Circadian rhythms are often tightly confined around a mean of 24 hours with little variation in traditional model organisms in the absence of environmental time cues. Some spider species fall well outside this normal range with mean periods of 18 hours and variation around these means of 6 hours or more. This extreme variation in circadian rhythm is not well-understood and is the focus of the current study. Using Parasteatoda tepidariorum as a model organism, we investigated whether variation in eight circadian parameters could be explained by genetic variability, environmental conditions, or an endogenous feature of the circadian system of P. tepidariorum. No significant correlation was found between mother spiders and their offspring for all circadian parameters, nor was a significant difference found among groups exposed to different environmental conditions. We conclude that circadian variation seen in P. tepidariorum is likely a result of an innate circadian feature such as relaxed selection for a precise, 24-hour circadian rhythm.

No description available.

The objectives of this dissertation were to evaluate genetic influences on ewe productivity, its growth and reproductive components, and measures indicative of accelerated lambing performance. Genetic parameters were estimated for total weight of litter weaned per ewe lambing (TW) and its components, number of lambs born (NB), number of lambs weaned (NW) and average weight of lambs weaned (AW), measured as traits of the ewe, and lamb survival (LS) and weaning weight (WW), measured as traits of the lamb, in Katahdin sheep. Heritabilities of TW, NB, NW, and AW, were 0.12, 0.12, 0.09, and 0.13, respectively. Heritability of WW was 0.15 to 0.20. Genetic effects on LS were negligible. Genetic correlation of TW with NB, NW, and AW averaged 0.30, 0.90, and 0.74, respectively, those of NB with NW and AW averaged 0.72 and 0.01, respectively, and that between NW and AW averaged 0.50. Direct genetic effects on WW were independent of NB and NW, but correlation between maternal genetic effects on WW and animal genetic effects on NW averaged 0.35. Ewe fertility, NB, LS, and WW were modeled using stochastic simulation and used to derive NW, AW, and TW to test alternative predictors of genetic merit for TW. A random 8% of WW observations were set to missing values and AW and TW were recalculated to evaluate the effects of data reporting inconsistencies on efficacy of different prediction strategies. Four alternative predictors of estimated breeding values (EBV) for TW involved direct univariate prediction (TW1), an index of EBV for NW and AW (TW2), indirect prediction using data for NW and AW and genetic correlations among NW, AW and TW (TW3), and indirect prediction augmenting TW3 with data and genetic correlations involving NB (TW4). To validate efficacy of predictors, daughter data sets were generated from the original ewes and their realized TW were regressed on alternative predictors. Regression coefficients from TW1, TW3, and TW4 were close to the expected value of 0.50 whereas those from TW2 were less than 0.50. Model Rsquare statistics were similar among predictors when there were no missing WW data but regressions involving TW1 had lowest model R-square when some WW data was missing. Ewe lamb fertility (ELF), ages at first, second, and third lambings (AGE1 to AGE3), first and second lambing intervals (INT1 and INT2), and number of lambings by 38 mo of age (LAMB3) were evaluated for an accelerated lambing Polypay flock. Relationships among these traits and NB and WW were estimated. Heritability of ELF, AGE1, AGE2, AGE3, INT1, INT2, and LAMB3 were 0.14, 0.39, 0.28, 0.36, 0.00, 0.09, and 0.27, respectively. Heritability of AGE2 and AGE3 were negligible after accounting for variation in AGE1. Genetic correlations of ELF with AGE1 and AGE2 were -0.89, -0.91, respectively, and that with LAMB3 was 0.89. Genetic correlations of LAMB3 with AGE1 and AGE2 were -0.49 and -1.00, respectively. Genetic correlations of ELF and LAMB3 with direct genetic effects on WW were close to -0.70, but correlations with maternal genetic effects on WW were 0.88 and 0.58, respectively. Prolificacy was independent of ELF and LAMB3. / Ph. D.

