Proteome allocation and the evolution of metabolic cross-feeding.

In a common instance of metabolic cross-feeding (MCF), an organism incompletely metabolizes nutrients and releases metabolites that are used by another to produce energy or building blocks. Why would the former waste edible food, and why does this preferentially occur at specific locations in a metabolic pathway have challenged evolutionary theory for decades. To address these questions, we combine adaptive dynamics with an explicit model of cell metabolism, including enzyme-driven catalysis of metabolic reactions and the cellular constraints acting on the proteome that may incur a cost to expressing all enzymes along a pathway.

Hormonal pleiotropy and the evolution of allocation trade-offs.

Recent empirical evidence suggests that trade-off relationships can evolve, challenging the classical image of their high entrenchment. For energy reliant traits, this relationship should depend on the endocrine system that regulates resource allocation. Here, we model changes in this system by mutating the expression and conformation of its constitutive hormones and receptors.

Robust Frankia phylogeny, species delineation and intraspecies diversity based on Multi-Locus Sequence Analysis (MLSA) and Single-Locus Strain Typing (SLST) adapted to a large sample size.

Diazotrophic Actinobacteria of the genus Frankia represent a challenge to classical bacterial taxonomy as they include many unculturable strains. As a consequence, we still have a poor understanding of their diversity, evolution and biogeography. In this study, a Multi-Locus Sequence Analysis (MLSA) using atpD, dnaA, ftsZ, pgk, and rpoB loci was done on a large set of cultured and uncultured strains, compared to 16S rRNA and correlated to Average Nucleotide Identity (ANI) from available Frankia genomes.

The Biased Evolution of Generation Time.

Many life-history traits are important determinants of the generation time. For instance, semelparous species whose adults reproduce only once have shorter generation times than iteroparous species that reproduce on several occasions, assuming equal development duration. A shorter generation time ensures a higher growth rate in stable environments where resources are in excess and is therefore a positively selected feature in this situation.

Haematophagy is costly: respiratory patterns and metabolism during feeding in Rhodnius prolixus.

Feeding on the blood of vertebrates is a risky task for haematophagous insects and it can be reasonably assumed that it should also be costly in terms of energetic expenditure. Blood circulates inside vessels and it must be pumped through narrow tubular stylets to be ingested. We analysed the respiratory pattern and the energetic cost of taking a blood meal in Rhodnius prolixus using flow-through and stop-flow respirometry to measure carbon dioxide emission, oxygen consumption and water loss before and during feeding.

Invasion speeds of Triatoma dimidiata, vector of Chagas disease: An application of orthogonal polynomials method.

Demographic processes and spatial dispersal of Triatoma dimidiata, a triatomine species vector of Chagas disease, are modeled by integrodifference equations to estimate invasion capacity of this species under different ecological conditions. The application of the theory of orthogonal polynomials and the steepest descent method applied to these equations, allow a good approximation of the abundance of the adult female population and the invasion speed. We show that: (1) under the same mean conditions of demography and dispersal, periodic spatial dispersal results in an invasion speed 2.

Life History Traits and Demographic Parameters of Triatoma infestans (Hemiptera: Reduviidae) Fed on Human Blood.

Triatoma infestans (Klug, 1834) (Hemiptera: Reduviidae), the main vector of Chagas disease in South America, feeds primarily on humans, but ethical reasons preclude carrying out demographical studies using people. Thus, most laboratory studies of T. infestans are conducted using bird or mammal live hosts that may result in different demographic parameters from those obtained on human blood.

In-planta sporulation phenotype: a major life history trait to understand the evolution of Alnus-infective Frankia strains.

Two major types of Frankia strains are usually recognized, based on the ability to sporulate in-planta: spore-positive (Sp+) and spore-negative (Sp-). We carried out a study of Sp+ and Sp- Frankia strains based on nodules collected on Alnus glutinosa, Alnus incana and Alnus viridis. The nodules were phenotyped using improved histology methods, and endophytic Frankia strain genotype was determined using a multilocus sequence analysis approach.

