May gen. n. (Araneae: Sparassidae): A unique lineage from southern Africa supported by morphological and molecular features

A new genus of huntsman spiders, May gen. n. is described from southern Africa, together with four new species: M. bruno sp. n. (♂, ♀; South Africa), M. ansie sp. n. (♂; Namibia), M. rudy sp. n. (♂; Namibia) and M. norm sp. n. (♀; Namibia). Diagnostic characters proposed include not only those for the genus but also for the so-called African clade. Unique within the entire family are the reduction of the gnathocoxal serrula and the prolaterad embolus. Special claw tuft setae and metatarsi I to III with three prolateral and retrolateral spines, respectively, occur in the entire African clade. A proximal cymbial shoulder in the male palp, the fused lateral lobes of the epigyne and the prolateral proximal spine of leg I shifted to a median position is characteristic for May gen. n. A family-wide analysis of genetic distance in the nuclear 28SrDNA gene (28s), including M. bruno sp. n., supports its isolated placement and thus the genus hypothesis

The bug in a teacup—monitoring arthropod–plant associations with environmental DNA from dried plant material

Environmental DNA analysis (eDNA) has revolutionized the field of biomonitoring in the past years. Various sources have been shown to contain eDNA of diverse organisms, for example, water, soil, gut content and plant surfaces. Here we show that dried plant material is a highly promising source for arthropod community eDNA. We designed a metabarcoding assay to enrich diverse arthropod communities while preventing amplification of plant DNA. Using this assay, we analysed various commercially produced teas and herbs. These samples recovered ecologically and taxonomically diverse arthropod communities, a total of over a thousand species in more than 20 orders, many of them specific to their host plant and its geographical origin. Atypically for eDNA, arthropod DNA in dried plants shows very high temporal stability, opening up plant archives as a source for historical arthropod eDNA. Considering these results, dried plant material appears excellently suited as a novel tool to monitor arthropods and arthropod–plant interactions, detect agricultural pests and identify the geographical origin of imported plant material. The simplicity of our approach and the ability to detect highly diverse arthropod communities from all over the world in tea bags also highlights its utility for outreach purposes and to raise awareness about biodiversity

A phylogeographic, ecological and genomic analysis of the recent range expansion of the wasp spider Argiope bruennichi

