Ancestral state reconstruction reveals multiple independent evolution of diagnostic morphological characters in the "Higher Oribatida" (Acari), conflicting with current classification schemes

<p>Abstract</p> <p>Background</p> <p>The use of molecular genetic data in phylogenetic systematics has revolutionized this field of research in that several taxonomic groupings defined by traditional taxonomic approaches have been rejected by molecular data. The taxonomic classification of the oribatid mite group Circumdehiscentiae ("Higher Oribatida") is largely based on morphological characters and several different classification schemes, all based upon the validity of diagnostic morphological characters, have been proposed by various authors. The aims of this study were to test the appropriateness of the current taxonomic classification schemes for the Circumdehiscentiae and to trace the evolution of the main diagnostic traits (the four nymphal traits scalps, centrodorsal setae, sclerits and wrinkled cuticle plus octotaxic system and pteromorphs both in adults) on the basis of a molecular phylogenetic hypothesis by means of parsimony, likelihood and Bayesian approaches.</p> <p>Results</p> <p>The molecular phylogeny based on three nuclear markers (28S rDNA, <it>ef-1α</it>, <it>hsp82</it>) revealed considerable discrepancies to the traditional classification of the five "circumdehiscent" subdivisions, suggesting paraphyly of the three families Scutoverticidae, Ameronothridae, Cymbaeremaeidae and also of the genus <it>Achipteria</it>. Ancestral state reconstructions of six common diagnostic characters and statistical evaluation of alternative phylogenetic hypotheses also partially rejected the current morphology-based classification and suggested multiple convergent evolution (both gain and loss) of some traits, after a period of rapid cladogenesis, rendering several subgroups paraphyletic.</p> <p>Conclusions</p> <p>Phylogenetic studies revealed non-monophyly of three families and one genus as a result of a lack of adequate synapomorphic morphological characters, calling for further detailed investigations in a framework of integrative taxonomy. Character histories of six morphological traits indicate that their evolution followed a rather complex pattern of multiple independent gains (and losses). Thus, the observed pattern largely conflicts with current morphological classifications of the Circumdehiscentiae, suggesting that the current taxonomic classification schemes are not appropriate, apart from a recently proposed subdivision into 24 superfamilies.</p

Die Verteilung von Verfügungsrechten in italienischen Franchisenetzwerken

In dieser Arbeit wird versucht, sich dem Problem der Allokation von Entscheidungsrechte und Besitzansprüche in italienischen Franchise-Netzwerken aus property-rights-theoretischer Sicht zu nähern. Nach der Theorie der Verfügungsrechte soll die Verteilung residualer Entscheidungsrechte von der Verteilung der immateriellen Vermögensvorteile innerhalb des Netzwerkes abhängig gemacht werden. Je wichtiger die immateriellen Wissensressourcen der Akteure (hier Franchisegeber und Franchisenehmer) für das Erwirtschaften von residualem Einkommen sind, desto mehr Entscheidungsautonomie sollte ihnen zugesprochen werden. Durch diese property-rights-induzierte Sichtweise wird demnach auch die Dezentralisierung des Netzwerks bestimmt. In vorliegender Arbeit wird insbesondere anhand der Grundaussagen der Property-Rights und Principal-Agent-Theorie argumentiert, dass die Verteilung von Entscheidungskompetenzen vor allem von den nicht transferierbaren Wissensvorteilen der Vertragspartner abhängt. Dies wird im italienischen Sektor mit Zuhilfenahme eines Fragebogens empirisch getestet. Weiters wird überprüft, welche Anreizmechanismen in den italienischen Franchise-Organisationen installiert werden müssen, damit keiner der Parteien ein Nachteil widerfährt und das ökonomische Voranschreiten des Systems gesichert ist. Außerdem wird die duale Struktur von italienischen Franchise-Netzwerken anhand der Befragungsergebnisse durchleuchtet und mit Hilfe der verschiedenen neoinstitutionalistischen Theorien erklärt. Die Ergebnisse der empirischen Studie bestätigen die Hypothesen der Property Rights und erörtern den Systemzentralisierungsgrad in italienischen Franchise-Organisationen. Außerdem wird bestätigt, dass mit der Zuhilfenahme von Eigentumssurrogaten ein Ausgleichsverhältnis zwischen den Franchisenehmern und den Franchisegebern geschaffen wird, um franchisespezifische Probleme und Opportunismus der beiden Vertragspartner einzuschränken.This work offers a property rights explanation for the allocation of decision and ownership rights in Italian franchise networks. According to the property rights approach, the distribution of residual decision rights depends on the division of intangible knowledge assets within a system. Therefore, as the participants’ (i.e. franchisor and franchisee) immaterial knowledge resources increase in importance, their level of decision autonomy should strengthen accordingly. This perspective also determines the degree of decentralization of a network. In addition, the following work outlines the basic statements of the Property Rights and Principal-Agent theories, which argue that distribution of decision competence should be dependent on the non-transferable knowledge advantages of the contracting partners. The hypotheses are empirically tested in the Italian franchise sector with the help of an electronic enquiry. The results of the empirical study confirm both the hypotheses of the Property Rights and the degree of network (de)centralization in Italian franchise organizations. In addition, the dual structure of Italian franchise organizations is analyzed and explained using the various neo-institutionalistic theories of relevant literature. Incentive mechanisms (i.e. ownership surrogates) are also examined, as a way in which to ensure that none of the parties feel disadvantaged and that the economic progress of the system is secure. Furthermore it is confirmed that the adoption of ownership surrogates and franchise fees creates an equilibrium between the franchisor and the franchisee, allowing for the reduction of franchise-specific problems and of the creation of opportunism of the two parties

