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Habel J.C.,Natural History Museum Luxembourg | Husemann M.,Baylor University | Schmitt T.,University of Trier | Zachos F.E.,Natural History Museum Vienna | And 4 more authors.
PLoS ONE | Year: 2012

The immense biodiversity of the Atlas Mountains in North Africa might be the result of high rates of microallopatry caused by mountain barriers surpassing 4000 meters leading to patchy habitat distributions. We test the influence of geographic structures on the phylogenetic patterns among Buthus scorpions using mtDNA sequences. We sampled 91 individuals of the genus Buthus from 51 locations scattered around the Atlas Mountains (Antiatlas, High Atlas, Middle Atlas and Jebel Sahro). We sequenced 452 bp of the Cytochrome Oxidase I gene which proved to be highly variable within and among Buthus species. Our phylogenetic analysis yielded 12 distinct genetic groups one of which comprised three subgroups mostly in accordance with the orographic structure of the mountain systems. Main clades overlap with each other, while subclades are distributed parapatrically. Geographic structures likely acted as long-term barriers among populations causing restriction of gene flow and allowing for strong genetic differentiation. Thus, genetic structure and geographical distribution of genetic (sub)clusters follow the classical theory of allopatric differentiation where distinct groups evolve without range overlap until reproductive isolation and ecological differentiation has built up. Philopatry and low dispersal ability of Buthus scorpions are the likely causes for the observed strong genetic differentiation at this small geographic scale. © 2012 Habel et al.

Hess H.,Naturhistorisches Museum Basel | Thuy B.,Natural History Museum Luxembourg
Swiss Journal of Palaeontology | Year: 2016

Comatulid feather stars are rare fossils in the Early Jurassic, providing only patchy insights into the early evolution of the group. Here, we describe new finds of comatulids from the late Pliensbachian to late Toarcian of Feuguerolles, Calvados, France. They include new species belonging to four superfamilies. The dominant genus is Palaeocomaster, with P. structus n. sp. represented by centrodorsals. For Palaeocomaster, the family Palaeocomasteridae n. fam. is proposed; it is placed in the Superfamily Comatuloidea. Solanocrinites is represented by S. jagti n. sp. The new taxa Andymetra toarcensis n. sp. and Spinimetra chesnieri n. g. et n. sp. are Family incertae sedis. The diagnoses of Comatuloidea and Solanocrinitoidea are modified based on the new material. The paracomatulid Singillatimetratruncata n. sp. is represented by a columnal, as is Forcipicrinusnormannicus n. g. et n. sp. tentatively assigned to Pentacrinitina, Family incertae sedis. The material indicates that an important early comatulid radiation took place prior to the Toarcian Oceanic Anoxic Event, creating some basic types of these free-living crinoids. Along with the stratigraphic distribution patterns of the co-occurring stalked crinoids including the isocrinids Pentacrinitescollenoti, Isocrinus (Chladocrinus) basaltiformis, the millericrinid Amaltheocrinusamalthei, and the cyrtocrinids Cotylederma docens, Eudesicrinus mayalis, Praetetracrinusinornatus, Sacariacrinus n. sp. and Tetracrinus n. sp., the new feather star finds suggest that the Toarcian Oceanic Anoxic Event was not of major influence to crinoid diversity. © 2016 Akademie der Naturwissenschaften Schweiz (SCNAT)

Habel J.C.,Natural History Museum Luxembourg | Husemann M.,Baylor University | Schmitt T.,University of Trier | Dapporto L.,Instituto Comprensivo Materna Elementare Media Convenevole da Prato | And 2 more authors.
Journal of Heredity | Year: 2013

Numerous studies addressing the impact of habitat fragmentation on genetic diversity have been performed. In this study, we analyze the effects of a seemingly nonpermeable matrix on the population structure of the forest-dwelling butterfly Pararge aegeria in geographically isolated oases at the northern margin of the Sahara desert using microsatellites, morphological characters, and species distribution modeling. Results from all analyses are mostly congruent and reveal 1) a split between European and North African populations, 2) rather low divergence between populations from the eastern and western part of North Africa (Morocco vs. Tunisia), 3) a lack of differentiation between the oasis and Atlas Mountain populations, 4) as well as among the oasis populations, and 5) no reduction of genetic variability in oasis populations. However, one exception to this general trend resulted from the analyses of wing shape; wings of butterflies from oases are more elongated compared with those from the other habitats. This pattern of phenotypic divergence may suggest a recent colonization of the oasis habitats by individuals, which might be accompanied by a rather dispersive behavior. Species distribution modeling suggests a fairly recent reexpansion of the species' climatic niche starting in the Holocene at about 6000 before present. The combined results indicate a rather recent colonization of the oases by highly mobile individuals from genetically diverse founder populations. The colonization was likely followed by the expansion and persistence of these founder populations under relatively stable environmental conditions. This, together with low rates of gene flow, likely prevented differentiation of populations via drift and led to the maintenance of high genetic diversity. © The American Genetic Association. 2012. All rights reserved.

