Received: 25 February 2018 / Accepted: 30 July 2018 / Published online: 25 February 2018
Two new bioluminescent Henlea from Siberia and lack of molecular support for Hepatogaster (Annelida, Clitellata, Enchytraeidae)Download PDFAbstract
Two bioluminescent enchytraeids, Henlea petushkovi sp. n. and Henlea rodionovae sp. n., are described from the Krasnoyarsk and Irkutsk regions in Eastern Siberia. These large potworms exhibit the typical light-production pattern reported repeatedly in the genus and recently elucidated by Russian researchers in its main biophysical and biochemical aspects. Morphology and DNA indicate that the two species are very closely related, but clearly divergent in the strength of the body wall (thick and opaque in H. petushkovi), structure of the prostomium (in H. rodionovae unprecedentedly wrinkled and mobile), brain shape (almost equilateral in H. petushkovi), size of coelomocytes (60–85 μm in H. petushkovi) and structure of intestinal diverticula (tulip-shaped in H. petushkovi, apple-shaped in H. rodionovae). Limited hybridization seems to occur between them, supported by a single case of conflict between COI and morphology, and a few intermediate morphotypes were noted in greenhouse populations. The new species are phylogenetically distant from all known congeners so far DNA-barcoded, even those that, like them, respond to the diagnosis of the putative subgenus Hepatogaster Čejka, 1910 (multitubular gut diverticula in VIII, indented brain, dorsal blood vessel from IX, prominent spermathecal glands, and nephridia from 5/6). In fact, our phylogenetic analyses dismiss Hepatogaster as an artificial (polyphyletic) taxon. Issues related to the definition of H. nasuta (Eisen, 1878), H. ochracea (Eisen, 1878) and H. irkutensis Burov, 1929, three species originally described from Siberia, indicate that Henlea taxonomy is still in a state of flux, as regards not only species interrelationships but also species definitions.
Received: 25 July 2017 / Accepted: 30 July 2018 / Published online: 25 July 2017
Morphological specificities of vendace (Salmoniformes: Salmonidae: Coregoninae: Coregonus albula) population in Lake Pleshcheyevo (the Volga River basin): relationships of two phylogenetic lineages in a new zone of secondary contactDownload PDFAbstract
This is the report about the secondary contact zone of coregonids in the Upper Volga basin. Two mitochondrial DNA (mtDNA) phylogenetic lineages of vendace Coregonus albula (Linnaeus, 1758) living in Lake Pleshcheyevo have been analyzed and compared in terms of morphological characters. These lineages have developed under the conditions of allopatry and are characterized by strong differences of the mitochondrial DNA sequences. The lineages have coexisted in the same lake since the last glaciation maximum (about 10,000 years ago). The morphological analysis has shown that representatives of both lineages correspond to C. albula, while slight, morphological variations between lineages indicate different food preferences and locomotor abilities. Scenarios where multiple distinct coexisting phylogenetic lineages are characterized by low levels of morpho-ecological divergence are uncommon. These situations are important for understanding biodiversity dynamics and the mechanisms that drive coexistence, adaptive divergence, hybridization, and extinction when genetically divergent lineages meet in secondary contact.
Received: 12 September 2017 / Accepted: 28 December 2017 / Published online: 12 September 2017
Worldwide sampling reveals low genetic variability in populations of the freshwater ciliate Paramecium biaurelia (P. aurelia species complex, Ciliophora, Protozoa)Download PDFAbstract
Species (or cryptic species) identification in microbial eukaryotes often requires a combined morphological and molecular approach, and if possible, mating reaction tests that confirm, for example, that distant populations are in fact one species. We used P. biaurelia (one of the 15 cryptic species of the P. aurelia complex) collected worldwide from 92 sampling points over 62 years and analyzed with the three above mentioned approaches as a model for testing protistan biogeography hypotheses. Our results indicated that despite the large distance between them, most of the studied populations of P. biaurelia do not differ from each other (rDNA fragment), or differ only slightly (COI mtDNA fragment). These results could suggest that in the past, the predecessors of the present P. biaurelia population experienced a bottleneck event, and that its current distribution is the result of recent dispersal by natural or anthropogenic factors. Another possible explanation for the low level of genetic diversity despite the huge distances between the collecting sites could be a slow rate of mutation of the studied DNA fragments, as has been found in some other species of the P. aurelia complex. COI haplotypes determined from samples obtained during field research conducted in 2015–2016 in 28 locations/374 sampling points in southern Poland were shared with other, often distant P. biaurelia populations. In the Kraków area, we found 5 of the 11 currently known COI P. biaurelia haplotypes. In 5 of 7 reservoirs from which P. biaurelia was obtained, two different COI haplotypes were identified.
Received: 07 December 2017 / Accepted: 17 June 2018 / Published online: 07 December 2017
Evolution of post-weaning skull ontogeny in New World opossums (Didelphidae)Download PDFAbstract
Quantification of mammalian skull development has received much attention in the recent literature. Previous results in different lineages have shown an effect of historical legacy on patterns of skull growth. In marsupials, the skull of adults exhibits high variation across species, principally along a size axis. The development keys of the marsupial skull are fundamental to understanding the evolution of skull function in this clade. Its generally well-resolved phylogeny makes the group ideal for studying macroevolution of skull ontogeny. Here, we tested the hypothesis that ontogenetic similarity is correlated with phylogeny in New World marsupials, so that developmental patterns are expected to be conserved from ancestral opossums. We concatenated our previously published ontogenetic cranial data from several opossum species with new ontogenetic sequences and constructed an allometric space on the basis of a set of comparable cranial linear measurements. In this ontogenetic space, we determined the degree of correspondence of developmental patterns and the phylogeny of the group. In addition, we mapped ontogenetic trajectories onto the opossum phylogeny, treating the trajectories as composite, continuously varying characters. Didelphids differed widely in the magnitude of skull allometry across species. Splanchnocranial components exhibited all possible patterns of inter-specific variation, whereas mandibular variables were predominantly allometrically “positive” and neurocranial components were predominantly allometrically “negative.” The distribution of species in allometric space reflected the compounded effect of phylogeny and size variation characteristic of didelphids. The terminal morphology of related species differed in shape, so their ontogenetic trajectories deviated with respect to that of reconstructed common ancestors in varying degree. Phylogeny was the main factor structuring the allometric space of New World marsupials. Didelphids inherited an ancestral constellation of allometry coefficients without change and retained much of it throughout their lineage history. Conserved allometric values on the nodes splitting placental outgroups and marsupials suggest a developmental basis common to all therians.
Correction to: Reconstructed historical distribution and phylogeography unravels non-steppic origin of Caucasotachea vindobonensis (Gastropoda: Helicidae)Download PDFAbstract
One of the author’s name of this article was incorrectly published as “Chris Wade”. This is now presented correctly in this article as “Christopher M. Wade”.
