Assortative mating but no evidence of genetic divergence in a species characterized by a trophic polymorphism

Disruptive selection is a process that can result in multiple sub-groups within a population, referred to as diversification. Foraging related divergence has been described in many taxa, but many questions remain about the contribution of such divergence to reproductive isolation and potentially sympatric speciation. Here we use stable isotope analysis of diet and morphological analysis of body shape to examine phenotypic divergence between littoral and pelagic foraging ecomorphs in a population of pumpkinseed sunfish (Lepomis gibbosus). We then examine reproductive isolation between ecomorphs by comparing the isotopic compositions of nesting males to eggs from their nests (a proxy for maternal diet), and use nine microsatellite loci to examine genetic divergence between ecomorphs. Our data support the presence of distinct foraging ecomorphs in this population and indicate that there is significant positive assortative mating based on diet. We did not find evidence of genetic divergence between ecomorphs, however, indicating that isolation is either relatively recent or is not strong enough to result in genetic divergence at the microsatellite loci. Based on our findings, pumpkinseed sunfish represent a system in which to further explore the mechanisms by which natural and sexual selection contribute to divergence, prior to the occurrence of sympatric speciation

Restrictive covenants in Xanadu

Legal scholarship is naturally inclined towards explanations and justifications of contemporary law. In the case of restrictive covenants and building schemes this has led to a distorted perception of the historical record, as revealed in recorded case reports dating from the nineteenth century. It is argued that the restrictive covenant had its historical genesis not in a response to industrialisation and mass urbanisation, but in the developments of resort towns in the eighteenth and early nineteenth centuries, as a response to the needs of land developers. Furthermore, it is argued that a better historical understanding of these origins illuminates contemporary problems concerned with the adaptability of law and the potential roles of law in development

Climatic Cycles Recorded in Glacially Influenced Rhythmites of the Gowganda Formation, Huronian Supergroup

The Gowganda Formation of the 2.45–2.2 Ga Huronian Supergroup contains glacially-induced, varve-like rhythmites that potentially preserve a detailed record of climatic conditions during the Paleoproterozoic Era. Four rhythmic couplet thickness records were measured at two outcrops near Wharncliffe, Ontario for the purpose of time-series analysis. The couplets, which range from 1 to 32 mm thick, are composed of alternating layers of siltstone and claystone. Time-series analysis of the couplet thickness records using the MTM Toolkit of Mann and Lees (1996) consistently revealed periodicities in the range of 2.2–2.9 couplets per cycle, which is consistent with climatic cycles such as the quasi-biennial oscillation (QBO) and the El Niño Southern Oscillation (ENSO) observed in modern times. This periodicity suggests that the rhythmic couplets represent annual deposits (i.e. varves). Evidence for the presence of cycles at 3.0– 4.9 couplets, 6.6–6.9 couplets, 8.8–9.2 couplets, 22.8 couplets, and 30.1–31.0 couplets were also observed in some couplet thickness records; however, the presence of these longer term cycles was inconsistent from site to site

