Evolution, turnovers and spatial variation of the gastropod fauna of the late Miocene biodiversity hotspot Lake Pannon

AbstractLake Pannon constituted the biggest hotspot of biodiversity in the late Cenozoic of Europe, comprising a total diversity of almost 600 gastropod species. The gastropod fauna of this huge brackish system, which existed over about seven million years from the late Miocene to earliest Pliocene within the Pannonian Basin System, has been well documented by a great many of taxonomic works. In contrast, the faunal development within the lake has not been properly addressed from a statistical point of view. The present investigation demonstrates that species were not homogeneously distributed across space and time, generating uneven and temporally shifting patterns of species richness and degree of point endemism across the lake. The faunal compositions of the time intervals analyzed were highly different, contrasting simple species accumulation as suggested by the overall numbers. Shifting patterns of local diversity within the lake reflect changing paleo-shorelines, resulting from prograding river systems entering and successively diminishing the lake surface area. As mainly herbivorous grazers and predominantly shallow-water inhabitants, the gastropods traced the moving shelf margins and vegetation belts accordingly, producing the observed diversity shifts. In addition, each time interval is characterized by a high degree of provincialism, which is considered to reflect high habitat diversity. This claim is supported by the complex subaqueous topography and the presence of extensive delta plains produced by the incoming river systems. A potential driver for provincialism might be the adaptation of species to distinct water depths (and related parameters). Finally, the notable differences among the faunal compositions of the upper Pannonian strata and the succeeding lower Viviparus beds, especially regarding family-level, indicate an environmental turnover at the transition. Brackish-water species are mostly replaced by typical freshwater elements, indicating strong fluvial influence. Based on our results and latest stratigraphic data, we conclude that the Viviparus beds were deposited in a different environment, replacing Lake Pannon in the southern Pannonian Basin in the early Pliocene