Correction to: Multiple origin of flightlessness in Phaneropterinae bushcrickets and redefinition of the tribus Odonturini (Orthoptera: Tettigonioidea: Phaneropteridae)Download PDFAbstract
The data in the Table 1 of the original version of this article were inadvertently shifted during the editing process. Therefore the entries as published in this table did not correspond to their correct data.
Received: 05 March 2017 / Accepted: 01 November 2017 / Published online: 05 March 2017
Diel behavior in moths and butterflies: a synthesis of data illuminates the evolution of temporal activityDownload PDFAbstract
Lepidoptera (butterflies and moths) are one of the most taxonomically diverse insect orders with nearly 160,000 described species. They have been studied extensively for centuries and are found on nearly all continents and in many environments. It is often assumed that adult butterflies are strictly diurnal and adult moths are strictly nocturnal, but there are many exceptions. Despite the broad interest in butterflies and moths, a comprehensive review of diel (day-night) activity has not been conducted. Here, we synthesize existing data on diel activity in Lepidoptera, trace its evolutionary history on a phylogeny, and show where gaps lie in our knowledge. Diurnality was likely the ancestral condition in Lepidoptera, the ancestral heteroneuran was likely nocturnal, and more than 40 transitions to diurnality subsequently occurred. Using species diversity estimates across the order, we predict that roughly 75-85% of Lepidoptera are nocturnal. We also define the three frequently used terms for activity in animals (diurnal, nocturnal, crepuscular), and show that literature on the activity of micro-moths is significantly lacking. Ecological factors leading to nocturnality/diurnality is a compelling area of research and should be the focus of future studies.
Received: 16 March 2018 / Accepted: 17 June 2018 / Published online: 16 March 2018
Multiple origin of flightlessness in Phaneropterinae bushcrickets and redefinition of the tribus Odonturini (Orthoptera: Tettigonioidea: Phaneropteridae)Download PDFAbstract
The possession of wings and ability to fly are a unifying character of higher insects, but secondary loss of wings is widespread. Within the bushcrickets, the subfamily Phaneropterinae (Orthoptera: Tettigonioidea) comprises more than 2000 predominantly long-winged species in the tropics. However, the roughly 300 European representatives are mainly short-winged. The systematics of these radiations have been unclear, leading to their unreliable formal treatment, which has hindered analysis of the evolutionary patterns of flight loss. A molecular phylogeny is presented for 42 short-winged species and members of all European long-winged genera based on the combined data from three nuclear gene sequences (18S, H3, ITS2). We found four phylogenetic lineages: (i) the first included the short-wing species of the genus Odontura; (ii) a further branch is represented by the South-American short-winged Cohnia andeana; (iii) an assemblage of long-wing taxa with a deep branching pattern includes the members of the tribes Acrometopini, Ducetiini, Phaneropterini, and Tylopsidini; (iv) a large group contained all short-winged taxa of the tribe Barbitistini. Phaneropterinae flightlessness originated twice in the Western Palaearctic, with a number of mainly allo- and parapatrically distributed species of the Barbistini in Southeastern Europe, and the Middle East and a limited number of Odontura species in Northern Africa and Southwestern Europe. Both short-winged lineages are well separated, which makes it necessary to restrict the tribe Odonturini to the West-Palaearctic genus Odontura. Other flightless genera previously included in the Odonturini are placed as incertae sedis until their phylogenetic position can be established.
Received: 06 December 2017 / Accepted: 24 May 2018 / Published online: 06 December 2017
Increased taxon sampling provides new insights into the phylogeny and evolution of the subclass Calcaronea (Porifera, Calcarea)Download PDFAbstract
Calcaronean sponges are acknowledged to be taxonomically difficult, and generally, molecular data does not support the current morphology-based classification. In addition, molecular markers that have been successfully employed in other sponge taxa (e.g., COI mtDNA) have proven challenging to amplify due to the characteristics of calcarean mitochondrial genomes. A short fragment of the 28S rRNA gene (C-region) was recently proposed as the most phylogenetically informative marker to be used as a DNA barcode for calcareous sponges. In this study, the C-region and a fragment of the 18S rRNA gene were sequenced for a wide range of calcareous taxa, mainly from the subclass Calcaronea. The resulting dataset includes the most comprehensive taxon sampling of Calcaronea to date, and the inclusion of multiple specimens per species allowed us to evaluate the performance of both markers, as barcoding markers. 18S proved to be highly conserved within Calcaronea and does not have sufficient signal to resolve phylogenetic relationships within the subclass. Although the C-region does not exhibit a “proper” barcoding gap, it provides good phylogenetic resolution for calcaronean sponges. The resulting phylogeny supports previous findings that the current classification of the subclass Calcaronea is highly artificial, and with high levels of homoplasy. Furthermore, the close relationship between the order Baerida and the genus Achramorpha suggest that the order Baerida should be abandoned. Although the C-region currently represents the best available marker for phylogenetic and barcoding studies in Calcaronea, it is necessary to develop additional molecular markers to improve the classification within this subclass.
Received: 17 March 2017 / Accepted: 01 November 2017 / Published online: 17 March 2017
The cephalic morphology of free-living and cave-dwelling species of trechine ground beetles from China (Coleoptera, Carabidae)Download PDFAbstract
Morphological adaptations of cave-dwelling organisms including different groups of Coleoptera have fascinated researchers since a long time. Nevertheless, very few detailed documentations of the anatomy of cave beetles using modern techniques are available. In this study, we describe and illustrate external and internal cephalic features of free-living and cave-dwelling trechine carabid beetles using digital microscopy, SEM, micro-CT, and computer-based 3D reconstruction. Morphological characteristics found in three selected species with different habitat preferences are compared. The following derived features distinguish a troglobite species (Sinaphaenops wangorum Ueno et Ran 1998) from a species living in the entrance of caves (Trechiotes perroti Jeannel 1954) and from a fully epigean species (Bembidion sp.): (1) the optic lobes are completely missing; (2) the head capsule, mouth parts, and antennae are distinctly elongated; (3) some muscle attachment areas are shifted; and (4) an additional dilator of the pharynx is present. Despite of conspicuous differences likely related with subterranean habits, the link of some cephalic features to this specific habitat preference remains uncertain.
