Hybridization in plants can be common, may lead to increased genetic variation, and in some instances the formation of new species. For endangered species, hybridization can introduce novel genetic variation and potentially increase genetic diversity. In contrast, hybridization can negatively affect an endangered species or population by introducing maladaptive alleles into locally adapted lineages or lead to the homogenization of once distinct lineages. We used microsatellites, AFLP markers, and morphological data to identify potential hybridization between the endangered Roan Mountain bluet (Houstonia purpurea var. montana) and its commonly occurring congener (H. purpurea var. purpurea). We used these data to clarify the taxonomic relationship of these varieties and to assess population structuring of the Roan Mountain bluet. The results showed that these lineages are distinct and few individuals exhibited admixture in several populations. Additionally, the results showed there is genetic population structure among the remaining populations of H. purpurea var. montana, which is consistent with other mountaintop species. Our results show that Roan Mountain bluet populations should be protected to maintain genetic diversity and monitored to assess future hybridization, and additional studies that comprise a greater population sampling would provide more information.

Understanding reproductive isolation and divergence is the focus of speciation research. Recent evidence suggested that some Dendroctonus ponderosae populations produced hybrids with reproductive incompatibilities, a reproductive boundary undetected by phylogeographic analyses using molecular markers. Additionally, the unique bifurcated distribution of D. ponderosae and the proposed isolation-by-distance gene flow pattern around the Great Basin Desert provided a unique opportunity to investigate the evolution of postmating (postyzygotic) isolation while also understanding phenotypic divergence along latitudinal (climatic) gradients. First, I characterized the strength, biological pattern, and geographic pattern of postzygotic isolation in D. ponderosae by crossing increasingly divergent populations in a common garden environment. There was little evidence of hybrid inviability in these crosses, yet geographically distant crosses produced sterile males, consistent with expectations under Haldane's rule. Hybrid male sterility appeared at a threshold among increasingly divergent populations, was bidirectional (reciprocal crosses were affected), and less geographically distant crosses did not show significant gender-specific decreases in fitness. Second, a separate investigation of two critical phenotypic traits (body size and development time) was conducted on intrapopulation F2 generation offspring from a common garden experiment. Genetic differences contributing to phenotypic variance were interpreted within the context of the previously described reproductive incompatibilities, gene flow patterns, and latitudinal gradients. Genetic differences in development time were striking between faster developing and more synchronized northern populations and slower developing, less synchronized southern populations. Differences in development time were not detected between populations at similar latitudes. Body size, although more variable than developmental time, generally conformed to expectations, with northern populations being smaller than southern populations. Average adult size was found to be quite different between many populations and did vary between populations at similar latitudes, yet relative sexual size dimorphism was rather consistent. There was no evidence of correspondence between phenotypic traits (body size and development time) and either reproductive boundaries or gene flow patterns. The results suggest that latitudinally imposed climatic differences are likely driving phenotypic divergence between populations.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第17774号 / 理博第3897号 / 新制||理||1562(附属図書館) / 30581 / 京都大学大学院理学研究科生物科学専攻 / (主査)准教授 渡辺 勝敏, 教授 曽田 貞滋, 教授 疋田 努 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(人間・環境学) / 甲第18358号 / 人博第671号 / 新制||人||161(附属図書館) / 25||人博||671(吉田南総合図書館) / 31216 / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)教授 松井 正文, 教授 加藤 眞, 教授 市岡 孝朗 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20208号 / 理博第4293号 / 新制||理||1616(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)准教授 渡辺 勝敏, 教授 沼田 英治, 教授 曽田 貞滋 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Abstract Organic derivatives of tin, lead, mercury are the most widely distributed organometallic ecotoxicants in the environment. While some of these organometallic compounds exist in the environment as a result of direct discharge, anthropogenic emissions alone cannot explain the ubiquity, for example, of the organomercury and organolead compounds in marine and fresh waters, sediments and biota. It is known that some organometallic compounds are formed via a bioconversion from the inorganic contaminants. Depending on the source, they can enter the environment in varied forms inorganic species of different stability. These can be bio-converted further by environmental biota; for instance metals such as tin and lead can be discharged into the environment in the form of organometallic species which can undergo further transformation. Determination of organometallics in environmental and biological samples is difficult due to matrix effect and their low concentrations. Separation and preconcentration is necessary to enhance final determination. Speciation studies are even more complicated. Speciation is an important aspect and gives information about bioavailability of the metal thus their toxicity. This work focused on the development of a method for speciation of organospecies of tin, lead and mercury. A new derivatisation agent has been synthesised and used successfully. SLM probe extraction has been exposed to a new matrix. Different environmental samples have been analysed for organo-species of tin and lead and their pathways predicted. The SLM probe extraction gives the advantage of carrying out several extractions, reduction of the amount of solvent used and avoidance of emulsion problems. A simple system has been developed and applied successfully on organotin and organolead extraction from aqueous environmental sample. For reproducibility of the results, pH, salinity, stirring rate and extraction time were optimized. An analytical method for simultaneous in situ ethylation, using new derivatisation agent bromomagnesium tetraethylborate (Et4BMgBr), of organotin and organomercury compounds in sediment samples was developed. The determination of mercury and tin compounds is achieved by species-specific isotope dilution, derivatisation and gas chromatography – inductively coupled plasma mass spectrometry (GC-ICP-MS). In derivatisation, pH and the amount of derivatisation agent were studied. Percentage recovery and accuracy of the method was confirmed by comparison of experimental results with sediment and plant certified reference material (IAEA 405 for sediment and CRM 279 for plant). Although organolead compounds as a gasoline additive are banned in most countries, in some regions, lead is still added to gasoline in varying proportions of different tetraalkyllead compounds and contamination by organolead compounds is still present at different places, e.g.: lead alkyl manufactures The use of both tetraalkyllead and butyltin is banned (tetraalkyllead as gasoline additive and butyltin in antifouling pints and PVC materials). This work focussed on their conversion in water and soil. This should provide an insight into their presence in the environment and an understanding of their degradation in the environment. A method for full speciation and determination of alkyl lead and inorganic lead (II) after the tetramethyllead degradation in aqueous samples has been developed. This was accomplished by in situ derivatisation with sodium tetraphenyllead borate NaB(Ph)4 derivative. The derivatisation was carried out directly in the aqueous sample and the derivatives were extracted using the supported liquid membrane probe extraction (SLMPE). The extracted analytes were then transferred to a GC/MS for separation and detection. This study focused on the transformation of tetramethyllead in aqueous media, at different concentration of major elements, K+,Na+,Ca++, Mg++,Cl-,SO4 --. Adsorption / desorption on soil of ionic organolead and organotin were also studied. As South Africa is one of the world’s major producers of coal, mercury should be monitored as it is a side product in coal combustion. The trend of inorganic mercury and methylmercury in sediment found in this work indicated a possible methylation of inorganic mercury to methylmercury in Klipriver sediments.