Soybeans within a specific seed size range are often preferred for the manufacture of specialty soy products. This study examined the influence of row spacing and seeding rate on seed yield, average seed size, and seed size uniformity of Camp (small seeded) and V71-370 (large seeded) soybean cultivars [Glycine max (L.) Merr.]. Experiments were conducted in 1992 and 1993 at Kentland Farm near Blacksburg, Virginia. Row widths of 38 and 76 cm and seeding rates of 125, 250, 500, and 750 thousand seeds ha⁻¹ were used. Averaged over treatments, 38-cm row spacings yielded higher than 76-cm row spacing by 11.6%. Additionally, each increase in seeding rate resulted in increased yield up to 500,000 seeds ha and then leveled off. Yield of useful seed of Camp (total yield multiplied by the proportion of seed between 4.8 and 5.6 mm in diameter) was maximized at narrow row spacings and 500,000 seeds ha⁻¹. Neither row spacing nor seeding rate influenced V71-370 yield of usable seed (larger than 7.9 mm). Averaged over years and cultivars, soybean seed size was not influenced by row spacings or seeding rates. However, in 1993, smaller Camp seed was favored by narrow rows and low seeding rate. Seed size uniformity, as determined by analysis of variance of individual seed weights was, in general, not influenced by row spacing or seeding rates. In a separate investigation in 1992, heritabilities were estimated by two methods using plot data from two replications of lines from crosses of Camp with Jizuka, MD87L-0198, and Stafford soybean cultivars. Heritabilities based on F₃ progeny means regressed on F₂ parental means ranged from 24% to 41% and were lower than the corresponding heritability estimates based on analysis of variance which ranged from 43% to 83%. Correlations of seed size with other agronomic traits were generally low. Although low in magnitude, significant positive correlations of seed size with yield in some crosses might hinder progress of breeders when selecting for small-seeded, high yielding cultivars. / Ph. D.

Retina is a unique site in the human body where the microcirculation can be imaged directly and non-invasively, allowing us to study in vivo the structure and pathology of the human microcirculation. Retinal images can be quantitatively assessed with computerized imaging techniques, enabling us to measure several different quantitative traits derived from the retinal vasculature. Arterial and venular calibres are the most extensively studied traits of the retinal microvasculature and numerous epidemiological studies demonstrated promising associations with systemic and ocular diseases as well as with disease markers. However, there has been a lack of research into pathophysiological processes leading to retinal vascular signs, and how they link retinal microcirculation with coronary and cerebral microvasculature change. Information about genetic determinants underlying retinal vascular structure is therefore important for understanding the processes leading to microvascular pathophysiology. Two genome wide association studies have been published so far revealing four loci associated with retinal venular calibre and one locus with arteriolar calibre. Here the results from the genome-wide association analysis of 10 different retinal vessel traits in two population based cohorts are presented. Retinal images were measured in non-mydriatic fundus images from 808 subjects in the Orkney Complex Disease Study (ORCADES) and 390 subjects from the Croatian island of Korcula, using the semi-automated retinal vasculature measurement programme SIVA and VAMPIRE. Using pairwise estimates of kinship based on genomic sharing, heritability was calculated for each trait. Estimates of tortuosity measure and fractal dimensions present first published reports of heritability estimates for those traits. In addition correlation analysis with systemic risk factor was also completed, confirming already published results as well as revealing some new associations. A genome wide association analysis of retinal arteriolar width revealed a genome wide significant hit (1.8x10-7) in a region of chromosome 2q32 (within TTN gene). Replication was sought in a further independent Scottish population (LBC) and additional 400 retinal images were graded. The result did not replicate, however the direction of the effect was consistent and a larger sample size is required. Analysis of the remaining traits did not yield genome wide significant result,s and will also require larger sample sizes. Genetic analysis of a binary retinal trait was also explored in a case control study of retinal detachment, which is an important cause of vision loss. A two-stage genetic association discovery phase followed by a replication phase in a combined total of 2,833 RRD cases and 7,871 controls was carried out. None of the SNPs tested in the discovery phase reached the threshold for association. Further testing was carried out in independent case-control series from London (846 cases) and Croatia (120 cases). The combined meta-analysis identified one association reaching genome-wide significance for rs267738 (OR=1.29, p=2.11x10-8), a missense coding SNP and eQTL for CERS2 encoding the protein ceramide synthase 2. Additional genetic risk score, pathway analysis and genetic liability analysis were also carried out.

Long term longitudinal surveys have the advantage to enable several sampling of the studied phenomena and then, with the repeated measures obtained, find a confirmed tendency. However, these long term surveys generate large epidemiological datasets including more sources of noise than normal datasets (e.g. one single measure per observation unit) and potential correlation in the measured values. Here, we studied data from a long-term epidemiological and genetic survey of malaria disease in two family-based cohorts in Senegal, followed for 19 years (1990-2008) in Dielmo and for 16 years (1993-2008) in Ndiop. The main objectives of this work were to take into account familial relationships, repeated measures as well as effect of covariates to measure both environmental and host genetic (heritability) impacts on the outcome of infection with the malaria parasite Plasmodium falciparum, and then use findings from such analyses for linkage and association studies. The outcome of interest was the occurrence of a P. falciparum malaria attack during each trimester (PFA). The two villages were studied independently; epidemiological analyses, estimation of heritability and individual effects were then performed in each village separately. Linkage and association analyses used family-based methods (based on the original Transmission Disequilibrium Test) known to be immune from population stratification problems. Then to increase sample size for linkage and association analyses, data from the two villages were used together.

