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Drosophila suzukii (Matsumura) (Diptera: Drosophila) is an invasive frugivore and has become a significant pest of small fruit, cherry and grape throughout the United States. It may be possible to determine if a Virginia vineyard is at risk of D. suzukii infestation by analyzing the biotic and abiotic factors around each vineyard. This pest is known to utilize a wide range of cultivated and wild host plants. A host plant survey was conducted at four vineyards in the Piedmont Region of Virginia to identify hosts used by D. suzukii around vineyards. The seasonal availability of host plants and adult emergence from them were tracked. Six host plant species of D. suzukii were identified, some available season-long. Monitoring D. suzukii in cultivated crops is crucial for the timing of spray applications. Homemade and commercially available baits and traps were deployed in two vineyards to determine the efficacy and selectivity towards D. suzukii. The homemade and commercially available baits that contained red wine caught the most D. suzukii, but none were exclusively attractive to D. suzukii. Wine grape susceptibility was assessed in laboratory choice and no-choice ovipositional bioassays. Ovipositional susceptibility was determined by measuring the physiological and morphological parameters using six wine grape varieties. More eggs were laid in grapes as penetration force decreased. Penetration force and not skin thickness was the limiting factor for oviposition. Survivorship of eggs laid in intact grapes was analyzed and survivorship to adulthood was dependent upon variety and survivorship usually exceeded 9% survival seen in previous studies. Larval developmental parameters of D. suzukii were affected by grape variety and the density of Z. indianus. D. suzukii mortality was increased in most cases when in competition with Z. indianus, but was less pronounced when reared in Viognier grapes. My Z. indianus oviposition study demonstrated that they will follow injury created by D. suzukii, and then the Z. indianus larvae may outcompete D. suzukii within the berries. These studies greatly improved our understanding of D. suzukii biology and ecology in Virginia vineyards. / Ph. D.

Understanding variation in key functional traits across gradients in high diversity systems and the ecology of community changes along gradients in these systems is crucial in light of conservation and climate change. We examined inter- and intraspecific variation in leaf mass per area (LMA) of sun and shade leaves along a 3330-m elevation gradient in Peru, and in sun leaves across a forest-savanna vegetation gradient in Brazil. We also compared LMA variance ratios (T-statistics metrics) to null models to explore internal (i.e., abiotic) and environmental filtering on community structure along the gradients. Community- weighted LMA increased with decreasing forest cover in Brazil, likely due to increased light availability and water stress, and increased with elevation in Peru, consistent with the leaf economic spectrum strategy expected in colder, less productive environments. A very high species turnover was observed along both environmental gradients, and consequently, the first source of variation in LMA was species turnover. Variation in LMA at the genus or family levels was greater in Peru than in Brazil. Using dominant trees to examine possible filters on community assembly, we found that in Brazil, internal filtering was strongest in the forest, while environmental filtering was observed in the dry savanna. In Peru, internal filtering was observed along 80% of the gradient, perhaps due to variation in taxa or interspecific competition. Environmental filtering was observed at cloud zone edges and in lowlands, possibly due to water and nutrient availability, respectively. These results related to variation in LMA indicate that biodiversity in species rich tropical assemblages may be structured by differential niche-based processes. In the future, specific mechanisms generating these patterns of variation in leaf functional traits across tropical environmental gradients should be explored.

This study investigates the hybridization of two species of cattails, Typha latifolia (Common Cattail) and T. angustifolia (Narrow-leaved Cattail) in the Czech Republic. The aim of this study was to determine, how often T. latifolia and T. angustifolia hybridize, whether hybridization is allowed by overlapping flowering time of these species and whether it is possible these species controlled cross in a culture. For detection of hybrid individuals were used microsatellite DNA markers, which allow to detect hybridization events and differentiate hybrids from the parental species. Molecular analysis revealed that hybridization of T. latifolia and T. angustifolia occurs in the Czech Republic, but it is not frequent. Of the 267 analyzed individuals, 130 individuals were pure species T. latifolia, 108 individuals pure species T. angustifolia and 29 individuals were hybrids. Of the hybrids, 23 were advanced hybrids, 5 were backcrosses and only one individual was F1 hybrid. Flowering time of T. latifolia and T. angustifolia overlaps, which allows hybridization, and flowering time to not act as a prezygotic reproductive isolation barrier and gametes T. latifolia and T. angustifolia can blend together. In controlled crosses the female spikes T. latifolia and T. angustifolia created seeds, but these were...

