Paleogeographic Events Research Articles

Five new unexpected populations of endangered tuco-tuco Ctenomys rionegrensis (Rodentia, Ctenomyidae) help understanding its distribution and historical biogeography

In this study, we conducted a survey of newly discovered populations of tuco-tuco (subterranean rodents of the genus Ctenomys) in the Entre Ríos province, in an area characterized by its unexplored nature and its climatic and biogeographic complexity within Argentina, which includes two National Parks. We characterize the nucleotide sequences of the cytochrome-b gene, revealing the presence of seven novel haplotypes within Ctenomys rionegrensis, a species known to inhabit both sides of the Uruguay River. Through Bayesian analyses, we estimated the divergence times of the oldest lineages of C. rionegrensis, as well as those of the haplotypes located east of the Uruguay River, dating back approximately 630,000 years before present (ybp) and 526,000 ybp, respectively. These estimates correspond with significant paleogeographic events in the region. Our findings may raise questions regarding the taxonomic classification of the species and suggest potential modifications to its current endangered status as designated by the International Union for Conservation of Nature (IUCN). Consequently, this research provides valuable insights that may inform future revisions of the species' conservation status and guide the development of informed management strategies/policies.

Historical biogeography of the Neotropical noctilionoid bats (Chiroptera: Noctilionoidea), revisited through a geographically explicit analysis.

Biogeographic studies have generally relied on methods that use a few, large predefined areas, which may overlook fine-scale patterns. Here we test previous hypotheses about the biogeographic history of a diverse bat clade regarding its association with major Neotropical geological formations, particularly the Antilles, the South American Dry Diagonal, the Andes and the Panamanian land bridge, by applying a recently available method that uses actual distributions instead of predefined areas. We compiled and curated spatially explicit, georeferenced data of 173 bat species (Mammalia: Chiroptera: Noctilionoidea) from the online database Global Biodiversity Information Facility. By taking a previous comprehensive phylogeny as an evolutionary framework, we performed computationally intensive analyses using the Geographically-explicit Event Model. This method uses the observed species distributions to reconstruct the ancestral areas and biogeographic events at each phylogeny node. We found that sympatric speciation was the most frequently reconstructed event, and involved mainly the Panamanian Isthmus and northern South America (SA), but all sympatry reconstructions were different and specific to each node. Allopatric events were important in the Andes; vicariance caused both west/east and north/south disjunctions that went unnoticed previously. Founder events indicated bidirectional dispersal between the mainland and the Antilles since the Miocene, and across the incomplete Panamanian bridge and the SA Dry Diagonal since the early Pliocene. Overall, we found support for previous hypotheses on the influence of major Neotropical paleogeographic events in the diversification of the group, but additionally revealed multi-scale patterns that are embedded within the mainland and were previously overlooked. Our results highlight a trans-isthmian centre of diversification in the biogeographic history of Noctilionoidea including the Panamanian Isthmus and Northern SA.

Ensemble species distribution modeling and multilocus phylogeography provide insight into the spatial genetic patterns and distribution dynamics of a keystone forest species, Quercus glauca

BackgroundForests are essential for maintaining species diversity, stabilizing local and global climate, and providing ecosystem services. Exploring the impact of paleogeographic events and climate change on the genetic structure and distribution dynamics of forest keystone species could help predict responses to future climate change. In this study, we combined an ensemble species distribution model (eSDM) and multilocus phylogeography to investigate the spatial genetic patterns and distribution change of Quercus glauca Thunb, a keystone of East Asian subtropical evergreen broad-leaved forest.ResultsA total of 781 samples were collected from 77 populations, largely covering the natural distribution of Q. glauca. The eSDM showed that the suitable habitat experienced a significant expansion after the last glacial maximum (LGM) but will recede in the future under a general climate warming scenario. The distribution centroid will migrate toward the northeast as the climate warms. Using nuclear SSR data, two distinct lineages split between east and west were detected. Within-group genetic differentiation was higher in the West than in the East. Based on the identified 58 haplotypes, no clear phylogeographic structure was found. Populations in the Nanling Mountains, Wuyi Mountains, and the southwest region were found to have high genetic diversity.ConclusionsA significant negative correlation between habitat stability and heterozygosity might be explained by the mixing of different lineages in the expansion region after LGM and/or hybridization between Q. glauca and closely related species. The Nanling Mountains may be important for organisms as a dispersal corridor in the west-east direction and as a refugium during the glacial period. This study provided new insights into spatial genetic patterns and distribution dynamics of Q. glauca.

