Neogene Research Articles

Trace element and Sr-Nd isotopic features of ultramafic xenoliths from Kurose, Southwest Japan

Ultramafic xenoliths from Kurose, Southwest Japan, are fragments of the lithospheric mantle beneath the back arc of the active Southwest Japan volcano-tectonic arc. Trace element and Sr-Nd isotopic compositions of the clinopyroxenes in the ultramafic xenoliths suggest that several enrichment processes are responsible for the geochemical variation. These xenoliths would have witnessed the following events: (1) open-system partial melting of the continental lithosphere with an influx of an asthenospheric melt with MORB-like isotopic composition during the formation of the back-arc basin that resulted from the Japan Sea opening, (2) open-system melting under an influx of a fluid/melt derived from a subducted slab, and (3) metasomatism after these partial melting events by an island arc tholeiitic basalt melt in the Neogene period. Moreover, variations in the depletion levels of Zr and Ti in the clinopyroxenes suggest that source depletion preceded the melting and metasomatic events.

Tectonic evolution of the central Levant domain (Lebanon) since Mesozoic time

Abstract The tectonic history of the central part of the Levant domain (Lebanon) is re-evaluated. Examination of the tectonic structures and mechanical analysis of the meso-scale brittle deformation indicate that Lebanon has experienced four major tectonic events since Late Mesozoic time. The first was an Early Cretaceous extensional phase orientated north–south to NNE–SSW. It produced WSW–ENE to WNW–ESE normal faults with offsets up to several hundreds of meters and led to the development of an approximately WNW–ESE-trending basin. A second extension, with similar driving stresses, occurred during Eocene time and persisted, perhaps until Oligocene times. The Early Neogene period marked a dramatic change in the structural evolution of Lebanon after which strike–slip and reverse faulting and folding dominated. During Early Miocene times, an east–west compression produced moderate folding and faulting. A second, but much more severe, folding event occurred during Late Miocene time owing to a NNW–SSE compression. This new tectonic history allows the discussion of several aspects of the Eastern Mediterranean basin development and the later deformation of its continental margin and surroundings, in particular: (1) the driving mechanisms of the Levant basin opening; (2) the inversion of its adjacent margin; and (3) the age, origin, and evolution of the restraining bend of the Dead Sea Transform in Lebanon.

A new large didelphid of the genus Thylophorops (Mammalia: Didelphimorphia: Didelphidae), from the late Tertiary of the Pampean Region (Argentina)

A new large didelphid of the genus Thylophorops (Mammalia: Didelphimorphia: Didelphidae), from the late Tertiary of the Pampean Region (Argentina)

Identification of Genes Cooperating with Mpl Signaling Using Retroviral Insertional Mutagenesis.

