Predation is a key factor in evolutionary dynamics. It disrupts the potential of fossilisation in prey items and is poorly recorded in the fossil record; failed predation in conical marine gastropods is recorded in scars. Quantifying the scar distribution and collection and taphonomic biases present in the fossil record of the gastropod Neptunea contraria, of the Red Crag Formation, Gelasian, Pleistocene, UK is necessary to approach this dynamic. Neptunea contraria is highly abundant in the Red Crag Formation which is easily accessed. The size and scarring on a large number (450+) of individuals was collected, recorded and measured from pre-existing and new material. The size distribution of Neptunea contraria is non-normal and is enriched in larger individuals, the scar distribution – expected to be Poisson – is not so. Taphonomic and Collection bias had a large influence over the size and scar distributions of Neptunea contraria. Material from the same localities shows very different size distributions. The lack of Poisson distribution suggests different rates of unsuccessful predation over life history of Neptunea contraria, assuming the data is valid. / Predation anses vara en viktig faktor inom ekologi och evolution men till vilken grad har effekterna av predation förändrats genom geologisk tid? Det centrala fokuset i denna studie ligger i att frambringa en förståelse av både population- och predationsfördelningen bland marina snäckor av arten Neptunea contraria av Pleistocen ålder från Red Crag-formationen, East Anglia, Storbritannien.Framgångsrik predation resulterar i förstörelsen av snigeln och dess livshistoria registreras i deras skal. Misslyckad predation bevaras i skalen bland individer som överlevt genom ärrbildningar. Det finns ett okänt samband mellan misslyckad och framgångsrik predation.Samlingen av fossilt material från Sedgwick-museet i Cambridge, Storbritannien, ligger till grund för denna studie. Detta material är ofullständigt (d.v.s. material saknas) och noterbart fragmenterat vilket orsakats av nedbrytande processer, därav tafonomi. Denna studie belyser flertalet källor som ger upphov till ett ofullständigt fossilt register, därav processer direkt relaterade till fossilisering och antropogen insamling. Genom att jämföra flertalet uppsättningar av fossilt material som insamlats av olika personer så kan graden av bias i förhållande till insamlingen undersökas. Resultatet av denna studie visar att samlingen av fossila sniglar som för närvarande finns på Sedgwick-museet är ofullständig. Detta är ett tillstånd som uppkommit delvis på grund av inkomplett insamling.Fördelningen av ärr orsakade av misslyckad predation förväntades följa en poissonfördelning. Denna förutsägelse motsägs sannerligen av nuvarande data. Troligtvis har detta förorsakats av en låg ”miss-lyckad predationsfrekvens”, vilket antyder att graden av predation inte är konstant.Sniglar av en större storlek saknar ärr på den övre delen av sina skal, vilket tyder på att frekvensen av misslyckad predation var låg i de juvenila stadierna. (

No description available.

