Next Generation Sequencing New sequencing technologies enable biologists to obtain complete genome and New sequencing technologies enable biologists to obtain complete transcriptome data of non-model organisms. genome and transcriptome data of non-model organisms. A complete genome even of tiny organisms like oribatid mites consist of an A complete genome, even of tiny organisms like oribatid mites, enormous amount of data. consist of an enormous amount of data. This unprecedented amount of genetic information enables biologists to This unprecedented quantity of genetic information enables investigate a variety of evolutionary and ecological questions with a single biologists to investigate a variety dataset. of evolutionary and ecological questions with a single dataset. We are interested in the genetic patterns of long-term asexual reproduction. Oribatid mites, our (non-) model organisms, are small soil-living arthropods. Many oribatid mite species consist of all female populations indicating that females produce daughters from unfertilized eggs (also known as thelytoky). The long-term existence of genetic lineages without recombination of female and male genomes is theoretically not possible due to the accumulation of mutations and limited adaptability to changing environmental conditions. Only few animals (oribatid mites and bdelloid rotifers) managed to persist as so called evolutionary scandals. We compare complete genome and transcriptome data of sexual and parthenogenetic oribatid mite species to identify consequences of long-term asexual reproduction and to understand how oribatid mites managed to sustain as evolutionary scandals. Analytical methods include Comparative Genomics, Phylogenomics and Population Genomics. For more information on running and upcomming projects, contact: Jens Bast (jbast@gwdg.de)
Next Generation Sequencing Population Genomics with springtails (Collembola) near Göttingen Some species of Collembola are ubiquitous in a diversity of habitats but it is not clear, if these species are generalists or if they form a cryptic species complex that specialized along an ecological gradient. With RAD-Seq data we are investigating, if gene flow exists between populations or if populations differ genetically between habitats. In this study, three populations of one springtail species will be sampled from three different habitats Forest Agriculatural Field Genetic diversity within and between populations Grassland will be compared and combined with environmental parameters from the different habitats including feeding preferences (fatty acid analyses) of populations. The combination of fine-scale population structure and ecological traits allows to investigate ecological speciation of soil-living arthropods. Ting-Wen Chen (tchen2@gwdg.de)
Phylogeography of earthworms in Europe Phylogeography reconstructs colonization and dispersal events at a large geographic scale. Genetic diversity of many European species show a pattern of southern richness and northern purity that resulted from the recolonisation of central and northern Europe by a fraction of animals that survived in larger populations in southern Europe during the past glacial cycles. Earthworms probably did not survive in glaciated areas during the last ice age. But today they are distributed across whole Europe. As earthworms have very limited dispersal ability, human mediated dispersal by trading soil-born goods and transport of soil due to traffic and construction works probably is of major importance. We are going to analyse the genetic structure of two common earthworm species from six countries across Europe. For this, four genes will be sequenced from individual earthworms and investigated with phylogenetic and spatial analyses. Results of this study provide insight into small and large scale distribution of earthworms in Europe and the impact of anthropogenic dispersal in natural populations. Andreas Klein (aklein1@gwdg.de)
Populationgenetics of invasive earthworms in North America European earthworms are invasive species in North America. Introduced by European settlers they are now established in wide areas in northern USA and Canada. Their presence has strong (negative) effects on community structure and biodiversity of native plants and animal species and is a major concern across the North American continent. Human mediated transport along roads and dumping of fishing baits contributes massivley to the wide distribution of earthworms and their potential as invasive species. This study will investigate the genetic structure of two common fishing bait species in Minnesota using microsatellite markers. Both species differ in tolerance to abiotic environmental factors, life-style and mobility. Gene flow, migration (human mediated) and genetic similarity will be investigated in neigbouring and distant populations. We expect that genetic patterns differ between species and that populationsof the more mobile and tolerant species are genetically divers and have stronger genetic structure. Additionally, we expect that anthropogenic influence will have a stronger effect on population structure of the less tolerant and less mobile species. This is the first study that investigates population genetic structure in invasive earthworm species and will provide information on factors facilitating invasiveness of European earthworms in North America. Andreas Klein (aklein1@gwdg.de)
Above ground dispersal of soil-living animals Oribatid mites and springtails (Collembola) are tiny soil-living arthropods and many species occur everywhere in the northern hemisphere. Dispersal agents are little known, but due to their small body size and the strong texture of their habitat, active dispersal is very limited. Within the Swedish Malaise Trap Project flying insects were collected in liquid traps for three years across Sweden. Although traps are designed for flying insects many soil-living arthropods are also present in these traps. The potential for phoresy (passive transport by attachment to other animals) and wind dispersal is apparently high in these animals but only very few studies are available with detailed and long-term records of above ground traps. Further, long-distance dispersal is probably not equally developed in all species of oribatid mites and Collembola. In this project we are going to investigate if aboveground dispersal is a common trait in soil-living arthropods or if only certain taxa are able of long-distance dispersal. Further, we are analysing with statistical and phylogenetic methods if phoresy or wind dispersal are adaptive traits. This project comprises an excellent and unprecedented long-term and large-scale sampling for comprehensive analyses of dispersal ability of soil-living microarthropods.
Oribatid mite and springtail communities in temperate forests - the enigma of soil-animal diversity - Oribatid mites and springtails (Collembola) show high alpha diversity but low beta diversity. This means that the number of species are high at local scale, but differ little at regional scale. Communities (species assembly) of soil-living microarthropods can be determined by several factors. Regional Processes: Dispersal Environmental Hetergogeneity Phylogeny: Coexistence Of Species Due To Similar Traits Similar Evolutionary History Landscape Connectivity Local Processes: Niche Differentiation Microhabitat Heterogeneteity Local Environment Despite superficial similarities in ecology, function, feeding types and evolutionary age, communities of oribatid mites and Collembola likely are structured by different factors. In this project oribatid mite and springtail communities of three coniferous and beech forests will be analysed with phylogenetic, statistical and spatial methods. This project investigates if environmental filtering or density-dependent interactions structure the communities of important and ubiquitous functional groups in the soil-system. Bernhard Eitzinger (beitzin@gwdg.de) Ting-Wen Chen (tchen2@gwdg.de)