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39 result(s) for "Horáček, Ivan"
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Late Pleistocene-Holocene paleobiogeography of the genus Apodemus in Central Europe
Wood mice of the genus Apodemus are an essential component of small mammal communities throughout Europe. Molecular data suggest the postglacial colonization of current ranges from south European glacial refugia, different in particular species. Yet, details on the course of colonization and Holocene history of particular species are not available, partly because of a lack of reliable criteria for species identification in the fossil record. Using a sample of extant species, we analyzed variation patterns and between-species overlaps for a large set of metric and non-metric dental variables and established the criteria enabling the reliable species identification of fragmentary fossil material. The corresponding biometrical analyses were undertaken with fossil material of the genus (2528 items, 747 MNI) from 22 continuous sedimentary series in the Czech Republic and Slovakia, from LGM to Recent. In Central Europe, the genus is invariantly absent in LGM assemblages but regularly appears during the Late Vistulian. All the earliest records belong to A. flavicollis, the species clearly predominating in the fossil record until the Late Holocene. A. uralensis accompanied it in all regions until the late Boreal when disappeared from the fossil record (except for Pannonia). A few items identified as A. sylvaticus had already appeared in the early Holocene assemblages, first in the western part of the region, yet the regular appearance of the species is mostly in the post-Neolithic age. A. agrarius appeared sparsely from the Boreal with a maximum frequency during the post-Neolithic period. The results conform well to the picture suggested by molecular phylogeography but demonstrate considerable differences among particular species in dynamic of the range colonization. Further details concerning Holocene paleobiogeography of individual species in the medium latitude Europe are discussed.
Highly divergent lineage of narrow-headed vole from the Late Pleistocene Europe
During the Late Pleistocene, narrow-headed voles ( Lasiopodomys gregalis ) inhabited Eurasia’s vast territories, frequently becoming the dominant small mammal species among steppe-tundra communities. We investigated the relationship between this species’ European and Asiatic populations by sequencing the mtDNA genomes of two extant specimens from Russia and 10 individuals from five Central European sites, dated to the post-LGM period. Phylogenetic analyses based on a large portion of mtDNA genomes highly supported the positioning of L. gregalis within Arvicolinae . The phylogeny based on mtDNA cytochrome b sequences revealed a deep divergence of European narrow-headed voles from Asiatic ones and their sister position against the extant L. gregalis and L. raddei . The divergence of the European lineage was estimated to a minimum 230 thousand years ago. This suggest, contrary to the current biogeographic hypotheses, that during the interglacial periods narrow-headed vole did not retreat from Europe but survived the unfavourable conditions within the refugial areas. Based on this result, we propose to establish a cryptic species status for the Late Pleistocene European narrow-headed vole and to name this taxon Lasiopodomys anglicus .
Paleoenvironmental and neotectonic insights from the pliocene fossil record of Velika Pasica Cave, Slovenia: Implications for karst system evolution
Velika Pasica Cave, situated on a karst plateau at an altitude of 665 meters above sea level, offers a unique record of paleontological, speleological, and tectonic processes. The cave, predominantly filled with allogenic sediments and speleothems, contains fossilized remains of the aquatic cave invertebrate Marifugia cavatica and terrestrial small mammals, characteristic of the early Pliocene (MN15–16). Paleontological dating estimates the cave sediments to be approximately 4 Ma old, while U/Th dating of the overlying flowstone indicates deposition at 410 ± 21 ka. These findings suggest that stagnant phreatic conditions prevailed prior to tectonic uplift and basin subsidence, which reshaped the karst landscape. This study highlights the dynamic interplay between neotectonics, karst system evolution, and biodiversity changes. By integrating speleobiology, geomorphology, and biostratigraphy, it provides valuable insights into the environmental history of the northern Dinarides and the impact of geological processes on karst ecosystems.