We examined the short-term (1 - 4 years postharvest) effects of 7 silvicultural treatments on terrestrial salamander populations at 4 sites in southwest Virginia and West Virginia. The 3 silvicultural treatments with the most canopy removal (4-7 m2 basal area Shelterwood, Leavetree, Clearcut) had significantly fewer salamanders than the control (p < 0.10) postharvest. No differences were found among treatments in age class distribution, the percent of females that were gravid, or average clutch size. We tested the nighttime, surface-count census method for visibility and behavior-induced bias among silviculture treatments and estimated the proportion of a salamander population that is active on the surface in harvested and control habitats. Instantaneous rates of salamander activity ranged from 1.3 to 11.7% of the population for redback (Plethodon cinereus) and slimy salamanders (P. glutinosus). Timber harvest caused up to a 2-fold increase or decrease in activity rates. There was evidence for bias in the night census method, but differences were not consistent enough to suggest general bias corrections. We also tested whether poorly fed salamanders exhibited risk-sensitive foraging in a dry environment in a laboratory experiment. Poorly fed salamanders were observed out of their simulated burrows less than well fed salamanders suggesting salamanders, particularly females and small adults, are risk-averse. / Master of Science

Resumo: 1. As armadilhas convencionais são amplamente utilizadas em estudos com pequenos mamíferos não-voadores, mas geralmente acarretam um viés de amostragem. Além disso, efeitos da qualidade do microhabitat e da sazonalidade podem influenciar a estimativa da diversidade. 2. Nós comparamos dois métodos de amostragem de pequenos mamíferos: armadilhas de captura viva e de queda, sendo a riqueza de espécies e número de indivíduos variáveis resposta. Os levantamentos de campo foram realizados em uma área contínua de Mata Atlântica. Os efeitos das variáveis de microhabitat e da sazonalidade sobre capturabilidade também foram investigados. 3. As armadilhas de queda capturaram maior número de espécies e indivíduos durante a estação chuvosa, quando comparadas com armadilhas de captura viva. Portanto, as armadilhas de queda foram o melhor método para estimar a riqueza e abundância de pequenos mamíferos, principalmente de espécies semi-fossoriais. 4. Nossos resultados mostraram a importância de considerar o esforço amostral despendido em armadilhas de captura vida e de queda ao se comparar a eficiência de captura entre elas. O uso da abundância relativa resolveu problemas de sub e de superestimativa da capturabilidade em cada tipo de armadilha. 5. Embora o microhabitat seja considerado um importante fator que pode influenciar o número de indivíduos em determinada área de estudo, não encontramos influência do mesmo na capturabilidade de armadilhas de captura viva e de queda na comunidade de pequenos mamíferos. No entanto, verificamos que as estações de captura que apresentaram maior área basal de samambaias e de árvores mortas capturaram mais indivíduos de Brucepattersonius soricinus, Oligoryzomys nigripes e Akodon montensis. 6. Concluímos, portanto que a maioria dos inventários de pequenos mamíferos em regiões tropicais não conseguiu captar a riqueza... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: 1. Conventional traps are widely used in studies of non-volant small mammals, but usually lead to sampling bias. Also, microhabitat quality and seasonality effects may influence the estimate of diversity. 2. We compared two small mammal sampling methods: live and pitfall traps. Species richness and number of individuals were our response variables, and field surveys were carried out in a continuous area of the Brazilian Atlantic Forest. Effects of microhabitat variables and seasonality on trappability were also investigated. 3. Pitfall traps captured more number of species and more individuals during the wet season, when compared with live traps. Therefore, pitfall-traps were a better method for estimating the richness and abundance of small mammals, especially semi-fossorial species. 4. Our results showed the importance of considering the sampling effort dispended in live and pitfall traps when comparing the capture efficiency between them. The use of weighted abundance solved trappability problems of underestimation and overestimation in each trap type to capture small mammals. 5. Although the microhabitat is considered an important factor that can influence the number of individuals in the study area, we found no influence of microhabitat on trappability of live and pitfall traps on small mammal community. However, we found that the trap stations with higher basal area of dead trees and ferns captured more individuals of Brucepattersonius soricinus, Oligoryzomys nigripes, and Akodon montensis. 6. We conclude that most small mammal inventories in tropical regions failed to capture the true species richness. Several species considered "rare" and underlisted as data deficient in IUCN criterion could be in fact common / Orientador: Mauro Galetti / Coorientador: Maria José de Jesus Silva / Banca: Marco Aurélio Pizo Ferreira / Banca: Denis Cristiano Briani / Mestre