Received: 28 February 2018 / Accepted: 16 August 2018 / Published online: 28 February 2018
The biogeography of non-marine molluscs in the Tuscan Archipelago reveals combined effects of current eco-geographical drivers and paleogeographyDownload PDFAbstract
We investigated the role of present (Recent) and historical (Pleistocene, i.e., Würmian Last Glacial Maximum) eco-geographical variables on the richness and diversity of non-marine molluscs in the Tuscan Archipelago, as well as inter-island faunal dissimilarity and relationships with source pools (Sardinia and Corsica, Tuscany). The association between species richness and present and historical eco-geographical variables were assessed with Spearman’s rank correlation test, while faunal dissimilarity both between islands and with their source pools was analyzed through beta-diversity partitioning (Sørensen index and its nestedness and turnover component) with UPGMA clustering tested with a multiscale bootstrap procedure. Non-metric multidimensional scaling in RGB color space was also used. Multiple regressions on distance matrices were then applied to explain assemblage composition between islands. Analyses were performed on all species and on all species except aliens. The overall framework showed the combined effects of current eco-geographical and paleogeographical imprints on non-marine malacofauna in the Tuscan Archipelago. However, excluding aliens, differences in species spatial turnover showed a clear correlation with Pleistocene inter-island distances, evidence of stronger historical biogeographical relationships between islands. This may indicate that widespread native species established their distribution during the Pleistocene, while alien species spread into the Tuscan Archipelago through stochastic and human-mediated dispersion events in recent times. Interestingly, Giglio’s relationships do not agree with the most accepted paleogeographical model, suggesting that this island might have been connected to the Tuscan mainland during the Würmian Last Glacial Maximum. An in-depth revision of the paleogeographic framework of the northern Tyrrhenian is therefore called for.
Received: 06 June 2017 / Accepted: 28 December 2017 / Published online: 06 June 2017
Species tree phylogeny, character evolution, and biogeography of the Patagonian genus Anarthrophyllum Benth. (Fabaceae)Download PDFAbstract
Geologic events promoting the aridization of southern South America contributed to lineage divergences and species differentiation through geographic (allopatric divergence) and biotic and abiotic factors (ecological divergence). For the genus Anarthrophyllum, which is distributed in arid and semi-arid regions of Patagonia, we assessed how these factors affected species diversification and reconstructed its possible biogeographic history in South American arid environments. Sequences were obtained from two molecular markers: the ITS nuclear region and the trnS-trnG plastid region. Using Parsimony, Maximum likelihood and Bayesian inference individual gene trees were reconstructed, and a species tree was obtained using multi-species coalescent analysis. Divergence times among species were estimated using secondary calibrations. Flexible Bayesian models and stochastic character mapping were used to elucidate ancestral geographic distributions and the evolution of the floral and vegetative phenotypes in the genus. Gene trees and species tree analyses strongly support Anarthrophyllum as monophyletic; all analyses consistently retrieved three well-supported main clades: High Andean Clade, Patagonian Clade 1, and Patagonian Clade 2. Main diversification events occurred concomitant with the Andean uplift and steppe aridization; the Andean mountain range possibly acted as a species barrier for the High Andean Clade. Vegetative traits showed adaptations to harsh climates in some clades, while pollinator-related floral features were associated with independent diversification in bee- and bird-pollinated clades within both Patagonian Clades. In conclusion, evolutionary and biogeographic history of Anarthrophyllum resulted from the action of ecological, historical, and geographic factors that acted either alternatively or simultaneously.
Received: 21 December 2017 / Accepted: 16 August 2018 / Published online: 21 December 2017
Anatomy of the Tantulocarida: first results obtained using TEM and CLSM. Part I: tantulus larvaDownload PDFAbstract
The morphology of Tantulocarida, a group of minutely sized ectoparasitic Crustacea, is described here using for the first time transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). This enabled a detailed analysis of their internal anatomy to a level of detail not possible with previous light microscopic investigations. We studied the infective stage, the tantulus larva, attached on the crustacean host in two species, Arcticotantulus pertzovi and Microdajus tchesunovi, and put special emphasis on cuticular structures, muscles, adhesive glands used in attachment, sensory and nervous systems, and on the organs used in obtaining nutrients from the host. This allowed description of structures that have remained enigmatic or unknown until now. A doubly folded cuticular attachment disc is located at the anterior-ventral part of the cephalon and used for gluing the larva to the host surface with a cement substance released under the disc. Four cuticular canals run from a cement gland, located ventrally in the cephalon, and enter an unpaired, cuticular proboscis. The proboscis can be protruded outside through a separate opening above the mouth and is used for releasing cement. An unpaired and anteriorly completely solid cuticular stylet is located centrally in the cephalon and is used only for making a 1-μm-diameter hole in the host cuticle, through which passes a rootlet system used for obtaining nutrients. The rootlet system is a direct extension of the anterior gut of the tantulus, but inside the host, it consists of cuticle only. Several muscular systems seem to degenerate very quickly after the tantulus has settled on the host. The central nervous system is reduced to an absolute minimum in terms of both cell size and number. We discuss the morphology of the tantulus in light of the Tantulocarida being a sister group to the Thecostraca or even nested within that taxon.
Received: 10 November 2017 / Accepted: 26 January 2018 / Published online: 10 November 2017
Do we similarly assess diversity with microscopy and high-throughput sequencing? Case of microalgae in lakesDownload PDFAbstract
Diatoms are a species-diverse phylum of microalgae often presenting high biomass in aquatic habitats. This makes them excellent ecological indicators in rivers and lakes. They are routinely used to assess ecological quality of rivers and lakes using microscopy, which is time consuming. An alternative is to determine species in samples based on short DNA barcodes and high-throughput sequencing (HTS). Former studies showed that community structure and water quality assessments based on diatoms deliver similar results with both methods. But, none evaluated if diversities were assessed in the same way despite the importance of this ecological metric. Based on littoral benthic samplings carried out in 56 pristine alpine lakes, we compared different diversity indices measured with microscopy and metabarcoding. Each lake was sampled in three different places of its littoral. We showed that α (diversity measured in a single sampling site of a given lake) and ϒ (total diversity in a lake where three independent samples were considered) diversities obtained with HTS were higher than those obtained with microscopy. This may be explained by the capacity of HTS to detect morphologically cryptic species and to better detect rare taxa. On the other hand, β diversity obtained with HTS was smaller, which may be explained by the capacity of HTS to detect very rare species and free-floating extracellular DNA. Nevertheless, diversity indices obtained with both methodologies were well correlated each other. This study validates the possibility to assess diatom diversity with HTS in a comparable way to the classical microscopic analysis.