Phylogeographic History of Endangered Hokuriku Salamander, Hynobius takedai (Amphibia: Caudata).

Knowledge of the phylogeographic history of organisms is valuable for understanding their evolutionary processes. To the best of our knowledge, the phylogeographic structure of Hokuriku salamander, Hynobius takedai, an endangered species, remains unclear. This study aimed to elucidate the phylogeographic history of H. takedai, which is expected to be strongly influenced by paleogeographic events. Phylogenetic analysis based on partial sequences of the mitochondrial DNA cytochrome b gene confirmed the genetic independence of H. takedai, and the divergence time with closely related species was estimated to be from the Late Pliocene to the Early Pleistocene. In the phylogenetic tree, two clades were identified within H. takedai, and their haplotypes were found in samples collected from the west and east of the distribution range. These intraspecific divergences were strongly influenced by geohistorical subdivisions of the current major distribution areas in the Middle Pleistocene. One clade was further subdivided and its formation may have been influenced by sea level changes in the Late Pleistocene.

On the conservation of white-clawed crayfish in the Iberian Peninsula: Unraveling its genetic diversity and structure, and origin.

European crayfish species are a clear example of the drastic decline that freshwater species are experiencing. In particular, the native species of the Iberian Peninsula, the white clawed-crayfish (WCC) Austropotamobius pallipes, is listed as "endangered" by the IUCN and included in Annex II of the EU Habitat Directive and requires especially attention. Currently, implemented conservation management strategies require a better understanding of the genetic diversity and phylogeographic patterns, as well as of its evolutionary history. For this purpose, we have generated the largest datasets of two informative ribosomal mitochondrial DNA regions, i.e., cytochrome oxidase subunit I and 16S, from selected populations of the WCC covering its geographical distribution. These datasets allowed us to analyze in detail the (i) genetic diversity and structure of WCC populations, and (ii) divergence times for Iberian populations by testing three evolutionary scenarios with different mtDNA substitution rates (low, intermediate, and high rates). The results indicate high levels of haplotype diversity and a complex geographical structure for WCC in the Iberian Peninsula. The diversity found includes new unique haplotypes from the Iberian Peninsula and reveals that most of the WCC genetic variability is concentrated in the northern and central-eastern regions. Despite the fact that molecular dating analyses provided divergence times that were not statistically supported, the proposed scenarios were congruent with previous studies, which related the origin of these populations with paleogeographic events during the Pleistocene, which suggests an Iberian origin for these WCC. All results generated in this study, indicate that the alternative hypothesis of an introduced origin of the Iberian WCC is highly improbable. The result of this study, therefore, has allowed us to better understand of the genetic diversity, structure patterns, and evolutionary history of the WCC in the Iberian Peninsula, which is crucial for the management and conservation needs of this endangered species.