Abstract 4558The thrombopoietin receptor (Mpl) regulates the proliferation of hematopoietic progenitors, their differentiation into mature megakaryocytes, and formation of platelets. Mutations in the Mpl gene have been shown to be associated with myeloproliferative neoplasms (MPN). We attempted to identify genes cooperating with Mpl signaling that could provide cell survival and proliferative advantage using MSCV based retroviral insertional mutagenesis coupled with an inducible Mpl signaling system. The retroviral Mpl vectors used in our screening system were based on the well-described retroviral vector MGIFM. That vector carried a bacterial shuttle plasmid coding for the Neo gene and a bacterial origin of replication in its 3′ untranslated region, and also coding sequences of a drug dependent, dimerizable, fusion protein containing the cytoplasmic domain of Mpl. This vector can interrupt gene structure through insertion, and its intact long terminal repeats can activate adjacent genes. The shuttle plasmid allows nonbiased recovery of proviral genomic integration sites (RIS). The retroviral Mpl vectors were used to transduce the human leukemia cell line K562. Selection for Mpl signaling dependent cells required blocking of the endogenous transforming Bcr-Abl kinase with imatinib and supplying the dimerizer drug, AP20187. Similar selection approach was applied in another leukemia cell line, a cytokine dependent UT7 cells, after transduction depriving them of exogenous cytokines and supplying the AP20187. In multiple independent transductions only a few percent of the transduced cells survived in the presence of AP20187, as assessed by the GFP expression, which was co-expressed with the Mpl fusion gene through an internal ribosome entry site. The surviving cells in long term culture were dependent on Mpl signaling and were sensitive to a Jak2 inhibitor, AG490. A wide variation in the mean fluorescent intensity of the surviving cells (from 37.5 to 238.8) in independent transductions indicated that a high level of Mpl expression was not the critical factor of selection. Transduction conditions were designed so that each experiment started with 30,000 independent insertion events from which selection of an Mpl-dependent cell population could be derived. Thirty six independent transductions have been performed with a presumed ∼ 1.89 × 106 independent insertions in the initial non-selected, cell population. After selection, 668 retroviral insertion sites (RIS) have been recovered that represent 203 independent insertion events. Within each independent transduction, a small number of RISs were identified suggesting selection of insertion events that result in a proliferative advantage. This was not observed in an independent experiment in K562 cells, in which the cells were not switched to Mpl dependent growth. Insertion events that occurred in close proximity are considered to indicate a potential cooperating mutation that results in a proliferative and/or survival advantage to the cell. Insertional events in several instances fell in regions of known frequent chromosomal aberrations in MPN. The distribution of insertions appears to be non-random. Many sites are adjacent to genes that have been identified as regulators of apoptosis, proliferation and myeloid development (data not shown). We are validating this conclusion by performing a parallel screening of RIS in multiple (40) populations of independent transductions of the K562 and UT7 cells transduced with retrovirus/Mpl vector without selection on AP20187. This screening will provide sufficient data to statistically compare the outcome of the two sets of data, AP20187- selected versus non selected cell populations. To date, we have a number of candidate genes. The Discs large homolog-associated protein 1 (DLGAP1) gene is implicated secondary to three independent insertion events at 18p11.3. All insertions are in the fourth intron. This protein interacts with a known tumor suppressor and is being investigated as a possible novel hematopoietic regulator. Disclosures:No relevant conflicts of interest to declare.

DIVERSIFICATION OF THE SOUTH AMERICAN AVIFAUNA: PATTERNS AND IMPLICATIONS FOR CONSERVATION IN THE ANDES1

By combining distributions and phylogenies for large groups of birds, it is now possible to disentangle the relative roles of contemporary ecology and history in explaining the distribution of biodiversity on earth. In South America, avian lineages, which represent radiations during the warm parts of the Tertiary, are best represented in the tropical lowlands and Andean forelands. During the upper Tertiary, diversification was most intense in the tropical Andes region, with recruitment back into the tropical lowlands and into South America's open biomes. Within the tropical Andes, endemism (mean inverse range size) and mean branch length (number of phylogenetic nodes on lineages) increase from the foothills up to the tree line and then decline again in the barren highlands, suggesting that the tree-line zone plays a special role in the diversification process. The resulting endemism is locally aggregated, often with marked peaks in areas immediately adjacent to ancient population centers. Thus, the process of evolution of new species is linked with local factors that, over a shorter time perspective, were also favorable for people. If we want to maintain the process of diversification, it becomes essential to supplement the traditional approach of preserving biodiversity in wilderness areas with few people with efforts to support sustainable development in populated areas.

Geochemical variations in igneous rocks of the Central Andean orocline (13 S to 18 S): Tracing crustal thickening and magma generation through time and space

