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Dienstag, 27 November 2007 |
Conservation Genetics, Paternity Analysis, Phylogeography, Biodiversity, Speciation, Phylogeny, CAOS DNA-Barcoding and Hox Gene Expression
Our research topics include population genetics, phylogeny, phylogeography and conservation genetics in dragonflies and damselflies in Europe and the tropics, mainly Southern Africa and the Neotropics. To answer questions concerning population dynamics, dispersal potential, fragmentation effects, genetic isolation and speciation processes, we employ different genetic markers like microsatellite systems and sequence markers. To investigate aspects of climate change we perform gene expression experiments to analyze the ability of adaptation by rising temperatures.  Trithemis arteriosa  Trithemis kirbyi  Orthetrum julia
1. Employment of microsatellites
Integrating genetic aspects in conservation biology may provide useful information about the status of populations. Because of the increasing number of threatened ecosystems through humans, the natural habitats of animals and plants are more and more endangered and often fragmented and isolated. To gain insights into the ability of a population to adapt to changing environmental conditions we use microsatellites to analyze different population genetic parameters like genetic variability and heterozygosity rates.
For example, we developed a microsatellite system for Othetrum coerulescens, which is a red listed species in Germany, to analyze genetic consequences (short and long term) of human interferences at its breeding habitat (Hadrys et al 2007). In Trithemis arteriosa we analyse how water-dependent species like Odonata are able to survive in desert regions. T. arteriosa is also an excellent bioindicator species for evaluating the quality of the rare water resources in Namibia (Giere & Hadrys 2006 ; Giere & Hadrys in prep).
Another aspect of our research is the application of microsatellites in parentage analyses. Here we developed a microsatellite system for the two sister species Anax imperator and Anax parthenope, to investigate the sperm precedence mechanism of these two species and to compare their different mating systems (Hadrys et al 2007).
2. Population genetics and phylogeny by means of sequence markers
Long term experiences in population genetics in Odonata carried out that the mitochondrial marker NADH-dehydrogenase subunit 1 (ND1) is an appropriate marker to study population dynamics and structures in this group (Groenefeld et al 2006). Therefore, we used this marker in diverse studies in different groups of dragonflies and damselflies. One main topic of our research is the comparison of dispersal potential of Southern African dragonfly species like in the genera Trithemis, Orthetrum and Crocothemis to investigate the genetic consequences of different habitat specialization in Namibia, Kenya and Tansania. We also analyze evolutionary aspects of speciation processes. Thus, we perform phylogenic analysis for the genera Trithemis, Anax, Pseudagrion. In the genus Trithemis through the employment of genetic markers a new cryptic species was found. For the phylogenic analysis we also use additional markers like 16S rDNA, Cytochromoxidase I (COI), Elongationfactor 1α (EF1) and the Internal Spacer region I and II (ITS I and II).
3. Gene expression studies in modern ecology
The ability to adapt to different environmental conditions is highly important for any kind of organisms especially in times of global warming and anthropogenic impacts of humans in their natural habitats. The integration of physiology in biodiversity research provides new insights into the potential of adaptation of organisms in a changing environment.
Therefore we described the Hsp70 protein for dragonflies, which belongs to the big group of chaperons and is one of the first genes expressed in a stressed organism. Hsp70 is a powerful biomarker for the early detection of stressful situations. Stress can be induced, for example, through a temperature shift at a given habitat or anthropogenic impacts like chemicals. The inclusion of Hsp70 as a biomarker in conservation projects may provide an early-warning measurement for environmental changes and pollution and we have a sensitive genetic tool to measure the water quality of the larval habitat and to evaluate the environmental conditions for the adult stage. We also could examine the potential of our domestic species to adapt by processes of global warming and compare to invasive tropical species, like Crocothemis erythreae, which is originally distributed through Africa and southern Europe and already able to preserve stable populations in the middle of Germany. Tsauchab River (Namibia)  collecting samples  Okavango River (Popa Falls, Namibia) 4. Character-based DNA barcoding
DNA barcoding has recently become very popular as a rapid and general method for the identification of organisms. Researchers are yet exploring suitable procedures that make DNA barcoding simple and reliable. Currently, distance approaches and tree building methods have been used to define species boundaries and discover cryptic species. These approaches highlight a central question: How can a species be defined? Obviously, a universal threshold of genetic distance values to distinguish taxonomic groups cannot be determined. A new promising alternative for DNA barcoding is the character-based approach. Here species are delimited through the presence or absence of discrete characters within a DNA sequence. Our data suggest that “character-based” DNA barcoding delivers an identification system that achieves (i) the assignment of odonate specimens to taxonomic groups and (ii) the discovery of conservation units rapidly and accurately. We show that character based DNA barcoding is a powerful alternative and harbors several advantages compared to phenetic approaches currently being used.
Odonates are excellent bioindicators for a variety of ecosystems due to substantial differences in habitat specificity and their complex life cycles. A reliable identification system for this insect group is therefore valuable for conservation management. |
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Last Updated ( Donnerstag, 28 Mai 2009 )
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