Master of Science / Department of Animal Sciences and Industry / Daniel W. Moser / Among working dogs, the role of a guide dog ranks as one of the most noble and useful occupations and thus was recognized early as a category of working dogs worthy of focused research. Behavior issues top the list of most common reasons for rejecting dogs from working as guides. The objective of this study was to estimate genetic parameters for each of the 101 questions and 12 subscale factors measured by the Canine Behavioral Assessment and Research Questionnaire (C-BARQ). The C-BARQ is a standardized questionnaire that contains seven behavioral categories: training and obedience, aggression, fear and anxiety, separation-related behavior, excitability, attachment and attention-seeking, and a miscellaneous category. These categories and questions allow the evaluator to describe any dog's behavior. For this study, questionnaire responses were obtained on 3,149 and 3,348 Labrador Retrievers (LR) from Guiding Eyes for the Blind (GEB) and 989 and 1,187 Labrador Retrievers, 608 and 692 Golden Retrievers (GR), and 966 and 1,348 German Shepherd Dogs (GSD) from The Seeing Eye, Inc. (TSE) at 6- and 12-months of age, respectively. The estimates of heritability and standard errors from TSE dogs indicate that there is much genetic variation that could be exploited in selection against "Familiar dog-directed aggression/fear" (0.27 ± 0.12) of GR at 6-months, "Chasing" (0.22 ± 0.10) of GR at 6-months, and "Nonsocial fear" (0.27 ± 0.09) of GR at 12-months or in selection for improved "Trainability" of LR (0.46 ± 0.07), GSD (0.47 ± 0.07), and GR (0.20 ± 0.08) at 12-months. In general, the remaining factors and most of the 101 questions were found to be lowly heritable (< 0.10). These estimates are useful to understand more about the nature of behavioral traits leading to the production of successful working guides.

Resumo: O temperamento bovino é uma característica geralmente definida por um conjunto de comportamentos dos animais em relação ao homem. Essa característica influencia o potencial produtivo de rebanhos por estar correlacionada com características de desempenho e qualidade de carcaça e ter relação com aspectos facilitadores do dia a dia do manejo, bem-estar e segurança dos animais e funcionários. O temperamento (T) apresenta estimativas de herdabilidade de moderadas a baixas e é influenciado por práticas de manejo e condições ambientais, sendo importante o conhecimento de tais fatores para ações de seleção. O relacionamento de características de desempenho, como ganho de peso pós-desmama (GPD) e de biotipo por escores visuais, como conformação (C), precocidade (P) e musculosidade (M), vem sendo utilizado em diversos programas de melhoramento visando a melhor identificar animais de conformação produtiva superior pela associação de desempenho com tipo morfológico. Neste trabalho foram utilizados 33.967 registros de escores de temperamento, GPD, C, P e M de animais da raça Nelore controlados pelo programa de melhoramento genético da Lagoa da Serra Ltda. (PAINT®). Os dados foram analisados utilizando modelo animal, com análises uni e bi-catacterísticas, pelo método de máxima verossimilhança restrita, em que se estimaram parâmetros genéticos, fenotípicos e ambientais para as características, e verificaram os benefícios do uso da medida de temperamento em um programa de melhoramento genético. As herdabilidades estimadas foram 0,18 l 0,02; 0,26 l 0,03; 0,28 l 0,03; 0,33 l 0,03 e 0,35 l 0,03 para T, GPG, C, P e M, respectivamente. Os valores de correlação genética entre temperamento e as outras características mostraram-se de pequena magnitude, mas favoráveis. Os resultados demonstraram que as características podem responder à seleção e que há tendência de resposta correlacionada. / Abstract: Bovine temperament is a trait generally defined by a set of behaviors of the animals in relation to man. This trait has demonstrated influence on productive potential of herds, due to its correlation with performance and quality of carcass traits, as well as a day by day relation with aspects of handling, welfare and security of animals and employees, besides significant reduction on investments or rationalization of these in other production system areas. Temperament has heritability ranging from moderate to low and it is affected by handling practices and environmental conditions, so, it is important to know such factors for selection issues. The relationship between performance traits, as weight gain after weaning (GPD) and biotype for visual scores, as conformation (C), precocity (P) and musculature (M), has been used by several breeding programs aiming better identification of animals showing good productive conformation through the association of performance with morphological traits. Data of score of temperament, GPD, C, P and M recorded on 33,967 Nelore animal pertaining to PAINT®, the Lagoa da Serra Ltda. breeding program were used. The data were analyzed using an animal model, by the Restricted Maximum Likelihood method to estimate genetic, phenotypic and environmental parameters for T, GPD, C, P and M. Uni and bi-trait analyses were carried out for T and GPD, C, P and M to estimate genetic correlation and heritabilites of these traits. The estimates of heritability were 0.18 l 0.02; 0.26 l 0.03; 0.28 l 0.03; 0.33 l 0.03 and 0.35 l 0.03 for T, GPG, C, P and M, respectively. The values of genetic correlation between temperament and the other traits were low, but favorable. The results demonstrated that the traits could respond to selection and, that selection for T could show indirect response on productive traits. / Orientadora: Sandra Aidar de Queiroz / Coorientador: Luiz Alberto Fires / Banca: Maurício Mello de Alencar / Banca: Joanir Pereira Eler / Mestre