Compositional variations of Central Andean subduction-related igneous rocks reflect the plate-tectonic evolution of this active continental margin through time and space. In order to address the effect on magmatism of changing subduction geometry and crustal evolution of the upper continental plate during the Andean orogeny, we compiled more than 1500 major- and trace-element data points, and 650 Sr-, 610 Nd-, and 570 Pb-isotopic analyses of Mesozoic-Cenozoic (190–0 Ma) magmatic rocks in southern Peru and northern Chile (Central Andean orocline), mostly from new data and the literature. This data set documents compositional variations of magmas since Jurassic time, with a focus on the Neogene period, when major crustal thickening developed and its influence on magma composition was most pronounced. We relate the observed variations in Sr/Y, La/Yb, La/Sm, Sm/Yb, and Dy/Yb ratios, as well as in Sr-, Nd-, and Pb-isotopic ratios, to the crustal structure and evolution of the Central Andean orocline. In particular, the evolution of Dy/Yb and Sm/Yb ratios, which track the presence of the higher-pressure minerals amphibole and garnet, respectively, in the lower crust, documents that crustal thickness has grown through time. Spatial variations in trace elements and isotopic ratios further suggest that crustal domains of distinct composition and age have influenced magma composition through some assimilation. The crustal input in Quaternary magmas is quantified to have been between 7% and 18% by simple two-components mixing. When comparing our geochemical data set to the geological record of uplift and crustal thickening, we observe a correlation between the composition of magmatic rocks and the progression of Andean orogeny. In particular, our results support the interpretation that major crustal thickening and uplift were initiated in the mid-Oligocene (30 Ma) and that crustal thickness has kept increasing until present day. Our data do not support delamination as a general cause for major late Miocene uplift in the Central Andes and instead favor continued crustal thickening.

Literature Review of Unconsolidated Sediment in San Francisco Bay and Nearby Pacific Ocean Coast

A review of the geologic literature regarding sedimentation in the San Francisco Bay estuarine system shows that the main part of the bay occupies a structural tectonic depression that developed in Pleistocene time. Eastern parts, including San Pablo Bay and Suisun Bay, have had sedimentation throughout late Mesozoic and Tertiary. Carquinez Strait and the Golden Gate may represent antecedent stream erosion. Sedimentation has included estuarine, alluvial, and eolian deposition. The ages of estuarine deposition includes the modern high sea level stand and earlier Pleistocene interglacial periods. Sediment sources can be generally divided into the Coast Ranges, particularly the Franciscan Complex, and “Sierran.” Much of the estuarine system is floored by very fine sediment, with local areas of sand floor. Near the Golden Gate, sediment size decreases in both directions away from the deep channel. Bedforms include sand waves (submarine dunes), flat beds, and rock and boulders. These are interpreted in terms of dominant transport directions. Near the Golden Gate is an ebb-tidal delta on the outside (including San Francisco bar) and a flood-tidal delta on the inside (parts of Central Bay). The large tidal prism causes strong tidal currents, which in the upper part of the estuary are normally much stronger than river currents, except during large floods. Cultural influences have altered conditions, including hydraulic mining debris, blasting of rocks, dredging of navigation channels, filling of the bay, and commercial sand mining. Many of these have served to decrease the tidal prism, correspondingly decreasing the strength of tidal currents.

The occurrence of Contogenys-like lizards in the Late Cretaceous and Early Tertiary of the western interior of the U.S.A.

ABSTRACT Based on diagnostic jaw and dental material from the Cenomanian–middle Paleocene of the western U.S.A., we erect a new fossil lizard taxon, Contogeniidae taxon nov., that contains the following species: Contogenys sloani Estes, 1969 (Maastrichtian–early Paleocene, Montana); Contogenys ekalakaensis sp. nov. (middle Paleocene, Montana); Palaeoscincosaurus middletoni Sullivan and Lucas, 1996 (early Paleocene, Colorado); Palaeoscincosaurus pharkidodon sp. nov. (Campanian, Utah); Utahgenys evansi gen. et sp. nov. (Turonian, Utah); and Utahgenys sp. indet. (Cenomanian, Utah). These taxa share unique characteristics of tooth and jaw morphologies (e.g., tooth crowns truncate and bearing longitudinal apical grooves; hypertrophied inferior alveolar canal). Phylogenetic analysis indicates that among squamates, Contogeniidae taxon nov. is most closely related to Xantusiidae.

