My thesis focuses on maternal phenotypic plasticity in two neonatal traits and population genetic structure at different spatial scales in a wild red deer <i>(Cervus elaphus) </i>population on the Isle of Rum, Scotland. Specifically, I present: • An analysis of offspring birth weight-spring temperature plasticity in female red deer using linear regression to measure individual reaction norms. I found evidence of variation in plasticity between females and show that early experiences of high population density reduce female plasticity. • The description of a mixed-effects linear model approach to analysing phenotypic plasticity from a reaction norm perspective, and application of this model to birth date in the Rum deer population. I use the model to examine variation in phenotypic plasticity between females and selection on plasticity at different population density levels. • An examination of population history and structure in red deer from across the Isle of Rum using mitochondria) DNA and microsatellite markers. Analysis revealed that deer in this introduced population came from geographically isolated ancestral populations, and there was genetic evidence for strongly male-biased dispersal. Recent management practices on the island may have led to spatial variation in effective male dispersal on Rum. • A comparison of fine-scale spatial genetic structure between male and female deer in the North Block study area using microsatellite markers and census data. There was evidence of structure at extremely fine spatial scales amongst females but not males, and a decline in the structure amongst females over time. • An analysis of the spatial distribution of different mtDNA haplotypes in male and female red deer across the North Block. There was evidence for spatial structuring of haplotypes in both sexes.

This thesis describes novel data about reproductive isolation between the toad species <i>Bombina bombina </i>and <i>Bombina variegata </i>in a mosaic hybrid zone at Apahida in north-west Romania. The hybrid zone at Apahida forms a fine-scaled mosaic, with the genetic composition of subpopulations varying with the aquatic habitat, even over small distances. I conducted a mark-recapture study which showed that adults move between sites at a high rate and move over distances greater than those separating different habitat types. Variation between sites could be maintained with this movement pattern if there is habitat preference. I use mark-recapture data to test for evidence that adult <i>Bombina </i>are choosing their sites with a preference that correlates with allele frequency at neutral loci; the conclusions vary depending on the assumptions of the analysis. An adult habitat preference for mating site can result in the continuation of the habitat association in the next generation. I test for evidence of this in the genotypes of the resulting eggs, and find no evidence that habitat preferences create habitat associations. Morphology also varies between habitats. I examine the distribution and association of quantitative traits across the hybrid zone. This demonstrates that considerable dispersal occurs from sites whose populations are most similar to the pure species to sites of intermediate phenotype. It also provides some evidence that pure species combinations of these traits are favoured over mixed combinations. These results show that the habitat association of adult <i>Bombina </i>may not be as important in preventing introgression as it would first appear. However it also reveals that major changes to the composition of populations occur between egg laying and adulthood, changing the frequency of neutral alleles and generating linkage disequilibria and a deficit of heterozygotes.

This study investigates the genetic structure of natural populations of the nematode parasite, <I>Strongyloides ratti. S. ratti </I>has an unusual life-cycle that may be wholly asexual, or include a free-living adult phase where conventional sexual reproduction occurs. The population genetic structure of <I>S. ratti</I> was investigated i) in relation to the partitioning of parasites within and between hosts, within and between difference geographical locations and ii) in relation to the intensity of infection of different hosts. In this manner, the extent of population subdivision was characterised and the breeding structure measured. <I>S. ratti</I> was sampled from 11 colonies of rats in England and Scotland, there being 123 rats in total. 76 were infected giving an overall prevalence of infection of 62%. Small numbers of rats were also sampled from sites within Germany, 16% of which were infected. 1472 infective larvae were collected from these rats and the genotypes determined for each polymorphic locus. Analyses of variance and F-statistics were used to ensure the distribution of genetic variation at the following hierarchical levels - within parasites, within hosts, between hosts and between samples from spatially separated geographical areas. Mixed-genotype infections were common with 76% of rats containing two or more parasite genotypes. A large proportion of the total genetic diversity was found within single rats (96%). Rats with high-intensity infections tended to obtain genetically more diverse parasite populations. A small amount (0 - 1.4%) of the total genetic diversity was attributable to variation between sampling sites, showing that limited population differentiation occurs. The frequency of sexual reproduction was low within the parasite populations studied but appeared to be adequate to establish Hardy-Weinberg equilibria proportions of genotypes within most sample sites. However, some populations show deviations from Hardy-Weinberg proportions. In particular one population had a significant excess of heterozygotes. This is taken as evidence of limited allelic segregation as a consequence of the low levels of sexual reproduction within this parasite population.

No description available.

Dying molecular hybridisation reactions with a cDNA Copy, the complexity of polysomal polyadenylated mRNA from the day-old chick lens was found to correspond to 5800-7200 sequences of average size, arranged in three abundance classes. Experiments with heterologous cDNA are consistent with the interpretation that essentially all the sequences expressed in eight-day embryonic neural retina and pigmented epithelium were found to be present in lens mRNA. A cDNA fraction complementary to the most abundant lens mRNAs (presumably the crystallin mRNAS), and representing a minimum of four sequences, was used to assay the dosage of putative crystallin sequences in other embryonic tissues. Neural retina and pigmented epithelium cytoplasmic mRNAs have low concentrations of these sequences, and they appear to be absent from mRNA prepared from headless bodies and muscle. Additionally, the sequences are amplified during appearance of crystallin-containing lentoid bodies in neural retina culture.