La décomposition des litières est un processus clé du fonctionnement du sol contribuant à de nombreux services écosystémiques. En climat tempéré, les lombriciens en interaction avec les micro-organismes du sol, contribuent significativement à ce processus. Cependant, les connaissances sur les lombriciens ciblent le plus souvent les trois catégories écologiques selon lesquelles ils sont définis : les épigés, les endogés et les anéciques. Les anéciques sont très répandus dans les sols tempérés, constituent la majeur partie de la biomasse lombricienne et interviennent dans la décomposition des litières. Plusieurs études ont observé des traits comportementaux, morphologiques et physiologiques distinguant deux sous-catégories au sein des anéciques : les épi-anéciques et les anéciques stricts. Le premier objectif de ce travail de thèse était de vérifier si cette distinction avait une réalité dans le cadre du processus de décomposition des litières. En conditions contrôlées, nous avons évalué (i) le rôle des principales espèces anéciques dans le processus de décomposition, (ii) l’impact de ces espèces sur les communautés de microorganismes et (iii) les activités enzymatiques des microorganismes du sol et (vi) l’impact des interactions entre espèces anéciques sur le processus de décomposition. A partir d’observations sur le terrain, le second objectif de ce travail de thèse était de définir les règles d’assemblages des communautés lombriciennes en prairie compte-tenu de leurs rôles majeurs dans divers processus du sol. Les résultats obtenus ont confirmé la distinction entre lombriciens anéciques stricts et épi-anéciques : les épi-anéciques étant les seuls à contribuer au processus de décomposition des litières et celui-ci étant corrélé à la biomasse individuelle moyenne de chaque espèce. Cette contribution passe par une plus forte stimulation des activités enzymatiques du sol, indépendamment des espèces considérées. En revanche, contrairement aux bactéries, les communautés fongiques du sol dépendent de l’espèce épi-anécique avec laquelle ils interagissent. Ce travail met également en évidence que l’abondance, la biomasse et la diversité des communautés lombriciennes des sols prairiaux sont régulées par différents filtres environnementaux dont la diversité du paysage. Cette thèse met en évidence que les deux sous-catégories écologiques au sein des anéciques ont des rôles différents sur le processus de décomposition des litières et qu’elles contribuent donc à des services écosystémiques fournis par le sol de manière différenciée. / Litter decomposition is a key process in soil functioning that contributes to many ecosystem services. In temperate climates, earthworms interacting with soil microorganisms contribute significantly to this process. However, knowledge about earthworms most often targets the three ecological categories in which they are defined: epigeics, endogeics and anecics. Anecics are very common in temperate soils, constitute the major part of the earthworm biomass and are involved in the litter decomposition. Several studies have observed behavioral, morphological and physiological traits that distinguish two subcategories within anecics: epi-anecics and strict-anecics. The first objective of this thesis was to verify if this distinction had a reality in the context of the litter decomposition process. Under controlled conditions, we evaluated (i) the role of the main anecic earthworm species in the decomposition process, (ii) the impact of these species on microorganism communities and (iii) soil enzymatic activities and (vi) the impact of interactions between anecic species on the decomposition process. Taking into account their major roles in various soil processes, based on field observations, the second objective of this thesis was to define the assembly of earthworm communities in grassland, The results obtained confirmed the distinction between epi and strict-anecic earthworms: only epic-anecics contribute to the litter decomposition process, which is correlated to the average individual biomass of each species. This contribution involved a greater stimulation of soil enzymatic activities, regardless of the species considered. In contrast to bacteria, soil fungal communities depend on the epi-anecic earthworm species with which they interact. This work also highlights that the abundance, biomass and diversity of earthworm communities in grassland soils are regulated by different environmental filters, including landscape diversity. This thesis highlights that the two ecological subcategories within the anecic category have different roles in the litter decomposition process and therefore contribute to ecosystem services provided by the soil in a differentiated way.

