@phdthesis{Chaianunporn2012,
  author    = {Chaianunporn, Thotsapol},
  title     = {Evolution of dispersal and specialization in systems of interacting species},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-76779},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2012},
  abstract  = {A metacommunity approach will be a useful framework to assess and predict changes in biodiversity in spatially structured landscapes and changing environments. However, the relationship between two core elements of metacommunity dynamics, dispersal and species interaction are not well understood. Most theoretical studies on dispersal evolution assume that target species are in isolation and do not interact with other species although the species interactions and community structure should have strong interdependence with dispersal. On the one hand, a species interaction can change the cost and benefit structure of dispersing in relation to non-dispersing individuals. On the other hand, with dispersal, an individual can follow respectively avoid species partners. Moreover, it is also important to explore the interdependence between dispersal and species interaction with spatial and temporal heterogeneity of environment because it would allow us to gain more understanding about responses of community to disturbances such as habitat destruction or global climate change, and this aspect is up to now not well-studied. In this thesis, I focus on the interactive and evolutionary feedback effects between dispersal and various types of interspecific interactions in different environmental settings. More specifically, I contrast dispersal evolution in scenarios with different types of interactions (chapter 2), explore the concurrent evolution of dispersal and habitat niche width (specialization) in spatial heterogeneous landscape (chapter 3) and consider (potential) multidimensional evolutionary responses under climate change (chapter 4). Moreover, I investigate consequences of different dispersal probability and group tolerance on group formation respectively group composition and the coexistence of 'marker types' (chapter 5). For all studies, I utilize individual-based models of single or multiple species within spatially explicit (grid-based) landscapes. In chapter 5, I also use an analytical model in addition to an individual-based model to predict phenomenon in group recognition and group formation. ...},
  subject      = {Tiergesellschaft},
  language  = {en}
}
@phdthesis{daCruzGueerisoli2021,
  author    = {da Cruz G{\"u}erisoli, Irene Maria},
  title     = {Investigating the murine meiotic telomere complex TERB1-TERB2-MAJIN: spatial organization and evolutionary history},
  doi       = {10.25972/OPUS-21056},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-210562},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Einess der faszinierenden Merkmale der meiotischen Prophase I sind die hochkonservierten kr{\"a}ftigen Bewegungen homologer Chromosomen. Diese Bewegungen sind entscheidend f{\"u}r den Erfolg von Schl{\"u}sselereignissen wie die Ausrichtung, Paarung und Rekombination der homologen Chromosomen. Mehrere bisher untersuchte Organismen, darunter S{\"a}ugetiere, W{\"u}rmer, Hefen und Pflanzen, erreichen diese Bewegungen, indem sie die Chromosomenenden an spezialisierten Stellen in der Kernh{\"u}lle verankern. Diese Verankerung erfordert Telomer-Adapterproteine, die bisher in der Spalthefe und der Maus identifiziert wurden. Die meiosespezifischen Telomer-Adapterproteine der Maus, TERB1, TERB2 und MAJIN, sind an der Verankerung des ubiquit{\"a}ren Telomer-Shelterin-protein an den LINC-Komplex beteiligt, mit einem analogen Mechanismus, wie er die Spalthefe beschrieben wird. Obgleich die meiose-spezifischen TelomerAdapterproteine eine wesentliche Rolle spielen, ist der genaue Mechanismus der Verankerung der Telomere an die Kernh{\"u}lle sowie ihre evolution{\"a}re Geschichte bisher noch wenig verstanden. Das Hauptziel dieser Arbeit ist daher die Untersuchung der Organisation des meiosespezifischen TelomerAdapterkomplexes TERB1-TERB2-MAJIN der Maus und dessen Evolutionsgeschichte. Im ersten Teil dieser Arbeit wurde die Organisation des TERB1-TERB2-MAJIN Komplexes mittels hochaufl{\"o}sender Mikroskopie (SIM), an Mausspermatozyten untersucht, sowie die Lokalisation in Bezug auf TRF1 des Telomer-ShelterinKomplexes und die telomerische DNA analysiert. In den Stadien Zygot{\"a}n und Pachyt{\"a}n zeigten die Fluoreszenzsignale eine starke {\"U}berlappung der Verteilung der meiotischen Telomer-Komplex-Proteine, wobei die Organisation von TERB2 an den Chromosomenenden heterogener war als die von TERB1 und MAJIN. Außerdem konnte die TRF1-Lokalisation an den Enden der Lateralelemente (LEs) mit einer griffartigen Anordnung um die TERB1- und MAJIN-Signale im Zygot{\"a}n- und Pachyt{\"a}n-Stadium gezeigt werden. Interessanterweise erwies sich die telomerische DNA als lateral verteilt und teilweise {\"u}berlappend mit der zentralen Verteilung der meiotischen Telomer-Komplex-Proteine an den Enden der LEs. Die Kombination dieser Ergebnisse erlaubte die Beschreibung eines alternativen Modells der Verankerung der Telomer an die Kernh{\"u}lle w{\"a}hrend der meiotischen Prophase I. Der zweite Teil dieser Arbeit analysiert die Evolutionsgeschichte der Mausproteine von TERB1, TERB2 und MAJIN. Die fehlende {\"U}bereinstimmung zwischen den Meiose-spezifische Telomer-Adapteproteinen der Maus und der Spalthefe hat die Frage