The evolutionary history of the field vole species complex revealed by modern and ancient genomes
Background The field vole, an abundant and widespread microtine rodent, is a complex comprised of three cryptic species: the short-tailed field vole ( Microtus agrestis ) which is present over much of Eurasia, the Mediterranean field vole ( Microtus lavernedii ) in southern Europe, and the Portuguese field vole ( Microtus rozianus ) in western Spain and Portugal. Previous research has shown high genomic differentiation of these three lineages. However, the details of the process underlying their divergence remain unknown. Results We analyse 70 mitogenomes and 16 nuclear genomes of modern specimens, and 83 mitogenomes and 12 nuclear genomes of ancient specimens spanning the last 75 thousand years (ka). We estimate the divergence of Portuguese from short-tailed and Mediterranean field voles to be ca. 220 ka ago and of the latter two species to be ca. 110 ka ago, earlier than previous estimates involving only modern sequences. The divergence times we obtain match those between major mitochondrial lineages of cold-adapted and steppe rodents in Europe. We find signatures of gene flow within and between field vole lineages, with some analyses suggesting a hybrid origin of the Mediterranean lineage. Ancient specimens from the Italian Peninsula reveal a previously unrecognised lineage that show evidence of genetic exchange with other populations. Conclusions The pattern of genetic variation in the field vole species complex demonstrates the impact of stadial-interstadial cycles in generating recurrent episodes of allopatry and connectivity of populations, a situation which could only be revealed by our dense genomic sampling over time.
From Mesolithic hunters to Iron Age herders
In a continuous, perfectly stratified sedimentary sequence which was discovered under a large sandstone overhang in northern Bohemia, Czech Republic, we analysed multiple biological remains, archaeological features and artefacts. This multi-proxy record has allowed us to examine the interactions between woodland and humans in a permanently wooded environment throughout almost the entire Holocene. We paid most attention to massive finds of dung pellets from sheep, goats or pigs and bedding layers which show that the site was used as a pen and shelter for livestock which grazed in the woods. Our results imply that such practices have occurred since the Neolithic, but the most robust evidence of these is for the Iron Age and early Middle Ages. Detailed analyses of the dung indicate woodland grazing and foddering with branches, acorns, beechnuts and crop processing remains. In addition, the wide palaeoenvironmental range of this detailed investigation provides evidence of the impact of wood pasturing on ecological functions, taxon composition and diversity of the local woodland ecosystem in the Holocene.
Phenotypic diversification and island evolution of pipistrelle bats (Pipistrellus pipistrellus group) in the Mediterranean region inferred from geometric morphometrics and molecular phylogenetics
Aim: The Mediterranean Basin is a centre of radiation for numerous species groups. To increase our understanding of the mechanisms underlying speciation and radiation events in this region, we assessed the phenotypic variability within the Pipistrellus pipistrellus-pygmaeus-hanaki species complex. Although bats form the second largest mammalian order, studies of insular evolution in this group are scarce. We approached this problem from a microevolutionary perspective and tested for the recurrence of the insular syndrome. Location: The Mediterranean Basin, with a special focus on isolated populations from Corsica, the Maghreb, Cyprus, Cyrenaica and Crete. Methods: Phenotypic variability was assessed by cranial morphometrics using the coordinates of 41 3D landmarks and associated geometric-morphometric methods. We analysed 125 specimens representing all of the lineages in the species complex. Differences between taxa and between insular and continental populations in cranial size, shape, form and allometries were tested using analyses of variance and visualized using boxplots and canonical variate analysis. Relationships between molecular data from a previous study (cytochrome b sequences) and morphometric data were tested with co-inertia analyses (RV test) and multivariate regressions. Results: The three species were relatively well differentiated in cranial size and shape, and each species showed a significant amount of inter-population variability. Comparisons of pairs of insular versus continental populations revealed heterogeneities in cranial patterns among island phenotypes, suggesting no recurrent insular syndrome. Molecular and phenotypic traits were correlated, except for molecular and lateral cranium shape. Main conclusions: The Pipistrellus pipistrellus-pygmaeus-hanaki species complex exhibits phenotypic variability as a result of the fragmentation of its distribution (especially on islands), its phylogenetic and phylogeographic history and, most probably, other evolutionary factors that were not investigated in this study. We found no recurrent pattern of evolution on islands, indicating that sitespecific factors play a prevailing role on Mediterranean islands. The correlation between molecular and phenotypic data is incomplete, suggesting that factors other than phylogenetic relationships, potentially connected with feeding ecology, have played a role in shaping cranial morphology in this species complex.
BETWEEN BILZINBSLEBEN AND VÉRTÉSSZÖLÖS
Lower Paleolithic research in the Czech Republic underwent a complex history, with alternating periods of enthusiasm and scepticism. Certain archaeological sites are actually rejected and some deserve a revision. Here we discuss two promissing sites of Middle Pleistocene age (MIS 11-9, based on chronostratigraphy and faunal record) associated to the small-sized industries, predominantly made of quartz: Račiněves and Karlštejn.