Received: 20 July 2017 / Accepted: 22 April 2018 / Published online: 20 July 2017
Further progress towards the delimitation of Cheilanthes (Cheilanthoideae, Pteridaceae), with emphasis on South American speciesDownload PDFAbstract
Cheilanthoid ferns (Cheilanthoideae sensu PPG 1 2016) constitute an important group within the Pteridaceae and are cosmopolitan in distribution. In South America, there are 155 species distributed in 13 genera, among which the largest are Adiantopsis (35), Cheilanthes (27), and Doryopteris (22). Most of the cheilanthoid species are morphologically adapted to grow in arid to semi-arid conditions and show convergent evolution, which has implied difficulties in defining the genera throughout their taxonomic history (Copeland 1947, Tryon & Tryon 1973, Gastony & Rollo 1995, 1998, Kirkpatrick Systematic Botany, 32: 504–518, 2007, Rothfels et al. Taxon, 57: 712–724, 2008). Here, we sequenced two plastid markers (rbcL + trnL-F) of 33 South American cheilanthoid species, most of which have not been included in phylogenetic analyses previously. The South American species were analyzed together with South African and Australasian Cheilanthes and representatives of related cheilanthoid genera. The phylogenetic analysis showed that most Cheilanthes species are related to the genus Hemionitis, constituting different groups according to their distribution; moreover, three species—C. hassleri, C. pantanalensis, and C. obducta—appear as the sister clade of Hemionitis. Cheilanthes micropteris, the type species, is strongly supported in a clade with Australasian Cheilanthes plus five South American Cheilanthes species, all of which show a reduction in the number of spores per sporangium; this feature would be a synapomorphy for core Cheilanthes s.s. We found no support uniting other South American Cheilanthes to either the group of South African Cheilanthes or to core Cheilanthes s.s. On the other hand, C. geraniifolia, C. goyazensis, and C. bradei formed a clade related to Doryopteris that, with further study, could be considered as a new genus. The phylogenetic hypotheses presented here contribute substantially to the delimitation of Cheilanthes s.s. and related groups and provide the basis for re-examining the generic taxonomy.
Received: 05 May 2018 / Accepted: 11 October 2018 / Published online: 05 May 2018
Cladogenesis and reticulation in Cuscuta sect. Denticulatae (Convolvulaceae)Download PDFAbstract
As traditionally circumscribed, Cuscuta sect. Denticulatae is a group of three parasitic plant species native to the deserts of Western USA (Cuscuta denticulata, Cuscuta nevadensis) and the central region of Baja California, Mexico (Cuscuta veatchii). Molecular phylogenetic studies confirmed the monophyly of this group and suggested that the disjunct C. veatchii is a hybrid between the other two species. However, the limited sampling left the possibility of alternative biological and methodological explanations. We expanded our sampling to multiple individuals of all the species collected from across their entire geographical ranges. Sequence data from the nuclear and plastid regions were used to reconstruct the phylogeny and find out if the topological conflict was maintained. We obtained karyotype information from multiple individuals, investigated the morphological variation of the group thorough morphometric analyses, and compiled data on ecology, host range, and geographical distribution. Our results confirmed that C. veatchii is an allotetraploid. Furthermore, we found previously unknown autotetraploid population of C. denticulata, and we describe a new hybrid species, Cuscuta psorothamnensis. We suggest that this newly discovered natural hybrid is resulting from an independent (and probably more recent) hybridization event between the same diploid parental species as those of C. veatchii. All the polyploids showed host shift associated with hybridization and/or polyploidy and are found growing on hosts that are rarely or never frequented by their diploid progenitors. The great potential of this group as a model to study host shift in parasitic plants associated with recurrent allopolyploidy is discussed.
Received: 25 September 2017 / Accepted: 03 April 2018 / Published online: 25 September 2017
Ecological and evolutionary diversification in the Australo-Papuan scrubwrens (Sericornis) and mouse-warblers (Crateroscelis), with a revision of the subfamily Sericornithinae (Aves: Passeriformes: Acanthizidae)Download PDFAbstract
Understanding how the complex geotectonic and climatic history of the Australo-Papuan region has promoted the ecological and evolutionary diversification of its avifauna remains a challenge. Outstanding questions relate to the nature and timing of biogeographical connections between Australia and the emerging island of New Guinea and the mechanisms by which distinctive altitudinal replacement sequences have evolved amongst congeneric species in montane New Guinea. Here, we combine analyses of phylogenetic and eco-morphological data to investigate ecological and evolutionary patterns of diversification in the largely mesic-adapted Australo-Papuan scrubwrens (Sericornis) and mouse-warblers (Crateroscelis). We find evidence of ecological convergence and present a revised taxonomic and systematic treatment of the subfamily integrating information from new (ND2) and existing molecular phylogenetic reconstructions. Biogeographical connections indicate at least three phases of faunal interchange between Australia and New Guinea commencing in the mid to late Miocene. We also find little support for the proposed time dependency of ecological sorting mechanisms linked to divergence in foraging niche amongst altitudinal replacements. Instead, physiological adaptations to hypoxia and increased thermal efficiency at higher altitudes may better account for observed patterns of diversification in montane New Guinea. Indirect support for this hypothesis is derived from molecular clock calibrations that indicate a pulse of diversification across the Miocene-Pliocene boundary coincident with a phase of rapid mountain uplift. Simple ecological and climatic models appear inadequate for explaining observed patterns and mechanisms of diversification in the New Guinean montane avifauna. Further insights will require multidisciplinary research integrating geotectonic, palaeoclimatic, genetic, ecological and physiological approaches.
Received: 28 October 2015 / Accepted: 25 January 2016 / Published online: 28 October 2015
Same same but different: a stunning analogy between tracheal and vascular supply in the CNS of different arachnidsDownload PDFAbstract
Described herein is an as yet unprecedented structural and functional analogy of both the tracheal supply of the prosomal ganglion in opilionids and the arterial supply of the prosomal ganglion in pulmonate arachnids. Within Arachnida, two different modes of respiration can be observed: the so-called book lungs, and the tube-like tracheae. These different respiratory modes always correlate with a specific setup concerning the complexity of the circulatory system. This fact has a particular influence on the supply of certain organ systems, such as the central nervous system. It has recently been shown that pulmonate arachnids possess a highly complex pattern of intraganglionic arteries. Here, we show that Opiliones (harvestmen) possess a complex tracheal system (which supplies the different organ systems with oxygen) and only a relatively simple vascular system, comprising a short heart and an anterior aorta that runs directly to the prosomal ganglion. Using a variety of modern and classical morphological methods, we studied the vascular, tracheal and nervous systems of different representatives from all higher taxa of Opiliones. We show that the prosomal ganglion is extensively supplied with intraganglionic tracheae. What is especially surprising is the high degree of correspondence between the pattern of these ganglionic tracheae in harvestmen and the pattern of arteries in the prosomal ganglion of pulmonate arachnids. We aim to provide mechanistic causal explanations of these analogous patterns by applying the concepts of role analogy and constructional analogy. We also aim to establish the circulatory system as a model organ system and hope that this may, in turn, provide a starting point for future research programmes.