Holocene and Pleistocene gastropod biodiversity in European freshwater systems

Diese Arbeit gibt einen Einblick in die Entwicklung der Süßwassergastropoden-Vielfalt der europäischen kontinentalen Wassersysteme während des Neogens und Quartärs. Drei Hauptaspekte werden untersucht: 1) die Verteilung der Gastropoden in modernen Seen Europas, 2) die räumlichen und zeitlichen Muster der Arten im Quartär und 3) die Entwicklung von Artenreichtum-Hotspots während der letzten 23 Mill. Jahre.Insgesamt wurden 244 Arten von Süßwasserschnecken aus 898 Seen erfasst. Die Auswirkung von sieben Prädiktor-Variablen, nämlich Oberfläche, Längengrad und Breitengrad des Zentroids, Höhenlage und Isolation der Seen, jährlicher Niederschlag und Jahresmitteltemperatur, sowie der Einfluss der spätpleistozänen Deglaziation auf Artenreichtum wurden unter Verwendung von multiplen linearen Regressionsmodellen ausgewertet. Die Struktur der Beta-Diversität zwischen den Seen-Subsets mit verschiedener Deglaziationsgeschichte wurde ebenfalls untersucht. Die Ergebnisse zeigten, dass sowohl Artenreichtum als auch Beta-Diversität zum Teil durch Umweltfaktoren und Deglaziationsgeschichte erklärt werden. Innerhalb der Seen-Subsets wird die Artenzusammensetzung auch durch die beschränkte Ausbreitungsfähigkeit der Arten gesteuert. Die Verteilung der Gastropoden in den modernen europäischen Seen ist ein junges Muster. Seit dem Ende der letzten Eiszeit haben Gastropoden europäische Seen wiederbesiedelt ein Prozess, der noch immer im Gange ist.Für das Quartär wurden 398 Arten aus 1129 Lokalitäten erfasst. Arten und Lokalitäten wurden in sechs verschiedene Zeitintervalle unterteilt, nämlich Gelasium, Calabrium, Ionium, letztes Interglazial, letztes Glazial und Holozän; für die Auswertung des plio-pleistozänen Turnovers wurde auch das späte Pliozän miteinbezogen. Die Analysen von Artenreichtum und die Zusammensetzung und geographischen Reichweiten der Arten zeigten signifikante Unterschiede zwischen den Zeitintervallen. Lokalitäten des Gelasiums und Calabriums sind außerordentlich reich; der zeitliche Turnover ist besonders hoch zwischen Spät-Pliozän und Gelasium. Wie im Pliozän stammten auch früh-pleistozäne Arten noch Großteils aus langlebigen Seen, ein Resultat, das sich auch in den geringen biogeographischen Affinitäten zwischen den Lokalitäten widerspiegelt. Im Vergleich dazu sind wenige langlebige Seen aus dem Mittelpleistozän bis Holozän bekannt und die Arten sind meist aus kurzlebigen fluvialen und/oder lakustrine Systemen. Der zeitliche Turnover zwischen diesen Zeitintervallen ist niedriger und die Anzahl von Generalisten mit großen geografischen Reichweiten ist erhöht, was zu einem Verlust des für die neogenen und frühquartären Süßwassergastropoden-Faunen typischen provinziellen Charakters führte.Die Studie der miozänen bis heutigen Verteilungen von Süßwassergastropoden ergab, dass die Entwicklung von kontinentalen aquatischen Hotspots in Europa an seine geodynamische Geschichte geknüpft ist, die die Entstehung mehrerer langlebiger Seen mit diversen Faunen begünstigte. Regressionsanalysen zeigten ferner, dass Artenreichtum in langlebigen Seen mit wärmerem Klima und größerer Oberfläche ansteigt. Die prominentesten Hotspots des Neogens existierten im späten Miozän und Pliozän, inklusive des größten von allen, dem Pannon-See. Der Niedergang der meisten langlebigen Seen am Ende des Pliozäns und die quartären Vereisungenen trugen zum Verschwinden solcher Hotspots bei. Im heutigen Europa sind drei Gastropoden-Artenreichtums-Hotspots bekannt. Zwei von ihnen, das Kaspische Meer und der Ohrid-See, entwickelten sich in Becken, die während oder schon vor dem Pleistozän vorhanden waren. Der dritte Hotspot ist um die Ostsee gelegen und besteht aus geologisch jungen Seen und Süßwasserlagunen und resultiert wahrscheinlich aus konstanter Akkumulation von Arten durch Immigration seit der Deglaziation.This thesis provides insights into the evolution of freshwater gastropod diversity of European continental aquatic systems during the Neogene and Quaternary. Three main aspects are explored: 1) the distribution of gastropods in modern lakes of Europe, 2) the spatial and temporal patterns of species during the Quaternary and 3) the evolution of richness hotspots during the last 23 myr.In total, 244 species of freshwater gastropods have been recorded for 898 European lakes. The effect of seven predictor variables, i.e., surface area, longitude and latitude of lake centroid, lake altitude, lake isolation, annual precipitation and annual mean temperature, and the influence of Late Pleistocene deglaciation on species richness were evaluated using multiple linear regression models. Beta diversity patterns between lake subsets with different deglaciation history, as well as the influence of varied species dispersal abilities and environment factors on species composition within these subsets, were also investigated. The results indicated that both species richness and beta diversity are partly explained by environmental factors and deglaciation history. Within the lake subsets, species composition is also controlled by dispersal limitations of species. The distribution of gastropods in modern European lakes is a young pattern. Since the end of the last Ice Age gastropods have recolonized European lakes a process that is still ongoing.For the Quaternary, 398 species were recorded from the lacustrine and fluvio-lacustrine deposits of 1129 localities. Species and localities were separated into six distinct time intervals of the Quaternary, i.e., Gelasian, Calabrian, Ionian, Last Interglacial, Last Glacial and Holocene; for evaluation of the Plio-Pleistocene turnover the late Pliocene was included as well. Analyses of species richness, composition and geographical ranges revealed significant differences between the time intervals. Gelasian and Calabrian localities are exceptionally rich; the temporal turnover is high especially between the late Pliocene and the Gelasian. As for the Pliocene, early Pleistocene species still mostly derive from long-lived lakes, a result that is also reflected in the low biogeographical affinities of the localities. In comparison, few long-lived lakes are known for the Middle Pleistocene to Holocene and species derive mostly from short-lived fluvial and/or lacustrine systems. Temporal turnover between those time intervals is lower and the number of generalist species with wide geographical ranges is increased, resulting in the loss of the provincial character typical of the Neogene and Early Quaternary freshwater gastropod faunas.The study of Miocene to Recent freshwater gastropod distributions revealed that the evolution of continental aquatic hotspots of Europe is related to its geodynamic history that facilitated the formation of several long-lived lakes with diverse faunas. Regression analyses further showed that species richness in long-lived lakes increases with warmer climate and larger surface area. The most prominent hotspots of the Neogene existed in the Late Miocene and Pliocene, including the biggest of all, Lake Pannon. The demise of most long-lived lakes at the end of the Pliocene and Quaternary glaciations contributed to the disappearance of such hotspots. In present-day Europe three hotspots of gastropod species richness are recognized. Two of them, the Caspian Sea and Lake Ohrid, evolved in basins that were present already during or before the Pleistocene. The third hotspot is located around the Baltic Sea and consists of a series of geologically young lakes and freshwater lagoons and likely results from constant species accumulation by immigration since deglaciation.vorgelegt von MSc. Elisavet GeorgopoulouKumulative Dissertation aus 4 ArtikelnZusammenfassung in deutscher SpracheKarl-Franzens-Universität Graz, Dissertation, 2016OeBB(VLID)211697

