Riverscape Community Genomics of Ozark Fishes: A Comparative Framework to Infer Ecological and Evolutionary Determinants of Genetic Diversity

Genetic variation is a crucial component of biodiversity and represents the variability and spatial structure of alleles within and among organisms. Evolution modulates this variability over time through mutation, selection, gene flow, and genetic drift. However, our capacity to test foundational theories of population genetics has always been at the mercy of molecular approaches available to quantify patterns of genetic diversity. Initially, techniques for empirical DNA studies were in their infancy and limited by technologies and the price per unit of genetic information. Because of these constraints, our pursuits have generally been limited to investigations of one or a few species simultaneously, hampering our power to draw broadly applicable conclusions. Advances in molecular technologies, e.g., high-throughput sequencing, now provide so much information at so little cost that a multispecies comparative approach to uncovering generalities about evolution is within reach even for applied studies on non-model organisms. Ultimately, genotyping individuals from all species within a community will be feasible and easily replicated across sampling locations and span entire regions. Variability of genetic diversity, within and among species, can be leveraged to explore the relationship between ecology and evolution and between micro- and macroevolution.For my dissertation research, I employed a multispecies framework to link ecological and evolutionary processes driving spatial patterns of biodiversity through comparative analyses of genotypic variability among sympatric species of freshwater fish that inhabit a large sub-basin of the Mississippi River. First, I quantified the extent of admixed ancestry among species within a community by assessing genomic variability among individuals from many species. My analyses uncovered that fish in nature — particularly minnows — have higher than expected hybridization rates. My data even show evidence of hybrid viability and genetic exchange among species (i.e., introgression). I interpret these findings of widespread admixture among distinct species as an indicator that admixture plays a critical role in ecology and evolution – more so than previously considered. Second, I tested for general mechanisms that define spatial genomic variability within species by comparing models of extrinsic drivers of genetic divergence. The river network, or stream hierarchy model, best explained species\u27 genomic variability, as evidenced by the correspondence between genetic divergence and riverine architecture. This general pattern emerged for all species, but the degree of genetic divergence differed widely, indicating that the intrinsic traits of each species may also play an important role. Finally, I further explored how phenotypic traits may modulate species\u27 genetic diversity and ultimately evolutionary trajectories by comparing relationships between traits and metrics of genetic variability among species within a comparative framework. Significant associations between trait values and genetic patterns emerged, allowing me to develop predictive models of genetic diversity using traits alone, without requiring direct genetic assessments. These trait-based models can be applied to prioritize species for conservation and management. My dissertation research demonstrates that modern molecular approaches are uniquely positioned to help unite ecology and evolution, bridging the long-standing dichotomy between these two disciplines. I provide a comparative framework for conservation biology that integrates various temporal and spatial scales and demonstrate with an empirical example how it can be applied to assess thousands of informative genetic markers across entire communities of non-model organisms. My dissertation research elevates population genomics to the community level and outlines how to explore new dimensions in our long-standing inquiry: What drives variation in genetic diversity among species

Quantum Key Distribution over 67 km with a plug & play system

We present a fibre-optical quantum key distribution system. It works at 1550nm and is based on the plug & play setup. We tested the stability under field conditions using aerial and terrestrial cables and performed a key exchange over 67 km between Geneva and Lausanne.Comment: 8 pages, 3 figures, 2 tables. Submitted to the New Journal of Physic

Faint laser quantum key distribution: Eavesdropping exploiting multiphoton pulses

The technological possibilities of a realistic eavesdropper are discussed. Two eavesdropping strategies taking profit of multiphoton pulses in faint laser QKD are presented. We conclude that, as long as storage of Qubits is technically impossible, faint laser QKD is not limited by this security issue, but mostly by the detector noise.Comment: 7 pages, 6 figure

Femtosecond Time-Bin Entangled Qubits for Quantum Communication

We create pairs of non-degenerate time-bin entangled photons at telecom wavelengths with ultra-short pump pulses. Entanglement is shown by performing Bell kind tests of the Franson type with visibilities of up to 91%. As time-bin entanglement can easily be protected from decoherence as encountered in optical fibers, this experiment opens the road for complex quantum communication protocols over long distances. We also investigate the creation of more than one photon pair in a laser pulse and present a simple tool to quantify the probability of such events to happen.Comment: 6 pages, 7 figure

Long distance quantum teleportation in a quantum relay configuration

A long distance quantum teleportation experiment with a fiber-delayed Bell State Measurement (BSM) is reported. The source creating the qubits to be teleported and the source creating the necessary entangled state are connected to the beam splitter realizing the BSM by two 2 km long optical fibers. In addition, the teleported qubits are analyzed after 2,2 km of optical fiber, in another lab separated by 55 m. Time bin qubits carried by photons at 1310 nm are teleported onto photons at 1550 nm. The fidelity is of 77%, above the maximal value obtainable without entanglement. This is the first realization of an elementary quantum relay over significant distances, which will allow an increase in the range of quantum communication and quantum key distribution.Comment: 4 pages, submitte