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Results for “experimental evolution”

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At least 217 records · Page 12Linked to original sources
PubMed1981

The evolution of experimentally induced hydrosalpinges in rabbits.

Damage to fallopian tubes caused by hydrosalpinges is a major reason for persisting infertility. We describe the mucosal changes that occur following induction of experimentally induced hydrosalpinges in 25 rabbits. Ampullary biopsies obtained at varying intervals were examined with light microscopy and scanning and transmission electron microscopy. Mucosal folds showed progressive atrophy. The epithelium was flattened. The population of ciliated cells decreased and, finally, deciliation became generalized. The morphology of nonciliated cells changed from an initial high content of granules of secretion to a final stage of vacuolated cytoplasm. Cell desquamation was common.

Animals↗
PubMed1978

[Influence of a hot environmental temperature on the evolution of experimental paludism of the mouse with Plasmodium berghei berghei].

Swiss Mice infected with Plasmodium berghei berghei and maintained in permanence in a hot environmental temperature undergo a chronic infection whereas controls maintained at the laboratory temperature develop always an acute and lethal infection. The hot environmental temperature does not seem to have any action on the pathogenicity of the parasites. Host defences are stimulated.

Animals↗
PubMed2006

Evolution under relaxed sexual conflict in the bulb mite Rhizoglyphus robini.

The experimental evolution under different levels of sexual conflict have been used to demonstrate antagonistic coevolution in muscids, but among other taxa a similar approach has not been employed. Here, we describe the results of 37 generations of evolution under either experimentally enforced monogamy or polygamy in the bulb mite Rhizoglyphus robini. Three replicates were maintained for each treatment. Monogamy makes male and female interests congruent; thus selection is expected to decrease harmfulness of males to their partners. Our results were consistent with this prediction in that females from monogamous lines achieved lower fecundity when housed with males from polygamous lines. Fecundity of polygamous females was not affected by mating system under which their partners evolved, which suggests that they were more resistant to male-induced harm. As predicted by the antagonistic coevolution hypothesis, the decrease in harmfulness of monogamous males was accompanied by a decline in reproductive competitiveness. In contrast, female fecundity and embryonic viability, which were not expected to be correlated with male harmfulness, did not differ between monogamous and polygamous lines. None of the fitness components assayed differed between individuals obtained from crosses between parents from the same line and those obtained from crosses between parents from different lines within the same mating system. This indicates that inbreeding depression did not confound our results. However, interpretation of our results is complicated by the fact that both males and females from monogamous lines evolved smaller body size compared to individuals from polygamous lines. Although a decrease in reproductive performance of males from monogamous lines was still significant when body size was taken into account, we were not able to separate the effects of male body size and mating system in their influence on fecundity of their female partners.

Animals↗
PubMed2001

Predicting the emergence of resistance to antifungal drugs.

The emergence of antifungal drug resistance is inevitable. Here I discuss antibiotic resistance in the context of the adaptive potential of fungi and I propose an approach to predicting the evolution of antifungal resistance using experimental evolution of DNA sequences and microbial populations. Prediction is based on determination of evolutionary potential at two levels, the gene and the genome. At the level of the gene, evolutionary potential depends on the sequence space of candidate resistance genes defined by the fitness effects of all possible mutations in all possible combinations. At the level of the genome, evolutionary potential depends on the adaptive landscape defined by the fitness effects of all possible interactions among alleles constituting the genotype.

Antifungal Agents↗
PubMed2025

Constraints in temperature adaptation reinforce differences in thermal niche between mesophilic and psychrotolerant Bacillus cereus group species.

Experimental evolution has demonstrated that mesophilic microbes readily adapt to increases in temperature. However, many microbes are psychrotolerant and resistant to cold, which is associated with physiological specializations, suggesting constraints in thermal adaptation. We hypothesized that constraints would limit adaption differently in a mesophilic species (Bacillus thuringiensis) compared with its psychrotolerant relative B. mycoides-with adaptation at cooler temperatures and adaptation at higher temperatures being constrained in each species, respectively. To test this hypothesis, we imposed 140 generations of selection at temperatures at and below the optimum for productivity for both species. The fitness and thermal performance of evolved bacteria showed ancestral thermal niche plays a role in thermal adaptation over this time scale, in support of our hypothesis of adaptive constraints. Temperature-dependent trade-offs appeared common in B. mycoides, with fitness gains associated with decreases in operational niche width; fitness gains at one temperature caused a decrease in the range of temperatures that the bacterium showed appreciable growth. Genome resequencing showed that variation in mutation supply and selection strength could not explain temperature-dependent responses to selection. Importantly, metabolic theory only held true for mesophilic B. thuringiensis, showing abundant but less studied psychrotolerant species could follow different adaptive trajectories.

Bacillus thuringiensis↗