Biogeographic history of the Late Pleistocene and Holocene European small hamsters (subfamily Cricetinae)
The prevailing paleobiogeographic hypothesis suggests that many steppe and tundra-steppe taxa currently found in Central Asia expanded into Europe during Pleistocene glacial periods, when open habitats dominated. However, previous studies have shown that one such species, the European narrow-headed vole ( Stenocranius anglicus ), diverged from its Asiatic counterparts over 200 thousand years ago, implying its prolonged isolation and survival in European refugia through the Eemian interglacial period. To test whether this was an exception or part of a broader pattern, we analysed the mitochondrial genomes from 33 Late Pleistocene and Holocene small hamster (Cricetinae) remains from Central and Western Europe, the Balkans, and Anatolia, all previously identified morphologically as grey dwarf hamster ( Nothocricetulus migratorius ). Contrary to expectations, 16 Late Pleistocene Central European samples were assigned to the hairy-footed hamster ( Cricetiscus sungorus ), a species currently restricted to northern Kazakhstan and southern Russia, whereas 17 samples from the Balkans and Anatolia belonged to the grey dwarf hamster. In both cases, the Late Pleistocene samples formed clades sister to modern populations; however, with relatively recent divergence times. This suggests population continuity or repeated expansion of hamsters from Asiatic sources rather than long-term isolation in Europe, as previously observed in narrow-headed voles. Our findings indicate that steppe species, despite occupying similar ecological niches, respond to past climate change in a species-specific manner. Therefore, broad generalisations regarding their evolutionary history may be misleading.
Spatial networks differ when food supply changes: Foraging strategy of Egyptian fruit bats
Animals are faced with a range of ecological constraints that shape their behavioural decisions. Habitat features that affect resource abundance will also have an impact, especially as regards spatial distribution, which will in turn affect associations between the animals. Here we utilised a network approach, using spatial and genetic data, to describe patterns in use of space (foraging sites) by free-ranging Egyptian fruit bats (Rousettus aegyptiacus) at the Dakhla Oasis in Egypt. We observed a decrease in home range size during spring, when food availability was lowest, which was reflected by differences in space sharing networks. Our data showed that when food was abundant, space sharing networks were less connected and more related individuals shared more foraging sites. In comparison, when food was scarce the bats had few possibilities to decide where and with whom to forage. Overall, both networks had high mean degree, suggesting communal knowledge of predictable food distribution.
Large-scale spatial patterns of small-mammal communities in the Mediterranean region revealed by Barn owl diet
Due to mainly opportunistic hunting behaviour of Barn owl can be its diet composition used for assessing local structure of small-mammal community. We evaluated the structure of small-mammal communities in the Mediterranean region by analysing Barn owl diet using own pellets and literature data (85 localities comprising 182,343 prey individuals). Contrary to widely accepted macroecological theory, we found a latitudinal increase of small-mammal alpha diversity, a less distinct west–east increase and lower diversity on islands. The mean prey weight decreased with increasing latitude, while on islands it decreased with increasing island area. The mean prey weight on islands was further negatively affected by mean land modification by human and positively affected by its range. The diet diversity on islands was not affected either by island area or its distance from the mainland. Its composition largely conformed to the main pattern pronounced over whole the region: an unexpected homogeneity of small-mammal community structure. Despite high beta diversity and large between-sample variation in species composition, Crocidura (+  Suncus etruscus ) and murids ( Apodemus , Mus , Rattus , in marginal regions partly replaced by gerbillids, Meriones or Microtus ) composed more than 90% of owl prey in 92% of samples. Peak abundances of these widespread species are associated with a dynamic mosaic of dense patches of sparse herb vegetation and evergreen sclerophyllous shrublands interspersing areas of human activity, the dominant habitat of the inner Mediterranean and richest food resource for foraging Barn owls. The respective small-mammal species can be looked upon as invasive elements accompanying large scale human colonization of the region since the Neolithic and replacing original island biota. Our study documented that desertification of the Mediterranean played an important role in shaping inverse latitudinal gradient in diversity of small-mammals that contradicts to widely accepted mecroecological theory.