nach dem evolutionsbedingten Ursprung dieses spezifischen Komplexes aufgeworfen. Um vermeintliche Orthologen der Mausproteinevon TERB1, TERB2 und MAJIN {\"u}ber Metazoen hinweg zu identifizieren, wurden computergest{\"u}tzte Verfahren und phylogenetische Analysen durchgef{\"u}hrt. Dar{\"u}ber hinaus wurden Expressionsstudien implementiert, um ihre potenzielle Funktion w{\"a}hrend der Meiose zu testen. Die Analysen haben ergeben, dass der Meiose-spezifische Telomer-Komplex der Maus sehr alt ist, da er bereits in den Eumetazoen entstand, was auf einen einzigen Ursprung hindeutet. Das Fehlen jeglicher Homologen des meiosespezifischen Telomerkomplexes in Nematoden und die einigen wenigen in Arthropoden nachgewiesenen Kandidaten, deuten darauf hin, dass die Telomer-Adapterproteine in diesen Abstammungslinien verloren/ersetzt oder stark diversifiziert worden sind. Bemerkenswerterweise zeigten Proteindom{\"a}nen von TERB1, TERB2 und MAJIN, die an der Bildung des Komplexes sowie an der Interaktion mit dem Telomer-Shelterin-Protein und den LINC-Komplexen beteiligt sind, eine hohe Sequenz{\"a}hnlichkeit {\"u}ber alle Kladen hinweg. Abschließend lieferte die Genexpression im Nesseltier Hydra vulgaris den Beweis, dass der TERB1-TERB2-MAJIN-Komplex selektiv in der Keimbahn exprimiert wird, was auf die Konservierung meiotischer Funktionen {\"u}ber die gesamte Metazoen-Evolution hinweg hindeutet. Zusammenfassend bietet diese Arbeit bedeutende neue Erkenntnisse hinsichtlich des Meiose-spezifischen Telomer-Adapterkomplex, seines Mechanismus zur Verankerung der Telomer an die Kernh{\"u}lle und die Entschl{\"u}sselung seines Ursprungs in den Metazoen.},
  language  = {en}
}
@phdthesis{Dornhaus2002,
  author    = {Dornhaus, Anna},
  title     = {The role of communication in the foraging process of social bees},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-3468},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2002},
  abstract  = {In the various groups of social bees, different systems of communication about food sources occur. These communication systems are different solutions to a common problem of social insects: efficiently allocating the necessary number of workers first to the task of foraging and second to the most profitable food sources. The solution chosen by each species depends on the particular ecological circumstances as well as the evolutionary history of that species. For example, the outstanding difference between the bumble bee and the honey bee system is that honey bees can communicate the location of profitable food sources to nestmates, which bumble bees cannot. To identify possible selection pressures that could explain this difference, I have quantified the benefits of communicating location in honey bees. I show that these strongly depend on the habitat, and that communicating location might not benefit bees in temperate habitats. This could be due to the differing spatial distributions of resources in different habitats, in particular between temperate and tropical regions. These distributions may be the reason why the mostly temperate-living bumble bees have never evolved a communication system that allows them to transfer information on location of food sources, whereas most tropical social bees (all honey bees and many stingless bees) are able to recruit nestmates to specific points in their foraging range. Nevertheless, I show that in bumble bees the allocation of workers to foraging is also regulated by communication. Successful foragers distribute in the nest a pheromone which alerts other bees to the presence of food. This pheromone stems from a tergite gland, the function of which had not been identified previously. Usage of a pheromone in the nest to alert other individuals to forage has not been described in other social insects, and might constitute a new mode of communicating about food sources. The signal might be modulated depending on the quality of the food source. Bees in the nest sample the nectar that has been brought into the nest. Their decision whether to go out and forage depends not only on the pheromone signal, but also on the quality of the nectar they have sampled. In this way, foraging activity of a bumble bee colony is adjusted to foraging conditions, which means most bees are allocated to foraging only if high-quality food sources are available. In addition, foraging activity is adjusted to the amount of food already stored. In a colony with full honeypots, no new bees are allocated to foraging. These results help us understand how the allocation of workers to the task of food collection is regulated according to external and internal nest conditions in bumble bees.},
  subject      = {Hummel},
  language  = {en}
}
@phdthesis{Drescher2011,
  author    = {Drescher, Jochen},
  title     = {The Ecology and Population structure of the invasive Yelllow Crazy Ant Anoplolepis gracilipes},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-57332},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2011},