Geographical isolation as reproductive barrier in phylogenetically related Aquilegia species (Ranunculaceae)

Knowing the determinants of biodiversity is crucial to understanding the differentiation of living organisms. Several gene-flow limiting processes can drive divergence, including adaptive ecological differentiation or geographical isolation both constituting environmental-dependent reproductive barriers. Furthermore, the strength of these processes may be associated to the degree to which ecological niches are conserved and shared by phylogenetically related species. Here, we aim to disentangle these two alternatives reproductive barriers by evaluating the degree of ecological niche similarity among phylogenetically related species. We performed ecological niche modelling (ENM) on four species belonging to a recently diversified genus (Aquilegia, Ranunculaceae) occurring in montane environments of the Alpine and Apennine chains (southern Europe). Results show that niche differentiation among species is related to phylogenetic distinctiveness. Nevertheless, niche similarity tests indicated that the conditions selected by the species are more similar than expected from the null models, even though they are sparsely available in the respective ecological spaces, suggesting that the observed pattern may result from phylogenetic niche conservatism. These results, highlight that paleogeographic events in south-European mountains may have driven divergence by isolation in Aquilegia while partially retaining the possibly ancestral characters of the niches.

C, O, and Sr Isotope Compositions of Belemnites from the Bajocian–Bathonian of Arctic Siberia: Implications for Global Correlations and Paleogeographic Reconstructions

Abstract —The Middle Jurassic sedimentary strata of Siberia remain poorly studied chemostratigraphically. We contribute to the knowledge with pioneering C, O, and Sr isotopic data for carbonate material of belemnites from the Yuryung-Tumus Peninsula and the lower reaches of the Lena River, as a basis for comprehensive description of the north Siberian Bajocian and lower Bathonian. The obtained chemostratigraphic constraints, with new 87Sr/86Sr ratios and previous δ13C and δ18O estimates, also include data for the lower Bathonian in the Sokur section (Central Russia). Despite the limited amount of material, chemostratigraphy, along with the available biostratigraphic data, allows reliable correlation of the Boreal sections with the primary standard of Northwest Europe, which is impossible for these strata with any of the two methods alone. The δ13C, δ18О, and 87Sr/86Sr patterns correlate with the records of eustatic, climatic, tectonic, and paleogeographic events. The new δ18O data and the inferred paleotemperatures for the latest early Bajocian and the Bajocian/Bathonian boundary reveal two excursions of notable seawater warming near the Siberian Arctic coast, which were synchronous with episodes of global sealevel rise. It was presumably during the eustatic events that the N–S Komi Strait (first naming) opened twice in the territory of the Russian Plate. The strait connected the Boreal and Tethyan seas and thus changed the oceanic circulation patterns. Specifically, it opened a gateway for a warm current from the south to northern Siberia responsible for the high seawater temperatures recorded in the δ18О patterns of belemnites.

New data on the Late Miocene chondrichthyans from the Western Mediterranean region (Alcoy Basin, Eastern Spain)

ABSTRACT The Mediterranean Basin has been subjected to important geological and paleogeographic events that have shaped the evolution of the faunal assemblages that inhabit it. Two main events can be highlighted, the closure of its eastern margin by the Gomphotherium Land Bridge, and the temporal closure of the connection to the Atlantic Basin during the Messinian Salinity Crisis. These two events shaped the diversity of the chondrichthyan assemblages of the Mio–Pliocene Mediterranean, and their consequences can be observed even in the modern faunal composition. To better understand the taxonomic and ecological composition of the Mediterranean chondrichthyan faunas between the aforementioned events, and how they affected their evolutionary dynamics, we have performed a complete systematic and paleoenvironmental study of the chondrichthyan assemblage recovered from various Late Miocene localities at the municipality of Alcoy Basin (Alicante, eastern Spain). Our analysis allowed us to recognize up to 20 taxa of sharks and rays recovered from Miocene deposits. In addition, we reconstruct the paleobathymetry of the El Muro fossil site, based on the estimation of the Oceanization Index for foraminifera, as well as by the elasmobranch fossil assemblage via weighted bootstrap analysis. We expect that this first description and study of the Miocene chondrichthyan taxa from this area of eastern Spain could help us create a comparative framework to compare these communities with other areas, as well as show the changes in the elasmobranch species that have inhabited the Mediterranean Basin during and after the Messinian Salinity Crisis.