L’Afrique centrale atlantique (ACA) englobe l’ensemble du domaine bas-guinéen, les îles du Golfe de Guinée et une partie de l’archipel afromontagnard. Plusieurs centres d’endémisme ont été identifiés en son sein et sont généralement considérés comme liés à la présence de refuges forestiers durant les périodes glaciaires. Cependant, l’origine de cet endémisme, sa localisation et les méthodes permettant d’identifier ces centres restent controversées. La localisation de ces zones d’endémisme et des plantes rares qu’elles abritent, est pourtant un prérequis indispensable pour la mise en place de politiques cohérentes de conservation et demeure une priorité pour les organisations privées, institutionnelles ou gouvernementales actives dans la gestion et le maintien durable de la biodiversité. Cette étude phytogéographique porte sur la famille des Orchidaceae et est basée sur l’analyse de la distribution des taxons endémiques de l’ACA. Elle s’appuie sur un jeu de données original résultant d’un effort d’échantillonnage important au Cameroun et d’un travail d’identification et de localisation de spécimens dans les principaux herbaria européens abritant des collections d’ACA. Durant cette étude, (i) nous avons tout d’abord identifié ces taxons endémiques et documenté leur distribution au travers de plusieurs contributions taxonomiques et floristiques, (ii) nous nous sommes ensuite intéressé aux nouvelles méthodes permettant d’analyser ces données d’herbier de plantes rares et donc pauvrement documentées, testant aussi l’intérêt des Orchidaceae comme marqueurs chorologiques, et finalement, appliquant ces méthodes à notre jeu de données, (iii) nous avons délimité des centres d’endémisme et identifié les territoires phytogéographiques des Orchidaceae en ACA. (i) Une révision taxonomique des genres Chamaeangis Schltr. et Stolzia Schltr. a été réalisée respectivement. Sept nouveaux taxons ont été décrits: Angraecum atlanticum Stévart & Droissart, Chamaeangis spiralis Stévart & Droissart, Chamaeangis lecomtei (Finet) Schltr. var. tenuicalcar Stévart & Droissart, Polystachya engogensis Stévart & Droissart, Polystachya reticulata Stévart & Droissart, Stolzia repens (Rolfe) Summerh var. cleistogama Stévart, Droissart & Simo et Stolzia grandiflora P.J.Cribb subsp. lejolyana Stévart, Droissart & Simo. Plusieurs notes taxonomiques, phytogéographiques et écologiques supplémentaires ont également été redigées. Au total, nous avons identifié 203 taxons d’Orchidaceae endémiques d’ACA parmi lesquels 193 sont pris en compte pour l’étude des patrons d’endémisme. (ii) Au Cameroun, les patrons de distribution des Orchidaceae et des Rubiaceae endémiques d’ACA ont été étudiés conjointement. Des méthodes de rééchantillonnage des données (raréfaction) ont été appliquées pour calculer des indices de diversité et de similarité. Elles ont permis de corriger les biais liés à la variation de l’effort d’échantillonnage. Un gradient de continentalité a été observé, les parties côtières étant les plus riches en taxons endémiques d’ACA. Contrairement à la région du Mont Cameroun et aux massifs de Kupe/Bakossi qui ont connu une attention particulière des politiques et des scientifiques, la partie côtière du sud Cameroun, presque aussi riche, reste mal inventoriée pour plusieurs familles végétales. Cette analyse à l’échelle du Cameroun a également permis de comparer les patrons d’endémisme des Orchidaceae et des Rubiaceae. Les différences observées seraient principalement dues à la présence d’Orchidaceae terrestres dans les végétations basses et les prairies montagnardes de la dorsale camerounaise alors que les Rubiaceae sont généralement peu représentées dans ces habitats. Au sein des habitats forestiers, la concordance entre les patrons d’endémisme des Orchidaceae et des Rubiaceae remet en question l’utilisation des capacités de dispersion des espèces comme critère pour choisir les familles permettant l’identification des refuges forestiers