  abstract  = {The invasive Yellow Crazy Ant Anoplolepis gracilipes is a widespread tropical ant species which is particularly common in anthropogenically disturbed habitats in South-East Asia and the Indopacific region. Its native range is unknown, and there is little information concerning its social structure as a potential mechanism facilitating invasion as well as its ecology in one of the putative native ranges, South-East Asia. Using mitochondrial DNA sequences, I demonstrated that the majority of the current Indopacific colonies were likely introduced from South-East Asian populations, which in turn may have been introduced much earlier from a yet unidentified native range. By conducting behavioral, genetic and chemical analyses, I found that A. gracilipes supercolonies contain closely related individuals, thus resembling enlarged versions of monogynous, polydomous colonies of other ant species. Furthermore, mutually aggressive A. gracilipes supercolonies were highly differentiated both genetically and chemically, suggesting limited or even absent gene flow between supercolonies. Intranidal mating and colony-budding are most likely the predominant, if not the exclusive mode of reproduction and dispersal strategy of A. gracilipes. Consequently, a positive feedback between genetic, chemical and behavioral traits may further enhance supercolony differentiation though genetic drift and neutral evolution. This potential scenario led to the hypothesis that absent gene flow between different A. gracilipes supercolonies may drive them towards different evolutionary pathways, possibly including speciation. Thus, I examined one potential way by which gene flow between supercolonies of an ant species without nuptial flights may be maintained, i.e. the immigration of sexuals into foreign supercolonies. The results suggest that this option of maintaining gene flow between different supercolonies is likely impaired by severe aggression of workers towards allocolonial sexuals. Moreover, breeding experiments involving males and queens from different supercolonies suggest that A. gracilipes supercolonies may already be on the verge of reproductive isolation, which might lead to the diversification of A. gracilipes into different species. Regarding the ecological consequences of its potential introduction to NE-Borneo, I could show that A. gracilipes supercolonies may affect the local ant fauna. The ant community within supercolonies was less diverse and differed in species composition from areas outside supercolonies. My data suggest that the ecological dominance of A. gracilipes within local ant communities was facilitated by monopolization of food sources within its supercolony territory, achieved by a combination of rapid recruitment, numerical dominance and pronounced interspecific aggression. A. gracilipes' distribution is almost exclusively limited to anthropogenically altered habitat, such as residential and agricultural areas. The rate at which habitat conversion takes place in NE-Borneo will provide A. gracilipes with a rapidly increasing abundance of suitable habitats, thus potentially entailing significant population growth. An potentially increasing population size and ecological dominance, however, are not features that are limited to invasive alien species, but may also occur in native species that become 'pests' in an increasing abundance of anthropogenically altered habitat. Lastly, I detected several ant guests in supercolonies of A. gracilipes. I subsequently describe the relationship between one of them (the cricket Myrmecophilus pallidithorax) and its ant host. By conducting behavioral bioassays and analyses of cuticular hydrocarbon (CHC) profiles, I revealed that although M. pallidithorax is attacked and consumed by A. gracilipes whenever possible, it may evade aggression from its host by a combination of supreme agility and, possibly, chemical deception. This thesis adds to our general understanding of biological invasions by contributing species-specific data on a previously understudied invasive organism, the Yellow Crazy Ant Anoplolepis gracilipes. Introductions which may have occurred a long time ago may make it difficult to determine whether a given species is an introduced invader or a native pest species, as both may have pronounced ecological effects in native species communities. Furthermore, this thesis suggests that supercolonialism in invasive ants may not be an evolutionary dead end, but that it may possibly give rise to new species due to reproductive boundaries between supercolonies evoked by peculiar mating and dispersal strategies.},
  subject      = {Dem{\"o}kologie},
  language  = {en}
}
@phdthesis{Fichtner2020,
  author    = {Fichtner, Alina Suzann},
  title     = {Alpaca, armadillo and cotton rat as new animal models for nonconventional T cells: Identification of cell populations and analysis of antigen receptors and ligands},
  doi       = {10.25972/OPUS-16910},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-169108},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2020},
  abstract  = {In this thesis, three species were investigated for the conservation of two non-conventional T cell systems, the CD1d/ iNKT cell system and the BTN3/ Vγ9Vδ2 T cell system. Non-conventional T cells are αβ or γδ T cells that do not fit into the classical mode of antigen recognition and adaptive responses. These T cells recognize antigens different from classical peptide antigens and are not restricted to the polymorphic MHC molecules but rather to non-polymorphic antigen-presenting molecules. The iNKT cell subset is restricted by the lipid antigen-presenting molecule CD1d and carries out immunomodulatory functions by rapid cytokine secretion. The molecular basis of this system, the semi-invariant iNKT TCR chains and CD1d were proven to be expressed and compared to homologs in human and rodents. Cotton rats possess multiple