ENVIRONMENT DEVELOPMENT AND THE EVOLUTION OF GNILOE LAKE (SOUTH-EASTERN PRIMORYE) DURING THE LAST 3300 YEARS<a href="#FN1"><sup>1</sup></a>

A continuous record of paleogeographic events in south-eastern Primorye has been reconstructed based on the deposits of Gniloe Lake. The lake is located on the northern coast of Nakhodka Bay. Starting from 3240 cal. BP. 5 warming periods were identified: 3240–2500, 1865–1653, 1330–838, 733–624 cal. BP and from the second half of the 17th century to the present; 4 periods of cooling: 2500–1865, 1653–1330, 838–733 and 624–322 cal. BP; 6 wet periods: 3240–2500, 1865–1653, 1479–1330, 1056–838, 733–624 cal. BP and last 280 years; 5 dry periods: 2500–1865, 1653–1479, 1330–1056, 838–733 and 624–210 cal. BP. According to palynological analysis, the expansion of Pinus koraiensis and dark coniferous species occurred during the second phase of the Mid-Subatlantic cooling of 1479–1330 cal. BP. In the last 150 years, the most significant changes have been associated with the anthropogenic transformation of landscapes as a result of urbanization. The area of forests and their species composition have decreased. At present, shrubs have occupied areas of the deforested oak forests. Based on the results of diatom analysis, 7 stages of the development of Gniloe Lake were identified. There was a shallow semi-open lagoon at a sea level 1–1.5 m higher than the present day about 3240 cal. BP. Cooling and decrease in humidity about 2500 cal. BP led to the formation of a slightly saline semi-enclosed lagoon. Shallowing of the lagoon about 2000 cal. BP was due to a decrease in sea level. Finally, the lagoon separated from the sea about 1450 cal. BP. The transformation of the lagoon into a fresh lake occurred around 1080 cal. BP. During the period of cooling 840–733 cal. BP the shallowing of the lake began, which continued in the Little Ice Age. The increase of the lake level associated with moderate warming and an increase in humidity began at 210 cal. BP. Traces of three catastrophic events were recorded in the sediments of Gniloe Lake – a high-intensity storm about 3000 cal. BP and 2 tsunamis around 2000 and 1560 cal. BP.

Caspian transgressive-regressive cycles across the Lower Volga region during the Quaternary reconstructed from the borehole at Ulan-Khol (Kalmykia, Russia)

During the Quaternary, the Lower Volga region was typically a shallow shelf of the Caspian Sea. This region regularly and distinctively responded to sea level fluctuations by changing both sediments and biota. This region is therefore a key to understanding the history of the transgressive-regressive cycles of the Caspian Sea during the Quaternary. There is a wealth of information about the Quaternary deposits of the Lower Volga region; however, their diversity of facies, erosional processes, and fragmented sections create difficulties in stratigraphic interpretation and the development of paleogeographic models. The studied 500-m section of borehole 8 Ulan-Khol is among the few in the Caspian region that allows for the sequential reconstruction of the Quaternary history of the region in one section. These borehole data offer a unique opportunity to reconstruct transgressive-regressive cycles in Pleistocene basins located in the most southeastern part of Europe (the Caspian region). Based on biostratigraphic, sedimentological, and paleomagnetic methods, we were able to define main Early, Middle, and Late Pleistocene units, which were correlated with regional stratigraphical units. Each unit corresponds to regional paleogeographic events and sedimentation modes characterized either by basinal (brackish water) or continental conditions when lagoons and fluvial landscapes dominated. The borehole interpretation integrated with regional data demonstrates a complex history of Caspian basin development during Apsheronian time (MIS 63–20) with the presence of a strong regression in its final stage, accompanied by a previously unknown advance of the Paleo-Volga valley to the latitude of Astrakhan city and further south. This regression and the formation of the Paleo-Volga valley continued during Tyurkyanian time (MIS 19). By the end of the Tyurkyanian, the regression was followed by a transgressive stage, which culminated in Bakunian time (MIS 18–12). The Khazarian stage (MIS 11–5) of Caspian Sea development was characterized by a constant change from alluvial-marine to marine and estuarine environments. The borehole data support our earlier conclusion that the Singilian deposits separate the lower (MIS 11–7) and upper (MIS 5) Khazarian units. New data support the existence of only one transgression of the Caspian Sea during Khvalynian time (MIS 3–2); after its maximum stage the sea level gradually decreased with the formation of coastlines at several terrace levels. Due to its high deposit thickness and rich paleontological, stratigraphic and lithological information, Ulan-Khol borehole 8 can be considered a key site for the Northern Caspian area.