La flore adventice est à la base des chaînes trophiques dans les agroécosystèmes. Leur diminution dans les parcelles cultivées est une des causes de la baisse de la biodiversité. Par conséquent, des alternatives sont étudiées pour diminuer l’utilisation des herbicides dans le cadre du plan ECOPHYTO. Par exemple, la gestion de la flore adventice via les consommateurs de graines. En effet, les agroécosystèmes sont des milieux où des espèces granivores ont les capacités de consommer les graines d’adventices. Parmi les vertébrés, nous pouvons y trouver des oiseaux (alouette des champs) ainsi que des micromammifères (mulot). Parmi les invertébrés, les carabes sont identifiés comme principaux granivores dans les agroécosystèmes tempérés. L’objectif général de cette thèse est d’étudier les interactions entre carabes et graines d’adventices afin d’apporter des connaissances sur les interactions interspécifiques et d’identifier les traits physiologiques des espèces influençant la force des interactions entre les espèces. Un protocole a été établi afin de standardiser toutes les expériences et de garder comme variables uniquement l’espèce de graines et celle du carabe. Ensuite, nous avons étudié les interactions entre les graines d’adventices et les carabes selon deux axes de recherche. Le premier a permis de comparer les niveaux de consommation de la communauté de carabes sur une même espèce de graines. Nous avons pu ainsi observer que la masse corporelle des carabes n’était pas en relation avec la variation des niveaux de consommation. Mais le ratio entre la longueur des mandibules et la largeur du labrum (force mandibulaire) a un effet significatif lorsque seules les espèces consommant plus de cinq graines sont prises en compte. Pour le deuxième axe, nous avons mesuré la consommation des carabes sur 42 espèces de graines pour identifier les capacités de consommation et explorer la stratégie d’alimentation selon deux caractéristiques : la masse des graines (taille) et leur concentration lipidique. Les graines de faibles masses avec un taux lipidique élevé sont mangées en plus grand nombre. Enfin, nous avons déterminé les types de réponse fonctionnelle pour évaluer le potentiel de régulation de 4 espèces de carabes sur deux espèces de graines d’adventices. Pour chaque espèce (mâle et femelle) nous avons trouvé une réponse fonctionnelle de type II, sauf pour les femelles de P.rufipes. Cependant nos résultats doivent être interprétés avec précaution car en milieu naturel d’autres facteurs interviennent dans les interactions, telle que la présence de proies alternatives ou d’autres prédateurs. En conclusion, nous montrons que les interactions entre les graines d’adventices et les carabes sont nombreuses et complexes. Les caractéristiques physiologiques intervenant dans les interactions sont très nombreuses et très variables selon les espèces. Des études supplémentaires sont nécessaires pour évaluer l’intérêt agronomique des carabes dans la gestion des adventices. / Weed flora limits crop yields therefore herbicides inputs are important in order to manage weeds. Weeds are at the bottom of the trophic pyramid in agroecosystems, and this explains partly the decrease of biodiversity. Alternatives to manage weeds are studied to reduce negative effect of herbicides on the environment in order to preserve biodiversity. For example, weeds could be managed with granivorous species. Indeed, weed seeds are the origin of the weed community, thus seed consumption could limit weed abundance in cultivated fields. In agroecosystems, several taxa are known to be granivorous such as vertebrates (birds and rodents) and invertebrates (ground beetles). Ground beetles are considered as the main granivorous taxa in agroecosystems and are abundant in temperate agroecosystems. The main goal of this PhD was to study trophic interactions between communities, weed seed and ground beetles, with a prey-predator system in order to estimate the role of ground beetles through their seed consumption in weed seeds management. First, we established a protocol with standardize steps in order to restrain variables to weed seed species at ground beetles’ species. A similar protocol has been adapted to replicate experimentation with the same individuals to measure consumption