members of the AV14 and BV8 family and only one isoform of CD1d which is comparable to findings in the rat. Moreover, the reactivity of primary cells to glycolipid antigens could be shown, and an iNKT cell-like population was detected in primary cells using newly developed cotton rat CD1d oligomers. These were also applied to test the capacity of CD1d to present typical glycolipid antigens to iNKT TCR transductants. In addition, expression of cotton rat iNKT TCR α and β chains in TCR-negative cell lines was used to show successful pairing and detection of glycolipids in the context of CD1d. In summary, the conservation of a functional CD1d/iNKT cell system in the cotton rat could be shown, and tools were developed to study this cell subset in the course of infectious diseases. The Vγ9Vδ2 T cell subset is the major γδ T cell subset in human peripheral blood and has the unique ability to contribute to immune surveillance by detecting pyrophosphorylated metabolites of isoprenoid synthesis that indicate cell stress, transformation or infection. Up to this date, phosphoantigen-reactive γδ T cells have only been shown in primate species. However, evidence for the existence and functional conservation of the genes implied in the BTN3/Vγ9Vδ2 T cell system was found in several placental mammal species, and two candidate species were chosen for further investigation. The nine-banded armadillo, a valuable model for leprosy research, was shown to possess homologous genes to TRGV9, TRDV2 and BTN3. In this study, the expression of productive rearrangements of TRDV2 gene segments could be shown in peripheral blood samples, but no evidence was found for the expression of a functional TRGV9 rearrangement or BTN3 molecules. Moreover, determinants of phosphoantigen-reactive Vγ9Vδ2 T cells and functional BTN3 molecules were found to still be prevalent in armadillo genes. This makes the armadillo an interesting model to study the structural determinants that allow phosphoantigen recognition by a functional Vγ9Vδ2 T cell subset although this species is merely a witness for a functional system in a placental mammal ancestor. In contrast, alpacas were shown to express functional Vγ9Vδ2 T cells which conserved many features of the human counterpart. Expression of Vγ9Vδ2 pairings could be shown by single-cell PCR and functional phosphoantigenreactive pairings were observed. This phosphoantigen reactivity was also shown in PBMC cultures with a newly developed antibody specific for alpaca Vδ2Jδ4 chains. Moreover, a more detailed study of the alpaca TCR repertoire showed similarities to "γδ high" species like camelids and cattle which possess an extended family of TRDV genes. The γ and δ loci of alpaca TCR genes were drafted based on genomic information and cDNA studies and provide an overview for more detailed studies. Conservation of phosphoantigen recognition by the single BTN3 molecule of alpacas was shown in 293T knock out cell lines, and BTN3 detection on PBMCs was investigated with a newly developed alpaca BTN3-specific antibody. These findings prove the existence of a functional BTN3-dependent phosphoantigen-reactive Vγ9Vδ2 T cell subset and provide a basis for the future study of this cell system in a non-primate species. Moreover, as the first non-primate candidate species with the BTN3/Vγ9Vδ2 T cell system the alpaca is an important outgroup for research in this field. The use of a single BTN3 variant in contrast to three human isoforms that work together renders the alpaca a unique and to this date indispensable model for Vγ9Vδ2 T cells. In conclusion, this study provides an overview of the applicability of new animal models in the study of the non-conventional T cell subsets iNKT cells and Vγ9Vδ2 T cells and leads the way for a better understanding of structural and functional relationships.},
  subject      = {T-Lymphozyt},
  language  = {en}
}
@phdthesis{Fraune2014,
  author    = {Fraune, Johanna},
  title     = {The evolutionary history of the mammalian synaptonemal complex},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-100043},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2014},
  abstract  = {Der Synaptonemalkomplex (SC) ist eine hochkonservierte Proteinstruktur. Er weist eine dreiteili-ge, leiter{\"a}hnliche Organisation auf und ist f{\"u}r die stabile Paarung der homologen Chromosomen w{\"a}hrend der Prophase der ersten meiotischen Teilung verantwortlich, die auch als Synpase be-zeichnet wird. Fehler w{\"a}hrend der Synpase f{\"u}hren zu Aneuploidie oder Apoptose der sich entwi-ckelnden Keimzellen. Seit 1956 ist der SC Gegenstand intensiver Forschung. Seine Existenz wurde in zahlreichen Orga-nismen von der Hefe bis zum Menschen beschrieben. Seine Struktur aus zwei parallel verlaufen-den Lateralelementen (LE), die durch eine Vielzahl von sogenannten Transversalfilamenten (TF) verbunden werden und dem Zentralen Element (CE) in der Mitte des SC ist dabei offensichtlich {\"u}ber die Millionen von Jahren der Evolution erhalten geblieben. Einzelne Proteinkomponenten des SC wurden jedoch nur in wenigen Modelorganismen charakterisiert, darunter Saccharomyces cerevisiae, Arabidopsis thaliana, Drosophila melanogaster, Ceanorhabditis elegans und Mus mus-culus. Unerwarteter Weise gelang es bei dieser Charakterisierung nicht, eine evolution{\"a}re Ver-wandtschaft, d.h. eine Homologie zwischen den Proteinsequenzen der verschiedenen SCs nach-zuweisen. Diese Tatsache sprach gegen die grunds{\"a}tzliche