et semble ainsi confirmer la pertinence de l’utilisation des Orchidaceae comme marqueur chorologique. La distribution potentielle a été utilisée pour étudier en détail l’écologie, la distribution et le statut de conservation de Diceratostele gabonensis Summerh., une Orchidaceae endémique de la région guinéo-congolaise uniquement connue d’un faible nombre d’échantillons. Cette méthodologie semble appropriée pour compléter nos connaissances sur la distribution des espèces rares et guider les futurs inventaires en Afrique tropicale. (iii) En ACA, les Orchidaceae permettent d’identifier plusieurs centres d’endémisme qui coïncident généralement avec ceux identifiés précédemment pour d’autres familles végétales. Ces constats supportent aussi l’utilisation des Orchidaceae comme marqueur chorologique. La délimitation des aires d’endémisme des Orchidaceae a ainsi permis de proposer une nouvelle carte phytogéographique de l’ACA. Les éléments phytogéographiques propres à chacune des dix phytochories décrites ont été identifiés et leurs affinités floristiques discutées. Les résultats phytogéographiques obtenus (a) soutiennent l’existence d’une barrière phytogéographique matérialisée par la rivière Sanaga entre les deux principaux centres et aires d’endémisme de l’ACA, (b) étendent l’archipel afromontagnard situé principalement au Cameroun au plateau de Jos (Nigeria) et (c) montrent l’importance de la chaîne montagneuse morcelée Ngovayang-Mayombe pour la distribution de l’endémisme en ACA. Cette chaîne de montagne, qui s’étend le long des côtes de l’océan du sud Cameroun au Congo-Brazzaville et qui correspond à plusieurs refuges forestiers identifiés par de nombreux auteurs, est ici considérée comme une seule aire d’endémisme morcelée./ Atlantic central Africa (ACA) covers the Lower Guinean Domain, the four islands of the Gulf of Guinea and a part of the afromontane archipelago. Different centres of endemism have been identified into this area and are usually considered as related to glacial forest refuges. However, the origin of this endemism, the localization of the centres and the methods employed to identify these centres are subject to debate. Yet, the localization of these centres of endemism and the identification of the rare plants they harbor is an essential prerequisite to setting up rational conservation policies, and remains a priority for private, institutional and governmental organizations which are dealing with the sustainable management of biodiversity. This phytogeographical study focuses on Orchidaceae and analyses the distribution of the taxa endemic to ACA. We use an original dataset resulting from an important sampling efforts and the identification of specimens coming from all the principal herbaria where collections from ACA are housed. During this study, (i) we first identified the taxa endemic to ACA and documented their distribution through several taxonomic and floristic contributions, (ii) we used and developed new methods allowing to correct for sampling bias associated with the use of rare and poorly documented taxa, testing at the same time the use of Orchidaceae as chorological markers, and finally, applying these methods to our dataset, (iii) we delimited the centres of endemism and identified the phytogeographical territories of Orchidaceae in ACA. (i) A taxonomic revision of Chamaeangis Schltr. and Stolzia Schltr. respectively was carried out. Seven new taxa were described: Angraecum atlanticum Stévart & Droissart, Chamaeangis spiralis Stévart & Droissart, Chamaeangis lecomtei (Finet) Schltr. var. tenuicalcar Stévart & Droissart, Polystachya engogensis Stévart & Droissart, Polystachya reticulata Stévart & Droissart, Stolzia repens (Rolfe) Summerh var. cleistogama Stévart, Droissart & Simo and Stolzia grandiflora P.J.Cribb subsp. lejolyana Stévart, Droissart & Simo. Several additional taxonomic, phytogeographical and ecological notes were also published. We finally identified 203 Orchidaceae taxa endemic to ACA, among which 193 were used to study the patterns of endemism. (ii) In Cameroon, the distribution patterns of both Orchidaceae and Rubiaceae endemic to ACA were studied. Subsampling methods (rarefaction) were applied to calculate diversity and similarity indices and to correct potential bias associated with heterogeneous sampling intensity. A gradient of continentality was confirmed in Cameroon, the coastal part being the richest in taxa endemic to ACA. The Cameroon Mountain and the Kupe/Bakossi mountain massifs have received a great consideration of politics and scientists. On the contrary, the Southern coastal