Sex-specific spatial variation in fitness in the highly dimorphic Leucadendron rubrum.

Sexual dimorphism in plants may emerge as a result of sex-specific selection on traits enhancing access to nutritive resources and/or to sexual partners. Here we investigated sex-specific differences in selection of sexually dimorphic traits and in the spatial distribution of effective fecundity (our fitness proxy) in a highly dimorphic dioecious wind-pollinated shrub, Leucadendron rubrum. In particular, we tested for the effect of density on male and female effective fecundity.

Costs and benefits of multiple mating in a species with first-male sperm precedence.

Different patterns of sperm precedence are expected to entail different costs and benefits of mating for each sex that translate into distinct predictions regarding mating system evolution. Still, most studies addressing these costs and benefits have focused on species with mixed paternity or last male precedence, neglecting first-male sperm precedence. We attempted to understand whether this latter pattern of sperm precedence translates into different costs and benefits for each sex in the haplodiploid spider mite Tetranychus urticae, a species in which female multiple mating is prevalent but most offspring are sired by first males.

Endosymbiont diversity and prevalence in herbivorous spider mite populations in South-Western Europe.

Bacterial endosymbionts are known as important players of the evolutionary ecology of their hosts. However, their distribution, prevalence and diversity are still largely unexplored. To this aim, we investigated infections by the most common bacterial reproductive manipulators in herbivorous spider mites of South-Western Europe.

Male spider mites use chemical cues, but not the female mating interval, to choose between mates.

The choice of the partner an individual will mate with is expected to strongly impact its fitness. Hence, natural selection has favoured the evolution of cues to distinguish among mates that will provide different fitness benefits to the individual that is choosing. In species with first-male sperm precedence, this is particularly important for males, as mating with mated females will result in no offspring.

Why evolution matters for species conservation: perspectives from three case studies of plant metapopulations.

We advocate the advantage of an evolutionary approach to conservation biology that considers evolutionary history at various levels of biological organization. We review work on three separate plant taxa, spanning from one to multiple decades, illustrating extremes in metapopulation functioning. We show how the rare endemics Centaurea corymbosa (Clape Massif, France) and Brassica insularis in Corsica (France) may be caught in an evolutionary trap: disruption of metapopulation functioning due to lack of colonization of new sites may have counterselected traits such as dispersal ability or self-compatibility, making these species particularly vulnerable to any disturbance.

Effects of host plant on life-history traits in the polyphagous spider mite Tetranychus urticae.

Studying antagonistic coevolution between host plants and herbivores is particularly relevant for polyphagous species that can experience a great diversity of host plants with a large range of defenses. Here, we performed experimental evolution with the polyphagous spider mite Tetranychus urticae to detect how mites can exploit host plants. We thus compared on a same host the performance of replicated populations from an ancestral one reared for hundreds of generations on cucumber plants that were shifted to either tomato or cucumber plants.

Local mate competition mediates sexual conflict over sex ratio in a haplodiploid spider mite.

In haplodiploids, females pass their genes on to all their offspring, whereas a male's genes are only passed on to his daughters. Hence, males always benefit from female-biased sex ratios, whereas for females the optimal offspring sex ratio depends on the level of local mate competition (LMC), ranging from highly female-biased under strict LMC to unbiased in Panmixia. This generates a sexual conflict over sex ratio, the intensity of which depends on the LMC level, with most intense conflict in Panmixia.

Convergent and correlated evolution of major life-history traits in the angiosperm genus Leucadendron (Proteaceae).

Natural selection is expected to cause convergence of life histories among taxa as well as correlated evolution of different life-history traits. Here, we quantify the extent of convergence of five key life-history traits (adult fire survival, seed storage, degree of sexual dimorphism, pollination mode, and seed-dispersal mode) and test hypotheses about their correlated evolution in the genus Leucadendron (Proteaceae) from the fire-prone South African fynbos. We reconstructed a new molecular phylogeny of this highly diverse genus that involves more taxa and molecular markers than previously.

Developing nuclear DNA phylogenetic markers in the angiosperm genus Leucadendron (Proteaceae): a next-generation sequencing transcriptomic approach.

Despite the recent advances in generating molecular data, reconstructing species-level phylogenies for non-models groups remains a challenge. The use of a number of independent genes is required to resolve phylogenetic relationships, especially for groups displaying low polymorphism. In such cases, low-copy nuclear exons and non-coding regions, such as 3' untranslated regions (3'-UTRs) or introns, constitute a potentially interesting source of nuclear DNA variation.

The joint evolution of dispersal and dormancy in a metapopulation with local extinctions and kin competition.

Dispersal and dormancy are two strategies that allow recolonization of empty patches and escape from kin competition. Because they presumably respond to similar evolutionary forces, it is tempting to consider that these strategies may substitute for each other. Yet in order to predict the outcome of the evolution of dispersal and dormancy, and to characterize the emerging covariation between both traits, it is necessary to consider models where dispersal and dormancy evolve jointly.

Sex-ratio adjustment in response to local mate competition is achieved through an alteration of egg size in a haplodiploid spider mite.

Sex-ratio adjustments are commonly observed in haplodiploid species. However, the underlying proximate mechanisms remain elusive. We investigated these mechanisms in Tetranychus urticae, a haplodiploid spider mite known to adjust sex ratio in response to the level of local mate competition (LMC).

Experimental evolution.

Experimental evolution is the study of evolutionary processes occurring in experimental populations in response to conditions imposed by the experimenter. This research approach is increasingly used to study adaptation, estimate evolutionary parameters, and test diverse evolutionary hypotheses. Long applied in vaccine development, experimental evolution also finds new applications in biotechnology.