Annahme, dass der SC in der Evolution nur einmal entstanden sei. Diese Arbeit hat sich nun der Aufgabe gewidmet, die Diskrepanz zwischen der hochkonservierten Struktur des SC und seiner augenscheinlich nicht-homologen Proteinzusammensetzung zu l{\"o}sen. Dabei beschr{\"a}nkt sie sich auf die Analyse des Tierreichs. Es ist die erste Studie zur Evolution des SC in Metazoa und demonstriert die Monophylie der S{\"a}uger SC Proteinkomponenten im Tierreich. Die Arbeit zeigt, dass mindestens vier von sieben SC Proteinen der Maus sp{\"a}testens im letzten gemeinsamen Vorfahren der Gewebetiere (Eumetazoa) enstanden sind und auch damals Teil ei-nes urspr{\"u}nglichen SC waren, wie er heute in dem Nesseltier Hydra zu finden ist. Dieser SC weist die typische Struktur auf und besitzt bereits alle notwendigen Komponenten, um die drei Dom{\"a}-nen - LE, TF und CE - zu assemblieren. Dar{\"u}ber hinaus ergaben die einzelnen Phylogenien der verschiedenen SC Proteine der Maus, dass der SC eine sehr dynamische Evolutionsgeschichte durchlaufen hat. Zus{\"a}tzliche Proteine wurden w{\"a}hrend der Entstehung der Bilateria und der Wir-beltiere in den SC integriert, w{\"a}hrend andere urspr{\"u}ngliche Komponenten m{\"o}glicherweise Gen-Duplikationen erfuhren bzw. besonders in der Linie der H{\"a}utungstiere verloren gingen oder sich stark ver{\"a}nderten. Es wird die These aufgestellt, dass die auf den ersten Blick nicht-homologen SC Proteine der Fruchtfliege und des Fadenwurms tats{\"a}chlich doch von den urspr{\"u}nglichen Prote-inenkomponenten abstammen, sich aber aufgrund der rasanten Evolution der Arthropoden und der Nematoden bis zu deren Unkenntlichkeit diversifizierten. Zus{\"a}tzlich stellt die Arbeit Hydra als alternatives wirbelloses Modellsystem f{\"u}r die Meiose- und SC-Forschung zu den {\"u}blichen Modellen D. melanogaster und C. elegans vor. Die k{\"u}rzlich gewon-nenen Erkenntnisse {\"u}ber den Hydra SC sowie der Einsatz der Standard-Methoden in diesem Orga-nismus werden in dem abschließenden Kapitel zusammengefasst und diskutiert.},
  subject      = {Synaptinemal-Komplex},
  language  = {en}
}
@phdthesis{Gros2008,
  author    = {Gros, Andreas},
  title     = {Interactions in the evolution of dispersal distance and emigration probability},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-29226},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2008},
  abstract  = {Chapter 1 - Evolution of local adaptations in dispersal strategies The optimal probability and distance of dispersal largely depend on the risk to end up in unsuitable habitat. This risk is highest close to the habitat's edge and consequently, optimal dispersal probability and distance should decline towards the habitat's border. This selection should lead to the emergence of spatial gradients in dispersal strategies. However, gene flow caused by dispersal itself is counteracting local adaptation. Using an individual based model I investigate the evolution of local adaptations of dispersal probability and distance within a single, circular, habitat patch. I compare evolved dispersal probabilities and distances for six different dispersal kernels (two negative exponential kernels, two skewed kernels, nearest neighbour dispersal and global dispersal) in patches of different size. For all kernels a positive correlation between patch size and dispersal probability emerges. However, a minimum patch size is necessary to allow for local adaptation of dispersal strategies within patches. Beyond this minimum patch area the difference in mean dispersal distance between center and edge increases linearly with patch radius, but the intensity of local adaptation depends on the dispersal kernel. Except for global and nearest neighbour dispersal, the evolved spatial pattern are qualitatively similar for both, mean dispersal probability and distance. I conclude, that inspite of the gene-flow originating from dispersal local adaptation of dispersal strategies is possible if a habitat is of sufficient size. This presumably holds for any realistic type of dispersal kernel. Chapter 2 - How dispersal propensity and distance depend on the capability to assess population density We analyze the simultaneous evolution of emigration probability and dispersal distance for species with different abilities to assess habitat quality (population density) and which suffer from distance dependent dispersal costs. Using an individual-based model I simulate dispersal as a multistep (patch to patch) process in a world consisting of habitat patches surrounded by lethal matrix. Our simulations show that natal dispersal is strongly driven by kin-competition but that consecutive dispersal steps are mostly determined by the chance to immigrate into patches with lower population density. Consequently, individuals following an informed strategy where emigration probability depends on local population density disperse over larger distances than individuals performing density-independent emigration; this especially holds when variation in environmental conditions is spatially correlated. However, already moderate distance-dependent dispersal costs prevent the evolution of long-distance dispersal irrespectively of the chosen dispersal strategy. Chapter 3 - Evolution of sex-biased dispersal: the role of sex-specific dispersal costs, demographic stochasticity, and inbreeding Inbreeding avoidance and asymmetric competition over resources have both been identified as factors favouring the