Due to active tectonic evolution of the Aegean Area during Miocene and Pleistocene, the Balkans and Anatolia have repeatedly connected and disconnected causing isolation and secondary contact of populations along the present Dardanelles – Sea of Marmara – Bosphorus waterway. This has led to an outstandingly rich fauna and a reticulate biogeography in the area. A typical example is Orthoptera having here possibly highest diversity within the Western Palaearctic. With the present study, we concentrate on the bush‐cricket genus Isophya, which is characteristic with a large share of endemics in the Balkans and Anatolia. We aim to understand when and how the isolation of marine or other barriers in the region of the Turkish Straits System influenced the evolution of the morpho‐acoustic groups of species found on both sides of the strait. For this purpose, sequences of two mitochondrial (COI and ND2) and two nuclear (ITS1 and ITS2) markers were obtained and used for phylogenetic reconstructions, time estimations for lineage divergence and automatic species delineation (statistical parsimony, GMYC, ABGD) tests. The phylogenetic analyses did not support all the existing morphogroups and was in favour of a geographical subdivision for the young lineages. Automatic species delineation tests confirmed most of the present morpho‐acoustic species and suggested further cryptic species, at the same time unifying some phenetic species. Time estimation analyses suggested time to most recent common ancestor of the genus as 8.28 Ma corresponding to the Late Tortonian. As a result of the study, we reached to the following conclusions: (i) most of the studied phenetic species are monophyletic, but some earlier suggested morpho‐species groups are not, (ii) three main episodes dominate the evolutionary history of Isophya (7.32–5.84 Myr in the Messinian, 2.2–2.5 Myr in the beginning of the Pleistocene and at around 0.75 Ma corresponding to the end of the Mid‐Pleistocene transition), all of which well correlate with episodes of existing terrestrial connections between Anatolia and the Balkans, and (iii) there are several faunal exchanges in both directions between Anatolia and the Balkans.
Review of the Balkan Isophya (Orthoptera: Phaneropteridae) with particular emphasis on the Isophya modesta group and remarks on the systematics of the genus based on morphological and acoustic data (Zootaxa 3658) 81 pp.; 30 cm.
Abstract. We report the karyotype characteristics including chromosome numbers of Saga campbelli campbelli, S. c. gracilis, and S. rammei using the following classical cytogenetic methods: C-banding, silver staining, and fluorochrome staining DAPI and CMA3. We also present FISH data showing the distribution of telomeric repeats and 18S rDNA on the chromosomes of these species and the results of similar studies cited in the literature on S. hellenica, S. natoliae, and S. rhodiensis. The five European Saga species exhibit a high rate of karyotype evolution. In addition to changes in chromosome number and morphology (by chromosomal inversion and/or chromosome fusion), interspecific autosomal differentiation involved changes in the distribution and quantity of constitutive heterochromatin and GC-rich regions, as well as the number and location of NORs. In the present study we focused on testing a hypothetical model of karyotype evolution in Saga, with particular reference to the cytogenetic mapping of rDNA and telomeric sequences. Variation in the distribution of rDNA and location of Ag-NORs are novel phylogenetic markers for the genus Saga.
Abstract.Chromosomes of the males of five species of Odontura, belonging to the subgenera Odontura and Odonturella, were analyzed. Intensive evolution of the karyotype was recorded, both in terms of changes in the numbers of chromosomes (from 2n = 31 to 27) and the sex chromosome system (from X0 to neo-XY and X0 to neo-X1X2Y). Karyotype evolution was accompanied by tandem autosome fusions and interspecific autosomal and sex chromosome differentiation involving changes in the locations of nucleolar organizer regions, NORs, which were revealed by silver impregnation and confirmed by FISH using an 18S rDNA probe. O. (Odonturella) aspericauda is a polytypic species with X0 and neo-X1X2Y sex determination. The latter system is not common in tettigoniids. It possibly originated by a translocation of a distal segment of the original X chromosome onto a medium sized autosome, resulting in a shortened neo-X1 and a metacentric neo-Y. The remaining autosome homologue became the neo-X2 chromosome. This shift from X0 to neo-X1X2Y is supported by the length of the X chromosome and location of the NOR/rDNA.
BackgroundPoecilimon and Isophya are the largest genera of the tribe Barbitistini and among the most systematically complicated and evolutionarily intriguing groups of Palearctic tettigoniids. We examined the genomic organization of 79 taxa with a stable chromosome number using classical (C–banding, silver and fluorochrome staining) and molecular (fluorescence in situ hybridization with 18S rDNA and (TTAGG)
n
telomeric probes) cytogenetic techniques. These tools were employed to establish genetic organization and differences or similarities between genera or species within the same genus and determine if cytogenetic markers can be used for identifying some taxonomic groups of species.ResultsDifferences between the karyotypes of the studied genera include some general changes in the morphology of the X chromosome in Isophya (in contrast to Poecilimon). The number of major rDNA clusters per haploid genome divided Poecilimon into two main almost equal groups (with either one or two clusters), while two rDNA clusters predominated in Isophya. In both genera, rDNA loci were preferentially located in the paracentromeric region of the autosomes and rarely in the sex chromosomes. Our results demonstrate a coincidence between the location of rDNA loci and active NORs and GC-rich heterochromatin regions. The C/DAPI/CMA3 bands observed in most Poecilimon chromosomes suggest the presence of more families of repetitive DNA sequences as compared to the heterochromatin patterns in Isophya.ConclusionsThe results show both differences and similarities in genome organization among species of the same genus and between genera. Previous views on the systematics and phylogenetic grouping of certain lineages are discussed in light of the present cytogenetic results. In some cases, variation of chromosome markers was observed to correspond with variation in other evolutionary traits, which is related to the processes of ongoing speciation and hybridization in zones of secondary contact. It was concluded that the physical mapping of rDNA sequences and heterochromatin may be used as an additional marker for understanding interspecific relationships in these groups and their routes of speciation.
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