Summary of the thesis Rapid, poleward range expansions are observed for an increasing number of species in the past decades. These distributional changes are commonly attributed to global environmental change. Recent research, however, indicates that genetic adaptation might also play an important role in explaining the success of range expansions. Considering the fast pace of many range expansions, such contemporary evolutionary processes are unlikely to rely on the emergence of new mutations. Instead, standing genetic variation acts as important resource to fuel adaptation. This variation can be present in a population´s gene pool or it is introduced by secondary contact and admixture of formerly isolated genetic lineages. In the past years, ample evidence has been compiled for an association of admixture, adaptation and range expansions for numerous plant and animal species. Here, I present an analysis of the recent range expansion of the European wasp spider Argiope bruennichi. Originally, this species inhabited the Mediterranean region and warm oceanic climates in France and South-Western Germany. From around 1930 onwards, the spider started expanding its range into increasingly continental climates and can now be found as far north as Finland. This thesis aims to disentangle environmental and genetic factors, involved in the species´ range expansion. In particular, I analyze the interconnection of genetic admixture and invasion success. I approach these questions using population genetic and phylogeographic methods, morphological analyses, ecological experiments and finally whole genome- and transcriptome sequencing. In chapter one, I conduct a detailed genetic and ecological analysis of the spider´s range expansion. I base this study on a dense sampling of more than 2.000 contemporary specimens. In addition, I include about 500 historical spiders from natural history collections. I present genetic and morphological data, as well as several ecological experiments on thermal tolerance and preference and a reciprocal transplant study. My results indicate that the spider´s range expansion is associated with admixture of formerly isolated genetic lineages from around 1930 onwards. The ecological experiments indicate that invasive spider populations have simultaneously adapted to colder temperatures by shifting their thermal preference and tolerance. Like many other spider species, Argiope bruennichi has a wide ranging Palearctic distribution. In chapter two, I conduct a phylogeographic survey over the species´ whole range, from the Macaronesian islands over Europe to East Asia. Next to Argiope bruennichi, I include a second widely distributed spider species, the nursery web spider Pisaura mirabilis. The study is based on mitochondrial and nuclear genetic markers. I highlight the importance of outer-European glacial refugia for the wasp spider. I then show the effects of secondary contact in shaping the postglacial genetic structure of the two species. The analysis identifies several instances of incongruent phylogenetic patterns for mitochondrial and nuclear DNA markers, possibly due to recurrent selection on mitochondria. DNA from natural history collections provides a valuable resource to trace historical genetic changes during range expansions. For that reason, I present an analysis of DNA sequencing and microsatellite genotyping success in historical spider specimens in chapter three. In addition, I exemplarily illustrate the utility of historical specimens to trace historical genetic changes in populations. In the above chapters, I have presented evidence for admixture leading to differential adaptation in spider populations. However, the functional basis of this adaptation remains unknown. For that reason I embark towards unraveling its genomic architecture in chapter four. Initially, I generate the first available draft genome sequence of a spider species. Based on this data, I analyze genome-wide differences of native and invasive wasp spider populations across an environmental gradient. Gene regulatory evolution is a possible mechanism to provide the means for rapid contemporary adaptation to environmental stress. For this reason, I conduct a genome-wide gene expression analysis of native and invasive wasp spiders, which have been exposed to temperature stress in chapter five. I discuss the gene expression divergence between Northern and Southern European spiders in relation to the possibility of recent contemporary adaptation.Table of Contents Summary of the thesis ......................................................................................................... 4 Zusammenfassung der Dissertation .................................................................................... 6 General introduction ........................................................................................................... 9 Species ranges, their limits and expansion in a changing world................................. 9 Adaptations and range expansions - Impediments and possibilities ......................... 10 Hybridization – Destructive or creative force? ......................................................... 11 Phylogenetics and phylogeography - Detecting genetic structure and hybridization 13 Detecting the phenotypic consequences of adaptation ............................................. 13 Genomics of adaptation - Detecting its functional signatures and architecture........ 14 The wasp spider Argiope bruennichi - A new model species for studying adaptation in the face of global change ...................................................................................... 17 Summary ................................................................................................................... 19 Chapter 1: Northern range expansion of European populations of the wasp spider Argiope bruennichi is associated with global-warming-correlated genetic admixture and population specific temperature adaptations ..................................................................... 21 1.1 Introduction ............................................................................................................. 21 1.2 Material and methods .............................................................................................. 23 Sample collection and morphological analysis ......................................................... 23 Molecular analysis .................................................................................................... 24 Phylogeographic and population genetic analysis .................................................... 26 Thermal preference tests and reciprocal transplant experiment ............................... 27 1.3 Results ..................................................................................................................... 29 Mitochondrial data .................................................................................................... 29 Microsatellite data ..................................................................................................... 34 SNP data.................................................................................................................... 35 Body size ................................................................................................................... 38 Thermal preference and overwintering ..................................................................... 39 1.4 Discussion ............................................................................................................... 41 Phylogeography of the species.................................................................................. 41 Introgression, admixture and range expansion ......................................................... 42 Adaptation and phenotypic responses ....................................................................... 44 The role of other factors on the species´ invasion success ....................................... 46 1.5 Conclusion .............................................................................................................. 48 Chapter 2: Phylogeographic surveys of two widely distributed Palearctic spider species highlight the importance of extra-European glacial refugia and reveal a pronounced incongruence between nuclear - and mitochondrial markers ........................................... 49 2.1 Introduction ............................................................................................................. 