evolution of sex- biased dispersal. It has also been recognized that sex-specific costs of dispersal would promote selection for sexspecific dispersal, but there is little quantitative information on this aspect. In this paper I explore (i) the quantitative relationship between cost-asymmetry and a bias in dispersal, (ii) the influence of demographic stochasticity on this effect, and (iii) how inbreeding and cost-asymmetry interact in their effect on sex-specific dispersal. I adjust an existing analytical model to account for sex-specific costs of dispersal. Based on numerical calculations I predict a severe bias in dispersal already for small differences in dispersal costs. I corroborate these predictions in individualbased simulations, but show that demographic stochasticity generally leads to more balanced dispersal. In combination with inbreeding, cost asymmetries will usually determine which of the two sexes becomes the more dispersive. Chapter 4 - Evolution of sex-biased dispersal: the role of sex-specific dispersal costs, demographic stochasticity, and inbreeding Inbreeding depression, asymmetries in costs or benefits, and the mating system have been identified as potential factors underlying the evolution of sex-biased dispersal. We use individual-based simulations to explore how the mating system and demographic stochasticity influence the evolution of sex-specific dispersal in a metapopulation with females competing over breeding sites, and males over mating opportunities. Comparison of simulation results for random mating with those for a harem system (locally, a single male sires all offspring) reveal that even extreme variance in local male reproductive success (extreme male competition) does not induce a male bias in dispersal. The latter evolves if between-patch variance in reproductive success is larger for males than females. This can emerge due to demographic stochasticity if habitat patches are small. More generally, members of a group of individuals experiencing higher spatio-temporal variance in fitness expectations may evolve to disperse with greater probability than others.},
  subject      = {Theoretische {\"O}kologie},
  language  = {en}
}
@phdthesis{Herzner2004,
  author    = {Herzner, Gudrun},
  title     = {Evolution of the pheromone communication system in the European Beewolf Philanthus triangulum F. (Hymenoptera: Crabronidae)},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-11651},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2004},
  abstract  = {Darwin's theory of sexual selection explains the evolution of flamboyant male traits through female choice. It does not, however, address the question why males typically court and females choose. This asymmetry is now thought to be the result of the dichotomy in reproductive expenditures: Females invest primarily in parental care and males invest predominantly in mate attraction or competition. Based on this view, several hypotheses for the origin and maintenance of female preferences have been proposed. They include the classical sexual selection models, i.e. female choice for direct and indirect benefits as well as the more recent concepts of female choice for genetic compatibility and receiver bias models. The complementary choice scenario assumes that females choose mates with regard to genetic compatibility. The receiver bias concept views male traits and female preferences within the framework of communication theory and encompasses various more or less distinct models, two of which are sensory exploitation and sensory trap. Both models postulate that male signals evolved in response to pre-existing perceptual biases of females. The sensory trap hypothesis additionally emphasizes that pre-existing female preferences for certain cues evolved in non-sexual contexts, like e.g. foraging. Males that mimic these cues and elicit a favourable out-of-context response by females may increase their reproductive success. This thesis examines the evolution of the pheromone communication in the European Beewolf Philanthus triangulum. Beewolf females are specialized hunters of honeybees and provision their progeny with paralyzed prey. Male beewolves establish and scent mark territories with a pheromone from a head gland to court females. The concordant occurrence of the otherwise rare alcohol (Z)-11-eicosen-1-ol in the male pheromone and in the alarm pheromone of honeybees, the exclusive prey of the females, suggests a sensory trap process as an explanation for the evolution of the male pheromone in P. triangulum. According to this hypothesis, we tested three predictions: First, foraging honeybees should emit eicosenol. Via chemical analysis we could show that honeybee workers in fact smell of eicosenol during foraging. The occurrence of eicosenol on the cuticle and in the headspace of honeybees is a new finding. Second, beewolf females should use eicosenol as a cue for prey detection or identification. Using behavioural assays, we demonstrated that prey recognition in beewolf females is accomplished by olfactory cues and that eicosenol is an essential cue in this process. The sensory sensitivity of beewolf females to eicosenol must be extremely high, since they perceive the trace amounts present in the head space of honeybees. This sensitivity may be due to specialized olfactory receptors on the antennae of beewolf females. An inventory of the flagellar sensilla of both sexes showed that females carry one type of