Received: 19 June 2017 / Accepted: 09 May 2018 / Published online: 19 June 2017
Evolutionary pattern of the forewing shape in the Neotropical genus of jumping plant-lice (Hemiptera: Psylloidea: Russelliana)Download PDFAbstract
Geometric morphometric and phylogenetic analyses, applied to 43 species of Russelliana, shed light on the evolution of insect wing shape. Unconstrained and constrained ordination techniques are introduced to detect patterns of the forewing shape variation within genus. Results show a high congruence between forewing shape variation and host-plant preference supporting monophyly of most phylogenetic groups in Russelliana. Reconstruction of the ancestral forewing state shows its similarity to a forewing shape of Solanaceae feeding species defined as ancestors by the phylogenetic study supporting a hypothesis as to a primary association of Russelliana with Solanaceae. In contrast to some other comparative studies on insect wing shape, results of the present study reveal a strong correlation between variation of forewing shape in Russelliana and its phylogeny. Potential influence of vicariant events and host shifts on the evolution of forewing shape is discussed.
Received: 15 December 2017 / Accepted: 09 March 2018 / Published online: 15 December 2017
A review of the palm genus Acrocomia: Neotropical green goldDownload PDFAbstract
The genus Acrocomia, popularly known as macaw palm or macaúba, occurs in savanna areas and open forests of tropical America, with distribution from Central to southern South America. They are important oleaginous palm trees, due to their role in ecosystems and local economies and their potential for biofuel production and vegetable oil. Although the taxonomy of the genus is not resolved because of observed phenotypic diversity in A. aculeata (Jacq.) Lodd. ex Mart., there are several conflicting treatments. Some authors recognize three caulescent spp. occurring in South America: A. aculeata, A. intumescens Drude, and A. totai Mart, although a new one was described recently—Acrocomia corumbaensis. Because some Latin American governments want to expand production of macaw palm in their territory as raw material for agro-energy, several groups have been encouraged to study this genus, focusing on the production of biodiesel, seed germination, phenotypic aspects, and genetic diversity. The goal of this review is to compile key information available in the literature and herbarium data, focusing on South American populations of the genus.
Received: 28 July 2017 / Accepted: 26 October 2017 / Published online: 28 July 2017
Absence of co-phylogeny indicates repeated diatom capture in dinophytes hosting a tertiary endosymbiontDownload PDFAbstract
Tertiary endosymbiosis is proven through dinophytes, some of which (i.e. Kryptoperidiniaceae) have engulfed diatom algae containing a secondary plastid. Chloroplasts are usually inherited together permanently with the host cell, leading to co-phylogeny. We compiled a diatom sequence data matrix of two nuclear and two chloroplast loci. Almost all endosymbionts of Kryptoperidiniaceae found their closest relatives in free-living diatoms and not in other harboured algae, rejecting co-phylogeny and indicating that resident diatoms were taken up by dinophytes multiple times independently. Almost intact ultrastructure and insignificant genome reduction are supportive for young, if not recent events of diatom capture. With their selective specificity on the one hand and extraordinary degree of endosymbiotic flexibility on the other hand, dinophytes hosting diatoms share more traits with lichens or facultatively phototrophic ciliates than with green algae and land plants. Time estimates indicate the dinophyte lineages as consistently older than the hosted diatom lineages, thus also favouring a repeated uptake of endosymbionts. The complex ecological role of dinophytes employing a variety of organismic interactions may explain their high potential and plasticity in acquiring a great diversity of plastids.
Received: 19 March 2018 / Accepted: 18 August 2018 / Published online: 19 March 2018
Immediate and heritable costs of desiccation on the life history of the bdelloid rotifer Philodina roseola
The long-term persistence of the ‘ancient asexual’ bdelloid rotifers, a clade of small aquatic invertebrates, is often tied to their ability to enter anhydrobiosis. This ability has both clear benefits (e.g. survival of desiccating conditions), but offers considerable costs (e.g. subsequent repair of the genome as well as physiological and metabolic costs to re-establish the phenotype). Despite these costs, several studies show that the time spent dry is effectively ignored with respect to life expectancy (the Sleeping Beauty hypothesis) and that reconstruction of the genome after a desiccation event might even be necessary to repair mistakes accumulated in it from obligate parthenogenesis while the animals were active. We propose that this genomic repair might not derive exclusively because desiccation per se, but could also result from genetic exchange that appears to occur between individuals during this time. By comparing individuals of Philodina roseola Ehrenberg, 1832 desiccated in groups versus individually, we document costs to desiccation in the isolated treatment group that impact negatively on lifespan and reproduction. In addition, comparing both groups with continuously active individuals reveals no strong evidence for the Sleeping Beauty hypothesis in this species nor any decline in fitness over a six-month period for the latter group. Finally, many treatment effects are at least partly heritable and were found in the untreated F1 generations. In particular, individuals desiccated in groups and their offspring could both reproduce faster than the offspring of continuously active individuals. Thus, our results offer additional support for the hypothesis of genetic exchange occurring during desiccation events in P. roseola and highlight the importance of considering this factor, and desiccation in general, in explaining bdelloid fitness. Moreover, our results provide additional context for understanding how the genetic information of bdelloids is ultimately shaped.
Received: 12 October 2017 / Accepted: 22 April 2018 / Published online: 12 October 2017
Genome size of chrysophytes varies with cell size and nutritional modeDownload PDFAbstract
The cellular content of nuclear DNA varies up to 200,000-fold between eukaryotes. These differences can arise via different mechanisms. In particular, cell size and nutritional mode may influence evolution of the nuclear DNA content. Chrysophytes comprise organisms with different cell organizations and nutritional modes. Heterotrophic clades evolved independently several times from phototrophic or mixotrophic ancestors. Thus, chrysophytes are an ideal model taxon for investigating the effect of the nutritional mode on cellular DNA content. We investigated the genome size of heterotrophic, mixotrophic, and phototrophic chrysophytes. We demonstrate that cell sizes and genome sizes differ significantly between taxa with different nutritional modes. Phototrophic strains tend to have larger cell volumes and larger genomes than heterotrophic strains do. The investigated mixotrophic strains had intermediate cell volumes and small to intermediate genome sizes. Heterotrophic chrysophytes had the smallest genomes and cell volumes compared to other chrysophytes. In general, genome size increased with cell volume, but cell volume only partially explained the variation in genome size. In particular, genome sizes of mixotrophic strains were smaller than expected based on cell sizes.