Mating modifies female life history in a haplodiploid spider mite.

Mating usually modifies females' resource allocation pattern, often as a result of conflicts between male and female partners. Can such a switch occur even in the absence of sexual conflicts? We addressed this issue in the haplodiploid spider mite Tetranychus urticae, whose biology and population structure considerably reduce conflicts between males and females over reproductive decisions. Comparing virgin and mated females, we tested the hypothesis that mated females modify their allocation pattern so as to maximize their probability of producing daughters.

Monitoring adaptive genetic responses to environmental change.

Widespread environmental changes including climate change, selective harvesting and landscape alterations now greatly affect selection regimes for most organisms. How animals and plants can adapt to these altered environments via contemporary evolution is thus of strong interest. We discuss how to use genetic monitoring to study adaptive responses via repeated analysis of the same populations over time, distinguishing between phenotypic and molecular genetics approaches.

Heritability and artificial selection on ambulatory dispersal distance in Tetranychus urticae: effects of density and maternal effects.

Dispersal distance is understudied although the evolution of dispersal distance affects the distribution of genetic diversity through space. Using the two-spotted spider mite, Tetranychus urticae, we tested the conditions under which dispersal distance could evolve. To this aim, we performed artificial selection based on dispersal distance by choosing 40 individuals (out of 150) that settled furthest from the home patch (high dispersal, HDIS) and 40 individuals that remained close to the home patch (low dispersal, LDIS) with three replicates per treatment.

Experimental evolution of reduced sex ratio adjustment under local mate competition.

Theory predicts that local mate competition (LMC) favors the evolution of female-biased sex ratios. Empirical support of this prediction is indirect and comes from comparative studies or from studies showing that individuals can adjust their offspring sex ratio in response to varying LMC intensities. Replicate lines from a population of the spider mite Tetranychus urticae were selected under three LMC intensities for up to 54 generations.

Sex allocation in haplodiploids is mediated by egg size: evidence in the spider mite Tetranychus urticae Koch.

Haplodiploid species display extraordinary sex ratios. However, a differential investment in male and female offspring might also be achieved by a differential provisioning of eggs, as observed in birds and lizards. We investigated this hypothesis in the haplodiploid spider mite Tetranychus urticae, which displays highly female-biased sex ratios.

Live where you thrive: joint evolution of habitat choice and local adaptation facilitates specialization and promotes diversity.

We derive a comprehensive overview of specialization evolution based on analytical results and numerical illustrations. We study the separate and joint evolution of two critical facets of specialization-local adaptation and habitat choice-under different life cycles, modes of density regulation, variance-covariance structures, and trade-off strengths. A particular feature of our analysis is the investigation of arbitrary trade-off functions.

Darwin's wind hypothesis: does it work for plant dispersal in fragmented habitats?

Using the wind-dispersed plant Mycelis muralis, we examined how landscape fragmentation affects variation in seed traits contributing to dispersal. Inverse terminal velocity (Vt(-1)) of field-collected achenes was used as a proxy for individual seed dispersal ability. We related this measure to different metrics of landscape connectivity, at two spatial scales: in a detailed analysis of eight landscapes in Spain and along a latitudinal gradient using 29 landscapes across three European regions.

Are adaptation costs necessary to build up a local adaptation pattern?

Background: Ecological specialization is pervasive in phytophagous arthropods. In such specialization mode, limits to host range are imposed by trade-offs preventing adaptation to several hosts. The occurrence of such trade-offs is inferred by a pattern of local adaptation, i.

Evolution of cannibalism and female's response to oviposition-deterring pheromone in aphidophagous predators.

1. Egg cannibalism by larvae is common in Coccinellidae and is known to be advantageous for the cannibals. Furthermore, larvae of aphidophagous ladybirds usually produce an oviposition-deterring pheromone (ODP), which inhibits oviposition by adult females.

Alternative mechanisms of range expansion are associated with different changes of evolutionary potential.

Human-induced and natural range expansion of species are expected to lead to different patterns of genetic diversity, which might themselves be trait dependent. Recent studies examined the molecular and quantitative genetic variation following the range expansion of three plant species. The results suggest that contrasting diversity patterns among species reflect how range expansion has occurred and the level of fragmentation of the original habitat.

Genetic, ecological, behavioral and geographic differentiation of populations in a thistle weevil: implications for speciation and biocontrol.

Because weevils are used as biocontrol agents against thistles, it is important to document and understand host shifts and the evolution of host-specificity in these insects. Furthermore, such host shifts are of fundamental interest to mechanisms of speciation. The mediterranean weevil Larinus cynarae normally parasitizes either one of two thistle genera, Onopordum and Cynara, being locally monophagous.

Horizontal gene transfer and homologous recombination drive the evolution of the nitrogen-fixing symbionts of Medicago species.

Using nitrogen-fixing Sinorhizobium species that interact with Medicago plants as a model system, we aimed at clarifying how sex has shaped the diversity of bacteria associated with the genus Medicago on the interspecific and intraspecific scales. To gain insights into the diversification of these symbionts, we inferred a topology that includes the different specificity groups which interact with Medicago species, based on sequences of the nodulation gene cluster. Furthermore, 126 bacterial isolates were obtained from two soil samples, using Medicago truncatula and Medicago laciniata as host plants, to study the differentiation between populations of Sinorhizobium medicae, Sinorhizobium meliloti bv.