A resource-based mechanistic framework for castration-resistant prostate cancer (CRPC).

Cancer therapy often leads to the selective elimination of drug-sensitive cells from the tumour. This can favour the growth of cells resistant to the therapeutic agent, ultimately causing a tumour relapse. Castration-resistant prostate cancer (CRPC) is a well-characterised instance of this phenomenon.

Population size shapes trade-off dilution and adaptation to a marginal niche unconstrained by sympatric habitual conditions.

How does niche expansion occur when the habitual (high-productivity) and marginal (low-productivity) niches are simultaneously available? Without spatial structuring, such conditions should impose fitness maintenance in the former while adapting to the latter. Hence, adaptation to a given marginal niche should be influenced by the identity of the simultaneously available habitual niche. This hypothesis remains untested.

Bacteria evolve macroscopic multicellularity by the genetic assimilation of phenotypically plastic cell clustering.

The evolutionary transition from unicellularity to multicellularity was a key innovation in the history of life. Experimental evolution is an important tool to study the formation of undifferentiated cellular clusters, the likely first step of this transition. Although multicellularity first evolved in bacteria, previous experimental evolution research has primarily used eukaryotes.

The effect of migration and variation on populations of Escherichia coli adapting to complex fluctuating environments.

Migration, a critical evolutionary force, can have contrasting effects on adaptation. It can aid as well as impede adaptation. The effects of migration on microbial adaptation have been studied primarily in simple constant environments.

Desiccation Stress Acts as Cause as well as Cost of Dispersal in .

AbstractEnvironmental stress is one of the important causes of biological dispersal. At the same time, the process of dispersal itself can incur and/or increase susceptibility to stress for the dispersing individuals. Therefore, in principle, stress can serve as both a cause and a cost of dispersal.

Interplay of population size and environmental fluctuations: A new explanation for fitness cost rarity in asexuals.

Theoretical models of ecological specialisation commonly assume that adaptation to one environment leads to fitness reductions (costs) in others. However, experiments often fail to detect such costs. We addressed this conundrum using experimental evolution with Escherichia coli in several constant and fluctuating environments at multiple population sizes.

Genomic signatures of UV resistance evolution in Escherichia coli depend on the growth phase during exposure.

Physiological states can determine the ability of organisms to handle stress. Does this mean that the same selection pressure will lead to different evolutionary outcomes, depending on the organisms' physiological state? If yes, what will be the genomic signatures of such adaptation(s)? We used experimental evolution in Escherichia coli followed by whole-genome whole-population sequencing to investigate these questions. The sensitivity of Escherichia coli to ultraviolet (UV) radiation depends on the growth phase during which it experiences the radiation.

Dispersal evolution diminishes the negative density dependence in dispersal.

In many organisms, dispersal varies with the local population density. Such patterns of density-dependent dispersal (DDD) are expected to shape the dynamics, spatial spread, and invasiveness of populations. Despite their ecological importance, empirical evidence for the evolution of DDD patterns remains extremely scarce.

Mate-finding dispersal reduces local mate limitation and sex bias in dispersal.

Sex-biased dispersal (SBD) often skews the local sex ratio in a population. This can result in a shortage of mates for individuals of the less-dispersive sex. Such mate limitation can lead to Allee effects in populations that are small or undergoing range expansion, consequently affecting their survival, growth, stability and invasion speed.

Larger bacterial populations evolve heavier fitness trade-offs and undergo greater ecological specialization.

Evolutionary studies over the last several decades have invoked fitness trade-offs to explain why species prefer some environments to others. However, the effects of population size on trade-offs and ecological specialization remain largely unknown. To complicate matters, trade-offs themselves have been visualized in multiple ways in the literature.

Adapting in larger numbers can increase the vulnerability of Escherichia coli populations to environmental changes.

Larger populations generally adapt faster to their existing environment. However, it is unknown if the population size experienced during evolution influences the ability to face sudden environmental changes. To investigate this issue, we subjected replicate Escherichia coli populations of different sizes to experimental evolution in an environment containing a cocktail of three antibiotics.