A review of Eupholidoptera (Orthoptera, Tettigoniidae) from Crete, Gavdos, Gavdopoula, and Andikithira.

Being nocturnal, hiding in prickly bushes and shrubs during the day, Eupholidoptera species in Crete and its neighbouring islands are easily overlooked, and until now our knowledge about their distribution was based on some thirty sightings across 11 species. In this paper results are presented of a study of Eupholidoptera specimens collected between 1987 and 2020 by hand-catches and pitfall and fermenting traps on the Greek islands of Crete, Gavdos, Gavdopoula, and Andikithira. Diagnostic features of all known species are presented and illustrated with stacked images. An updated key to all species is provided. Eupholidopterafrancisae Tilmans & Odé, sp. nov. from Andikithira and southwestern Crete and Eupholidopteramarietheresae Willemse & Kotitsa, sp. nov. from Mt. Dikti are described. Female E.cretica, E.gemellata, and E.mariannae are described, and the female of E.astyla is redescribed. Bioacoustics for E.francisae Tilmans & Odé, sp. nov., E.giuliae, and E.jacquelinae are presented for the first time. Eupholidopterasmyrnensis is reported for the first time from Crete. A substantial amount of new distribution data for Eupholidoptera species on Crete is presented. The current distribution pattern and first analyses of phylogeny based on molecular data of Eupholidoptera species on Crete are discussed in relation to paleogeographical events.

Multidisciplinary Study of the Rybachya Core in the North Caspian Sea during the Holocene

Mollusk fauna is an important component of the Caspian Sea ecosystem alongside ostracods and diatoms. These faunal proxies are essential indicators of hydrological shifts reflecting global and regional climate changes. Adding lithological, geochemical, and geochronological (radiocarbon) data, we revealed paleogeographic events of different scales recorded in the sequence of the Rybachya core from the North Caspian Sea. Here, we present the reconstruction of Mangyshlak paleovalley sediments during the Holocene multi-stage Neocaspian transgression, reflecting global and regional climate changes varying in scale and direction. The determined age of paleovalley-fill sediments, 8070 ± 110 cal yr BP and 7020 ± 140 cal yr BP, suggests that sedimentation processes with extended warming and humidification started later and lasted longer than was assumed earlier. Biological proxies indicate quasi-cyclic variability and shifts from brackish to freshwater conditions throughout the studied interval. Rybachya core was obtained from the early Khvalynian deposits. The Mangyshlak flow formed the depression and eroded the late Khvalynian deposits, which we did not observe in the core structure. It possibly collapsed into paleodepression and acted as a host material for the freshwater lentic faunal association. During the Holocene, we detected a transition from a tranquil water regime to a more dynamic one during the paleovalley gradual filling, followed by marine conditions typical for the modern Caspian Sea.

Diatom assemblages of the Holocene sediments from the northeastern Norwegian-Greenland Basin

This paper presents the results of diatom analysis of Holocene sediments from the northeastern part of Norwegian-Greenland Basin in comparison with palynomorph and foraminifera data. Main Holocene paleogeographic events of Norwegian-Greenland Basin were established by micropaleontological data.