Received: 02 March 2018 / Accepted: 30 July 2018 / Published online: 02 March 2018
Do Antarctic populations represent local or widespread phylogenetic and ecological lineages? Complicated fate of bipolar moss concepts with Drepanocladus longifolius as a case studyDownload PDFAbstract
Bipolar moss species, extreme examples of large and disjunctive geographical ranges, belong to the most important components of the vegetation cover in Antarctica. Their appropriate taxonomic interpretations are essential for fine-scale biogeographical considerations but our knowledge on their phylogenetic affinities still remains limited. Here, we address the history of the Antarctic populations of Drepanocladus longifolius, a moss species widely considered a bipolar taxon. First, based on a worldwide sampling, we verify its assumed bipolar status. Then, we ask whether its current Antarctic populations have persisted throughout at least the last major glaciation in situ or, alternatively, are they a recent, postglacial element. Phylogenetic analyses together with investigation of morphological characters were used to infer relationships among accessions representing the whole distribution range of the taxon. Morphological and phylogenetic data strictly segregated specimens from the Southern and the Northern Hemisphere, with an exception of Australian populations that were included in the latter group. The Antarctic, sub-Antarctic and South American populations belong to a single clade and are treated as D. longifolius s. str., which consequently is not a bipolar taxon. All Northern Hemisphere populations and the ones from Australia represent D. capillifolius, a lately neglected taxon, which thus displays a true bipolar distribution pattern but not comprising the Antarctic and South American populations. These results provide a sound example of key importance of a detailed taxonomical and phylogenetic treatment as a basis for biogeographical studies. In D. longifolius s. str., a homogeneity in all non-coding nuclear and plastid regions was observed throughout the whole range. It contrasted with the presence of one missense mutation in the rps4 gene in all examined Antarctic populations, which correlated with their distinct ecological situation. While identity of non-coding sequences in D. longifolius populations indicates a postglacial recruitment of extant Antarctic populations from extra-regional locations rather than a long-term in situ survival, the mutation in the rps4 gene may be hypothesised to reflect an adaptive response of plants to the Antarctic environment.
Received: 02 June 2017 / Accepted: 26 October 2017 / Published online: 02 June 2017
When dwarf males and hermaphrodites copulate: first record of mating behaviour in a dwarf male using the androdioecious barnacle Scalpellum scalpellum (Crustacea: Cirripedia: Thoracica)Download PDFAbstract
Mating behaviour between a dwarf male and its hermaphrodite partner was observed for the first time in cirripedes using the androdioecious barnacle Scalpellum scalpellum. Mating between hermaphrodites was also observed. The dwarf males are located on the rim of the mantle cavity of the hermaphrodite partner. When mating, the male extends the penis, which is four times longer than its body. The penis first assumes a straight stance where it is waved around in a searching mode. Upon touching the cirri of the hermaphrodite, the penis and the cirri engage in prolonged contact during which hermaphrodite feeding is suspended. Thereafter the penis assumes a U-bend to reach into the brood chamber, where after the mantle valves are closed tightly around the penis. The nearly transparent penis is a tube of very thin cuticle, equipped with pairs of side branches but not containing any visible tissue. The penis enables the minute male, situated outside the brood chamber, to securely deposit sperm into its partner. Adjacently situated hermaphrodites interact socially in between feeding sessions by reorienting themselves on the peduncle to touch each other with their cirri. This can be followed by precopulatory behaviour, where one or both individuals extend the penis to touch their partner, leading again to actual copulation where the penis of one individual is inserted into the other. We discuss the results in the context of the diverse reproductive strategies found in cirripede barnacles.
Received: 21 July 2017 / Accepted: 12 December 2017 / Published online: 21 July 2017
Phylogeography of the Ibero-Maghrebian red-eyed grass snake (Natrix astreptophora)Download PDFAbstract
We examined phylogeographic differentiation of the red-eyed grass snake (Natrix astreptophora) using 1984 bp of mtDNA and 13 microsatellite loci from specimens collected across its distribution range in southwestern Europe and northwestern Africa. Based on phylogenetic analyses of mtDNA, European N. astreptophora constituted the sister clade to a weakly supported North African clade comprised of two deeply divergent and well-supported clades, one corresponding to Moroccan snakes and the other to snakes from Algeria and Tunisia. This tripartite differentiation was confirmed by analyses of microsatellite loci. According to a fossil-calibrated molecular clock, European and North African N. astreptophora diverged 5.44 million years ago (mya), and the two Maghrebian clades split 4.64 mya. These dates suggest that the radiation of the three clades was initiated by the environmental changes related to the Messinian Salinity Crisis and the reflooding of the Mediterranean Basin. The differentiation of N. astreptophora, with distinct clades in the Iberian Peninsula and in the western and eastern Maghreb, corresponds to a general phylogeographic paradigm and resembles the differentiation found in another co-distributed Natrix species, the viperine snake (N. maura). Despite both species being good swimmers, the Strait of Gibraltar constitutes a significant biogeographic barrier for them. The discovery that North Africa harbours two endemic lineages of N. astreptophora necessitates more conservation efforts for these imperilled snakes.
Received: 23 March 2018 / Accepted: 20 September 2018 / Published online: 23 March 2018
An integrative approach in the assessment of species delimitation and structure of the Merodon nanus species group (Diptera: Syrphidae)Download PDFAbstract
The Merodon nanus group (Diptera, Syrphidae) is a small group of closely related species with high morphological similarity. Until now, based on morphological characters, this group consisted of five species: M. nanus Sack, 1931; M. telmateia Hurkmans, 1987; M. kopensis Vujić et Hayat, 2015; M. neonanus Vujić et Taylor, 2015; and M. rasicus Vujić et Radenković, 2015. Here, using an integrative approach based on molecular characters (sequences of the D2–3 region of the nuclear 28S rRNA gene and the mitochondrial COI gene) and data obtained from geometric morphometry of wing shape, we distinguish all five previously morphologically defined species of the group. Additionally, we identify one species as being new to science, M. vladimiri Vujić et Kočiš Tubić sp. n. We emphasize the separation of this newly described species according to the sequences obtained from the slowly evolving 28S rRNA gene, which demonstrated four to five mutation positions between this species and morphologically the most similar M. neonanus species. Also, our results show a clear division of M. telmateia into at least three population groups that we designate as the subspecies: M. telmateia mediterraneus Ačanski et Kočiš Tubić subsp. n. and M. telmateia samosensis Ačanski et Kočiš Tubić subsp. n. exhibiting western distributions (western Anatolia and the Greek island of Samos, respectively) and the nominative subspecies M. telmateia telmateia with an eastern Anatolian distribution.