A Hydrostratigraphic Framework for the Paleozoic Bedrock of Southern Ontario

Groundwater systems in the intermediate to deep subsurface of southern Ontario are poorly understood, despite their value for a number of societal uses. A regional hydrostratigraphic framework is a necessary precursor for improving our understanding of groundwater systems and enabling development of a 3-D hydrostratigraphic model to visualize these groundwater systems. This study is a compilation and integration of published and unpublished geological, hydrogeological, hydrochemical and isotopic data collected over the past 10 years to develop that framework.Bedrock is covered by a thin veneer of surficial sediments that comprise an aquifer/aquitard system of considerable local variability and complexity. Aquifers in the bedrock are thin and regionally extensive, separated by thick aquitards, within a well-defined lithostratigraphic framework and a well-developed hydrochemical depth zonation comprising a shallow fresh water regime, an intermediate brackish to saline sulphur water regime, and a deep brine regime of ancient, evaporated seawater. Occurrence and movement of groundwater in shallow bedrock is principally controlled by modern (Quaternary) karstic dissolution of subcropping carbonate and evaporite rocks, and in the intermediate to deep subsurface by paleokarst horizons developed during the Paleozoic. Flow directions in the surficial sediments of the shallow groundwater regime are down-gradient from topographic highs and down the regional dip of bedrock formations in the intermediate regime. Shallow karst is the entry point for groundwater penetration into the intermediate regime, with paleo-recharge by glacial meltwater and limited recent recharge by meteoric water at subcrop edges, and down-dip hydraulic gradients in confined aquifers. Hydraulic gradient is up-dip in the deep brine regime, at least for the Guelph Aquifer and the Cambrian Aquifer, with no isotopic or hydrochemical evidence of infiltration of meteoric water and no discharge to the surface.Fourteen bedrock hydrostratigraphic units are proposed, and one unit comprising all the surficial sediments. Assignment of lithostratigraphic units as hydrostratigraphic units is based principally on hydrogeological characteristics of Paleozoic bedrock formations in the intermediate to deep groundwater regimes, below the influence of modern meteoric water. Carbonate and evaporite rocks which form aquitards in the subsurface may form aquifers at or near the surface, due to karstic dissolution by acidic meteoric water, necessitating compromises in assignment of hydrostratigraphic units.Les systèmes d'eaux souterraines du sous-sol intermédiaire à profond du sud de l'Ontario sont mal compris, malgré leur valeur pour de nombreux usages par la société. Un cadre hydrostratigraphique régional est un préalable nécessaire à l’amélioration de notre compréhension des systèmes d'eaux souterraines et au développement d'un modèle hydrostratigraphique 3D pour visualiser ces systèmes d'eaux souterraines. Cette étude est une compilation et une intégration de données géologiques, hydrogéologiques, hydrochimiques et isotopiques publiées et non publiées recueillies au cours des 10 dernières années afin de développer ce cadre.Le substrat rocheux est recouvert d'un mince placage de sédiments de surface qui comprend un système d’aquifères et d’aquitards d'une variabilité et d'une complexité locales considérables. Les aquifères du substrat rocheux sont minces et étendus au niveau régional, séparés par des aquitards épais, dans un cadre lithostratigraphique bien défini et une zonation hydrochimique verticale bien développée comprenant un régime peu profond d'eau douce, un régime intermédiaire d'eau sulfureuse saumâtre à saline et un régime profond de saumure résultant de l’évaporation d'eau de mer ancienne. La présence et le mouvement des eaux souterraines dans le substrat rocheux peu profond sont principalement contrôlés par la dissolution karstique moderne (quaternaire) des roches carbonatées et évaporitiques sub-affleurantes, et dans le sous-sol intermédiaire à profond par les horizons paléokarstiques développés au Paléozoïque. Les directions d'écoulement des eaux dans les sédiments de surface du régime peu profond sont en aval des sommets topographiques et en aval du pendage régional des formations de substrat rocheux dans le régime intermédiaire. Le karst peu profond est le point d'entrée pour l’infiltration des eaux souterraines dans le régime intermédiaire, avec une paléo-recharge d'eau de fonte glaciaire et une recharge récente limitée d'eau météorique aux bords de sous-affleurement, et un gradient hydraulique en aval-pendage dans les aquifères confinés. Le gradient hydraulique est en amont-pendage dans le régime profond de saumure, au moins pour l'aquifère de Guelph et l'aquifère du Cambrien, sans indication isotopique ou hydrochimique d'infiltration d'eau météorique et sans déversement à la surface.Quatorze unités hydrostratigraphiques du substrat rocheux sont proposées, et une unité comprenant tous les sédiments de surface. L'attribution des unités lithostratigraphiques en tant qu’unités hydrostratigraphiques repose principalement sur les caractéristiques hydrogéologiques des formations du substrat rocheux du Paléozoïque dans les régimes intermédiaires à profonds des eaux souterraines, sous l'influence des eaux météoriques modernes. Les roches carbonatées et évaporitiques qui forment les aquitards dans le sous-sol peuvent former des aquifères à la surface ou près de la surface, en raison de la dissolution karstique par l'eau météorique acide, ce qui nécessite des compromis dans l'attribution des unités hydrostratigraphiques