No description available.

Lineage diversification in the Neotropics is an interesting topic in evolutionary biology and one of the least understood. The complexity of the region precludes generalizations regarding the historical and evolutionary processes responsible for the observed high diversity. Here, I use molecular data to infer evolutionary relationships and test hypotheses of current taxonomy, species boundaries, speciation and biogeographic history in several lineages of Neotropical snakes. I comprehensively sampled a widely distributed Neotropical colubrid snake and Middle American pitvipers and combined my data with published sequences. Within the colubrid genus Leptodeira, mitochondrial and nuclear markers revealed a phylogeograhic structure that disagrees with the taxonomy based only on morphology. Instead, the phylogenetic structure corresponds to specific biogeographic regions within the Neotropics. Molecular evidence combined with explicit divergence time estimates reject the hypothesis that highland pitvipers in Middle America originated during the climatic changes during the Pleistocene. My data, instead, shows that pitviper diversification occurred mainly during the Miocene, a period of active orogenic activity. Using multiple lineages of Neotropical snakes in a single phylogenetic tree, I describe how the closure of the Isthmus of Panama generated several episodes of diversification as opposed to the Motagua-Polochic fault in Guatemala where a single vicariant event may have led to diversification of snakes with different ecological requirements. This finding has implications for future biogeographic studies in the region as explicit temporal information can be readily incorporated in molecular clock analyses. Bridging the gap between the traditional goals of historical biogeography (i.e., area relationships) with robust statistical methods, my research can be applied to multiple levels of the biological hierarchy (i.e., above species level), other regional systems and other sub-disciplines in biology such as medical research, evolutionary ecology, taxonomy and conservation.

The origin and geographical distribution of mammalian species (my examples are lemurs and bats) correlate with predictable chromosomal structural changes (KFT=karyotypic fission theory). Chromosome studies provide information about fertility between individuals and they are significant for identification of the geographical origin of reproductive isolation within mammal families. Each family predictably has chromosome sets with numbers that range from one to double the lowest number of chromosomes. The chromosome numbers of all species within a single family are used to reconstruct that family’s evolutionary geographical dispersion. Polymorphic chromosome numbers (that is a range such as 34, 35, 36, 37, and 38) in a single population indicate the location where chromosomal diversification arose. Chromosome numbers of descending order correlate with relative distance from fission epicenters as the fissioned chromosomes gradually spread to neighboring populations. Furthermore, the location of chromosomal diversification (that is “karyotypic fission events) is associated with geographical “zones of transition” (after Professor R.W. Wilkie). My analysis, mapped one (Lepilemuridae) of the five families of lemurs (Class Mammalia, Order Primates, sub-order Lemuridae). The origin of this family’s diversification is here hypothesized to have occurred at an ecological transition zone in Northern Madagascar between a humid evergreen-forest that extends to the East relative to a dry deciduous forest along the West Coast. My analysis of Vespertilionidae (insectivorous bats representing one third of all bat species) suggests a diversification event occurred in Asia; South China. Geographical distribution is important in the formation of biological diversity. A single species can inhabit a wide range and exhibit great diversity that is brought about by natural selection. The Holarctic reindeer found in Scandinavia, Russia, China, Canada and Alaska (including caribou) are all a single species Rangifertarandus that exhibits variation in size and in coat pattern, changes brought about by adaptive selection by the environment or human selective breeding but they all have 70 similar chromosomes and they are all reproductively compatible. There is a single species of reindeer. Although, there is measurable DNA sequence divergence; there has been no “speciation” as these circumpolar cervids are genetically compatible.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24233号 / 工博第5061号 / 新制||工||1790(附属図書館) / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 三浦 清貴, 教授 田中 勝久, 教授 藤田 晃司 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM