No description available.

Zugl.: Hohenheim, Univ., Diss., 2005

This work was focused on the genetic relatedness of pear trees. The first part of the thessis is focused on the survey of literature about history and distribution of Asian and European pear, description of the varieties and description of biotechnology, especially AFLP. The second part of the thesis is focused on the experimental part. There is described a procedure for isolating DNA, AFLP workflow methods, evaluation and reporting results. In this work there were found out some interesting results. For example was confirmed that the variety Zao Su Li probably belongs to Ussuriensis pear group. Were confirmed close relationships between Japanese pear, Chinese sand pear and Chinese white pear varieties. Interspecific hybrid Hood was identified like probably releated with European varieties. It was as well confirmed, that interspecific hybrids Kiffer and Rafsaz are probably releated with Pyrus pyrufolia (Burm.) Nak.

Abstract The evolution of sociality is often associated with close relatedness and genetic similarity of interacting individuals. However, colonies of advanced social insects (e.g. ants, bees and wasps) characterized by large colony size and division of tasks, are also shaped by acquisition of genetic diversity by polyandry, polygyny, recombination and even by hybridization. The balance between forces selecting for high relatedness on one hand and for improved colony performance though increased genetic diversity on the other hand forms an intriguing area of research. My study has produced the first genetic linkage maps for ants (Acromyrmex echinatior and Pogonomyrmex rugosus) and social wasps (Vespula vulgaris). Together with the findings of earlier honeybee research, it is shown that advanced eusocial insects have higher recombination rates than any other insect (or animal) studied so far. The estimates obtained here were 14 cM/Mb for P. rugosus, 9.7 cM/Mb for V. vulgaris and 6.2 cM/Mb for A. echinatior. Pogonomyrmex harvester ants have a genetic caste determination system in which workers arise from mating between two hybridizing lineages whereas sexuals are produced by within-lineage mating. I evaluated the origin of the lineages and the caste determination system by using 751 variable nuclear genetic markers. Fertile hybrids would lead to introgression, particularly in genomic regions characterized by a high recombination rate and lack of strongly selected loci. The hybridizing lineages (lineage pairs J1/J2 and H1/H2) showed many fixed differences. Nineteen of them were in the constructed linkage map, scattered in different linkage groups. The results suggest that there has been no recent introgression. As the hybrids are viable (as workers), caste differentiation can be affected by many loci scattered throughout the ant genome or by a small number of very strongly selected loci. Genetic diversity in colonies of the ant Formica cinerea is affected by varying levels of polygyny. I tested the hypotheses that the prevalence of endosymbiotic bacteria can vary in polygynous colonies but be either very low or very high in monogynous colonies. However, I found no association between the level of polygyny and endosymbiont prevalence. In addition to Wolbachia, I found two other endosymbiotic bacteria Cardinium and Candidatus Serratia symbiotica which have not been earlier reported from ants. Genetic diversity in insect colonies is affected by polyandry and polygyny. My results indicate that high a recombination rate is also an important factor influencing diversity. Genotypically diverse progenies can enhance colony success, e.g. through effects on division of labour or defence against pathogens. Recombination differs from the other factors in its effects on genetic relatedness among colony members.

Abstract The genetic structure at different spatial scales and growing habitats was studied on Silene tatarica, using AFLP and microsatellite markers. S. tatarica is a rare perennial plant occurring along riverbanks and shores of two annually flooding rivers in Finland. Regional scale analysis based on AFLP fragment analysis showed that at Oulanka River population structure represented mostly classical metapopulation model. In general, colonization-extinction processes had an important role, dispersal between subpopulations was limited and genetic differentiation was independent of geographic location. The same subpopulations were partly used to study spatial genetic structuring within subpopulations. Spatial autocorrelation revealed clear spatial genetic structure in each subpopulation. Paternity analysis in an isolated subpopulation showed small amounts of inbreeding, restricted seed dispersal and pollen flow through the subpopulation. Factors affecting the creation and maintenance of spatial genetic structure within subpopulation were most likely colonization events and restricted seed dispersal. The impact of river regulation on the genetic structure of populations was studied by comparing results from Oulanka River to the results obtained from second main growing area, Kitinen River. Oulanka River is a natural river system, whereas Kitinen is a regulated river. The overall regional scale studies did not indicate major differences between river systems. There were some clear population genetic differences between rivers but there were no clear evidence that those would have been caused by river regulation. More likely differences were related to the marginal location of Kitinen population at the edge of the distribution range. Studies indicated that regardless of the species rarity in Finland, active management measures are not currently needed in either S. tatarica growing area. Species specific microsatellite loci were isolated to complement AFLP studies. During the microsatellite isolation, an interesting amplification pattern was detected and studied further. It was suggested that there were repetitive areas within genome containing microsatellites resulting in unusual amplification. The most likely explanation for this phenomenon would be transposable elements containing proto-microsatellite areas. The microsatellites isolated could have evolved mostly from those proto-microsatellites.

