Host location in a specialist parasitoid wasp via olfactory cues – a physiological, behavioural and morphological study

For successful host location, parasitoids are thought to have evolved different strategies to filter relevant olfactory cues which indicate the presence of the host. Because of their versatility in their ecology and behaviour, as well as their fine tuned olfactory system to volatile compounds of the host and host plant, they have gained increasing recognition as model organisms to study learning and behaviour in an adaptive ecological context. However, neural and cellular mechanisms of olfactory detection and processing in parasitoids are mainly unknown.In this thesis physiological, behavioural and morphological experiments were used to determine neural and behavioural mechanisms of host location via olfactory cues in the specialist parasitoid Cotesia vestalis. C. vestalis showed significant antennal responses to a range of odour compounds. Behavioural experiments, however, have demonstrated that only the herbivore-induced plant volatile linalool attracts C. vestalis males and females, but 1-nonanol has a repulsive effect on females. A morphological study of the antennal lobe, the first brain area where olfactory information is processed, revealed 40 ordinary glomeruli in both males and females. In addition, a complex of 2-3 enlarged glomeruli (MGC) was found in males. The courtship behaviour observed in males and the MGC suggest that males could use sex pheromones to locate females. Finally, calcium imaging studies showed glomerular activity to olfactory stimulation in bees but not in parasitoids. In conclusion, the degree of host specialisation in C. vestalis appears to influence olfactory learning in males and females, which favours learning of volatiles related to its host and host plant, as well as the morphological organisation of the antennal lobe. Larger, fewer and possibly specialised glomeruli could enhance processing of odour cues which are important for this parasitoid

Incorporating plant community structure in species distribution modelling: a species co-occurrence based composite approach

Species distribution models (SDM) with remotely sensed (RS) imagery is widely used in ecological studies and conservation planning, and the performance is frequently limited by factors including small plant size, small numbers of observations, and scattered distribution patterns. The focus of my thesis was to develop and evaluate alternative SDM methodologies to deal with such challenges. I used a record of nine endemic species occurrences from the Athabasca Sand Dunes in northern Saskatchewan to assess five different modelling algorithms including modern regression and machine learning techniques to understand how species distribution characteristics influence model prediction accuracies. All modelling algorithms showed robust performance (>0.5 AUC), with the best performance in most cases from generalized linear models (GLM). The threshold selection for presence-absence analysis highlights that actively selecting the optimum level is the best approach compared to the standard high threshold approach as with the latter there is a potential to deliver inconsistent predictions compared to observed patterns of occurrence frequency. The development of the composite-SDM framework used small-scale plant occurrence and UAV imagery from Kernen Prairie, a remnant Fescue prairie in Saskatoon, Saskatchewan. The evaluation of the effectiveness of five algorithms clearly showed that each method was capable of handling a wide range of low to high-frequency species with strong GLM performance irrespective of the species distribution pattern. It is critical to highlight that, although GLM is computationally efficient, the method does not compromise accuracy for simplicity. The inclusion of plant community structure using image clustering methods found similar accuracy patterns indicating limited advantages of using high-resolution images. The study found for high-frequency species that prediction accuracy declines to be as low as the accuracy expected for low-frequency species. Higher prediction confidence was often observed with low-frequency species when the species occurred in a distinct habitat that was visually and spectrally distinct from the surroundings. Such a pattern is in contrast to species widespread in different grassland habitats where distinct spectral signatures were lacking. The study has substantial evidence to state that the optimal algorithmic performance is tied to a balanced number of presences and absences in the data. The co-occurrence analysis also revealed significant co-occurrence patterns are most common at moderate levels of species occurrence frequencies. The research does not indicate any consistent accuracy changes between baseline direct reflectance models and composite-SDM framework. Although accuracy changes were marginal with the composite-SDM framework, the method is well capable of influencing associated type 1 and type 2 error rates of the classification