Complex interaction of resource availability, life-history and demography determines the dynamics and stability of stage-structured populations.

The dynamics of stage-structured populations facing stage-specific variability in resource availability and/or demographic factors like unequal sex-ratios, remains poorly understood. We addressed these issues using a stage-structured individual-based model that incorporates life-history parameters common to many holometabolous insects. The model was calibrated using time series data from a 49-generation experiment on laboratory populations of Drosophila melanogaster, subjected to four different combinations of larval and adult nutritional levels.

Sex differences in dispersal syndrome are modulated by environment and evolution.

Dispersal syndromes (i.e. suites of phenotypic correlates of dispersal) are potentially important determinants of local adaptation in populations.

Evolution of dispersal syndrome and its corresponding metabolomic changes.

Dispersal is one of the strategies for organisms to deal with climate change and habitat degradation. Therefore, investigating the effects of dispersal evolution on natural populations is of considerable interest to ecologists and conservation biologists. Although it is known that dispersal itself can evolve due to selection, the behavioral, life-history and metabolic consequences of dispersal evolution are not well understood.

Extent of adaptation is not limited by unpredictability of the environment in laboratory populations of Escherichia coli.

Environmental variability is on the rise in different parts of the earth, and the survival of many species depends on how well they cope with these fluctuations. Our current understanding of how organisms adapt to unpredictably fluctuating environments is almost entirely based on studies that investigate fluctuations among different values of a single environmental stressor such as temperature or pH. How would unpredictability affect adaptation when the environment fluctuates between qualitatively very different kinds of stresses? To answer this question, we subjected laboratory populations of Escherichia coli to selection over ~ 260 generations.

Environmental fluctuations do not select for increased variation or population-based resistance in Escherichia coli.

Little is known about the mechanisms that enable organisms to cope with unpredictable environments. To address this issue, we used replicate populations of Escherichia coli selected under complex, randomly changing environments. Under four novel stresses that had no known correlation with the selection environments, individual cells of the selected populations had significantly lower lag and greater yield compared to the controls.

Rethinking inheritance, yet again: inheritomes, contextomes and dynamic phenotypes.

In recent years, there have been many calls for an extended evolutionary synthesis, based in part upon growing evidence for nongenetic mechanisms of inheritance, i.e., similarities in phenotype between parents and offspring that are not due to shared genes.

Stabilizing spatially-structured populations through adaptive Limiter Control.

Stabilizing the dynamics of complex, non-linear systems is a major concern across several scientific disciplines including ecology and conservation biology. Unfortunately, most methods proposed to reduce the fluctuations in chaotic systems are not applicable to real, biological populations. This is because such methods typically require detailed knowledge of system specific parameters and the ability to manipulate them in real time; conditions often not met by most real populations.

A comparison of six methods for stabilizing population dynamics.

Over the last two decades, several methods have been proposed for stabilizing the dynamics of biological populations. However, these methods have typically been evaluated using different population dynamics models and in the context of very different concepts of stability, which makes it difficult to compare their relative efficiencies. Moreover, since the dynamics of populations are dependent on the life-history of the species and its environment, it is conceivable that the stabilizing effects of control methods would also be affected by such factors, a complication that has typically not been investigated.

Stabilizing biological populations and metapopulations through Adaptive Limiter Control.

Despite great interest in techniques for stabilizing the dynamics of biological populations and metapopulations, very few practicable methods have been developed or empirically tested. We propose an easily implementable method, Adaptive Limiter Control (ALC), for reducing the magnitude of fluctuation in population sizes and extinction frequencies and demonstrate its efficacy in stabilizing laboratory populations and metapopulations of Drosophila melanogaster. Metapopulation stability was attained through a combination of reduced size fluctuations however, and synchrony at the subpopulation level.

FlyCounter: a simple software for counting large populations of small clumped objects in the laboratory.

While several software programs exist to count bacterial colonies on a Petri plate, no suitable solution is available for quick and reliable enumeration of small, live insects. We have written a program called FlyCounter that can obtain counts from images, even if insects are highly clumped in space. We also describe a simple and inexpensive system for anesthetizing and capturing high-quality images of the small insects.