at different weed seed densities. We then studied interactions between weed seeds and ground beetles with two research axes. We first explored interspecific variation of consumption on the same weed seeds species, Viola arvensis, by ground beetles. Body mass and ratios between mandible length and labrum width had no relation with seed consumption by ground beetles. Thus, other factors were suggested to explain consumption variation such as gut symbionts of ground beetles or preferences for specific weed seed species. Secondly, we measured consumption of 42 weed seed species by four ground beetles to identify abilities in weed seed consumption for these beetles and to explore feeding strategy according to two seed characteristics, seed mass (size) and seed lipid content. Generalism degrees are different according to ground beetles’ species and seem affected by physiological characteristics in both communities. Finally, to assess the potential in weed seed management of ground beetles we determined functional response to four ground beetles on two weed seeds species. We determined type II response for all species (male and female) tested, except for females of P.rufipes. Our results should be interpreted cautiously as, under natural conditions, generalist predators meet many alternatives prey and it could influence functional response type. We showed that there are many complex interactions between weed seed and ground beetles communities, especially due to a wide range of diversity in physiological characteristics in both communities. The potential of ground beetles to regulate seeds must be more precisely explored to evaluate their agronomic interest in weed management.

Lorsqu’ils s’adressent à leur chien beaucoup de propriétaires ont une modalité vocale particulière : le discours adressé à l’animal de compagnie. Ce registre de communication ressemble beaucoup à celui utilisé par les parents lorsqu’ils s’adressent à leurs nourrissons. Ce qui suggère des soubassements communs. Ces deux registres partagent des caractéristiques qui les distinguent du discours adressé à l’adulte, comme une fréquence fondamentale plus élevée et une modulation plus importante. Une série d’expériences réalisées à l’Ecole Nationale Vétérinaire d’Alfort, nous a permis d’étudier comment le discours adressé à l’animal de compagnie intervient dans l’interaction homme-chien. Le premier chapitre montre que les caractéristiques acoustiques et verbales du discours adressé à l’animal de compagnie varient en fonction du contexte de l’interaction. Le deuxième chapitre s’intéresse à la manière dont le chien traite l’information vocale humaine, nos résultats suggèrent de manière générale un biais en faveur de l’hémisphère droit. Le troisième chapitre indique que le discours adressé à l’animal de compagnie augmente significativement l’attention du chien. Ce phénomène n’est pas perçu par les observateurs humains comme le montre le quatrième chapitre. A travers l’ensemble de ces études, essentiellement centrées sur le discours adressé à l’animal de compagnie, nous mettons en lumière la complexité de la communication homme-chien. / When addressing their dogs, owners often use a special speech register called pet-directed-speech. This communication modality is very similar to infant-directed-speech used by parents when speaking to young children, which suggests common bases. These two types of speech share characteristics that differ from those of adult-directed-speech, such as a higher fundamental frequency and greater modulations. A series of experiments carried out at the National Veterinary School of Alfort allowed us to explore how pet-directed-speech occurs in the human-dog interaction. The first chapter shows that acoustic and verbal features of pet-directed-speech vary according to the interaction context. The second chapter aims to highlight how dogs process human vocal information; overall, our results reveal a right hemispheric advantage. The third chapter indicates that pet-directed-speech increases significantly dogs’ attentional state. This phenomenon is not perceived by human observers, as it is shown in chapter four. Together, these studies which mainly focused on pet-directed-speech bring to light the complexity of the human-dog communication.

