Využití cytonukleárních genetických markerů při studiu mezidruhového křížení parem (rod Barbus) v přírodní populaci

Katedra zoologieDepartment of ZoologyFaculty of SciencePřírodovědecká fakult

Experimental evidence that thermal selection shapes mitochondrial genome evolution

Mitochondria are essential organelles, found within eukaryotic cells, which contain their own DNA. Mitochondrial DNA (mtDNA) has traditionally been used in population genetic and biogeographic studies as a maternally-inherited and evolutionary-neutral genetic marker. However, it is now clear that polymorphisms within the mtDNA sequence are routinely non-neutral, and furthermore several studies have suggested that such mtDNA polymorphisms are also sensitive to thermal selection. These observations led to the formulation of the "mitochondrial climatic adaptation" hypothesis, for which all published evidence to date is correlational. Here, we use laboratory-based experimental evolution in the fruit fly, Drosophila melanogaster, to test whether thermal selection can shift population frequencies of two mtDNA haplogroups whose natural frequencies exhibit clinal associations with latitude along the Australian east-coast. We present experimental evidence that the thermal regime in which the laboratory populations were maintained drove changes in haplogroup frequencies across generations. Our results strengthen the emerging view that intra-specific mtDNA variants are sensitive to selection, and suggest spatial distributions of mtDNA variants in natural populations of metazoans might reflect adaptation to climatic environments rather than within-population coalescence and diffusion of selectively-neutral haplotypes across populations

Present and Future Salmonid Cytogenetics

Salmonids are extremely important economically and scientifically; therefore, dynamic developments in their research have occurred and will continue occurring in the future. At the same time, their complex phylogeny and taxonomy are challenging for traditional approaches in research. Here, we first provide discoveries regarding the hitherto completely unknown cytogenetic characteristics of the Anatolian endemic flathead trout, Salmo platycephalus, and summarize the presently known, albeit highly complicated, situation in the genus Salmo. Secondly, by outlining future directions of salmonid cytogenomics, we have produced a prototypical virtual karyotype of Salmo trutta, the closest relative of S. platycephalus. This production is now possible thanks to the high-quality genome assembled to the chromosome level in S. trutta via soft-masking, including a direct labelling of repetitive sequences along the chromosome sequence. Repetitive sequences were crucial for traditional fish cytogenetics and hence should also be utilized in fish cytogenomics. As such virtual karyotypes become increasingly available in the very near future, it is necessary to integrate both present and future approaches to maximize their respective benefits. Finally, we show how the presumably repetitive sequences in salmonids can change the understanding of the overall relationship between genome size and G+C content, creating another outstanding question in salmonid cytogenomics waiting to be resolved

Squid adjust their body color according to substrate

Coleoid cephalopods camouflage on timescales of seconds to match their visual surroundings. To date, studies of cephalopod camouflage-to-substrate have been focused primarily on benthic cuttlefish and octopus, because they are readily found sitting on the substrate. In contrast to benthic cephalopods, oval squid (Sepioteuthis lessoniana species complex) are semi-pelagic animals that spend most of their time in the water column. In this study, we demonstrate that in captivity, S. lessoniana Sp.2 (Shiro-ika, white-squid) from the Okinawa archipelago, Japan, adapts the coloration of their skin using their chromatophores according to the background substrate. We show that if the animal moves between substrates of different reflectivity, the body patterning is changed to match. Chromatophore matching to substrate has not been reported in any loliginid cephalopod under laboratory conditions. Adaptation of the chromatophore system to the bottom substrate in the laboratory is a novel experimental finding that establishes oval squid as laboratory model animals for further research on camouflage

Genetická struktura populací lína Tinca tinca (Linnaeus, 1758)

The tench is an important fish for aquaculture, which is undergoing intensive domestication, but only few studies have examined genetic structure of its populations. We present first results of a phylogeographic study based on DNA sequence data for four nuclear genes and one mitochondrial DNA gene from throughout the tench geographical distribution, including some of the known transfers outside its native Eurasian range. The multiple gene dataset revealed a strong phylogeographic partitioning between the western and eastern parts of the species range with a wide zone of overlap in Europe. Tench in European aquaculture largely represent mixtures of the two evolutionary lineages. We will discuss the likely historical processes underlying these findings. We suggest that human-mediated dispersal may have played an important role in shaping the present phylogeographic pattern