part of Cameroon, though almost as rich as the Northern part, remains poorly known for several plant families. This analysis also allowed us to compare patterns of endemism of Orchidaceae and Rubiaceae. The differences observed could be mainly due to the terrestrial habit of some Orchidaceae, which are only found in the grasslands of the highest part of the Cameroonian volcanic line where endemic Rubiaceae are rare. Within forest habitats, the concordance between the patterns of endemism of Orchidaceae and Rubiaceae question the widespread use of dispersal ability as a selection criterion for the families used to identify forest refuges. This also confirms the relevance of Orchidaceae as chorological marker. Species distribution modelling was used of an in depth study of the ecology, the distribution and the conservation status of Diceratostele gabonensis Summerh., an Orchidaceae endemic to the Guineo-Congolian regional centre of endemism which is only known from very few collections. This method is proved to be appropriate to complete our knowledge on the distribution of rare plant species and to guide the future inventories in tropical Africa. (iii) In ACA, an analysis of the distribution of endemic Orchidaceae confirmed the presence and location of several centres of endemism previously identified on the basis of other plant families. This result again supports the use of Orchidaceae as a chorological marker. The chorological study of the endemic Orchidaceae allowed us to propose a new phytogeographical map for ACA. Phytogeographical elements for each of the ten phytochoria described were identified and their floristic affinities were also discussed. Our results (a) support the existence of a phytogeographical barrier, materialized by the Sanaga River, between the two main centres and area of endemism of the ACA, (b) extend the limits of the afromontane archipelago to the Jos Plateau in Nigeria and (c) show the importance of the Ngovayang-Mayombe line to explain the distribution of endemism in ACA. This mountainous line, stretching along the ocean coast from Southern Cameroon to Congo-Brazzaville, corresponds to several forest refuges identified by many authors, and is here considered as an unique but discontinuous area of endemism.

abstract: This work investigates the effects of non-random sampling on our understanding of species distributions and their niches. In its most general form, bias is systematic error that can obscure interpretation of analytical results by skewing samples away from the average condition of the system they represent. Here I use species distribution modelling (SDM), virtual species, and multiscale geographically weighted regression (MGWR) to explore how sampling bias can alter our perception of broad patterns of biodiversity by distorting spatial predictions of habitat, a key characteristic in biogeographic studies. I use three separate case studies to explore: 1) How methods to account for sampling bias in species distribution modeling may alter estimates of species distributions and species-environment relationships, 2) How accounting for sampling bias in fossil data may change our understanding of paleo-distributions and interpretation of niche stability through time (i.e. niche conservation), and 3) How a novel use of MGWR can account for environmental sampling bias to reveal landscape patterns of local niche differences among proximal, but non-overlapping sister taxa. Broadly, my work shows that sampling bias present in commonly used federated global biodiversity observations is more than enough to degrade model performance of spatial predictions and niche characteristics. Measures commonly used to account for this bias can negate much loss, but only in certain conditions, and did not improve the ability to correctly identify explanatory variables or recreate species-environment relationships. Paleo-distributions calibrated on biased fossil records were improved with the use of a novel method to directly estimate the biased sampling distribution, which can be generalized to finer time slices for further paleontological studies. Finally, I show how a novel coupling of SDM and MGWR can illuminate local differences in niche separation that more closely match landscape genotypic variability in the two North American desert tortoise species than does their current taxonomic delineation. / Dissertation/Thesis / Doctoral Dissertation Geography 2018