49 2.2 Material and methods .............................................................................................. 51 Sample collection ...................................................................................................... 51 Molecular analysis .................................................................................................... 52 2.3 Results ..................................................................................................................... 53 Mitochondrial data .................................................................................................... 53 Nuclear microsatellites - and SNP loci ..................................................................... 55 Nuclear DNA sequences ........................................................................................... 56 Genetic diversity ....................................................................................................... 57 The nursery web spider Pisaura mirabilis ................................................................ 58 2.4 Discussion ............................................................................................................... 62 Pleistocene isolation and postglacial recolonization in Argiope bruennichi ............ 62 Secondary contact, differential introgression and limits to gene flow in a highly dispersive species ...................................................................................................... 63 The phylogeography of Pisaura mirabilis - differences and similarities with Argiope bruennichi ................................................................................................................. 66 2.5 Summary ................................................................................................................. 68 Chapter 3: An assessment of genotyping success in museum specimens identifies unexpected predictors of DNA integrity and shows an historical increase in genetic diversity in an expansive spider species ........................................................................... 69 3.1 Introduction ............................................................................................................. 69 3.2 Material and methods .............................................................................................. 70 Sample preparation and tests for genotyping success ............................................... 70 Changes of genetic diversity during a range expansion............................................ 72 3.3 Results ..................................................................................................................... 73 Factors, which affect DNA integrity in wet preserved spiders ................................. 73 Changes of genetic diversity during a range expansion............................................ 77 3.4 Discussion ............................................................................................................... 77 Factors, which affect DNA integrity in wet preserved spiders ................................. 77 Changes of genetic diversity during a range expansion............................................ 79 3.5 Conclusion .............................................................................................................. 79 Chapter 4: Whole genome sequencing reveals genetic signatures of ecological differentiation during a contemporary range expansion of a spider species ..................... 80 4.1 Introduction ............................................................................................................. 80 4.2 Material and methods .............................................................................................. 82 Generation of a reference transcriptome from an ontogenetic series ....................... 82 Generation of a wasp spider draft genome ............................................................... 83 Estimation of genomic divergence during a range expansion .................................. 85 A PCR based screen for range-wide genetic differentiation in genomic candidate loci............................................................................................................................ 87 4.3 Results ..................................................................................................................... 88 Reference transcriptome and - genome ..................................................................... 88 Estimation of genomic divergence during a range expansion .................................. 90 A PCR based screen for range-wide genetic differentiation in genomic candidate loci............................................................................................................................ 94 4.4 Discussion ............................................................................................................... 96 Reference genome and transcriptome ....................................................................... 96 Genetic structure, - diversity and introgression ........................................................ 97 Genomic divergence during a recent range expansion ............................................. 98 Clinal allele frequency variation over an environmental gradient .......................... 101 4.5 Outlook ................................................................................................................. 102 Chapter 5: Genome-wide patterns of gene expression divergence and evidence for a thermal niche shift during a contemporary range expansion of a spider species ............ 104 5.1 Introduction ........................................................................................................... 104 5.2 Methods................................................................................................................. 106 Analysis of gene expression divergence ................................................................. 106 Heat and cold tolerance experiments ...................................................................... 109 5.3 Results ................................................................................................................... 110 Heat and cold tolerance experiments ...................................................................... 110 Gene expression analysis ........................................................................................ 112 5.4 Discussion ............................................................................................................. 123 Range expansion, thermal niche shift and ecological divergence of gene expression................................................................................................................................ 123 Differentially expressed genes between Northern and Southern Europe and their possible association with thermal tolerance ............................................................ 125 Condition dependent gene expression within populations...................................... 126 Diapausing as a simple and rapidly evolving adaptation during a range expansion................................................................................................................................ 127 The influence of non-genetic factors on gene expression divergence .................... 128 5.5 Outlook ................................................................................................................. 129 Concluding remarks ........................................................................................................ 130 Acknowledgements ......................................................................................................... 131 References ....................................................................................................................... 132 My contributions to different chapters ............................................................................ 159 Appendix ......................................................................................................................... 160 Curriculum vitae ............................................................................................................. 200 Affidavit .......................................................................................................................... 20

