No description available.

No description available.

No description available.

Genetic diversity and the effect of lamb and dam inbreeding on multiple traits were analyzed in an 11-yr closed population of sheep established in 1983 and remained closed after 1987, with 50% Dorset, 25% Rambouillet, and 25% Finnsheep breeding to determine selection response for spring fertility. The population had been randomly divided in 1987 into a fall-lambing selection line (S) of 125 ewes and 10 rams, fall-lambing environmental control line (E) of 55 ewes and 5 rams, and a spring-lambing genetic control line (G) of 45 ewes and 5 rams. Inbreeding effects were estimated from 2678 lambs and 556 dams present after the creation of the respective lines. The traits assessed were ewe spring-fertility, lambing date, lamb birth, 60 d, and 120 d weight, and lamb survival to 1, 3, and 14 d. Genetic diversity was assessed by estimating change in inbreeding per generation (ΔF) and effective number of breeding animals (N_e), and parameters derived from gene drop simulations and an iterative procedure developed by Boichard et al. (1997); effective number of founders (f_e), effective number of ancestors (f_a), founder genome equivalents (f_g), and two additional measures of genetic diversity (GD₁, GD2). In order to estimate the diversity available in S and G, three sets of animals from the end of the study and one set of animals at line formation were considered in each line: all lambs born (including dead lambs), all matings (including potential offspring, even if a lamb was not born), and all rams and ewes available at the end of the study and at line formation. At the time of line formation, most of the loss in diversity was due to unequal founder representation. The smaller population of G, as compared to S, caused a greater decrease in diversity due to bottlenecks at line formation. Very little diversity was lost due to additional drift by the time of line formation because selection had not occurred and a random mixing of founders was the goal. Allelic diversity decreased moderately; of the 322 founder alleles, there were 71% in S and 58% in G of rams and ewes (RE) that appeared in at least 50 runs of gene drop. By the end of the study in 1998, the amount of allelic diversity had decreased substantially. Of the alleles possible in RE at the end of the study in S and G, only 6 and 8 %, respectively, appeared in greater than 50 simulations of gene drop. The measures of f_e, f_a, and f_g revealed there was not much additional loss in diversity from the line founders to the end of the study due to unequal founder representation, but there was a larger amount of loss due to bottlenecks and additional drift. The diversity loss was similar, which was the goal of the selection study, when values for RE were compared in S and G. The effects of lamb and dam inbreeding were estimated from REML analysis. Effects of lamb or dam inbreeding were negative but not significant for lambing date or survival to 1, 3, or 14 d. Spring fertility was estimated to decrease by 0.70 ± 0.30 %/% inbreeding of the ewe (P < 0.01), which seems even greater since the average spring fertility was only 47.5 %. Effects of lamb inbreeding on birth, 60-d, and 120-d weights were -0.012 ± 0.006 (P < 0.05), -0.045 ± 0.020 (P < 0.05), and -0.130 ± 0.034 kg/% (P < 0.01), respectively. Dam inbreeding had smaller effects on birth, 60-d, and 120-d weights of -0.008 ± 0.010 (ns), -.033 ± 0.034 (ns), and -0.087 ± 0.056 (P < 0.1) kg/%, respectively. / Master of Science

yes / In many species, the offspring of related parents suffer reduced reproductive success, a phenomenon known as inbreeding depression. In humans, the importance of this effect has remained unclear, partly because reproduction between close relatives is both rare and frequently associated with confounding social factors. Here, using genomic inbreeding coefficients (FROH) for >1.4 million individuals, we show that FROH is significantly associated (p < 0.0005) with apparently deleterious changes in 32 out of 100 traits analysed. These changes are associated with runs of homozygosity (ROH), but not with common variant homozygosity, suggesting that genetic variants associated with inbreeding depression are predominantly rare. The effect on fertility is striking: FROH equivalent to the offspring of first cousins is associated with a 55% decrease [95% CI 44–66%] in the odds of having children. Finally, the effects of FROH are confirmed within full-sibling pairs, where the variation in FROH is independent of all environmental confounding.

Call number: LD2668 .T4 1963 C47 / Master of Science

No description available.

Cooperative species have long been the focus of much research due to the ‘special difficulty’ cooperation poses to the theory of evolution via natural selection. Despite this long history of scientific interest we actually know relatively little about the evolutionary genetics of cooperative mammalian species, especially in the wild. In this study I use long-term data from the Kalahari Meerkat Project to investigate some aspects of the evolutionary genetics of meerkats (Suricata suricatta). First, I reconstructed a genetically-validated pedigree of the Kalahari meerkat population. 1,494 meerkats (83% of the total known population) were genotyped at a panel of 18 highly variable microsatellite markers. This genetic data, in combination with phenotypic information and two different programs, COLONY2 and MASTERBAYES, was used to infer familial relationships. The resulting pedigree spanned seven generations and included 1,614 individuals of which 1,076 had both parents known. I conclude by discussing the particular merits of using COLONY2 to infer familial relationships for social animals such as meerkats. Second, I investigated the extent of inbreeding and inbreeding depression in early life traits in the Kalahari meerkat population. In the pedigree, 44% of individuals have non-zero (F>0) inbreeding coefficients. Although I found more inbreeding in meerkats than initially expected, there were few cases of inbreeding between very close relatives. Nonetheless, even low to moderate inbreeding appeared to result in inbreeding depression for pup mass at emergence, hind-foot length, growth until independence, and juvenile survival. I also found some tentative evidence for a positive effect of the social environment in ameliorating the effects of inbreeding depression. Third, I conducted a quantitative genetic analysis on mass, skull length, skull width, forearm length, and hind-foot length in up to five key meerkat life stage periods, while accounting for a number of fixed effects, including inbreeding coefficient. By attempting to apportion variance in these traits to a variety of sources I found that birth litter identity often explained much of the variance in morphological traits, although the magnitude of this effect appeared to decline with age. Furthermore, when birth litter was removed from models, the amount of variance explained by additive genetic effects tended to increase. Finally, I conducted a quantitative genetic analysis on two measures of cooperative care and on adult mass. Fixed effects, including inbreeding and relatedness coefficients, were also examined, which revealed that inbred individuals contribute more to pup-feeding, and that helper-recipient relatedness was negatively associated with baby-sitting. I found low heritable variation for baby-sitting (h2 = 0.10) and pup-feeding (h2 = 0.08), and higher heritable variation for adult body mass (h2 = 0.19). I also estimated the magnitude of non-genetic sources of variation in these traits and provide evidence for positive genetic correlations between baby-sitting and pup-feeding, and baby-sitting and adult mass.

Thesis--University of Hawaii. / Includes bibliographical references.

Typescript. / Thesis (Ph. D.)--University of Hawaii, 1966. / Bibliography: leaves 139-146. / x, 232 l mounted illus., tables (part mounted)