Mutation, broadly defined, provides the raw material for evolution. Most mutations are deleterious, that is they confer a disadvantage and the tendency of natural selection is to eliminate them. Populations suffer a reduction in mean fitness, or load, as a consequence of deleterious mutation. One question of interest in evolutionary biology is: How large is the deleterious mutational load? On the other hand, a few mutations are beneficial, conferring an advantage. The establishment within a population, or fixation, of such mutations is the basis of adaptive evolution, but the probability that any one such mutation becomes fixed is small. A second question is: At what rate are beneficial mutants fixed? Some insight into the answers to these questions can be gained from analysis of theoretical population genetic models. In this thesis I concentrate on cases in which, to answer either question alone, it is necessary to understand the interaction between both deleterious and beneficial mutations. The first part of the thesis concentrates on models of asexual populations. Specifically, I explore how beneficial mutations sweeping through the population influences the deleterious mutational load, and how the load influences the probability that a given beneficial mutation becomes fixed. Clearly, the underlying mutation rate has great bearing on the questions addressed here, and in the second part of the thesis a number of modifier models for the evolution of mutation rates are developed. Separate models are studied for sexual and for asexual populations, but in both cases I examine how the mutation rate is expected to evolve under two conflicting pressures. Higher mutation rates are favoured because they are associated with more frequent beneficial mutations, but lower mutation rates are favoured because they are associated with reduced deleterious mutational load.

Five natural populations of Drosophila melanogaster from diverse geographical and ecological sites have been studied. Genetic variation within populations and genetic differentiation between populations were high. Two hundred and forty six strains, isogenic for second chromosomas, have been derived from these populations and surveyed for variation in the properties of the enzyme alcohol dehydrogenase (ADH). The majority of variation in ADH activity was attributable to the presence, in all five populations, of two electrophoretic forms of the enzyme. Within electrophoretic classes significant variation existed between populations and between some strains in ADH activity. Two strains showed abnormal ADH activities. Variation in the heat stability of ADH enzyme was almost wholly attributable to the presence of two electrophoretic forms. Only two strains showed best stabilities atypical of their electrophoretic class. The absence of heterogeneity within electrophoretic classes at this locus is discussed in view of the predictions of models of protein variation and recent experimental results. In the four strains exhibiting unusual properties of ADH activity or stability, the loci responsible map in the region of the ADH locus.

This study was aimed at understanding the genetics of growth in mice lines divergently selected body weight for 50 generations and to investigate the linearity or non-linearity of offspring-parent regression obtained from unselected, random bred mice lines. A large body of data comprising 1090 offspring (family mean) - parent pairs was used to investigate the relationship between offspring and parents. Linear and polynomial models were fitted for the regression of 6-week body weight in offspring on one or both parents. Regression analysis of offspring mean on mid-parent showed that heritability of 6-week body weight was similar to the estimates from simultaneously regressing offspring on both parents provided that the records were standardised within parent-sex category. Regression of offspring family means (sons and daughters) on sire's weights were somewhat non-linear, while offspring-dam regressions were generally linear. Multivariate regression analyses combining both parents gave similar results compared to results of offspring-one parent regression. The second study used data from 30 generations of the P6-lines divergently selected (within family) for high and low 10-week body weight (generation 21-50). These lines were previously selected for 20 generations based on an index of lean mass (P-lines), and crossed to form the P6-lines. The mean divergence in 10-week body weight at generation 21 was 13.3 g increasing to 32.2g at generation 50. The overall divergence relative to the base population (i.e. the P-lines) was 6.3σp. The low line (L) appeared to plateau at generation 40 and the plateau was associated with reduction in selection differentials. When response was considered separately for each sex in the P6-lines, females of the high line (H) responded more to upward selection than in the males, while males responded more than females in the L line. Sexual dimorphism (ratio of male/female mean) was consistently higher in the L line. The genetic correlation between male and female 10-week body weight estimated by Restricted Maximum Likelihood (REML) was 0.84±0.03.

In this thesis I examine inbreeding and its fitness consequences in two species of wild ungulates, red deer (<I>Cervus elaphus</I>) and Arabian oryx (<I>Oryx leucoryx</I>). The long term study of red deer on the Isle of Rum has included profiling of individuals at polymorphic protein and microsatellite loci. I developed a likelihood- based method for large-scale paternity inference and implemented it via the computer program CERVUS. The system allowed genetic inference of paternity with 80% confidence for 536 red deer calves. I used these data to construct pedigrees and found that 11% of calves were the offspring of matings between paternal half sibs; however most inbreeding coefficients were zero. Microsatellite-based measures of inbreeding and outbreeding, individual heterozygosity and mean <I>d<SUP>2</SUP></I>, were calculated using data from nine microsatellite loci. Among stags born 1982-1986, neither individual heterozygosity nor mean <I>d<SUP>2</SUP></I> influenced survival to reproductive age, while mean <I>d<SUP>2</SUP></I> but not individual heterozygosity positively influenced stag lifetime mating success among males which reproduced. Arabian oryx went extinct in the wild in 1972 and were reintroduced to Oman and Saudi Arabia after several generations of breeding in captivity. In reintroduced Arabian oryx in Oman no relationship was found between inbreeding coefficient and juvenile survival. However individual heterozygosity was positively related to juvenile survival while mean <I>d<SUP>2</SUP></I> was negatively related to juvenile survival, implying simultaneous inbreeding and outbreeding depression. Genetic, environmental and anthropogenic factors all influence the survival of reintroduced Arabian oryx, but despite the joint influence of these factors, the Omani population is growing rapidly.

No description available.