Received: 01 December 2017 / Accepted: 30 July 2018 / Published online: 01 December 2017
Time-calibrated molecular phylogeny reveals a Miocene–Pliocene diversification in the Amazon miniature killifish genus Fluviphylax (Cyprinodontiformes: Cyprinodontoidei)Download PDFAbstract
Species of Fluviphylax are widely distributed over the Amazon and Orinoco river drainages and are among the smallest fish in the neotropics, inhabiting areas near the margin of slow-flowing clear and black water streams and lakes. Here, we present the first multigene molecular phylogeny of Fluviphylax, including all five nominal species of Fluviphylax and three undescribed species. The analysis included fragments of one mitochondrial and five nuclear genes, totaling 5880 bp. The dataset was analyzed using maximum parsimony, maximum likelihood, and Bayesian inference approaches providing high-supported well-solved trees. A time-calibrated analysis was performed providing information on the origin and diversification of the miniature genus in the Amazon. We estimate that Fluviphylax lineage splits from its sister group, the Anablepidae and Poeciliidae (Poeciliinae sensu Parenti, 1981), during the Late Eocene, about 36.6 Mya; but lineage diversification started only in the Middle Miocene, about 16 Mya, during the formation of the Pebas system. Subsequent splits within Fluviphylax occurred in the Late Miocene–Pliocene, between 10 and 6 Mya and during the Pliocene, and were probably influenced by paleogeographical events such as the breaching of the Purus arch, the rise of the Vaupés arch, the uplift of the Fitzcarrald arch, and the capture of the Contigo and Uraricoera river drainages by the Branco River. The present time-calibrated analysis provides the first insight on the evolution of one of the smallest vertebrate taxa in the Amazon and Orinoco river drainages.
Received: 20 July 2017 / Accepted: 28 December 2017 / Published online: 20 July 2017
Towards a ground pattern reconstruction of bivalve nervous systems: neurogenesis in the zebra mussel Dreissena polymorpha
Bivalvia is a taxon of aquatic mollusks that includes clams, oysters, mussels, and scallops. Within heterodont bivalves, Dreissena polymorpha is a small, mytiliform, freshwater mussel that develops indirectly via a planktotrophic veliger larva. Currently, only a few studies on bivalve neurogenesis are available, impeding the reconstruction of a ground pattern in Bivalvia. In order to inject novel data into this discussion, we describe herein the development of the serotonin-like and α-tubulin-like immunoreactive (lir) neuronal components of D. polymorpha from the early trochophore to the late veliger stage. Neurogenesis starts in the early trochophore stage at the apical pole with the appearance of one flask-shaped serotonin-lir cell. When larvae reach the veliger stage, four flask-shaped serotonin-lir cells are present in the apical organ. At the same time, the anlagen of the cerebral ganglia start to form at the base of the apical organ. From the apical organ, one pair of cerebro-visceral connectives projects posteriorly and connects to a posterior larval sensory organ that contains serotonin- and α-tubulin-like flask-shaped cells. Additional, paired serotonin-lir neurites originate from the apical organ and project into the velum. One unpaired stomatogastric serotonin-lir cell develops ventrally to the stomach at the veliger stage. The low number of serotonin-lir cells in the apical organ of bivalve veligers is shared with larvae of basally branching gastropods and scaphopods and is thus considered a feature of the last common ancestor of Conchifera, while the overall simplicity of the larval neural architecture appears to be a specific trait of Bivalvia.
Received: 10 September 2017 / Accepted: 19 February 2018 / Published online: 10 September 2017
Heads up: evolution of exaggerated head length in the minute litter bug genus Nannocoris Reuter (Hemiptera: Schizopteridae)Download PDFAbstract
Evolutionary biologists have long been intrigued by exaggerated morphologies tied to sexual or natural selection. In insects, relatively few studies have investigated the evolution of such traits at the genus level and above and have used comparative phylogenetic methods to do so. We here investigate the interspecific evolution of head length in the minute litter bug genus Nannocoris Reuter based on the first phylogenetic hypothesis of the group (25 ingroup species, five gene regions, 3409 bp) and ancestral state reconstruction. Head lengths in this speciose genus range from approximately one sixth of the total body length to more than a quarter of the body length, while the head and mouthpart (rostrum) lengths are correlated. Different species therefore possess a markedly different reach of the rostrum when extended. The analyses show that head length evolution in Nannocoris is plastic, with head length elongations and reductions occurring in several clades, derived from ancestors with moderately elongated heads. Evidence is provided that exaggerated head lengths evolved through elongation of either the genal (pricei group) or the tip (arimensis group) region of the head. The biology of species in the genus Nannocoris is unknown, but given the lack of sexual dimorphism of head lengths, we speculate that head evolution in this genus may be driven by natural selection, potentially in the context of prey capture.
Received: 06 July 2017 / Accepted: 26 October 2017 / Published online: 06 July 2017
Global biodiversity research tied up by juridical interpretations of access and benefit sharingDownload PDFAbstract
The toolbox of instruments regulating access, transfer and use of biological material is currently re-equipped: the Nagoya Protocol was initiated to provide a legal framework to the third objective of the Convention on Biological Diversity – the fair and equitable sharing of benefits arising from the utilisation of genetic resources and associated traditional knowledge (an aspect not discussed here). In the ongoing implementation of the protocol, potentially harmful and far-reaching effects on biological research become evident. Here, we illustrate how vague definitions, lack of legal clarity and coordination, and often restrictive and complex regulations affect the transfer of biological material and associated data. Instead of promoting basic research in conservation and biodiversity, the current situation potentially jeopardises international collaboration, biodiversity research and its applications in monitoring, biocontrol and food safety. We address these challenges and discuss possible options for its practical implementation in the future.
Received: 27 June 2017 / Accepted: 01 November 2017 / Published online: 27 June 2017
Rolling into the deep of the land planarian genus Choeradoplana (Tricladida, Continenticola, Geoplanidae) taxonomyDownload PDFAbstract
The land planarian genus Choeradoplana (Plathelminthes, Tricladida) is currently integrated by 13 species. In previous works, morphological variation in its type species, Choeradoplana iheringi, was reported, but no attempt to test whether it is just a single species has been made yet. In order to disentangle the taxonomy of this species and further members of the genus, we sampled new specimens and combined morphological and molecular data and also have evaluated the performance of diverse methods of molecular species delimitation. Our data point to the presence of two cryptic species named C. iheringi, plus two new species, all hidden under the same general appearance. An in-depth morphological study of the specimens allowed detection of diagnostic morphological traits in each species, for which we also propose a molecular diagnosis. This integrative taxonomic study demonstrates once again the usefulness of molecular tools to weigh minor morphological characteristics and thus reveal the existence of species that would otherwise remain cryptic. However, under certain parameters, the molecular methods may over-split species with a high genetic structure, maybe pointing to incipient speciation. This makes critical the use of these methods combined with a comprehensive morphological approach. We also present a comprehensive phylogenetic tree including most Choeradoplana species. The tree, well supported, allows making some preliminary inferences on the evolution of the group and its historical biogeography.