A model for the paleoenvironmental distribution of larger foraminifera of Oligocene–Miocene carbonate rocks at Khaviz Anticline, Zagros Basin, SW Iran

Platform carbonate sediments of Oligocene–Miocene age (Asmari Formation) in the Zagros Basin (SW Iran) have been investigated in order to determine their paleoecology and depositional environment. The Zagros Basin is the result of the opening and closure of the Neo-Tethys Ocean along the northeastern border of the Arabian Plate. The thick sedimentary sequences of the Zagros Basin contain rocks ranging in age from Cambrian to recent. The geological evidence suggests that the region was part of a passive continental margin, which subsequently underwent rifting in the Permo-Trias and collision in the Late Tertiary. The Asmari carbonate system was dominated by foraminifera and corallinacean assemblage. Based on the distribution of the larger foraminifera, four assemblage zones have been recognised. Facies analysis allowed the recognition of nine microfacies types that are grouped into three depositional environments that correspond to the inner, middle and outer shelf. The biota assemblage of the Asmari Formation suggests that carbonate sedimentation took place in tropical waters and oligotrophic to slightly mesotrophic conditions. Our detailed analysis of microfacies and paleoecology shows that the Asmari Formation deposited on a carbonate open shelf dominated by heterozoan and, subordinately, photozoan skeletal assemblage.

The functional evidence for metastasis suppressor genes of liver cancer harboring on chromosome 8

Objective To find out the functional evidence for metastasis suppressor gene in liver cancer on human chromosome 8p. Methods The microcell hybrid clones Neo8/C5F-1-10, which were generated by introducing human chromosome 8 randomly marked with neo gene into C5F cell line by mi-crocell mediated chromosome transfer (MMCT) and the C5F cell line were subcutaneously implanted in 6-7 week-old female BALB/CA nude mice to perform the spontaneous metastasis assay. Serial dissections of the lung tissues were done to count the microscopic metastatic foci. The number of the metastatic foci was compared by one-way ANOVA. Results All the microceli hybrids implanted had grown into measurable tumors subcutaneously. The spontaneous metastasis assay for these microcell hybrid clones showed that 6 clones displayed prominent lung metastasis suppression (P<0.05). Among 2 of them, lung metastases had been totally suppressed. Conclusion The successful introduction of human chromosome 8 into meta-static rat liver cancer cell line had changed the metastatic behavior of C5F, which provided the direct func-tional evidence for the metastasis suppressor gene in liver cancer harboring on human chromosome 8. Key words: Carcinoma,hepatocellular; Chromosomes; Metastasis; Suppressor genes

A Late Tertiary Pollen Record from Niger Delta, Nigeria

A Late Tertiary Pollen Record from Niger Delta, Nigeria

Oil source analysis of Upper Tertiary Shawan Formation in Chepaizi area, in the northwest margin of Junggar basin

Well che89, located in the Chepaizi area in the northwest margin of Junggar basin, acquires high production industrial oil flow, which is an important breakthrough in the exploration of the south foreland slope area of Junggar basin. The Chepaizi area is near two hydrocarbon generation depressions of Sikeshu and Shawan, which have sets of hydrocarbon source rock of Carboniferous to Jurassic as well as Upper Tertiary. Geological and geochemical parameters are proper for the accumulation of mixed source crude oil. Carbon isotope, group composition and biomarkers of crude oil in Upper Tertiary of well Che89 show that the features of crude oil in Upper Tertiary Shawan Formation are between that of Permian and Jurassic, some of them are similar to these two, and some are of difference, they should be the mixed source of Permian and Jurassic. Geochemical analysis and geological study show that sand extract of Lower Tertiary Wulunguhe Formation has the same source as the crude oil and sand extract of Upper Tertiary Shawan Formation, but they are not charged in the same period. Oil/gas of Wulunguhe Formation is charged before Upper Tertiary sedimentation, and suffered serious biodegradation and oxidation and rinsing, which provide a proof in another aspect that the crude oil of Upper Tertiary Shawan Formation of well Che89 is not from hydrocarbon source rock of Lower Tertiary.