Made available in DSpace on 2014-06-11T19:30:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-02Bitstream added on 2014-06-13T18:59:59Z : No. of bitstreams: 1 neves_cl_me_rcla.pdf: 579299 bytes, checksum: 4e0eb889aafa2deb8e85b3bfdbcfb15a (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / As armadilhas convencionais são amplamente utilizadas em estudos com pequenos mamíferos não-voadores, mas geralmente acarretam um viés de amostragem. Além disso, efeitos da qualidade do microhabitat e da sazonalidade podem influenciar a estimativa da diversidade. 2. Nós comparamos dois métodos de amostragem de pequenos mamíferos: armadilhas de captura viva e de queda, sendo a riqueza de espécies e número de indivíduos variáveis resposta. Os levantamentos de campo foram realizados em uma área contínua de Mata Atlântica. Os efeitos das variáveis de microhabitat e da sazonalidade sobre capturabilidade também foram investigados. 3. As armadilhas de queda capturaram maior número de espécies e indivíduos durante a estação chuvosa, quando comparadas com armadilhas de captura viva. Portanto, as armadilhas de queda foram o melhor método para estimar a riqueza e abundância de pequenos mamíferos, principalmente de espécies semi-fossoriais. 4. Nossos resultados mostraram a importância de considerar o esforço amostral despendido em armadilhas de captura vida e de queda ao se comparar a eficiência de captura entre elas. O uso da abundância relativa resolveu problemas de sub e de superestimativa da capturabilidade em cada tipo de armadilha. 5. Embora o microhabitat seja considerado um importante fator que pode influenciar o número de indivíduos em determinada área de estudo, não encontramos influência do mesmo na capturabilidade de armadilhas de captura viva e de queda na comunidade de pequenos mamíferos. No entanto, verificamos que as estações de captura que apresentaram maior área basal de samambaias e de árvores mortas capturaram mais indivíduos de Brucepattersonius soricinus, Oligoryzomys nigripes e Akodon montensis. 6. Concluímos, portanto que a maioria dos inventários de pequenos mamíferos em regiões tropicais não conseguiu captar a riqueza... / 1onventional traps are widely used in studies of non-volant small mammals, but usually lead to sampling bias. Also, microhabitat quality and seasonality effects may influence the estimate of diversity. 2. We compared two small mammal sampling methods: live and pitfall traps. Species richness and number of individuals were our response variables, and field surveys were carried out in a continuous area of the Brazilian Atlantic Forest. Effects of microhabitat variables and seasonality on trappability were also investigated. 3. Pitfall traps captured more number of species and more individuals during the wet season, when compared with live traps. Therefore, pitfall-traps were a better method for estimating the richness and abundance of small mammals, especially semi-fossorial species. 4. Our results showed the importance of considering the sampling effort dispended in live and pitfall traps when comparing the capture efficiency between them. The use of weighted abundance solved trappability problems of underestimation and overestimation in each trap type to capture small mammals. 5. Although the microhabitat is considered an important factor that can influence the number of individuals in the study area, we found no influence of microhabitat on trappability of live and pitfall traps on small mammal community. However, we found that the trap stations with higher basal area of dead trees and ferns captured more individuals of Brucepattersonius soricinus, Oligoryzomys nigripes, and Akodon montensis. 6. We conclude that most small mammal inventories in tropical regions failed to capture the true species richness. Several species considered “rare” and underlisted as data deficient in IUCN criterion could be in fact common

Les modèles de distribution d’espèces ont été identifiées comme pertinents pour cartographier et caractériser la qualitéd’habitat des moustiques vecteurs du paludisme, Anopheles, afin de participer à l’estimation du risque de transmission decette maladie et à la définition de stratégies de lutte anti-vectorielle ciblées. La transmission du paludisme dépend de laprésence et de la distribution des vecteurs, qui dépendent elles-mêmes des conditions environnementales définissant laqualité des habitats écologiques des Anopheles. Cependant, dans certaines régions, les données de captures d’Anophelessont rares, et rend difficile la cartographie de leurs habitats. De plus, le recueil de ces données est très souvent soumis à desbiais d’échantillonnage.Cette thèse fournit une solution à la cartographie des vecteurs du paludisme, en considérant deux aspects très peu étudiésdans