<p>The distribution and abundance of many coral reef organisms are affected by their predator’s distribution and abundance. Loss of predators may cause a shift in species compositions that will cascade down to other ecological processes on the reef. One example of a shift like this is the growing sea urchin populations inhabiting the coral reefs of East Africa. Areas with high fishing pressure often have large populations of sea urchins. The large populations of sea urchins have a negative impact on the reef ecology both by their grazing and bio-erosion as well as on fish growth and the recovery of fish populations. Previous population genetic studies conducted on<em> Diadema setsosum</em>, using mtDNA and allozymes, found genetic structuring between populations on a large geographical and evolutionary scale. The aim of this study was to examine the genetic population structure of the sea urchin <em>Diadema setosum</em>, at four sites around Zanzibar. We used the amplified fragment length polymorphism (AFLP) technique, a fast and effective method with high resolution. The long term objective is to understand the migration pattern and colonization of <em>D. setosum</em> to facilitate possible management actions. We found a significant genetic structuring of <em>D. setosum</em> hence the populations can not be considered panmictic. The reason behind this structure does not seem to be based on the geography nor size. One possible explanation might be that the structure lies on a larger geographical scale than we have studied, further studies around the Western Indian Ocean may reveal this. Another explanation may be that the structuring is due to differences in spawning time between the different phenotypes and an analysis of gonad maturations may give information about this. To find the reasons behind the observed genetic structure is of great importance for management of the sea urchins and therefore the management of whole reef ecosystems.</p>

The distribution and abundance of many coral reef organisms are affected by their predator’s distribution and abundance. Loss of predators may cause a shift in species compositions that will cascade down to other ecological processes on the reef. One example of a shift like this is the growing sea urchin populations inhabiting the coral reefs of East Africa. Areas with high fishing pressure often have large populations of sea urchins. The large populations of sea urchins have a negative impact on the reef ecology both by their grazing and bio-erosion as well as on fish growth and the recovery of fish populations. Previous population genetic studies conducted on Diadema setsosum, using mtDNA and allozymes, found genetic structuring between populations on a large geographical and evolutionary scale. The aim of this study was to examine the genetic population structure of the sea urchin Diadema setosum, at four sites around Zanzibar. We used the amplified fragment length polymorphism (AFLP) technique, a fast and effective method with high resolution. The long term objective is to understand the migration pattern and colonization of D. setosum to facilitate possible management actions. We found a significant genetic structuring of D. setosum hence the populations can not be considered panmictic. The reason behind this structure does not seem to be based on the geography nor size. One possible explanation might be that the structure lies on a larger geographical scale than we have studied, further studies around the Western Indian Ocean may reveal this. Another explanation may be that the structuring is due to differences in spawning time between the different phenotypes and an analysis of gonad maturations may give information about this. To find the reasons behind the observed genetic structure is of great importance for management of the sea urchins and therefore the management of whole reef ecosystems.