Gas-bearing fluid influx sub-system for gas hydrate geological system in Shenhu Area, Northern South China Sea

Based on the comprehensive interpretation and study of the Neogene fracture system and diapiric structure, it can be concluded that the diapiric structures, high-angle fractures and vertical fissure system are the main gas-bearing fluid influx sub-system for gas hydrate geological system in Shenhu Area, northern South China Sea. The Neogene fractures widely developed in the study area may be classed into two groups: NW (NNW)-trending and NE (NNE)-trending. The first group was active in the Late Miocene, while the second one was active since the Pliocene. The NE (NNE)-trending fractures were characterized by lower activity strength and larger scale, and cut through the sediment layers deposited since the Pliocene. Within the top sediment layers, the high-angle fracture and vertical fissure system was developed. The diapiric structures display various types such as a turtle-back-like arch, weak piercing, gas chimney, and fracture (or crack, fissure). On the seismic profile, some diapiric structures show the vertical chimney pathway whose top is narrow and the bottom is wide, where some ones extend horizontally into pocket or flower-shaped structures and formed the seismic reflection chaotic zones. Within the overlying sediment layers of the diapiric structure, the tree branch, flower-shaped high-angle fractures and vertical fissures were developed and became the pathway and migration system of the gas-bearing fluid influx. In the study area, the diapiric structures indicate a high temperature/over pressure system ever developed. Closely associated and abundant bright-spots show the methane-bearing fluid influx migrated vertically or horizontally through the diapiric structures, high-angle fractures and vertical fissures. In the place where the temperature and pressure conditions were favor for the formation of gas hydrate, the hydrate reservoir deposition sub-system was developed.

The Melting Himalayas: Cascading Effects of Climate Change on Water, Biodiversity, and Livelihoods

The Greater Himalayas hold the largest mass of ice outside polar regions and are the source of the 10 largest rivers in Asia. Rapid reduction in the volume of Himalayan glaciers due to climate change is occurring. The cascading effects of rising temperatures and loss of ice and snow in the region are affecting, for example, water availability (amounts, seasonality), biodiversity (endemic species, predator-prey relations), ecosystem boundary shifts (tree-line movements, high-elevation ecosystem changes), and global feedbacks (monsoonal shifts, loss of soil carbon). Climate change will also have environmental and social impacts that will likely increase uncertainty in water supplies and agricultural production for human populations across Asia. A common understanding of climate change needs to be developed through regional and local-scale research so that mitigation and adaptation strategies can be identified and implemented. The challenges brought about by climate change in the Greater Himalayas can only be addressed through increased regional collaboration in scientific research and policy making.

Epitope-tagged Receptor Knock-in Mice Reveal That Differential Desensitization of α2-Adrenergic Responses Is because of Ligand-selective Internalization

Although ligand-selective regulation of G protein-coupled receptor-mediated signaling and trafficking are well documented, little is known about whether ligand-selective effects occur on endogenous receptors or whether such effects modify the signaling response in physiologically relevant cells. Using a gene targeting approach, we generated a knock-in mouse line, in which N-terminal hemagglutinin epitope-tagged alpha(2A)-adrenergic receptor (AR) expression was driven by the endogenous mouse alpha(2A)AR gene locus. Exploiting this mouse line, we evaluated alpha(2A)AR trafficking and alpha(2A)AR-mediated inhibition of Ca(2+) currents in native sympathetic neurons in response to clonidine and guanfacine, two drugs used for treatment of hypertension, attention deficit and hyperactivity disorder, and enhancement of analgesia through actions on the alpha(2A)AR subtype. We discovered a more rapid desensitization of Ca(2+) current suppression by clonidine than guanfacine, which paralleled a more marked receptor phosphorylation and endocytosis of alpha(2A)AR evoked by clonidine than by guanfacine. Clonidine-induced alpha(2A)AR desensitization, but not receptor phosphorylation, was attenuated by blockade of endocytosis with concanavalin A, indicating a critical role for internalization of alpha(2A)AR in desensitization to this ligand. Our data on endogenous receptor-mediated signaling and trafficking in native cells reveal not only differential regulation of G protein-coupled receptor endocytosis by different ligands, but also a differential contribution of receptor endocytosis to signaling desensitization. Taken together, our data suggest that these HA-alpha(2A)AR knock-in mice will serve as an important model in developing ligands to favor endocytosis or nonendocytosis of receptors, depending on the target cell and pathophysiology being addressed.