Využití cytonukleárních genetických markerů při studiu mezidruhového křížení parem (rod Barbus) v přírodní populaci

Department of ZoologyKatedra zoologieFaculty of SciencePřírodovědecká fakult

Molecular phylogeography of the tench Tinca tinca (Linnaeus, 1758)

The tench Tinca tinca (Linnaeus, 1758) is a valued table fish native to Europe and Asia, but which is now widely distributed in many temperate freshwater regions of the world as the result of human-mediated translocations. Spatial genetic analysis applied to sequence data from four unlinked loci (introns of three nuclear genes and mitochondrial DNA) defined two groups of populations that were little structured geographically but were significantly differentiated from each other, and it identified locations of major genetic breaks, which were concordant across genes and were driven by distributions of two major phylogroups. This pattern most reasonably reflects isolation in two principal glacial refugia and subsequent range expansions, with the Eastern and Western phylogroups remaining largely allopatric throughout the tench range. However, this phylogeographic variation was also present in European cultured breeds and some populations at the western edge of the native range contained the Eastern phylogroup. Thus, natural processes have played an important role in structuring tench populations, but human-aided dispersal have also contributed significantly, with the admixed genetic composition of cultured breeds most likely contributing to the introgression. I have then designed novel PCR-RFLP assays..

Molecular phylogeography of the tench Tinca tinca (Linnaeus, 1758)

The tench Tinca tinca (Linnaeus, 1758) is a valued table fish native to Europe and Asia, but which is now widely distributed in many temperate freshwater regions of the world as the result of human-mediated translocations. Spatial genetic analysis applied to sequence data from four unlinked loci (introns of three nuclear genes and mitochondrial DNA) defined two groups of populations that were little structured geographically but were significantly differentiated from each other, and it identified locations of major genetic breaks, which were concordant across genes and were driven by distributions of two major phylogroups. This pattern most reasonably reflects isolation in two principal glacial refugia and subsequent range expansions, with the Eastern and Western phylogroups remaining largely allopatric throughout the tench range. However, this phylogeographic variation was also present in European cultured breeds and some populations at the western edge of the native range contained the Eastern phylogroup. Thus, natural processes have played an important role in structuring tench populations, but human-aided dispersal have also contributed significantly, with the admixed genetic composition of cultured breeds most likely contributing to the introgression. I have then designed novel PCR-RFLP assays...Lín obecný Tinca tinca (Linnaeus, 1758) je ceněná konzumní ryba, jejíž oblastí přirozeného výskytu jsou Evropa a Asie, ale v současnosti se díky introdukcím vyskytuje v mnoha oblastech mírného a subtropického pásma po celém světě. Prostorová genetická analýza variability sekvencí čtyř nezávislých genů (intronů tří jaderných genů a mitochondriální DNA) odhalila dvě hlavní skupiny populací, z nich každá je jen málo geograficky strukturovaná, ale které se vzájemně významně liší. Lokalizovala rovněž hlavní geografické bariéry v toku genů (shodující se ve více genech), které jsou způsobeny pouze částečně se překrývajícím rozšířením dvou relativně vzdálených evolučních linií-Západní a Východní. Tyto linie mají pravděpodobně původ v odlišných glaciálních refugiích, ze kterých kolonizovaly své současné areály. Geny obou evolučních linií jsou také přítomny v evropských kulturních liniích. Východní evoluční linie se navíc vyskytuje v příměsích vpopulacích z volných vod západní Evropy, kde v některých oblastech dokonce početně převládá nad Západní linií. Toto je s největší pravděpodobností důsledek migrace zprostředkované lidskou činností. Ryby, lína nevyjímaje, jsou často vysazovány daleko od místa jejich původu, nehledě na genetickou podobnost a lokální adaptace. Nezřídka dokonce dochází k zarybňování...Department of ZoologyKatedra zoologieFaculty of SciencePřírodovědecká fakult