the Context of the Covid 19 Pandemic

https://doi.org/10.1016/j.procs.2023.03.123

Monica A. Rodriguez

Papers

Species-specific positive selection of the male-specific lethal complex that participates in dosage compensation in Drosophila.

Traditional Face-to-Face Educational Modality vs. Remote Face-to-Face: Its Impact on Academic Performance in the Context of the Covid 19 Pandemic

Simulation Model of the Effect of the COVID-19 Biosecurity Protocol in the Queues for the Return to Face-to-Face Classes