Augenstein B.,Natural History Museum Luxembourg | Ulrich W.,Nicolaus Copernicus University | Habel J.C.,Natural History Museum Luxembourg
Basic and Applied Ecology | Year: 2012

Oligotrophic calcareous grasslands are among the most species-rich habitats in temperate Europe. Land use changes caused a severe decline of these species-rich grasslands over the last decades. Today, these ecosystems exist as highly isolated and small remnants being threatened by abandonment, afforestation and the transformation into agricultural land. Local conservation activities caused changes in habitat structures within such oligotrophic calcareous grasslands and their often isolated character may have led to stochastic species extinctions due to population fluctuations. In this study we focus on potential changes of grassland biota over the past decades. We analyse retrospective species inventories (14 for carabid beetles and 7 for butterflies) from calcareous grasslands located in western Germany with adjoining parts of Luxembourg over a period from 1972 to 2011. Our data indicate two distinct temporal cohorts (past versus present) that differ strongly in the composition and structure of carabid beetles and butterfly communities. Patterns of species co-occurrences tended to be segregated in the past communities while the co-occurrences in recent communities were either random or aggregated. β-Diversity increased with time. Our results indicate a temporal shift from past communities dominated by species interactions towards recent neutral assemblages. These changes might be caused by diverging conservation management being restricted to local sites. This resulted in a higher diversity of environmental structures combined with a loss of grassland habitats and declining matrix permeability. However, we detected no loss of rare carabid beetles, while butterflies showed severe extinctions of species with specific habitat demands, high endangerment and/or low dispersal behaviour. These trends let us argue that carabid communities mirror local changes in habitat structure (caused by conservation action), while butterflies show additional effects due to environmental stochasticity, local extinctions and a subsequent lack of re-colonization from adjoining populations. © 2012.

Habel J.C.,Natural History Museum Luxembourg | Schmitt T.,University of Trier
Biological Conservation | Year: 2012

In general, species with large ecological amplitudes are equipped with high genetic diversities. In contrast, more specialised species with narrow ecological amplitudes show low levels of genetic diversity. Generalist species are mostly rather marginally affected by recent land-use changes; specialist can be supported by specific conservation measures. We argue that, in the light of Conservation Genetics, species being ecologically intermediate between these two extremes are the most seriously affected ones by recent environmental changes. Such species which formerly occurred in large population networks have to sustain their high level of genetic variability via gene flow. Today, species from the latter group are negatively affected by rapid habitat collapses causing sudden lacks of population interconnectivity. Therefore, species with intermediate habitat demands and originally high genetic diversity might be at highest risk due to inbreeding depressions. © 2011 Elsevier Ltd.

Thuy B.,Natural History Museum Luxembourg | Kiel S.,University of Gottingen | Dulai A.,Hungarian Natural History Museum | Gale A.S.,University of Portsmouth | And 5 more authors.
Proceedings of the Royal Society B: Biological Sciences | Year: 2014

Owing to the assumed lack of deep-sea macrofossils older than the Late Cretaceous, very little is known about the geological history of deep-sea communities, andmost inference-based hypotheses argue for repeated recolonizations of the deep sea fromshelf habitats followingmajor palaeoceanographic perturbations.We present a fossil deep-sea assemblage of echinoderms, gastropods, brachiopods and ostracods, from the Early Jurassic of the Glasenbach Gorge, Austria, which includes the oldest known representatives of a number of extant deep-sea groups, and thus implies that in situ diversification, in contrast to immigration from shelf habitats, played a much greater role in shaping modern deep-sea biodiversity than previously thought. A comparison with coeval shelf assemblages reveals that, at least in some of the analysed groups, significantly more extant families/superfamilies have endured in the deep sea since the Early Jurassic than in the shelf seas, which suggests that deepsea biota are more resilient against extinction than shallow-water ones. In addition, a number of extant deep-sea families/superfamilies found in the Glasenbach assemblage lack post-Jurassic shelf occurrences, implying that if there was a complete extinction of the deep-sea fauna followed by replacement from the shelf, it must have happened before the Late Jurassic. © 2014 The Authors Published by the Royal Society. All rights reserved.

Husemann M.,Baylor University | Schmitt T.,University of Trier | Stathi I.,University of Crete | Habel J.C.,Natural History Museum Luxembourg
Journal of Heredity | Year: 2012