Native prairie grasses of western Canada have the potential for development as turf and forage grass cultivars for semiarid environments. Nuttall’s salt-meadow, or alkali grass (Puccinellia nuttalliana (Shultes) Hitchc.), is a native grass species in North America well known for its salt tolerance. Little information is available about the genetic diversity of natural populations of this species. Understanding the genetic diversity of this species is a prerequisite for developing populations for forage or turf use in western Canada. The objectives of this study were to assess the variation in agronomic/morphological characters and AFLP markers of collections of Puccinellia and identify promising populations and genotypes for turf and forage utilization. A four replicate randomized complete block field nursery of twenty-four collections from western Canada was established in 2010. Plant height, tiller number, crown diameter, dry matter yield, seed yield, and leaf related characters were measured for each collection in the summers of 2011 and 2012. Considerable phenotypic variation was detected among and within the twenty-four populations. Promising populations and genotypes were identified with respect to their superior turf and forage related characteristics. The amplified fragment length polymorphism (AFLP) technique was used to assess the comparative genetic diversity of the collections. Five AFLP primer pairs were employed to screen 15 genotypes from each population, and 185 polymorphic AFLP bands were scored for each sample. Their frequencies of occurrence ranged from 0.02 to 0.99 with a mean of 0.61. The analysis of molecular variance revealed more than 96% of the total AFLP variation resided within populations. Populations were not highly differentiated with only 4% of the total AFLP variation residing among populations. A Mantel test revealed a significant but low correlation between genetic and geographic distances (r=0.293; P=0.024) and non-significant correlation between genetic and phenotypic distances (r=0.070; P=0.282). Implications for P. nuttalliana conservation, germplasm sampling, and cultivar development are discussed.

Beta-carotene presence or absence in muskmelon is controlled by two genes, green flesh gf and white flesh wf. In its dominant form the wf gene is responsible for orange flesh color; however, the epistatic interactions of gf and wf can create three flesh colors: orange, white and green. Two F2 populations, consisting of 77 greenhouse grown and 117 field grown plants, from the cross of ‘Sunrise’ (white fleshed) by ‘TAM Uvalde’ (orange fleshed), were used to examine the relationships of beta-carotene content, flesh color, and flesh color intensity. Bulk segregent analysis was used with RAPD markers to identify molecular markers associated with high beta-carotene content. Flesh color and flesh color intensity both had significant relationships with beta-carotene content. A significant correlation between total soluble solids and beta-carotene content was also found. Molecular markers were identified in both F2 populations and all significant, associated markers from ‘TAM Uvalde’ were linked with WF. A single QTL was also found to be linked with the WF locus. The identified QTL can be used to screen potential breeding lines for high beta-carotene. It was also confirmed that the visual ratings of flesh color intensity can be reliably used to select high beta-carotene content melons.

Molecular marker analysis of seven putative onion (Allium cepa) doubled haploid (DH) lines developed at Texas A&M University was conducted to verify genetic homozygosity. Analysis was also conducted on five equivalent conventional inbred lines, breeding lines developed from the same parental crosses as the DH lines, and the original parent lines. The markers have revealed polymorphisms within the parental lines and the conventional inbreds, but not in the DH lines. We can conclude therefore that these seven lines are true DH lines. Performance of these DH lines was tested in two field locations and compared to commercial check lines. Bulbs from the various crosses were evaluated for eight bulb traits: diameter, height, centers/bulb, ring thickness, number of rings/bulb, bulb weight, soluble solids content, and pungency. Some crosses were detected that yielded significantly greater bulb weight than the check lines. However, these lines also had significantly greater numbers of centers per bulb. To test how these lines would perform in a breeding program, two full diallel analyses were conducted according to Griffing’s Model I, Method 1. The first consisted of a four parent diallel cross using two red DH lines and two yellow DH lines. Bulbs from the various crosses were evaluated for the same eight bulb traits mentioned above. Significant variation was detected for genotypic, general combining ability (GCA), specific combining ability (SCA), reciprocal (REC), maternal (MAT), and nonmaternal (NMAT) effects for all traits except number of rings/bulb, soluble solids content, and pungency. Significant environmental effects were only detected with number of centers per bulb. The second diallel analysis, a four parent diallel with two DH lines and two inbred lines from the breeding program, showed significant variation for the same effects for all traits except soluble solids content. Generally, GCA effects were more important than SCA effects in explaining the variation observed between crosses. For all traits GCA and SCA were always larger than the reciprocal effects (divided into maternal and nonmaternal components).