Synchroniser son comportement sur celui d’autrui est adaptatif et essentiel au maintien des interactions et de la cohésion sociale : plus deux individus sont affiliés, plus leurs comportements sont synchronisés, et inversement. Cela est observé au sein de nombreuses espèces, dont l’humain, mais l’existence de ce phénomène au niveau interspécifique n’est que peu documentée.Les travaux de thèse révèlent que les chiens de compagnie, du point de vue productif, synchronisent leurs comportements sur ceux de leur propriétaire lors de déplacements en intérieur ou en extérieur, et également lors d’une rencontre avec une personne inconnue. De plus, les comparaisons du comportement de ces dyades avec ceux des chiens de refuge accompagnés de leur soigneur montrent que la nature du lien affiliatif joue un rôle essentiel dans le degré de synchronisation comportementale. Par contre, ce phénomène n’est que peu modulé par le sexe, l’âge et la race. Enfin, inversement, du point de vue perceptif, le présent travail montre pour la première fois que les chiens de compagnie préfèrent les humains qui synchronisent leur comportement avec le leur.En conclusion, comme entre humains, la synchronisation comportementale joue le rôle de glue sociale entre les chiens et les humains. C’est la première fois qu’une telle capacité est mise en évidence entre une espèce de primate et une espèce de canidé ; cela suggère une convergence évolutive de ce comportement, et l’existence de processus cognitifs s’apparentant à ceux des humains chez le chien. Les implications pratiques et théoriques de ces résultats sont finalement discutées à la lueur des quatre questions de Tinbergen (1963). / Non-conscious behavioral synchronization is adaptive, depending on affiliation and participating in fostering social cohesion. It is found within various species, including humans, but little is known about such a phenomenon between species. Due to their close association, dog and human dyads is a good biological model to study interspecific behavioral synchronization.For the first time, behavioral synchronization of dogs with humans was evidenced between highly affiliated partners (i.e. pet dogs and their owners) when freely walking inside or in open outside area, and when facing an unfamiliar person. The effect of affiliation was also investigated: lower affiliated partners (i.e. shelter dogs and their caregiver) exhibited lower degree of synchronization with human compare to highly affiliated partners, similarly than between humans. This is the first time that the effect of affiliation on behavioral synchronization has been evidenced at interspecific level. Almost no effect of age, sex or breed was evidenced. Finally, it was evidenced that pet dogs exhibit increased affiliation towards humans who synchronized their behavior with them. It is the third species in which such an ability is evidenced, and the first time it is found in canids.To conclude, as in humans, behavioral synchronization acts as a social-glue between dogs and humans. It is the first time that such a skill is evidenced between a primate species and a canid species; it suggests a convergent evolution of this behavior, and human-like processes in dogs. Applied implications of such findings, as well as Tinbergen (1963) four’s inquiries for behavioral synchronization are discussed.

The ability to accurately identify species is fundamental to ecological research and environmental monitoring. Current taxonomic identifications often rely on differentiation of morphologically ambiguous characters, and a process of categorization which is tedious and often leads to misidentifications. This is compounded by the presence of cryptic taxa, which may be prevalent among Polychaete worms (Polychaeta: Annelida). With increased access to genetic techniques, Cytochrome c oxidase subunit I has been suggested as a possible aid to assist in the discrimination of species resources. In this study, I tested the hypothesis that the mtDNA COI gene locus is effective in discriminating morphologically recognised species of Polychaete worms. A 543 base-pair fragment of the COI locus was successfully extracted for 111 individuals from 16 out of 20 morphologically recognised species. Average intraspecific divergences were 0.8 %, ranging from 0 % to 5 %. Average interspecific variation was 26.4 %, ranging from 13.8 % to 36.8 %. The lowest divergences were found between two Nereid species (13.8 %), and two Glycera americana species (17.2 %). Relatively high maximum divergences of over 30 % suggest that some species may have reached a divergence saturation level, which may partially explain why familial groupings in constructed trees were not monophyletic. Divergences within the different Nereid species - a group previously known to have morphologically cryptic species - did not reveal the presence of any cryptic taxa. Pairwise comparisons showed a clear divide between percentages of intra- and interspecific divergences, and the suggested threshold of 11 % is effective for the taxa investigated here. On the basis of these results, I conclude that sequence variation in the mtDNA COI gene locus is effective in discriminating morphologically recognised species of Polychaete worms, but may not be appropriate for deeper (e.g. generic or familial) phylogenetic relationships among taxa.