The evolution of bet hedging in response to local ecological conditions.

Genotypes that hedge their bets can be favored by selection in an unpredictably varying environment. Bet hedging can be achieved by systematically expressing several phenotypes, such as one that readily attempts to reproduce and one that procrastinates in a dormant stage. But how much of each phenotype should a genotype express? Theory predicts that evolving bet-hedging strategies depend on local environmental variation, on how the population is regulated, and on exchanges with neighboring populations.

Large-scale patterns in morphological diversity and species assemblages in Neotropical Triatominae (Heteroptera: Reduviidae).

We analysed the spatial variation in morphological diversity (MDiv) and species richness (SR) for 91 species of Neotropical Triatominae to determine the ecological relationships between SR and MDiv and to explore the roles that climate, productivity, environmental heterogeneity and the presence of biomes and rivers may play in the structuring of species assemblages. For each 110 km x 110 km-cell on a grid map of America, we determined the number of species (SR) and estimated the mean Gower index (MDiv) based on 12 morphological attributes. We performed bootstrapping analyses of species assemblages to identify whether those assemblages were more similar or dissimilar in their morphology than expected by chance.

From income to capital breeding: when diversified strategies sustain species coexistence.

There is empirical evidence of many diversified ways for energy to be acquired and allocated to reproduction, notably with strategies ranging from strict income breeding (females fueling their gametes with energy gained concomitantly during reproduction) to strict capital breeding (females storing nutrients prior reproduction). Until now, the question of whether diversification of these strategies might impact the way communities are organized has not been considered. Here, we suggest that diversified resource allocation strategies among competing species may contribute to their coexistence.

Influence of vectors' risk-spreading strategies and environmental stochasticity on the epidemiology and evolution of vector-borne diseases: the example of Chagas' disease.

Insects are known to display strategies that spread the risk of encountering unfavorable conditions, thereby decreasing the extinction probability of genetic lineages in unpredictable environments. To what extent these strategies influence the epidemiology and evolution of vector-borne diseases in stochastic environments is largely unknown. In triatomines, the vectors of the parasite Trypanosoma cruzi, the etiological agent of Chagas' disease, juvenile development time varies between individuals and such variation most likely decreases the extinction risk of vector populations in stochastic environments.

Endosymbiont diversity among sibling weevil species competing for the same resource.

Background: Whereas the impact of endosymbionts on the ecology of their hosts is well known in some insect species, the question of whether host communities are influenced by endosymbionts remains largely unanswered. Notably, the coexistence of host species competing with each other, which is expected to be stabilized by their ecological differences, could be facilitated by differences in their endosymbionts. Yet, the composition of endosymbiotic communities housed by natural communities of competing host species is still almost unknown.

Emergence and prevalence of human vector-borne diseases in sink vector populations.

Vector-borne diseases represent a major public health concern in most tropical and subtropical areas, and an emerging threat for more developed countries. Our understanding of the ecology, evolution and control of these diseases relies predominantly on theory and data on pathogen transmission in large self-sustaining 'source' populations of vectors representative of highly endemic areas. However, there are numerous places where environmental conditions are less favourable to vector populations, but where immigration allows them to persist.

Coexistence of insect species competing for a pulsed resource: toward a unified theory of biodiversity in fluctuating environments.

Background: One major challenge in understanding how biodiversity is organized is finding out whether communities of competing species are shaped exclusively by species-level differences in ecological traits (niche theory), exclusively by random processes (neutral theory of biodiversity), or by both processes simultaneously. Communities of species competing for a pulsed resource are a suitable system for testing these theories: due to marked fluctuations in resource availability, the theories yield very different predictions about the timing of resource use and the synchronization of the population dynamics between the competing species. Accordingly, we explored mechanisms that might promote the local coexistence of phytophagous insects (four sister species of the genus Curculio) competing for oak acorns, a pulsed resource.

Natural peroxisome proliferator-activated receptor-alpha agonist cream demonstrates similar therapeutic response to topical steroids in atopic dermatitis.

Background: Atopic dermatitis (AD) requires permanent skin care.