The stratigraphic distribution of inertinite

Abstract The paper presents the results of an investigation into the stratigraphic distribution of inertinite in humic coals, ranging from the Silurian to the Neogene periods. This range equals the time span during which both land plants and atmospheric oxygen evolved. The survey is based on a literature study of inertinite in coals covering a variety of depositional environments and climates in all continents. The inertinite percentages listed in this paper have been arranged in stratigraphic order. They are the mean values based on mineral-free, whole coal compilations. Maceral compositions listed in the literature for individual subsections have been averaged to represent complete coal seams/beds, although this might not have been always possible due to some ambiguity in the published record. Moreover, not all of the published and unpublished information could be used because of poor sample description, obscure geographic origin, or insufficient stratigraphic information. The results show that there have been times in the geological past, e.g. during the Late Permian, in which coals were particularly rich in inertinite compared with other times, e.g. during much of the Late Tertiary, in which many coals contained very little inertinite. Occasionally, such primary, global trends were modulated by a diffuse distribution of inertinite percentages that correspond to differences in climate, depositional settings, e.g. active orogenic margins versus tectonically inactive shelf margins, and other local or regional variations. Although various mechanisms for the generation of inertinite have been proposed in the past, the overall pattern in its stratigraphic distribution supports the notion of incomplete combustion as the main source of inertinite in coal. This points to secular variations in the atmospheric oxygen content as an explanation for the global changes in the inertinite distribution, while differential subsidence and climatically influenced reaction rates governed regional and local variations in inertinite percentages.

New gastropods from deep-sea hydrocarbon seeps off West Africa

Thirteen new species of gastropods are described from the Zairov 1-2 and Biozaire 1-3 cruises to the methane seeps off the Congo River: Patellogastropoda: Paralepetopsis sasakii sp. nov. (Neolepetopsidae); Cocculiniformia: Pyropelta oluae sp. nov. and P. sibuetae sp. nov. (Pyropeltidae); Tentaoculus granulatus sp. nov. (Pseudococculinidae); Neomphalina: Leptogyra costellata sp. nov. (Family uncertain); Vetigastropoda: Puncturella similis sp. nov. (Fissurellidae); Lepetodrilus shannonae sp. nov. (Lepetodrilidae); Caenogastropoda: Provanna reticulata sp. nov. and P. chevalieri sp. nov., Cordesia provannoides gen. et sp. nov. (Provannidae); Phymorhynchus coseli sp. nov. and P. cingulata sp. nov. (Conidae); Heterobranchia: Hyalogyrina rissoella sp. nov. (Hyalogyrinidae). All species except T. granulatus (from a settlement trap) belong to groups known from cold seeps and the entire seep fauna here is new to science. Biogeographical affinity of this gastropod fauna is to the West Atlantic seeps, not to the Mediterranean seeps or Mid-Atlantic vents. Fragments of the autecology of the species are presented. The evolution of the seep gastropod fauna is briefly discussed and a continuous immigration of taxa is supported. The oldest verified occurrences of modern taxa in the seeps date back to Cenomanian (Cretaceous) time, while some taxa seem not to appear until very late Tertiary.

Monocyte chemoattractant protein-1 (MCP-1), not MCP-3, is the primary chemokine required for monocyte recruitment in thioglycollate-induced peritonitis (94.5)

Abstract In this study, we generated a novel MCP-1-deficient (designated as MCP-1Ä/Ä) mouse model using the Cre/loxP system. As expected, MCP-1 was not produced by LPS-activated MCP-1Ä/Ä macrophages; however, the production of MCP-3 was unexpectedly increased. In contrast, macrophages from another mouse line with a neo gene cassette in intron 2 produced a significantly lower level of MCP-1 and MCP-3. Decreased MCP-3 production was also detected in previously generated MCP-1-deficient mice by the insertion of a neo gene cassette in exon 2 (designated as MCP-1 KO). Altered MCP-1 and/or MCP-3 production was observed in vivo in each mouse model in response to intraperitoneal injection of thioglycollate (TG). The up- and down-regulation of MCP-3 production in MCP-1Ä/Ä and MCP-1 KO mice, respectively, provided us with a unique opportunity to evaluate the role for MCP-3 in the recruitment of monocytes. Despite the increased MCP-3 production in MCP-1Ä/Ä mice, TG-induced monocyte accumulation was still reduced by about 50% compared to WT mice, which was similar to the reduction detected in MCP-1 KO mice. Thus, up-regulated MCP-3 production did not compensate for the loss of MCP-1, and MCP-3 appears to be a less effective mediator of monocyte recruitment than MCP-1 in this model. Our results also suggest the participation of other mediators regulating the recruitment of monocytes in this model.