When low dispersal ability of an organism meets geographical barriers, the evolution of inter- and intraspecific differentiation is often facilitated. In the Atlas massif of North Africa, the genus Buthus splits into several species and diverges into numerous genetic lineages, often following the orographic structures of mountain systems. Such high mountain ranges often act as barriers for species with reduced mobility even on small spatial scales. To study the effect of orographic structures on organisms with low dispersal ability, we collected 61 individuals of the scorpion species Buthus elmoutaouakili at 18 locations around the southwestern foothills of the High Atlas and Antiatlas and in the Sousse valley (western Morocco). We analyzed intraspecific differentiation patterns within this geographically restricted area of about 100 × 50 km using 452 bp of the cytochrome oxidase I mitochondrial gene. We detected 5 distinct genetic lineages. In a second analysis, we added 61 previously published sequences from Buthus species from Europe and North Africa. Using a molecular clock approach, we detected old splits (4-5 Ma) separating the samples from 1) the western High Atlas and north of these mountains, 2) the Sousse valley and adjoining mountain areas, and 3) the southwestern Antiatlas. Further differentiation happened in the first 2 geographical groups about 3 M.A. Thus, the divergence time estimates based on a Bayesian approach support the onset of differentiation into these main clades along the Pliocene (5-2.3 Ma) when climatic oscillations started and a constant global cooling preceded the glacial-interglacial cycles of the Pleistocene. Further genetic splits into parapatric groups are detectable for the Sousse valley main group in the early Pleistocene. The climatic oscillations of the Pliocene and early Pleistocene might have caused repeated range shifts, expansions, and retractions leading to repeated vicariance, hereby producing the hierarchical structure of genetic differentiation in B. elmoutaouakili. A taxonomic revision, including morphological and molecular data, is needed to assess the status of each of these Buthus scorpion lineages. © The American Genetic Association. 2012. All rights reserved.

Thuy B.,Natural History Museum Luxembourg | Kutscher M.,Dorfstrasse 10 | Plachno B.J.,Jagiellonian University
Acta Palaeontologica Polonica | Year: 2015

The fossil record of Paleozoic ophiuroids includes a number of forms which share striking similarities with modern relatives in terms of skeletal morphology. These so called modern-type Paleozoic ophiuroids yield an enormous potential for a better understanding of ophiuroid evolution, yet the scarcity of accurate and sufficiently detailed morphological descriptions available to date precludes any further-reaching assessments. Here, we describe an articulated ophiuroid specimen from the Late Tournaisian (early Carboniferous) of Czatkowice quarry, southern Poland, as a new species Aganaster jagiellonicus sp. nov. The good preservation of the specimen allowed for a morphological analysis at a level comparable to recent ophiuroid descriptions. It shows remarkable morphological similarities with extant former ophiolepidids Ophiomusium and Ophiosphalma. The new find thus contributes to a solid basis for future investigations on the position of the modern-type Paleozoic ophiuroid in the phylogeny of the class. © 2015 B. Thuy et al.

Ishida Y.,Kamiogi | Fujita T.,National Museum of Nature and Science | Thuy B.,Natural History Museum Luxembourg
Paleontological Research | Year: 2015

Well preserved specimens of two ophiuroid species, both assignable to an unknown family (formerly Ophiolepididae) and here placed in Ophiomusium and Ophiosphalma have been recovered from lower Miocene deep-sea formations in Japan. The material consists of an assemblage of over 75 articulated body fossils and numerous semiarticulated arm segments from the lower Miocene Oi Formation (Ichishi Group), Mie Prefecture, central Japan, identified as the extant species Ophiomusium lymani Wyville Thomson and a single articulated body fossil assigned to the extant Ophiosphalma cancellata (Lyman) from the lower Miocene Shida Formation (Oigawa Group), Shizuoka Prefecture, central Japan. These occurrences constitute the oldest fossil record of these present-day brittlestar species. The latter is the first fossil record for the genus Ophiosphalma. The new material documents that the closely related genera Ophiomusium and Ophiosphalma had already diverged by the early Miocene. Furthermore our findings suggest that the ancient Ophiomusium lymani and Ophiosphalma cancellata inhabited the same upper bathyal environment as their Recent counterparts. © by the Palaeontological Society of Japan 2015.

Thuy B.,Natural History Museum Luxembourg | Stohr S.,Swedish Museum of Natural History
PLoS ONE | Year: 2016

Ophiuroid systematics is currently in a state of upheaval, with recent molecular estimates fundamentally clashing with traditional, morphology-based classifications. Here, we attempt a long overdue recast of a morphological phylogeny estimate of the Ophiuroidea taking into account latest insights on microstructural features of the arm skeleton. Our final estimate is based on a total of 45 ingroup taxa, including 41 recent species covering the full range of extant ophiuroid higher taxon diversity and 4 fossil species known from exceptionally preserved material, and the Lower Carboniferous Aganaster gregarius as the outgroup. A total of 130 characters were scored directly on specimens. The tree resulting from the Bayesian inference analysis of the full data matrix is reasonably well resolved and well supported, and refutes all previous classifications, with most traditional families discredited as poly- or paraphyletic. In contrast, our tree agrees remarkably well with the latest molecular estimate, thus paving the way towards an integrated new classification of the Ophiuroidea. Among the characters which were qualitatively found to accord best with our tree topology, we selected a list of potential synapomorphies for future formal clade definitions. Furthermore, an analysis with 13 of the ingroup taxa reduced to the lateral arm plate characters produced a tree which was essentially similar to the full dataset tree. This suggests that dissociated lateral arm plates can be analysed in combination with fully known taxa and thus effectively unlocks the extensive record of fossil lateral arm plates for phylogenetic estimates. Finally, the age and position within our tree implies that the ophiuroid crown-group had started to diversify by the Early Triassic. © 2016 Thuy, Stöhr. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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