Early cretaceous topographic evolution associated with the collapse of the Mongol-Okhotsk orogen in Western Transbaikalia: an integrated analysis

ABSTRACT The Early Cretaceous topographic evolution of Transbaikalia was largely governed by the tectonic evolution of the Mongol-Okhotsk orogen. The collapse of the Mongol-Okhotsk orogen triggered the formation of metamorphic core complexes and associated extensional basins, widespread throughout Transbaikalia, North Mongolia, and North China. Numerous lithofacies and biostratigraphic studies have been carried out from the sedimentary deposits of the Transbaikalia basins. However, the absence of absolute ages for the sedimentary series, as well as sediment source-to-sink analysis do not allow to accurately characterize the regional topographic evolution. We focused our study on the Gusinoozersk Basin of Western Transbaikalia, where extensive sedimentary sections of Lower Cretaceous deposits have been preserved. We provide new U/Pb (LA-ICP-MS) data on detrital zircons from sedimentary series and 40Ar/39Ar data on intruding rocks. We review the paleontological data to clarify the age of the paleogeographic events associated with the collapse of the Mongol-Okhotsk orogen, as well as to correct the age of faunal complexes in Western Transbaikalia. Our geochronological results show that the formation of the Cretaceous basins of Transbaikalia began around 136–130 Ma, accompanying the main episode of extension associated with the exhumation of the metamorphic core complexes. The lowest coarse-clastic formation characterizes the rapid subsidence and the predominance of proximal sediment sources. Distal provinces also made a contribution to sedimentation indicating the rise of a positive topography characterizing the exhumation of the metamorphic core complexes. Overlying fine-grained formations indicate a significant smoothing of the topography, suggesting that from middle Aptian, Western Transbaikalia developed in a relatively calm tectonic regime. We also show that the basins of Transbaikalia were formed both in conjunction with the exhumation of metamorphic cores complexes and reactivated structural sutures. Revised data on dinosaur fauna and palynology, together with the dating of host deposits, provide insights on the Early Cretaceous paleoenvironmental evolution.

Cryptic diversity of Oxythyrea flower chafers and its implication for conservation of non‐forest biotopes in the Balkans

Abstract Flower chafers (Coleoptera: Scarabaeidae: Cetoniinae) are usually associated with saproxylophagous life strategies, and several of these taxa are considered as flagship species of insect conservation in Europe. Here, we discuss the significance of soil‐dwelling flower chafers for the conservation of natural habitats by reporting the rediscovery of two relict, habitat specialist flower chafers of the genus Oxythyrea in Europe. We compare the observed population structure of both species with their widespread congeners and discuss the detected deep genetic divergences among populations of both species, O. dulcis and O. albopicta. Surprisingly, deep genetic structure has been observed among the psammophilous O. dulcis, which is quite counterintuitive as psammophilous habitats are rather ephemeral and these species tend to be very vagile. Populations of soil‐dwelling, habitat specialist flower beetles may represent relicts of the past paleogeographic events, and their conservation value has to be thoroughly assessed.

КОМПЛЕКСНЫЙ ПОДХОД В ПАЛЕОРЕКОНСТРУКЦИЯХ ХАЗАРСКИХ ТРАНСГРЕССИЙ КАСПИЯ

Along with the malacofaunistic method, which is the main one for studying the paleo events of the Pleistocene, on which the system for diagnosing transgressions and their correlation on different coasts of the Caspian Sea is based, geomorphological and allometric methods were used in the work. Small rivers are very sensitive to small and short-term changes in sea level, which makes it possible to apply the geomorphological method for paleoreconstruction. An integrated approach makes it possible to diagnose a number of paleogeographic changes: fluctuations in sea level, passage of cold or warm currents, straits, changes in sea water temperature. According to the studied fossil complex, it is possible to obtain information about the parameters of the habitat of didacn, when comparing it with previous and subsequent ones, it is possible to judge the direction of paleogeographic events. The alternation of different complexes of bivalves, the use of morphometric characteristics of mollusk shells as an indicator of the ecological situation in the Quaternary period help to stratify the deposits in detail. The change in temperature and salinity of Paleocaspian waters is evidenced by the occurrence in Pleistocene sediments of representatives of didacnas of one of three groups (catillus, crassa, trigonoides). We have correlated the sections of the Khazar deposits of the Dagestan region.