Spatial analysis of the terrestrial mollusks of Crete

Στην παρούσα διατριβή γίνεται μία πρώτη προσέγγιση των πιθανών χωρικών προτύπων των χερσαίων σαλιγκαριών της Κρήτης. Διερευνήθηκαν οι πιθανές κατανομές 56 ειδών χερσαίων σαλιγκαριών της Κρήτης με τη χρήση της μεθόδου μέγιστης εντροπίας (MaxEnt). Το MaxEnt προβλέπει την πιθανή κατανομή ενός είδους σε μια συγκεκριμένη γεωγραφική περιοχή, με βάση τα γνωστά σημεία παρουσίας του είδους για ένα σύνολο επιλεγόμενων περιβαλλοντικών συνθηκών. Στο πλαίσιο αυτό, διερευνήθηκε ο ρόλος των περιβαλλοντικών παραμέτρων που επηρεάζουν την πιθανή κατανομή των χερσαίων σαλιγκαριών και αν σχηματίζονται ομάδες ειδών με παρόμοιες περιβαλλοντικές απαιτήσεις. Τα αποτελέσματα έδειξαν ότι για την πλειοψηφία των ειδών (35 από τα 56) σημαντικότερη συνεισφορά στην εξήγηση του μοντέλου της μέγιστης εντροπίας διαδραματίζουν παράγοντες που σχετίζονται με τη θερμοκρασία, τη βροχόπτωση και την κάλυψη γης. Επιπλέον, είδη με περιορισμένη κατανομή όπως το Albinaria eburnea έχουν υψηλότερες τιμές AUC (μεγαλύτερες του 0,8) ενώ αυτά που έχουν ευρύτερη εξάπλωση όπως το Cantareus aspersus έχουν χαμηλότερες τιμές AUC (μικρότερες του 0,7). Με τη χρήση απουσιών για τον υπολογισμό του δείκτη AUC, παρατηρείται βελτίωση της τιμής σε όλα τα είδη (53 είδη από τα 56 είχαν τιμές μεγαλύτερες του 0,75). Οι πιθανές κατανομές με βάση το μοντέλο μέγιστης εντροπίας είναι αρκετά ακριβείς όπως στα είδη Poiretia dilatata και Trochoidea sp. Παρόλα αυτά σε κάποιες περιπτώσεις, όπως στο είδος Metafruticicola dictaeus, το MaxEnt δεν λαμβάνει υπόψη τις ιστορικές αιτίες όπως η παλαιογεωγραφική ιστορία που φαίνεται να καθορίζει τα πρότυπα κατανομής κάποιων ειδών σαλιγκαριών.The current work is a first approach of the potential spatial distribution of the Cretan lands nails. The maximum entropy (MaxEnt) analysis was used to model the potential distributions of 56 land snail species. MaxEnt is a machine learning method that predicts the potential distribution of a target group over a geographical region from a sample of presence localities and a set of environmental data. The effect of the environmental parameters that were used to model the potential distribution of the species is explored. Results show that temperature contributes to the explanation of the potential distributions of 35 species, while two other important factors seem to be rainfall and land cover. Moreover, species with restricted distribution range like Albinaria eburnea, have higher AUC values (higher than 0.8), while species with a broader range like Cantareus aspersus have lower AUC values (lower than 0.7). The use of absences increases the AUC values (53 out of 56 species have values higher than 0.75). The potential distributions of most species like Poiretia dilatata και Trochoidea sp., are quite precise. Nevertheless, for some species like Metafruticicola dictaeus, MaxEnt does not take into account the historical reasons like the paleogeography of the study area, which are likely to affect the spatial distribution of the species