Genomics of clownfish adaptive radiation

How species diversify, creating the astonishing biodiversity observed on Earth, has been a central question since Darwin’s On the Origin of Species. Thanks to the sequencing revolution, this question can be approached today from a genomic perspective, examining how intrinsic genomic architecture and extrinsic biological and ecological factors interplay to shape the diversification of organisms. In this sense, clownfishes, which experienced an adaptive radiation following the acquisition of mutualism with sea anemones, represent a fascinating system. Thus, in this thesis, I combine comparative and population genomics approaches to study the genomic architecture underlying the diversification of this group. In the first two sections, I generate genomic resources for ten closely related but ecologically divergent clownfish species and the damselfish Pomacentrus moluccensis. Using this data, I question the genetic mechanisms underlying the acquisition of mutualism. I identify several candidate genes that experienced positive selection at the basis of clownfish radiation and show functions associated with sea anemones toxins discharge, thus likely involved in the evolution of clownfishes' ability to live unharmed within their otherwise-toxic hosts. In the last two sections, I dive into the diversification process of clownfishes. Through comparative genomics approaches, I show that the group experienced bursts of transposable elements, overall accelerated molecular evolution, and ancestral hybridization events, which likely facilitated the radiation of the group by generating the genomic variations necessary for natural selection to act on. I identify genes undergoing differential selective pressures linked with ecological divergence, suggesting that parallel evolution is shaping clownfish diversification, and I pinpoint candidate genes involved in the evolution of the particular size- based hierarchical social structure observed in the group. I finally focus on the mechanisms underlying the evolution of a clownfish clade, the skunk complex. Through population genomics approaches, I demonstrate that gene flow occurred throughout the diversification of the group. Indeed, the species experienced moderate ancestral gene flow, which lessened but still persists in sympatry. Moreover, contrary to what was previously suggested, I demonstrate that A. sandaracinos did not originate from hybrid speciation. I finally pinpoint candidate regions of introgression between species that likely played a role in the diversification of the complex. Overall, my work provides the first insights into the genomic mechanisms underlying clownfish adaptive radiation. -- Comprendre comment les espèces se diversifient et créent l'étonnante biodiversité observée sur Terre sont des questions centrales depuis l’écriture de l’Origine des espèces par Darwin. Grâce à la révolution du séquençage, ces questions peuvent être abordées aujourd'hui en examinant comment l'architecture génomique et les facteurs biologiques et écologiques interagissent et mènent à la diversification des organismes. En ce sens, les poissons-clowns, qui ont connu une radiation adaptative suite à l'acquisition du mutualisme avec les anémones de mer, représentent un système fascinant. Ainsi, dans cette thèse, j’étudie l'architecture génomique qui sous-tend la diversification de ce groupe. Dans les deux premières sections, je génère des ressources génomiques pour dix espèces de poissons-clowns ainsi que pour l’espèce de demoiselle Pomacentrus moluccensis. À partir de ces données, je questionne les mécanismes génétiques qui sous-tendent l'acquisition du mutualisme. J’identifie plusieurs gènes ayant subi une sélection positive à la base du rayonnement des poissons-clowns. Ces gènes ont des fonctions associées à la décharge des toxines des anémones, suggérant donc une implication dans l'évolution de la capacité des poissons-clowns à vivre au sein de leurs hôtes normalement toxiques. Dans les deux dernières sections, je me plonge dans le processus de diversification des poissons-clowns. Grâce à des approches de génomique comparative, je montre non seulement que ce groupe compte une importante quantité d'éléments transposables au sein de son génome, mais qu’il a également subi une évolution moléculaire accélérée ainsi que des événements d'hybridation ancestrale. La combinaison de ces différents éléments a probablement facilité leur diversification en générant les variations génomiques nécessaires à l'action de la sélection naturelle. J’identifie également des gènes ayant subi des pressions de sélection différentielles en lien avec des divergences écologiques, suggérant donc un processus d’évolution parallèle impliquée dans la diversification des poissons-clowns. Finalement, je me suis concentrée sur les mécanismes liés à l'évolution d'un clade de poisson- clown - le clade “skunk”. Je démontre qu’un flux de gènes modéré s'est produit tout au long de la diversification de ce groupe, et - bien que son amplitude ait diminué avec le temps - il persiste encore en sympatrie. De plus, j’identifie des régions candidates d'introgression entre espèces qui ont probablement joué un rôle dans la diversification du complexe. Dans l'ensemble, mon travail fournit les premières informations concernant les mécanismes génomiques impliqués dans la radiation adaptative des poissons-clowns

Enabling flexibility through strategic management of complex engineering systems

”Flexibility is a highly desired attribute of many systems operating in changing or uncertain conditions. It is a common theme in complex systems to identify where flexibility is generated within a system and how to model the processes needed to maintain and sustain flexibility. The key research question that is addressed is: how do we create a new definition of workforce flexibility within a human-technology-artificial intelligence environment? Workforce flexibility is the management of organizational labor capacities and capabilities in operational environments using a broad and diffuse set of tools and approaches to mitigate system imbalances caused by uncertainties or changes. We establish a baseline reference for managers to use in choosing flexibility methods for specific applications and we determine the scope and effectiveness of these traditional flexibility methods. The unique contributions of this research are: a) a new definition of workforce flexibility for a human-technology work environment versus traditional definitions; b) using a system of systems (SoS) approach to create and sustain that flexibility; and c) applying a coordinating strategy for optimal workforce flexibility within the human- technology framework. This dissertation research fills the gap of how we can model flexibility using SoS engineering to show where flexibility emerges and what strategies a manager can use to manage flexibility within this technology construct”--Abstract, page iii

Reared to become wild-like: addressing behavioral and cognitive deficits in cultured aquatic animals destined for stocking into natural environments-a critical review

Hatchery-reared aquatic animals tend to perform worse in natural environments than wild conspecifics. This was pointed out over a century ago and while there are many possible causes, one persistent observation is that unnatural rearing environments cause behavioral expressions unsuitable for a life in the wild. Behavioral traits being adaptive in barren, food-rich, and predator-free hatchery tanks likely differ from those being adaptive in nature. More recently, suspicions of cognitive deficiencies due to sensory deprivation have also been raised. Over the last few decades, substantial research has been devoted to produce more wild-like phenotypes in animals reared for stocking. This research includes life skills training programs, where animals learn to cope with important features of the natural environment (e.g., live food and predation risk), and environmental modifications aimed at stimulating the formation of adequate cognitive and behavioral traits (e.g., environmental enrichment and reduction of the number of individuals per tank). The main purpose of this paper is to provide a summary of the current state-of-knowledge of interventions aimed at ameliorating cognitive and behavioral deficiencies in aquatic animals reared for stocking. Furthermore, it aims to provide a foundation to assist in the development of future questions, hypotheses, and experiments to eventually improve the postrelease performance of these animals