The phylogeographical history of the Iberian steppe plant Ferula loscosii (Apiaceae): a test of the abundant‐centre hypothesis

The geology and climate of the western Mediterranean area were strongly modified during the Late Tertiary and the Quaternary. These geological and climatic events are thought to have induced changes in the population histories of plants in the Iberian Peninsula. However, fine-scale genetic spatial architecture across western Mediterranean steppe plant refugia has rarely been investigated. A population genetic analysis of amplified fragment length polymorphism variation was conducted on present-day, relict populations of Ferula loscosii (Apiaceae). This species exhibits high individual/population numbers in the middle Ebro river valley and, according to the hypothesis of an abundant-centre distribution, these northern populations might represent a long-standing/ancestral distribution centre. However, our results suggest that the decimated southern and central Iberian populations are more variable and structured than the northeastern ones, representing the likely vestiges of an ancestral distribution centre of the species. Phylogeographical analysis suggests that F. loscosii likely originated in southern Spain and then migrated towards the central and northeastern ranges, further supporting a Late Miocene southern-bound Mediterranean migratory way for its oriental steppe ancestors. In addition, different glacial-induced conditions affected the southern and northern steppe Iberian refugia during the Quaternary. The contrasting genetic homogeneity of the Ebro valley range populations compared to the southern Iberian ones possibly reflects more severe bottlenecks and subsequent genetic drift experienced by populations of the northern Iberia refugium during the Pleistocene, followed by successful postglacial expansion from only a few founder plants.

Mediterranean diversification of the grass‐feeding Anisopliina beetles (Scarabaeidae, Rutelinae, Anomalini) as inferred by bootstrap‐averaged dispersal–vicariance analysis

AbstractAim The circum‐Mediterranean region is one of the most complex regions of the Earth in terms of geography and natural history. The Old World species of the beetle subtribe Anisopliina (Scarabaeidae) feed almost exclusively on the pollen of grasses (Poaceae). Within this group, the ‘anisopliine clade’ forms a monophyletic group distributed mainly in the circum‐Mediterranean region. Here, we reconstruct the biogeographical history of the anisopliine beetles in relation to the diversification of grasses, and compare this reconstruction with previous hypotheses concerning the evolution of the Mediterranean fauna and with palaeogeographical accounts of the history of this region.Location The Mediterranean region, including North Africa, the Western Mediterranean, Balkans–Anatolia, Middle East and Caucasus.Methods Dispersal–vicariance analysis (diva) was used to reconstruct ancestral distributions based on the morphological phylogeny and to infer the biogeographical processes that have shaped the observed distribution patterns. To account for phylogenetic uncertainty in the biogeographical reconstruction, we ran alternative ancestral distributions derived by diva over a sample of trees obtained by bootstrapping the original data set, reflecting the relative confidence of the ancestral areas on the various clades in the phylogeny.Results The Eastern Mediterranean region and the Caucasus are inferred as the ancestral area of most of the anisopliine lineages. The Eastern Mediterranean region is also reconstructed as the source area of the majority of dispersal events, in particular towards North Africa and the Western Mediterranean. The Iberian Peninsula is inferred as part of the ancestral distribution of the anisopliine clade but also as the setting of several independent colonization events via both the North African platform (Anthoplia) and a European dispersal route (Anisoplia).Main conclusions Our results confirm the role played by the Eastern Mediterranean as an evolutionary cradle of diversity for Mediterranean lineages. This can be explained by a recent and intense orogenic activity that might have promoted isolation and allopatric speciation within lineages. Both the Anomalini fossil record and the close association of anisopliine beetles with grasses suggest that the anisopliine clade originated in the Late Tertiary and that its spatial and temporal evolution within the Mediterranean Basin coincided with that of its major food source, the Mediterranean Poaceae.