la modélisation : le faible nombre de sites de présence disponibles et l’existence d’un biais d’échantillonnage. Uneméthode originale de correction de l’effet du biais d’échantillonnage est proposée puis appliquée à des données de présencedu principal vecteur du paludisme en Guyane, Anopheles darlingi. Un modèle de distribution d’An. darlingi a ensuite étéconstruit, permettant d’obtenir une carte de qualité d’habitat en cohérence avec la connaissance des entomologistes etfournissant des performances de prédiction élevées. La méthode de correction proposée a ensuite été comparée auxméthodes existantes dans un contexte applicatif caractérisé par la rareté des données d’occurrence de l’espèce et laprésence d’un biais d’échantillonnage. Les résultats montrent que la méthode développée est adaptée aux cas où le nombrede sites de présence est faible. Cette thèse contribue, d’une part, à combler les lacunes théoriques et d’applicabilité desméthodes actuelles visant à corriger l’effet des biais d’échantillonnage et, d’autre part, à compléter la connaissance sur ladistribution spatiale et la bioécologie du principal vecteur du paludisme en Guyane française. / Species distribution models are identified as relevant to map and characterize the habitat quality of Anopheles genusmosquitoes, transmitting malaria, and thus to both participate in the estimation of the transmission risk of this disease and inthe definition of targeted vector control actions. The malaria transmission depends on the presence and distribution of thevectors, which are themselves dependent on the environmental conditions that define the quality of the ecological habitats of the Anopheles. However, in some areas, Anopheles collection data remain scarce, making it difficult to model these habitats. In addition, the collection of these data is very often subjected to significant sampling biases, due, in particular, to unequal accessibility to the entire study area. This thesis provides a solution to the mapping of malaria vectors, considering two very few studied aspects in modeling: the low number of available presence sites and the existence of a sampling bias. An original method for correcting the effect of the sampling bias is proposed and then applied to presence data of Anopheles darlingi species - the main vector of malaria in South America - in French Guiana. Then, a distribution model of An. darlingi was built to obtain a map of habitat quality consistent with entomologists’ knowledge and providing high prediction performances. The proposed correction method was then compared to existing methods in an application context characterized by the scarcity of the species occurence data and the presence of a sampling bias. The results show that the developed method is adapted to cases where the number of sites of presence is low. This thesis contributes, on the one hand, to fill theoretical and applicability lacuna of current methods intended to correct the effect of the sampling bias and, on the other hand, to supplement the knowledge on both the spatial distribution and the bio-ecology of the main malaria vector in French Guiana.

Der Aufstieg des maschinellen Lernens (ML) und die rasante Digitalisierung der Wirtschaft haben die Entscheidungsprozesse in der Finanzbranche erheblich verändert. Finanzinstitute setzen zunehmend auf ML, um die Entscheidungsfindung zu unterstützen. Kreditscoring ist eine der wichtigsten ML-Anwendungen im Finanzbereich. Die Aufgabe von Kreditscoring ist die Unterscheidung ob ein Antragsteller einen Kredit zurückzahlen wird. Finanzinstitute verwenden ML, um Scorecards zu entwickeln, die die Ausfallwahrscheinlichkeit eines Kreditnehmers einschätzen und Genehmigungsentscheidungen automatisieren. Diese Dissertation konzentriert sich auf drei große Herausforderungen, die mit dem Aufbau von ML-basierten Scorekarten für die Bewertung von Verbraucherkrediten verbunden sind: (i) Optimierung von Datenerfassungs- und -speicherkosten bei hochdimensionalen Daten von Kreditantragstellern; (ii) Bewältigung der negativen Auswirkungen von Stichprobenverzerrungen auf das Training und die Bewertung von Scorekarten; (iii) Messung und Sicherstellung der Fairness von Instrumenten bei gleichzeitig hoher Rentabilität. Die Arbeit bietet und testet eine Reihe von Instrumenten, um jede dieser Herausforderungen zu lösen und die Entscheidungsfindung in Finanzinstituten zu verbessern. Erstens entwickeln wir Strategien zur Auswahl von Merkmalen, die mehrere unternehmensbezogene Zielfunktionen optimieren. Unsere Vorschläge reduzieren die Kosten der Datenerfassung und verbessern