Comprehensive evaluation of Neoproterozoic source rocks formation

Based on comprehensive analysis of geological, geochemical, and paleotectonic settings, the conditions for the formation of Neoproterozoic oil and gas source rocks of the Earth are analyzed. A brief review of oil and gas fields in Eastern Siberia, China, the Middle East, Africa, and Australia is given, with Riphean and Vendian terrigenous and carbonate source rock. An overview of the oil and gas bearing basins of the world and a stratigraphic reference of the Neoproterozoic strata discovered within them, containing proven and suspected oil and gas source rocks, are given. The formation of Neoproterozoic oil and gas source rocks is analyzed in a complex way: simultaneously from the point of view of paleotectonics, paleogeographic and paleoclimatic conditions, paleobiological diversity and geochemical conditions. As part of paleotectonic analysis, the results of plate tectonic reconstructions for the Neoproterozoic stage are presented in accordance with one of the most currently relevant geodynamic models. Paleogeographic events and paleoclimatic conditions are described in the context of the specifics of the formation settings of carbonate-terrigenous oil and gas source rocks. In particular, the reasons for the accumulation of sediments enriched with organic carbon in the interglacial epochs of the Neoproterozoic and possible mechanisms for maintaining conditions favorable for their accumulation are considered. The conditions for the accumulation of oil and gas source rocks are also linked to global paleobiological pre-Phanerozoic events, and the analysis of the geochemical data of rocks makes it possible to characterize and correlate Neoproterozoic oil and gas source rocks on a global scale. On the basis of such a comprehensive assessment, a conclusion was made about fundamentally similar geological conditions for the formation of Neoproterozoic oil and gas source rocks in oil and gas bearing basins.

Mitonuclear discordance and patterns of reproductive isolation in a complex of simultaneously hermaphroditic species, the Allolobophora chlorotica case study

Historical events of population fragmentation, expansion and admixture over geological time may result in complex patterns of reproductive isolation and may explain why, for some taxa, the study of mitochondrial (mt) and nuclear (nu) genetic data results in discordant evolutionary patterns. Complex patterns of taxonomic diversity were recently revealed in earthworms for which distribution is largely the result of paleogeographical events. Here, we investigated reproductive isolation patterns in a complex of cryptic species of earthworms in which discordant patterns between mt and nu genetic lineages were previously revealed, the Allolobophora chlorotica aggregate. Using four nu microsatellite markers and a fragment of the cytochrome c oxidase subunit I mt gene, we carried out a parentage analysis to investigate the mating patterns (i) between individuals belonging to two divergent mt lineages that cannot be distinguished with nu markers and (ii) between individuals belonging to lineages that are differentiated both at the mt and nu levels. Amongst the 157 field‐collected individuals, 66 adults were used in cross‐breeding experiments to form 22 trios based on their assignment to a mt lineage, and 453 obtained juveniles were genotyped. We showed that adults that mated with both their potential mates in the trio produced significantly more juveniles. In crosses between lineages that diverged exclusively at the mt level, a sex‐specific pattern of reproduction characteristic to each lineage was observed, suggesting a possible conflict of interest concerning the use of male/female function between mating partners. In crosses between lineages that diverged both at the mt and nu levels, a high production of cocoons was counterbalanced by a low hatching rate, suggesting a post‐zygotic reproductive isolation. Different degrees of reproductive isolation, from differential sex allocation to post‐zygotic isolation, were thus revealed. Lineages appear to be at different stages in the speciation process, which likely explain the observed opposite patterns of mitonuclear congruence.