The ROM / UWO Mummy Project: A Microcosm of Progress in Mummy Research

The beginnings of the Royal Ontario Museum can be traced back to the excavations and collections of Charles Trick Currelly, a staff member of the Egyptian Exploration Fund in the early 1900s. Currelly excavated with Sir Flinders Petrie at Abydos and with Edouard Naville at Deir el Bahari. With the assistance of Robert Mond and others, Currelly amassed a rich and diverse collection that became the basis for the ROM, which opened its doors in 1914. Part of that collection included several Egyptian mummies (Currelly 1971) . The Egyptologicalholdings at the ROM include eight mummies: one dating to the Predynastic Period, five from the Pharaonic Period, one from the Roman Period and one without context. Two of these, Nakht and Djedmaatesankh, have been well studied by Peter Lewin and associates, while three more are the subjects of the current investigation. The objectives of this poster are to review the work and accomplishments of the previous research, to describe the preliminary results of the current research project and to outline directions for future work

Stable isotope ecology and interspecific dietary overlap among dolphins in the Northeast Atlantic

Dolphins are mobile apex marine predators. Over the past three decades, warm-water adapted dolphin species (short-beaked common and striped) have expanded their ranges northward and become increasingly abundant in British waters. Meanwhile, cold-water adapted dolphins (white-beaked and Atlantic white-sided) abundance trends are decreasing, with evidence of the distribution of white-beaked dolphins shifting from southern to northern British waters. These trends are particularly evident in Scottish waters and ocean warming may be a contributing factor. This mobility increases the likelihood of interspecific dietary overlap for prey among dolphin species previously separated by latitude and thermal gradients. Foraging success is critical to both individual animal health and overall population resilience. However, the degree of dietary overlap and plasticity among these species in the Northeast Atlantic is unknown. Here, we characterise recent (2015-2021) interspecific isotopic niche and niche overlap among six small and medium-sized delphinid species co-occurring in Scottish waters, using skin stable isotope composition (δ13C and δ15N), combined with stomach content records and prey δ13C and δ15N compiled from the literature. Cold-water adapted white-beaked dolphin have a smaller core isotopic niche and lower dietary plasticity than the generalist short-beaked common dolphin. Striped dolphin isotopic niche displayed no interspecific overlap, however short-beaked common dolphin isotopic niche overlapped with white-beaked dolphin by 30% and Atlantic white-sided dolphin by 7%. Increasing abundance of short-beaked common dolphin in British waters could create competition for cold-water adapted dolphin species as a significant portion of their diets comprise the same size Gadiformes and high energy density pelagic schooling fish. These priority prey species are also a valuable component of the local and global fishing industry. Competition for prey from both ecological and anthropogenic sources should be considered when assessing cumulative stressors acting on cold-water adapted dolphin populations with projected decline in available habitat as ocean temperatures continue to rise

Probing the hydrothermal system of the Chicxulub impact crater

The ~180-km-diameter Chicxulub peak-ring crater and ~240-km multiring basin, produced by the impact that terminated the Cretaceous, is the largest remaining intact impact basin on Earth. International Ocean Discovery Program (IODP) and International Continental Scientific Drilling Program (ICDP) Expedition 364 drilled to a depth of 1335 m below the sea floor into the peak ring, providing a unique opportunity to study the thermal and chemical modification of Earth’s crust caused by the impact. The recovered core shows the crater hosted a spatially extensive hydrothermal system that chemically and mineralogically modified ~1.4 × 105 km3 of Earth’s crust, a volume more than nine times that of the Yellowstone Caldera system. Initially, high temperatures of 300° to 400°C and an independent geomagnetic polarity clock indicate the hydrothermal system was long lived, in excess of 106 years