Nesting Habitat Selection and Breeding Distribution of Two Sympatric Insular Eagle Populations: The Golden Eagle and the Bonelli’s Eagle on the Island of Crete, Greece

In the current study we present data collected during the last two decades on the island of Crete (Greece) regarding the nesting habitat of two sympatric species namely the Golden Eagle (Aquila chrysaetos) and the Bonelli’s Eagle (Aquila fasciata). The factors that determine the species nest site selection were identified via a logistic regression model and nesting habitat suitability maps were constructed by using maximum entropy models and a Geographic Information System. At the spatial scale considered, the best predictors of nesting habitat were topographical variables such as altitude and slope indicative for the requirement of rugged terrain. The predictive maps represented by the subset of topographic variables were also able to predict nest-site selection by both species more adequately than subsets of bioclimatic or human disturbance variables. Based on the overlap of the available nesting habitat of the two eagle species, an ecological separation was detected most probably related to their diet spectrum and consequently foraging range. Compared to the Golden Eagle the Bonelli’s Eagle was found breeding on lower altitude, more often on sea cliffs or the ends of gorges and in the periphery of mountain areas. In the latter case human-induced mortality and land use changes are regarded as significant factors for the observed pattern

Land Snail Assemblages of Olive Orchards in Crete, Greece

Land snail biodiversity research in agroecosystems is limited, if non-existent. Here we investigate the land snail assemblages of olive orchards in Messara plain, Crete, Greece. Land snails were collected from 16 olive orchards. In addition, we performed a literature survey and recorded all species reported in the surrounding area. We found 18 species in the olive orchards among the 37 species found in the area and reported in the literature. Xerotricha conspurcata (Draparnaud, 1801) and Caracollina lenticula (Michaud, 1831) are reported for the first time in the study area. Their presence is probably a result of human-mediated dispersal. Olive orchards proved to be an important refuge for land snail diversity as they host 43% of the species found in the surrounding area. We highlight the importance of olive orchards as habitats with increased land snail richness. We suggest that land snails should be included in future biodiversity research in agricultural areas

Morphometrics data on Holocene Melanopsidae of Lake Petea

The dataset includes measurements of Microcolpia parreyssii parreyssii (Philippi, 1847) and Microcolpia parreyssii sikorai (Brusina, 1903) from Holocene deposits of Lake Petea near Oradea, Romania. Additionally, the tps-files generated with the program TpsDig2 and containing pairwise x,y-coordinates describing the outlines of the digitized images are supplied. Finally, the matrix of Fourier coefficients resulting from the Fast Fourier Transform is provided

Measurements of gastropods shell sizes from 23 fossil and extant long-lived lakes

Aim: To investigate shell size variation among gastropod faunas of fossil and recent long-lived European lakes and discuss potential underlying processes. Location: 23 long-lived lakes of the Miocene to Recent of Europe. Methods: Based on a dataset of 1412 species of both fossil and extant lacustrine gastropods, we assessed differences in shell size in terms of characteristics of the faunas (species richness, degree of endemism, differences in family composition) and the lakes (surface area, latitude and longitude of lake centroid, distance to closest neighbouring lake) using multiple and linear regression models. Because of a strong species-area relationship, we used resampling to determine whether any observed correlation is driven by that relationship. Results: The regression models indicated size range expansion rather than unidirectional increase or decrease as the dominant pattern of size evolution. The multiple regression models for size range and maximum and minimum size were statistically significant, while the model with mean size was not. Individual contributions and linear regressions indicated species richness and lake surface area as best predictors for size changes. Resampling analysis revealed no significant effects of species richness on the observed patterns. The correlations are comparable across families of different size classes, suggesting a general pattern. Main conclusions: Among the chosen variables, species richness and lake surface area are the most robust predictors of shell size in long-lived lake gastropods. Although the most outstanding and attractive examples for size evolution in lacustrine gastropods derive from lakes with extensive durations, shell size appears to be independent of the duration of the lake as well as longevity of a species. The analogue of long-lived lakes as 'evolutionary islands' does not hold for developments of shell size because different sets of parameters predict size changes