Sexual selection and the evolution of obligatory sex

<p>Abstract</p> <p>Background</p> <p>Among the long-standing conundrums of evolutionary theory, obligatory sex is one of the hardest. Current theory suggests multiple factors that might explain the benefits of sex when compared with complete asexuality, but no satisfactory explanation for the prevalence of obligatory sex in the face of facultative sexual reproduction.</p> <p>Results and Conclusion</p> <p>We show that when sexual selection is present obligatory sex can evolve and be maintained even against facultative sex, under common scenarios of deleterious mutations and environmental changes.</p

Emergence of Memory-Driven Command Neurons in Evolved Artificial Agents

Using evolutionary simulations we develop autonomous agents controlled by articial neural networks (ANNs). In simple life-like tasks of foraging and navigation, high performance levels are attained by agents equipped with fully-recurrent ANN controllers. In a set of experiments sharing the same behavioural task but diering in the sensory input available to the agents, we nd a common structure of a command neuron switching the dynamics of the network between radically dierent behavioural modes. When sensory position information is available the command neuron reects a map of the environment, acting as a location-dependent cell sensitive to the location and orientation of the agent. When such information is unavailable the command neuron&apos;s activity is based on a spontaneously evolving short-term memory mechanism, which underlies its apparent place-sensitive activity. A two-parameter stochastic model for this memory mechanism is proposed. We show that the parameter value..

Why is stress so deadly? An evolutionary perspective

The reaction of the body to prolonged stress has many harmful effects. Classical theory assumes that stress responses have evolved due to their short-term selective advantages (‘flight or fight’), and despite their adverse long-term effects. In contrast, we demonstrate that the adverse effects of stress responses may have a selective advantage. Using an analytical model we show that a gene that causes the early death of a relatively unfit individual can increase in frequency in a structured population even if it has no positive effect on that individual. This result offers a new perspective on the relations between stress factors, stress responses and stress-related diseases

Fibrolamellar carcinoma transcriptomic-based treatment prediction: complete response after nivolumab and ipilimumab

Fibrolamellar carcinoma (FLC) is a rare cancer of the liver that most commonly affects children and young adults. There is no clear standard of care for the disease, whose response to treatment seems to be very different from that of hepatocellular carcinoma. We present a case of FLC in a patient in her mid 30s that recurred and persisted despite resection and multiple lines of treatment. Following transcriptomic analysis, a combination of ipilimumab (anti-CTLA4) and nivolumab (anti-PD-1) led to complete remission, although common biomarkers for immune checkpoint blockade were all negative in this case. The patient is still in remission. Here, combined checkpoint blockade guided by novel transcriptomic analysis led to complete remission after failure of several lines of treatment