No description available.

A pecuária de corte brasileira tem sofrido grande pressão devido às questões ambientais, às exigências dos mercados consumidores por carne de qualidade e rígidos padrões sanitários. Esses fatores aumentam a importância da melhoria da eficiência produtiva da pecuária de corte. A proposta do presente trabalho foi avaliar o efeito da inclusão dos valores genéticos moleculares, de um painel de marcadores genéticos comerciais (Perfil IGENITY&reg; Nelore V3) na seleção de animais da raça Nelore. Foram utilizados dados de 9.749 animais da raça Nelore mensurados para área de olho de lombo, espessura de gordura subcutânea e espessura de gordura na picanha e 39.687 animais na matriz de parentesco. Dois modelos de análise foram utilizados. O modelo de análise uni-característica em que apenas os parâmetros genéticos do fenótipo foram estimados e o modelo bi-característica em que os valores genéticos moleculares de 3.033 animais foram incluídos como característica correlacionada. A inclusão dos valores genéticos moleculares no modelo aumentou as acurácias das estimativas dos valores genéticos preditos dos animais genotipados, principalmente dos machos jovens. As analises dos conflitos de seleção demonstraram maiores divergências nos touros e machos jovens que tiveram seus genótipos definidos. A taxa de ganho genético anual com a inclusão dos valores genéticos moleculares no modelo foi aumentada em 2,4% para área de olho de lombo, 0,9% para espessura de gordura subcutânea e 1,9% para espessura de gordura na picanha. Esses resultados demonstram que a utilização dos valores genéticos moleculares , mesmo quando oriundos de painéis de marcadores de DNA de baixa densidade, pode contribuir na seleção de animais superior mérito genético e, além de promover aumento nos ganhos genéticos dos programas de melhoramento genético da raça Nelore. / The Brazilian beef cattle chain is suffering a huge pressure due to environmental issues, the demand of consumer markets for meat quality and strict sanitary standards of the international market. These factors increase the importance of improving productive efficiency of beef cattle. The proposal of this study was to evaluate the effect of inclusion of the molecular breeding values of a commercial panel of genetic markers (Nellore Profile IGENITY&reg; V3) in the genetic selection of Nellore cattle. Data of 9,749 animals measured for ribeye area, fat thickness and rump fat thickness were used in this study, with a relationship matrix compound of 39,687 animals. Two models of analysis were performed. Single trait model was performed only for each observed phenotypes and two-trait model was performed phenotypes and molecular breeding values of 3,033 animals as a correlated trait. The inclusion of molecular information in genetic evaluation provided increases on the accuracies of predicted breeding values of genotyped animals and, mainly, for replacement young bulls. The divergences of selection for 20% best animals classified by 1-trait breeding values and 2-trait breeding values demonstrated highest divergence for sires and replacement young bulls. The genetic change rate on the 2-trait model increased 2,4% for ribeye area, 0,9 for fat thickness and 1,9% for rump fat thickness. These results demonstrated that the inclusion of molecular breeding values, even when estimated from low density genetic markers panels, on animal breeding evaluations can contribute on the selection of best genetic merit animals and increase of genetic change rate on animal breeding programs for Nellore cattle.