die Rentabilität der Modelle. Zweitens schlagen wir Methoden zur Abschwächung der negativen Auswirkungen von Stichprobenverzerrungen vor. Unsere Vorschläge gleichen die Verluste aufgrund von Verzerrungen teilweise aus und liefern zuverlässigere Schätzungen der künftigen Scorecard-Leistung. Drittens untersucht die Arbeit faire ML-Praktiken in Kreditscoring. Wir katalogisieren geeignete algorithmische Optionen für die Einbeziehung von Fairness-Zielen und verdeutlichen den Kompromiss zwischen Gewinn und Fairness. / The rise of machine learning (ML) and the rapid digitization of the economy has substantially changed decision processes in the financial industry. Financial institutions increasingly rely on ML to support decision-making. Credit scoring is one of the prominent ML applications in finance. The task of credit scoring is to distinguish between applicants who will pay back the loan or default. Financial institutions use ML to develop scoring models to estimate a borrower's probability of default and automate approval decisions. This dissertation focuses on three major challenges associated with building ML-based scorecards in consumer credit scoring: (i) optimizing data acquisition and storage costs when dealing with high-dimensional data of loan applicants; (ii) addressing the adverse effects of sampling bias on training and evaluation of scoring models; (iii) measuring and ensuring the scorecard fairness while maintaining high profitability. The thesis offers a set of tools to remedy each of these challenges and improve decision-making practices in financial institutions. First, we develop feature selection strategies that optimize multiple business-inspired objectives. Our propositions reduce data acquisition costs and improve model profitability and interpretability. Second, the thesis illustrates the adverse effects of sampling bias on model training and evaluation and suggests novel bias correction frameworks. The proposed methods partly recover the loss due to bias, provide more reliable estimates of the future scorecard performance and increase the resulting model profitability. Third, the thesis investigates fair ML practices in consumer credit scoring. We catalog algorithmic options for incorporating fairness goals in the model development pipeline and perform empirical experiments to clarify the profit-fairness trade-off in lending decisions and identify suitable options to implement fair credit scoring and measure the scorecard fairness.

Malaise traps are a common tool for collecting insects used by many researchers. Although there have been variations in the models and materials used for Malaise traps, the potential for sampling bias due to mesh gague has been explored inadequately. This study compared coarse and fine mesh Townes model Malaise traps in two habitats on the Grand Staircase-Escalante National Monument. The two habitats next to the Lick Wash trailhead were defined by dominant vegetation type – sagebrush and grasses or Piñon-Juniper. We collected from three sites per habitat type, over three consecutive days in June in both 2006 and 2007. A pair of Malaise traps consisting of one coarse mesh and one fine mesh trap were used at each site in order to compare differences in the diversity and in the average size of individuals collected by each type of Malaise trap. We measured diversity using both presence-absence data such as richness scores and Jaccard's Index of Similarity, and abundance-based measures of comparison, including Simpson's Index of Diversity and non-metric multidimensional scaling. We identified all individuals according to Order, and because of our interest in flies and their abundance, we further identified the Dipter ta to the Family level. Average insect size was determined by categorizing individuals according to one of 14 distinct size-classes. In sum, 71 samples totaling approximately 62,500 insects were identified and sized. Because we sampled from two adjacent habitats, we also discuss beta diversity across the sample sites. Although mesh-size appears to have a significant effect on the diversity of the catch according to some tests, not all of our analysis agrees. In addition, the gain in the amount of diversity collected by incorporating both mesh-sizes may not be worth the costs of that kind of sampling. Other means of collection may adequately make up that difference. Habitat on the other hand was a clear marker for difference in diversity. Size was not found to be significant overall, but there still may be reasons to examine the effect of mesh-size with respect to the Hymenoptera.