Received: 27 June 2018 / Accepted: 20 September 2018 / Published online: 27 June 2018
A comprehensive and integrative re-description of Synchaeta oblonga and its relationship to Synchaeta tremula, Synchaeta rufina and Synchaeta littoralis (Rotifera: Monogononta)Download PDFAbstract
A comprehensive re-description of the monogonont rotifer Synchaeta oblonga Ehrenberg, 1832 is presented with the aim of creating a specific and robust suite of characters to identify this species that takes account of its morphological intraspecific variability. To accomplish this, we used an integrative approach that combined morphological data of the habitus and trophi (light and scanning electron microscopy) together with ecological and molecular data to generate a data set that clearly delineates S. oblonga from the morphologically similar Synchaeta tremula (Müller, 1786) with which it is often confused. In addition, by comparing S. oblonga to all remaining members of the genus Synchaeta, we found that the literature descriptions of Synchaeta rufina Kutikova and Vasiljeva, 1982, a Lake Baikal endemic species, and Synchaeta littoralis Rousselet, 1902, a species whose taxonomic status with respect to S. oblonga had already been called into question, to both lie entirely within the range of intraspecific morphological variability present in S. oblonga. Thus, we conclude that S. oblonga can be clearly demarcated from S. tremula, but that no unambiguous morphological differences exist to delineate it from either S. rufina or S. littoralis. Because our molecular data indicate S. oblonga to be a single species despite the morphological intraspecific variability that is present, we recommend that thorough re-examinations of the taxonomic statuses of both S. rufina and S. littoralis should be performed on topotypes sampled from their type localities (Lake Baikal, Russia and Dundee, Scotland, respectively).
Received: 02 August 2017 / Accepted: 23 November 2017 / Published online: 02 August 2017
The only known white blister rust on a basal angiosperm is a member of the genus Albugo
Rare pathogens on unusual hosts are often providing valuable insight into the evolution of the pathogen group concerned, but it is often challenging to obtain sequence data for these, as because only very few, often decades-old specimens are available. One such example is Albugo tropica, the white blister pathogen of a basal angiosperm in the genus Peperomia (Piperaceae). For this species, only two, more than 70 and over 120-year-old collections available. Here, sequence data for A. tropica are reported and phylogenetic reconstructions reveal it as the sister group to all other white blister rusts of the genus Albugo. Its isolated position is also reflected by several morphological differences to the other species of the genus, such as very thin-walled sporangia and almost smooth oospores. The isolated phylogenetic position of the pathogen and its host might indicate that it is a relict species trapped on its host. The sister-group relationship to all members of the genus Albugo s.str., which have been investigated using molecular phylogenetics, hints at the possibility, that Albugo might have originated in South America or Gondwana and has later radiated in the holarctic on members of the Brassicales.
Received: 15 May 2018 / Accepted: 26 September 2018 / Published online: 15 May 2018
Evidence of positive selection suggests possible role of aquaporins in the water-to-land transition of mudskippersDownload PDFAbstract
Aquaporins are integral membrane proteins that exchange water and small solutes. They played an important role in the colonisation of terrestrial environments by tetrapod ancestors via the appearance of three exclusive paralogs. Like early tetrapods, mudskippers represent an independent case of amphibious lifestyle evolution that is unparalleled by other extant fish groups. Given this lifestyle parallelism and that aquaporins were relevant for tetrapod terrestrialisation, this study examines the aquaporins in mudskippers to investigate whether similar changes in aquaporins could have possibly occurred during their water-to-land transition. We have catalogued aquaporin genes in four mudskipper genomes and studied their diversity and molecular evolution (including detection of positive selection) in a broad phylogenetic context of vertebrates. Our genomic screening returned 55 aquaporin genes for mudskippers (none of them constituting novel paralogs) that can be assigned to 10 different known classes. We detected signatures of positive selection in AQP10a and AQP11b in mudskippers (both the entire clade and the clade containing the most terrestrial species, implying different evolutionary times). This suggests possible alteration of the molecular function of such paralogs caused by changes at specific protein sequence positions, some of them located in relatively close proximity to parts of the molecule involved in pore formation and substrate selectivity. Given the importance of aquaporins for osmotic regulation in fishes, it might be possible that these selective changes (perhaps allowing permeability to new solutes) could have played a role during the adaptation of mudskippers to an amphibious lifestyle.
Received: 10 February 2018 / Accepted: 16 August 2018 / Published online: 10 February 2018
Ecomorphology of a generalist freshwater gastropod: complex relations of shell morphology, habitat, and fecundityDownload PDFAbstract
Evolutionary and ecological situations in a species’ native and invasive ranges can be drastically different. This is the case for Potamopyrgus antipodarum Gray (1843) a morphologically highly variable freshwater snail native to New Zealand, where sexual and asexual individuals coexist and experience selective pressure by sterilizing endoparasites. By contrast, only a few asexual lineages have been established in invaded regions around the globe, where parasite infection is extremely rare. We analyzed the ecomorphology of 996 native P. antipodarum in a geometric morphometric framework, using brood size as proxy for fecundity, and mtDNA and nuclear SNPs to account for relatedness and identify reproductive mode. As expected, we found genetic and morphological diversity to be higher in native than in invasive snails investigated previously, but surprisingly no higher morphological diversity in sexual versus asexual individuals. The relationships between shell morphology, habitat, and fecundity were complex. Shape variation was primarily linked to genetic relatedness but specific environmental factors including flow rate induced similar shell shapes. By contrast, shell size was largely explained by environmental factors. Fecundity was correlated with size but showed trade-offs with shape in increasingly extreme conditions. With increasing flow and toward small springs, the trend of shell shape becoming wider was reversed, i.e., snails with narrower shells were brooding more embryos. We concluded that both genetic and environmental contributions to variation in shell morphology in P. antipodarum likely play an important role in the ability of this species to adapt to a wide spectrum of habitats.
Received: 23 August 2017 / Accepted: 10 November 2017 / Published online: 23 August 2017
Tracking the diversity of the flatworm genus Imbira (Platyhelminthes) in the Atlantic ForestDownload PDFAbstract
The genus Imbira Carbayo et al., 2013 encompasses two species, Imbira guaiana (Leal-Zanchet & Carbayo, 2001) and Imbira marcusi Carbayo et al., 2013, which occur in south Brazil, in areas originally covered by the Atlantic Forest. In the present study, we examine the genetic diversity within the genus, investigate the occurrence of molecular autapomorphies for its species and describe a new species for the genus based on an integrative approach. The Bayesian and maximum likelihood analyses based on DNA barcoding recovered the monophyly of the genus Imbira, but indicate that specimens representing I. marcusi correspond to five distinct lineages. These analyses, as well as sequence divergence data, revealed that the new species herein described is closely related to I. guaiana and that the specific status of specimens of I. marcusi available in GenBank should be reviewed. In addition, sequence analysis revealed 32 molecular autapomorphies for all independent evolutionary units within the genus. The new species described herein seems to be endemic to its type locality, a private area without legal protection.