sensillum that is missing in males, the large sensillum basiconicum. This chemo-sensitive sensillum most likely plays a role in prey recognition. The third prediction is that beewolf males incorporate bee-like substances, including eicosenol, into their pheromone, and possibly catch females in a sensory trap. A reanalysis of the male pheromone revealed, among others, eicosenol and several alkanes and alkenes as pheromonal compounds. Our own analyses of the chemical profiles of honeybee workers and beewolf pheromone disclosed a surprisingly strong resemblance between the two. Eight of the eleven substances of the male pheromone are also present on the cuticle and in the headspace of honeybees. Notwithstanding this similarity, the male pheromone does not function as a sensory trap for females. Nevertheless, the extensive congruence between the odour bouquets of the females' prey and the male pheromone strongly suggests that the male signal evolved to exploit a pre-existing female sensory bias towards bee odour, and, thus represents a case of sensory exploitation. In addition to the above described scenario concerning mostly the 'design' of the male pheromone, we addressed possible indirect benefits female beewolves may gain by basing their mating decisions on signal 'content'. We show that the pheromone of male beewolves varies between families and may, thus, contain information about the degree of relatedness between the female and a potential mate. Females could use this information to choose genetically complementary males to avoid inbreeding and the production of infertile diploid sons. Collectively, our results provide strong evidence for a receiver bias process in the evolution of the male pheromone of P. triangulum. They further indicate that the pheromone composition may subsequently have been influenced by other natural or sexual selection pressures, like e.g. complementary female choice.},
  subject      = {Philantus},
  language  = {en}
}
@phdthesis{Karunakaran2014,
  author    = {Karunakaran, Mohindar Murugesh},
  title     = {Evolution of Vγ9Vδ2 T-cells},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-99871},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2014},
  abstract  = {Human Vγ9Vδ2 T cells are the major subset of blood γδ T cells and account for 1-5\% of blood T cells. Pyrophosphorylated metabolites of isoprenoid biosynthesis are recognized by human Vγ9Vδ2 T cells and are called as phosphoantigens (PAg). Isopentenyl pyrophosphate (IPP) and (E)-4-Hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP) are among the few well studied PAg. IPP is found in all organisms while HMBPP is a precursor of IPP found only in eubacteria, plants and apicomplexaen parasite. Interestingly, the PAg reactive Vγ9Vδ2 T cells are so far identified only in human and higher primates but not in rodents. Hence, Vγ9Vδ2 T cells are believed to be restricted to primates. With regard to PAg recognition, a Vγ9JP recombined TCRγ chain and certain CDR3 motifs of the TCR chain are mandatory. The BTN3A1 molecule is essential for a response to PAg. BTN3 is a trans-membrane protein belonging to butyrophilin family of proteins. Though BTN3A1 was found to be essential for PAg presentation, the exact molecular basis of PAg presentation still remains unclear. This thesis presents new data on the evolution of Vγ9Vδ2 TCR and its ligands (BTN3) as well as the genetic basis of PAg presentation to Vγ9Vδ2 TCR. The comprehensive analysis of genomic database sequences at NCBI and other public domain databases revealed for the first time that Vγ9, Vδ2 and BTN3 genes emerged and co-evolved along with the placental mammals. Vγ9, Vδ2 and BTN3 genes are scattered across mammalian species and not restricted to primates. But interestingly, all three genes are highly conserved between phylogenetically distinct species. Moreover, the distribution pattern of Vγ9, Vδ2 TCR genes and BTN3 genes suggests a functional association between these genes representing the TCR - ligand relationship. Alpaca (Vicugna pacos), a member of the camelid family, is one among the 6 candidate non-primate species which were found to possess functional Vγ9, Vδ2 and BTN3 genes. From peripheral lymphocytes of alpaca, Vγ9 chain transcripts with a characteristic JP rearrangement and transcripts of Vδ2 chains with a CDR3 typical for PAg-reactive TCR were identified. The transduction of αβ TCR negative mouse thymoma BW cells with alpaca Vγ9 and Vδ2 TCR chains resulted in surface expression of the TCR complex as it was deduced from detection of cell surface expression of mouse CD3. Cross-linking of alpaca Vγ9Vδ2 TCR transductants with anti-CD3ε led to IL-2 production which confirmed that alpaca Vγ9 and Vδ2 TCR chains pair to form a functional TCR. Besides the conservation of human like Vγ9 and Vδ2 TCR chains, alpaca has conserved an orthologue for human BTN33A1 as well. Interestingly, the predicted PAg binding sites of human BTN3A1 was 100\% conserved in deduced amino acid sequence of alpaca BTN3A1. All together alpaca is a promising candidate for further studies as it might have preserved Vγ9Vδ2 T cells to function in surveillance of stress and infections. This thesis also provides the sequence of Vγ9Vδ2 TCR of African green monkey (Chlorocebus aethiops), which was previously unknown. Moreover, our data indicates the lack of any species specific barrier which could hinder the PAg presentation by African monkey derived COS cells to human Vγ9Vδ2 TCR and vice