An environmental isotope and computer flow model investigation of the freshwater aquifer in the Lake Huron to Lake Erie corridor (Ontario, Michigan).

An environmental isotope and computer flow model investigation was undertaken to assess the distribution of groundwater flow in the freshwater aquifer located in southwestern Ontario and southeastern Michigan within the Lake Huron to Lake Erie corridor. The freshwater aquifer consists of a discontinuous thin layer of granular material located at the glacial overburden--bedrock interface which is nearly everywhere confined by a thick clay till layer. Groundwater samples were obtained from the freshwater aquifer for which \sp{18}O concentration and electrical conductivity values were measured. These values were combined with \sp{18}O, deuterium and tritium concentrations and electrical conductivity values from previous studies completed within the study area to determine the residence times and movement patterns of groundwater within the aquifer. In addition, a discrete state mixing cell model was developed utilizing \sp{18}O concentration history to estimate groundwater flow rates in the freshwater aquifer. A one-dimensional discrete state mixing cell computer model, called the Simplified Discrete State Flow Model or SDSFM, was developed for this study from the equations of continuity. The model utilized \sp{18}O concentration history to estimate groundwater flow rates in the freshwater aquifer. Hydraulic conductivity (K) and average linear groundwater velocity ($\bar\upsilon$) was calculated. (Abstract shortened by UMI.)Dept. of Geological Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1991 .C856. Source: Masters Abstracts International, Volume: 31-01, page: 0250. Thesis (M.A.Sc.)--University of Windsor (Canada), 1991

A note on mate allocation for dominance handling in genomic selection

Estimation of non-additive genetic effects in animal breeding is important because it increases the accuracy of breeding value prediction and the value of mate allocation procedures. With the advent of genomic selection these ideas should be revisited. The objective of this study was to quantify the efficiency of including dominance effects and practising mating allocation under a whole-genome evaluation scenario. Four strategies of selection, carried out during five generations, were compared by simulation techniques. In the first scenario (MS), individuals were selected based on their own phenotypic information. In the second (GSA), they were selected based on the prediction generated by the Bayes A method of whole-genome evaluation under an additive model. In the third (GSD), the model was expanded to include dominance effects. These three scenarios used random mating to construct future generations, whereas in the fourth one (GSD + MA), matings were optimized by simulated annealing. The advantage of GSD over GSA ranges from 9 to 14% of the expected response and, in addition, using mate allocation (GSD + MA) provides an additional response ranging from 6% to 22%. However, mate selection can improve the expected genetic response over random mating only in the first generation of selection. Furthermore, the efficiency of genomic selection is eroded after a few generations of selection, thus, a continued collection of phenotypic data and re-evaluation will be required

The fitness consequences of inbreeding in natural populations and their implications for species conservation – a systematic map

Background: Threatened species often have small and isolated populations where mating among relatives can result in inbreeding depression increasing extinction risk. Effective management is hampered by a lack of syntheses summarising the magnitude of, and variation in inbreeding depression. Here we describe the nature and scope of the literature examining phenotypic/fitness consequences of inbreeding, to provide a foundation for future syntheses and management. Methods: We searched the literature for articles documenting the impact of inbreeding in natural populations. Article titles, abstracts and full-texts were assessed against a priori defined criteria, and information relating to study design, quality and other factors that may influence inbreeding responses (e.g. population size) was extracted from relevant articles. Results: The searches identified 11457 articles, of which 614 were assessed as relevant and included in the systematic map (corresponding to 703 distinct studies). Most studies (663) assessed within-population inbreeding resulting from self-fertilisation or consanguineous pairings, while 118 studies assessed among-population inbreeding due to drift load. Plants were the most studied taxon (469 studies) followed by insects (52 studies) and birds (43 studies). Most studies investigated the effects of inbreeding on components of fitness (e.g. survival or fecundity; 648 studies) but measurements were typically under laboratory/greenhouse conditions (486 studies). Observations were also often restricted to the first inbred generation (607 studies) and studies frequently lacked contextual information (e.g. population size). Conclusions: Our systematic map describes the scope and quality of the evidence describing the phenotypic consequences of inbreeding. The map reveals substantial evidence relating to inbreeding responses exists, but highlights information is still limited for some aspects, including the effects of multiple generations of inbreeding. The systematic map allowed us to define several conservation-relevant questions, where sufficient data exists to support systematic reviews, e.g. How do inbreeding responses vary with population size? However, we found that such syntheses are likely to be constrained by incomplete reporting of critical contextual information. Our systematic map employed the same rigorous literature assessment methods as systematic review, including a novel survey of study quality and thus provides a robust foundation to guide future research and syntheses seeking to inform conservation decision-making