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- Englisch (3) (entfernen)
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- Genetische Variabilität (3) (entfernen)
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The fragmentation of landscapes has an important impact on the conservation of biodiversity. The genetic diversity is an important factor for a population- viability, influenced by the landscape structure. However, different species with differing ecological demands react rather differently on the same landscape pattern. To address this feature, we studied ten xerothermophilous butterfly species with differing habitat requirements (habitat specialists with low dispersal power in contrast to habitat generalists with low dispersal power and habitat generalists with higher dispersal power). We analysed allozyme loci for about 10 populations (Ã 40 individuals) of each species in a western German study region with adjoining areas in Luxemburg and north-eastern France. The genetic diversity and genetic differentiation between local populations was discussed under conservation genetic aspects. For generalists we detected a more or less panmictic structure and for species with lower abundance and sedentarily behaviour the effect of isolation by distance. On the other hand, the isolation of specialists was mostly reflected by strong genetic differentiation patterns between the investigated populations. Parameters of genetic diversity were mostly significantly higher in generalists, compared to specialists. Substructures within populations as an answer of low intrapatch migration, low population densities and high population fluctuations could be shown as well. Aspects of landscape history (the historical distribution of habitats resulting of the presence of limestone areas) and the changes of extensive sheep pasturing and the loss of potential habitats in the last few decades (recent fragmentation) are discussed against the gained genetic data-set of the ten butterflies.
Hypothalamic-pituitary-adrenal (HPA) axis-related genetic variants influence the stress response
(2019)
The physiological stress system includes the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic-adrenal-medullary system (SAM). Parameters representing these systems such as cortisol, blood pressure or heart rate define the physiological reaction in response to a stressor. The main objective of the studies described in this thesis was to understand the role of the HPA-related genetic factors in these two systems. Genetic factors represent one of the components causing individual variations in physiological stress parameters. Five genes involved in the functioning of the HPA axis regarding stress responses are examined in this thesis. They are: corticotropin-releasing hormone (CRH), the glucocorticoid receptor (GR), the mineralocorticoid receptor (MR), the 5-hydroxytryptamine-transporter-linked polymorphic region (5-HTTLPR) in the serotonin transporter (5-HTT) and the brain-derived neurotrophic factor (BDNF) gene. Two hundred thirty-two healthy participants were genotyped. The influence of genetic factors on physiological parameters, such as post-awakening cortisol and blood pressure was assessed, as well as the influence of genetic factors on stress reactivity in response to a socially evaluated cold pressor test (SeCPT). Three studies tested the HPA-related genes each on three different levels. The first study examined the influences of genotypes and haplotypes of these five genes on physiological as well as psychological stress indicators (Chapter 2). The second study examined the effects of GR variants (genotypes and haplotypes) and promoter methylation level on both the SAM system and the HPA axis stress reactivity (Chapter 3). The third study comprised the characterization of CRH promoter haplotypes in an in-vitro study and the association of the CRH promoter with stress indicators in vivo (Chapter 4).
Phylogeographic analyses point to long-term survival on the spot in micro-endemic Lycian salamanders
(2020)
Lycian salamanders (genus Lyciasalamandra) constitute an exceptional case of microendemism of an amphibian species on the Asian Minor mainland. These viviparous salamanders are confined to karstic limestone formations along the southern Anatolian coast and some islands. We here study the genetic differentiation within and among 118 populations of all seven Lyciasalamandra species across the entire genus’ distribution. Based on circa 900 base pairs of fragments of the mitochondrial 16SrDNA and ATPase genes, we analysed the spatial haplotype distribution as well as the genetic structure and demographic history of populations. We used 253 geo-referenced populations and CHELSA climate data to infer species distribution models which we projected on climatic conditions of the Last Glacial Maximum (LGM). Within all but one species, distinct phyloclades were identified, which only in parts matched current taxonomy. Most haplotypes (78%) were private to single populations. Sometimes population genetic parameters showed contradicting results, although in several cases they indicated recent population expansion of phyloclades. Climatic suitability of localities currently inhabited by salamanders was significantly lower during the LGM compared to recent climate. All data indicated a strong degree of isolation among Lyciasalamandra populations, even within phyloclades. Given the sometimes high degree of haplotype differentiation between adjacent populations, they must have survived periods of deteriorated climates during the Quaternary on the spot. However, the alternative explanation of male biased dispersal combined with a pronounced female philopatry can only be excluded if independent nuclear data confirm this result.