versa of human cells to African green monkey Vγ9Vδ2 TCR which was in contradiction to previously reported findings. Apart from the above, the thesis also presents new data on the genetic basis of PAg presentation to Vγ9Vδ2 T cells, which revealed that human chromosome 6 is sufficient for the presentation of exogenous and endogenous PAg. By employing human/mouse somatic hybrids, we identified the role of human chromosome 6 in PAg presentation and in addition, we observed the lack of capacity of human chromosome 6 positive hybrids to activate Vγ9Vδ2 TCR transductants in the presence of the alkylamine sec-butylamine (SBA). Investigation of Chinese hamster ovary (CHO) cells containing the human chromosome 6 also yielded similar results. This suggests that aminobisphosphonates (zoledronate) and alkylamines employ different mechanisms for activation of Vγ9Vδ2 T cells although both have been described to act by inhibition of farnesyl pyrophosphate synthase activity which is known to increase intracellular levels of the IPP. In conclusion, this thesis suggests that Vγ9, Vδ2 and BTN3 genes controlling Vγ9Vδ2 TCR- ligand relationship emerged and co-evolved along with placental mammals; and also identified candidate non-primate species which could possess Vγ9Vδ2 T cells. Furthermore, it suggests alpaca as a promising non-primate species to investigate the physiological function of Vγ9Vδ2 T cells. With respect to PAg antigen presentation it was shown that chromosome 6 is essential and sufficient for exogenous and endogenous PAg presentation. Moreover, the alkylamine SBA and aminobisphosphonate zoledronate may engage different cellular mechanism to exert inhibition over IPP consumption. The thesis raises interesting questions which need to be addressed in future: 1) What are the environmental and evolutionary factors involved in preservation of Vγ9Vδ2 T cells only by few species? 2) What could be the functional nature and antigen recognition properties of such a conserved T cell subset? 3) What is the genetic and molecular basis of the differential capacity of human chromosome 6 bearing rodent-human hybridoma cells in activating Vγ9Vδ2 T cells in presence of SBA and aminobisphosphonates?},
  subject      = {Evolution},
  language  = {en}
}
@phdthesis{Keller2010,
  author    = {Keller, Alexander},
  title     = {Secondary (and tertiary) structure of the ITS2 and its application for phylogenetic tree reconstructions and species identification},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-56151},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2010},
  abstract  = {Biodiversity may be investigated and explored by the means of genetic sequence information and molecular phylogenetics. Yet, with ribosomal genes, information for phylogenetic studies may not only be retained from the primary sequence, but also from the secondary structure. Software that is able to cope with two dimensional data and designed to answer taxonomic questions has been recently developed and published as a new scientific pipeline. This thesis is concerned with expanding this pipeline by a tool that facialiates the annotation of a ribosomal region, namely the ITS2. We were also able to show that this states a crucial step for secondary structure phylogenetics and for data allocation of the ITS2-database. This resulting freely available tool determines high quality annotations. In a further study, the complete phylogenetic pipeline has been evaluated on a theoretical basis in a comprehensive simulation study. We were able to show that both, the accuracy and the robustness of phylogenetic trees are largely improved by the approach. The second major part of this thesis concentrates on case studies that applied this pipeline to resolve questions in taxonomy and ecology. We were able to determine several independent phylogenies within the green algae that further corroborate the idea that secondary structures improve the obtainable phylogenetic signal, but now from a biological perspective. This approach was applicable in studies on the species and genus level, but due to the conservation of the secondary structure also for investigations on the deeper level of taxonomy. An additional case study with blue butterflies indicates that this approach is not restricted to plants, but may also be used for metazoan phylogenies. The importance of high quality phylogenetic trees is indicated by two ecological studies that have been conducted. By integrating secondary structure phylogenetics, we were able to answer questions about the evolution of ant-plant interactions and of communities of bacteria residing on different plant tissues. Finally, we speculate how phylogenetic methods with RNA may be further enhanced by integration of the third dimension. This has been a speculative idea that was supplemented with a small phylogenetic example, however it shows that the great potential of structural phylogenetics has not been fully exploited yet. Altogether, this thesis comprises aspects of several different biological disciplines, which are evolutionary biology and biodiversity research, community and invasion ecology as well as molecular and structural biology. Further, it is complemented by statistical approaches and development of informatical software. All these different research areas are combined by the means of bioinformatics as the central connective link into one comprehensive thesis.},
  subject      = {Phylogenie},
  language  = {en}
}