Rapid range expansion is not restricted by inbreeding in a sexually cannibalistic spider

Few studies investigated whether rapid range expansion is associated with an individual’s short-term fitness costs due to an increased risk of inbred mating at the front of expansion. In mating systems with low male mating rates both sexes share potential inbreeding costs and general mechanisms to avoid or reduce these costs are expected. The spider Argiope bruennichi expanded its range recently and we asked whether rapid settlement of new sites exposes individuals to a risk of inbreeding. We sampled four geographically separated subpopulations, genotyped individuals, arranged matings and monitored hatching success. Hatching success was lowest in egg-sacs derived from sibling pairs and highest in egg-sacs derived from among-population crosses, while within-population crosses were intermediate. This indicates that inbreeding might affect hatching success in the wild. Unlike expected, differential hatching success of within- and among-population crosses did not correlate with genetic distance of mating pairs. In contrast, we found high genetic diversity based on 16 microsatellite markers and a fragment of the mitochondrial COI gene in all populations. Our results suggest that even a very recent settlement secures the presence of genetically different mating partners. This leads to costs of inbreeding since the population is not inbred

An amplicon sequencing protocol for attacker identification from DNA traces left on artificial prey

1. Clay model studies are a popular tool to identify predator–prey interactions that are challenging to observe directly in the field. But despite its wide use, the meth-od's applicability is limited by its low taxonomic resolution. Attack marks on clay models are usually identified visually, which only allows classification into higher taxonomic levels of predators. Thus, the method is often biased, lacks proof and, above all, standardization.2. Here, we tested whether precise identification of attackers can be provided by amplification and sequencing of mitochondrial DNA left in bite marks on clay models. We validated our approach in a controlled laboratory study as well as in a field experiment using clay models of a common European amphibian, the European fire salamander Salamandra salamandra. DNA-based taxonomic assign-ments were additionally compared to visual assessments of bite marks.3. We show that trace DNA of attackers can be routinely isolated and sequenced from bite marks, providing accurate species-level classification. In contrast, visual identification alone yielded a high number of unassigned predator taxa. We also highlight the sensitivity of the method and show likely sources of contamination as well as probable cases of secondary and indirect predation.4. Our standardized approach for species-level attacker identification opens up new possibilities far beyond the standard use of clay models to date, including food web studies at unprecedented detail, invasive species monitoring as well as biodi-versity inventories

Molecular diet analysis in mussels and other metazoan filter feeders and an assessment of their utility as natural eDNA samplers

Molecular gut content analysis is a popular tool to study food web interactions and has recently been suggested as an alternative source for DNA-based biomonitoring. However, the overabundant consumer's DNA often outcompetes that of its diet during PCR. Lineage-specific primers are an efficient means to reduce consumer amplification while retaining broad specificity for dietary taxa. Here, we designed an amplicon sequencing assay to monitor the eukaryotic diet of mussels and other metazoan filter feeders and explore the utility of mussels as natural eDNA samplers to monitor planktonic communities. We designed several lineage-specific rDNA primers with broad taxonomic suitability for eukaryotes. The primers were tested using DNA extracts of different limnic and marine mussel species and the results compared to eDNA water samples collected next to the mussel colonies. In addition, we analysed several 25-year time series samples of mussels from German rivers. Our primer sets efficiently prevent the amplification of mussels and other metazoans. The recovered DNA reflects a broad dietary preference across the eukaryotic tree of life and considerable taxonomic overlap with filtered water samples. We also show the utility of a reversed version of our primers, which prevents amplification of nonmetazoan taxa from complex eukaryote community samples, by enriching fauna associated with the marine brown algae Fucus vesiculosus. Our protocol will enable large-scale dietary analysis in metazoan filter feeders, facilitate aquatic food web analysis and allow surveying of aquacultures for pathogens. Moreover, we show that mussels and other aquatic filter feeders can serve as complementary DNA source for biomonitoring

Multiple paths toward repeated phenotypic evolution in the spiny-leg adaptive radiation (Tetragnatha; Hawai'i)

The repeated evolution of phenotypes provides clear evidence for the role of natural selection in driving evolutionary change. However, the evolutionary origin of repeated phenotypes can be difficult to disentangle as it can arise from a combination of factors such as gene flow, shared ancestral polymorphisms or mutation. Here, we investigate the presence of these evolutionary processes in the Hawaiian spiny-leg Tetragnatha adaptive radiation, which includes four microhabitat-specialists or ecomorphs, with different body pigmentation and size (Green, Large Brown, Maroon, and Small Brown). We investigated the evolutionary history of this radiation using 76 newly generated low-coverage, whole-genome resequenced samples, along with phylogenetic and population genomic tools. Considering the Green ecomorph as the ancestral state, our results suggest that the Green ecomorph likely re-evolved once, the Large Brown and Maroon ecomorphs evolved twice and the Small Brown evolved three times. We found that the evolution of the Maroon and Small Brown ecomorphs likely involved ancestral hybridization events, while the Green and Large Brown ecomorphs likely evolved through novel mutations, despite a high rate of incomplete lineage sorting in the dataset. Our findings demonstrate that the repeated evolution of ecomorphs in the Hawaiian spiny-leg Tetragnatha is influenced by multiple evolutionary processes.publishedVersio

Hybridization in parasites: consequences for adaptive evolution, pathogenesis and public health in a changing world

[No abstract available

Towards establishment of a centralized spider traits database

A main goal of ecological and evolutionary biology is understanding and predicting interactions between populations and both abiotic and biotic environments, the spatial and temporal variation of these interactions, and the effects on population dynamics and performance. Trait-based approaches can help to model these interactions and generate a comprehensive understanding of ecosystem functioning. A central tool is the collation of databases that include species trait information. Such centralized databases have been set up for a number of organismal groups but is lacking for one of the most important groups of predators in terrestrial ecosystems - spiders. Here we promote the collation of an open spider traits database, integrated into the global Open Traits Network. We explore the current collation of spider data and cover the logistics of setting up a global database, including which traits to include, the source of data, how to input data, database governance, geographic cover, accessibility, quality control and how to make the database sustainable long-term. Finally, we explore the scope of research questions that could be investigated using a global spider traits database.Peer reviewe