Divergent selection is the main driving force in sympatric ecological speciation and may also play a strong role in divergence between allopatric populations. Characterizing the genome-wide impact of divergent selection often constitutes a first step in unravelling the genetic bases underlying adaptation and ecological speciation. The Midas cichlid fish (Amphilophus citrinellus) species complex...

Recent advances in computing technology and our understanding of the processes involved in crater production, ejecta production, and crater erasure have permitted me to develop a highly-detailed Cratered Terrain Evolution Model (CTEM), which can be used to investigate a variety of questions in the study of impact dominated landscapes. In this work, I focus on the manner in which crater densitie...

Introduction: Synchronously rotating satellites bombarded by a heliocentric impactor population should have a difference in crater density between their apex and antapex of motion. Predictions by Zahnle et al. [1] indicate the crater density at the apex could be up to ~70x greater than at the antapex. An absence of such a difference could be caused by saturation crater-ing, periods of nonsynchr...

Introduction: Among the classic field-and laboratory studies of crater structure, a handful have mentioned the influence of fracture networks upon crater shapes [1,2,3] and few later investigations have addressed the problem directly (see [4] for a recent study and thorough review). A polygonal simple crater is thought to result when the excavation flow exploits planes-of-weakness in the target...

[1] High-resolution images from Chandrayaan-1 Terrain Mapping Camera and Lunar Reconnaissance Orbiter Camera reveal landslides and gully formation on the interior wall of a 7 km-diameter simple crater emplaced in Schrödinger basin on the farside of the Moon. These features occur on the steep upper crater wall, where the slope is ~35 . The gullies show a typical alcove-channel-fan morphology. So...

High-throughput culturing (HTC) methods that rely on dilution to extinction in very-low-nutrient media were used to obtain bacterial isolates from Crater Lake, Oregon. 16S rRNA sequence determination and phylogenetic reconstruction were used to determine the potential ecological significance of isolated bacteria, both in Crater Lake and globally. Fifty-five Crater Lake isolates yielded 16 diffe...

The polychromatic and trophically polymorphic Midas cichlid fish species complex (Amphilophus cf. citrinellus) is an excellent model system for studying the mechanisms of speciation and patterns of phenotypic diversification in allopatry and in sympatry. Here, we first review research to date on the species complex and the geological history of its habitat. We analyse body shape variation from ...

A broad class of “local response” theories seeks to predict morphology evolution during energetic particle irradiation in terms of average surface height response to individual impacts—an approach that has been generalized by the crater function formalism of Norris et al. [J. Phys.: Condens. Matter 21, 224017 (2009); Nat. Commun. 2, 276 (2011)]. Keeping only the terms in the crater function for...

Crater chains, presumably formed by weak asteroids or comets stretched apart by planetary tides, have been tentatively identiied on both the Earth and Moon. By modeling tidal disruption by the Earth and Moon of \rubble-pile" bodies, we nd that the Earth disrupts enough objects over the last 3.8 billion years to account for one or two lunar crater chains, but that the reciprocal production rate ...