Objective: A cream containing 2% SO (sunflower oleodistillate), with peroxisome proliferator-activated receptor-alpha (PPAR-α) agonist properties, has been compared to a topical steroid (hydrocortisone butyro-propionate 1 mg/g).

Methods: An open, randomized study included two groups of 40 children (aged 3 months to 4 years).

Adaptive developmental delay in Chagas disease vectors: an evolutionary ecology approach.

Background: The developmental time of vector insects is important in population dynamics, evolutionary biology, epidemiology and in their responses to global climatic change. In the triatomines (Triatominae, Reduviidae), vectors of Chagas disease, evolutionary ecology concepts, which may allow for a better understanding of their biology, have not been applied. Despite delay in the molting in some individuals observed in triatomines, no effort was made to explain this variability.

Spatially heterogeneous stochasticity and the adaptive diversification of dormancy.

Diversified bet-hedging, a strategy that leads several individuals with the same genotype to express distinct phenotypes in a given generation, is now well established as a common evolutionary response to environmental stochasticity. Life-history traits defined as diversified bet-hedging (e.g.

Adaptive dynamics of dormancy duration variability: evolutionary trade-off and priority effect lead to suboptimal adaptation.

Many plants, insects, and crustaceans show within-population variability in dormancy length. The question of whether such variability corresponds to a genetic polymorphism of pure strategies or a mixed bet-hedging strategy, and how the level of phenotypic variability can evolve remain unknown for most species. Using an eco-genetic model rooted in a 25-year ecological field study of a Chestnut weevil, Curculio elephas, we show that its diapause-duration variability is more likely to have evolved by the spread of a bet-hedging strategy than by the establishment of a genetic polymorphism.

Variations in sex ratio, feeding, and fecundity of Triatoma dimidiata (Hemiptera: Reduviidae) among habitats in the Yucatan Peninsula, Mexico.

Chagas' disease is a major public health concern in most Latin American countries and its prevention is based on insect vector control. Previous work showed that in the Yucatan peninsula of Mexico, houses are transiently infested by adult Triatoma dimidiata, which then fail to establish sustained colonies. The present study was designed to evaluate the seasonality and possible causes of the dispersal of sylvatic T.

An agent-based model for predicting the prevalence of Trypanosoma cruzi I and II in their host and vector populations.

Trypanosoma cruzi is the causative agent of Chagas disease, an endemic human parasitosis in Latin America. This protozoan is transmitted to human and other mammals by blood-feeding bugs belonging to the Triatominae subfamily. There are two strains (T.

Prolonged diapause: a trait increasing invasion speed?

Invasive species are considered to be the second cause of biodiversity erosion, and one challenge is to determine the life history traits that cause an increased invasion capacity. Prolonged diapause is a major trait in evolution and insect population dynamics, but its effects on invasion speed remain unknown. From a recently developed mathematical approach (integro-difference equations) applied to the insect dormancy, we show that despite a dispersal cost, bet-hedging diapause strategies with low (0.

Demographic and dispersal constraints for domestic infestation by non-domicilated chagas disease vectors in the Yucatan Peninsula, Mexico.

Chagas disease is one of the most important diseases in Latin America. Insecticides have been sprayed to control domiciliated vectors. However, some triatomine species are not strictly domiciliated, and the transmission risk posed by immigrants is identified as a major challenge.

Unexpected male choosiness for mates in a spider.

Sexual selection theory traditionally considers choosiness for mates to be negatively related to intra-sexual competition. Males were classically considered to be the competing, but not the choosy, sex. However, evidence of male choosiness is now accumulating.

Assessment of Triatoma dimidiata dispersal in the Yucatan Peninsula of Mexico by morphometry and microsatellite markers.

In the Yucatán Peninsula of Mexico, the main vector of Chagas disease is Triatoma dimidiata. Field studies suggest that natural transmission occurs through transient and seasonal invasion of houses by sylvatic/peridomestic triatomines, rather than through persistent domiciliated bug populations. We investigated the genetic structure of T.