The intertidal Fortuyniidae (Acari: Oribatida): new species, morphological diversity, ecology and biogeography

Pfingstl, Tobias (2015): The intertidal Fortuyniidae (Acari: Oribatida): new species, morphological diversity, ecology and biogeography. Zootaxa 3957 (4): 351-382, DOI: http://dx.doi.org/10.11646/zootaxa.3957.4.

Revealing the diversity of a once small taxon: the genus Selenoribates (Acari, Oribatida, Selenoribatidae)

Three new intertidal oribatid species, Selenoribates elegans sp. n., Selenoribates quasimodo sp. n. and Selenoribates satanicus sp. n. are described from the archipelago of Bermuda. Selenoribates elegans sp. n. is characterized by its slender body shape, S. quasimodo sp. n. possesses a hunchback in lateral view and S. satanicus sp. n. exhibits two horn-like projections on its anterior gastronotic region. Based on these new findings, the number of Selenoribates species doubled at once and the distribution of this genus, formerly limited to the Mediterranean and the Red Sea, includes now occurrences in the Atlantic and Indo-pacific Ocean as well. The morphology of S. quasimodo sp. n. and S. satanicus sp. n. deviates conspicuously from the other known members of Selenoribates, thus indicating that not only the number of species but also the anatomy of this genus is more diverse than formerly supposed. Nymphs of S. quasimodo sp. n. show an interesting case of ontogenetic neotrichy, with gastronotic setae being duplicated with each moult

New littoral mite species (Acari, Oribatida, Fortuyniidae) from the Galápagos archipelago, with ecological and zoogeographical considerations

Pfingstl, Tobias, Schatz, Heinrich (2017): New littoral mite species (Acari, Oribatida, Fortuyniidae) from the Galápagos archipelago, with ecological and zoogeographical considerations. Zootaxa 4244 (1): 39-64, DOI: https://doi.org/10.11646/zootaxa.4244.1.

Claw shape variation in oribatid mites of the genera Carabodes and Caleremaeus: exploring the interplay of habitat, ecology and phylogenetics

Background Claws are a commonly observed biological adaptation across a wide range of animal groups. They serve different functions and their link to evolution is challenging to analyze. While there are many studies on the comparative anatomy and morphology of claws in reptiles, birds and several arthropods, knowledge about claws of soil-living oribatid mites, is still limited. Recent research on intertidal oribatid mites has shown that claw shape is strongly correlated with microhabitat and is subject to ecological selective pressures. However, the selective constraints shaping claws in terrestrial oribatid mites are still unknown. Methods In this study, 300 specimens from 12 different species and two genera were examined. Geometric morphometrics were used to quantify claw length and curvature, and to analyze two-dimensional claw shape. In combination with molecular phylogenetic analyses of investigated populations phylogenetic signal was quantified within genera using Blomberg’s K and random replicates. Additionally, ecological information on the investigated species was gathered from previous studies and compiled into tables. Results The claw shapes of Carabodes species vary moderately, with the three species C. reticulatus, C. rugosior and C. tenuis deviating the most from the others. These three species are only found in a small number of habitats, which may require a more specialized claw shape. Our results show that there is a phylogenetic influence on claw shape in Carabodes but not in Caleremaeus. Additionally, habitat specificity and lifestyle were found to have ecological impact on claw shape in both genera. The present results demonstrate that characteristics of the claws of terrestrial oribatid mites are correlated with ecology, but this correlation is apparently weaker than in intertidal oribatid mites that are prone to strong external forces