Ostatni epizod vistuliańskiego chłodu: cechy diagnostyczne w obszarach ekstraglacjalnych

The general trend of paleogeographic events is dependent on global climate changes. In the analysis of short geological periods, a large role should be assigned to local conditions, understood both in the regional sense and, above all, at the microscale, i.e. the specificity of sites with different morphological location and lithological properties of the substratum, generating a strictly local course of morphogenetic processes reflected in geological records. In this context, a large role should be assigned to the smallest marks of disturbances. Interpretation difficulties that researchers of the Younger Dryas often encounter result from the small thickness of the sub-surface sediment and its weathering changes. The article shows how a detailed analysis of data from the abiotic sphere can be used to reconstruct the conditions prevailing in short geological periods. The area of study is situated in central Poland in an extraglacial zone of the last Quaternary ice sheet that during the Vistulian remained under periglacial conditions (Fig. 1). Among the diagnostic properties are: sedimentological palaeohydrological marks, traces of permafrost re-aggradation, oversnow deposits, aeolian specificity and random events. Changes in the hydrological regimes in rivers are reflected in changes in the sedimentary record showing effective floods (Fig. 2) and together with raising of groundwater table registered in biogenic baśni point two distinct phases of humidity. Traces of permafrost re-aggradation are scarce and found only in particular localities (e.g., under peatlands), but the environmental context of involutions reported from study sites allow us to conclude a return of frozen substratum (Figs 2, 4). The smallscale fissure and fault network in the deposits of the youngest unit of dry periglacial valleys dated to the Younger Dryas were linked to deposition on patches of frozen snow that lasted for several summers and, afterwards, a collapse of he deposit due to melting (Fig. 5). This process did not require the presence of permafrost. In the aeolian environment, the cool conditions of the Younger Dryas resulted locally in the deposition of thin sand covers (Figs 6, 8), which, in favourable topographic conditions, could even form initial dune ramparts (Fig. 7). In the Younger Dryas environment, morphogenetic processes may have been activated by a random event not necessarily associated with global climatic change. One potential example is traces of wildfires registered in a depositional sequence of the Żabieniec site.

ЗАПИСЬ ИЗМЕНЕНИЙ ПРИРОДНОЙ СРЕДЫ В ОЗЕРНО-БОЛОТНЫХ ОТЛОЖЕНИЯХ ГОРНОЙ ЧАСТИ ОСТРОВА ИТУРУП С ПОЗДНЕЛЕДНИКОВЬЯ

We received a unique material on the natural environment development for the last 12 400 cal. yr. BP in the central part of Iturup Island. The high-resolution paleoreconstructions were based on multi-proxy study of the paleolake sediments found on the plateau (height 400–420 m) located northwest of the Baransky Volcano. For the first time, a record of paleogeographic events was obtained for the Late Glacial and the early Holocene. The age model is based on 9 radiocarbon dates. Diatom analysis allowed us to distinguish 11 stages of lake-swamp evolution. The paleolake reached its maximum depth at ~9 890–7 900 cal. yr. BP and became extinct at 1 400 cal. yr. BP. The stages of vegetation development and the factors determining the change of landscapes have been restored. The Younger Dryas cooling recorded in Iturup was characterized by humidity changes. The role of forest vegetation abruptly increased at the Pleistocene-Holocene boundary of ~11 470 cal. yr. BP) under warmer climatic conditions. Distribution of shrub pine as an indicator of stable snow cover was analyzed. Dark-coniferous forests existed in the mountainous part of the island since the Late Glacial and were most widely developed in the early Holocene. The onset of birch forest expansion at 6 200 cal. yr. BP was associated with the intensification of volcanic activity and frequent ash falls. A number of cold events were identified, whose manifestations were enhanced by the weakening of the Soya warm current. The intensive transfer of allochthonous pollen from the southern Kuril Islands and the Japanese Islands at 3 540 cal. yr. BP is a sign of cyclogenesis intensification in the Kuril Islands. Manifestations of the Holocene climatic rhythms in the landscape development of the Iturup mountainous part, as well as the influence of warm and cold currents and other regional factors, were analyzed.