This illustrated essay highlights some conceptual problems that arise when we consider the nature of visual perception and its relationship to art. Science proceeds on the assumption that natural phenomena operate rationally and can be explained rationally. Yet the study of art shows that many ordinary acts of perception, such as looking at a picture, can be paradoxical, logically contradictory and self-referential. I conclude that we must confront these problems if we are to reconcile the scientific approach to explaining visual perception with artistic and philosophical discoveries.
Xin Tong and Bao-Zhen Hua
Neopanorpa, the second largest genus in Panorpidae, is mainly characterized by the well-developed notal organ on male tergum III. However, it remains largely unknown how the length of the notal organ influences the nuptial feeding behaviour of Neopanorpa. Here, we investigated the nuptial feeding by comparing the morphology of mating-related structures and the genital coupling of a) Neopanorpa lui Chou & Ran, 1981 with a weakly-developed notal organ, b) N. carpenteri Cheng, 1957 with a medium-sized notal organ, and c) N. longiprocessa Hua & Chou, 1997 with an extremely elongated notal organ. The couples of N. lui and N. carpenteri maintain an intermittent mouth-to-mouth mode but do not exchange any edible food. After that the males secrete a salivary mass onto the surface as a nuptial gift, which is distinctly larger in N. carpenteri than in N. lui. Correspondingly, the male salivary glands are more developed in N. carpenteri than in N. lui. Males of N. longiprocessa bear very short salivary glands corresponding to a coercive mating tactic. The genital couplings are similar among the three species of Neopanorpa. The paired hypovalves of males are used to control the cerci of females. The prominent basal processes of male gonostyli grasp the posterior portion of the female medigynium across the intersegmental membrane. The male aedeagus physically couples with the female medigynium to ensure the male phallotreme to connect to the female copulatory pore. The influence of the notal organ length on the nuptial feeding behaviour of Neopanorpa is briefly discussed.
Isabel T. Hyman and Frank Köhler
The helicarionid fauna of southeastern to mid-eastern Queensland is dominated by a group of semislugs with moderately reduced shells belonging to genera Fastosarion, Eungarion, Stanisicarion, Dimidarion, Macularion and Hymanarion. We comprehensively revise their systematic classification using comparative morpho-anatomy and mitochondrial phylogenetics, and demonstrate that these genera combined form a well-differentiated and monophyletic radiation. In our mitochondrial phylogeny, this radiation is divided into three main clades that are statistically well supported. One clade is also well defined in terms of diagnostic morpho-anatomical characters, but we could not identify diagnostic characters for the other two clades due to considerable levels of morpho-anatomical variation. We propose accepting only two genera, Fastosarion (with junior synonyms Eungarion, Dimidarion, and Hymanarion) and Stanisicarion (with junior synonym Macularion). Both genera represent mutually monophleytic sister taxa that can consistently be distinguished by the presence or absence of a penial verge that is fused to the penial wall and by egg shape. We also synonymise Fastosarion ameyi with F. aquavitae, F. schelli with F. helenkingae, Dimidarion peterbrocki and D. slatyeri with F. alyssa, Stanisicarion virens with S. freycineti. Revised species descriptions are presented for Fastosarion alyssa, F. aquavitae, F. brazieri, F. comerfordae, F. griseolus, F. hannianus, F. helenkingae, F. mcdonaldi, F. minerva, F. paluma, F. papillosus, F. pustulosus, F. superbus, Stanisicarion aquila and S. freycineti. Nine new species, Fastosarion deensis, F. ephelis, F. insularis, F. katatonos, F. longimentula, F. rowani, F. sarina, F. tuljun and Stanisicarion wolvi are described, bringing the total number of accepted species to 24.
Oksana A. Korzhavina, Bert W. Hoeksema and Viatcheslav N. Ivanenko
This review of copepod crustaceans associated with reef-dwelling cnidarians, sponges and echinoderms of the Greater Caribbean is based on published records, systematically arranged by the classification of symbiotic copepods and their hosts, sampling sites, coordinates, depth and date of sampling, literature sources, and three recent surveys (Cuba, St. Eustatius in the Eastern Caribbean and Curaçao in the Southern Caribbean). This resulted in totals of 532 records of 115 species of symbiotic copepods (47 genera, 17 families, three orders) hosted by 80 species of invertebrates, representing scleractinians (47%), octocorals (9%), echinoderms (3%), and sponges (1%). Among ten Caribbean ecoregions, the Greater Antilles (with 64 species of symbiotic copepods) as well as the Southern and Eastern Caribbean (with 46 and 17 species of copepods, respectively) are the most studied and best represented, whereas only six species of copepods are known from Bermuda, one from Southwestern Caribbean and none from the Gulf of Mexico. The absence of poecilostomatoid copepods (Anchimolgidae, Rhynchomolgidae and Xarifidae) on Caribbean stony corals as noted by Stock (1988) is confirmed. The results indicate that the diversity and ecology of Caribbean symbiotic copepods are still poorly investigated.
Yifan Chen, Qian Bai, Funan Ruan and Shuchai Su
The Pistacia chinensis Bunge is traditionally dioecious, and the female trees are more required to grow in practice for oil seed production. The discovery of monoecious P. chinensis Bunge in North China provided good raw materials to study the sex differentiation process. The objective of this study was to identify the differently expressed proteins in flower buds in two key sex differentiation phases in monoecious P. chinensis Bunge. Morphological observation and paraffin section were used to determine the key phenophases, and label-free quantitative technique was used for proteomic analysis. The results showed that the proteins related to oxidative stress resistance up-regulated while proteins involved in photosynthesis down-regulated during the female primordium differentiation in bisexual flower buds of the monoecious P. chinensis Bunge in early March, while proteins related to oxidative stress resistance, ribosome activity, and photosynthetic function up-regulated during the male primordium differentiation in bisexual flower buds of the monoecious P. chinensis Bunge in late May. The most up-regulated proteins all involved in the photosynthesis pathway in both kind of flower buds in late May compared to those in early March, and the down-regulated proteins all involved in the ribosome pathway. The identified differentially expressed proteins such as the Cu/Zn superoxide dismutases may be possible molecular markers for sex determination in monoecious P. chinensis Bunge.
Giulia Perina, Ana I. Camacho, Joel Huey, Pierre Horwitz and Annette Koenders
The stygofaunal family of Bathynellidae, is an excellent group to study the processes that shape diversity and distribution, since they have unknown surface or marine relatives, high level of endemism, and limited dispersal abilities. Recent research on Bathynellidae in Western Australia (Pilbara) has uncovered new taxa with unexpected distributions and phylogenetic relationships, but the biogeographical processes that drive their diversification on the continent are still unclear. By exploring the diversity, distribution, and divergence time of Bathynellidae in a setting such as the perched and isolated aquifers of the Cleaverville Formation in the north of the De Grey River catchment (Pilbara), we aim to test the hypothesis that vicariance has shaped the distribution of this family, specifically if one or multiple vicariant events were involved. We analysed the specimens collected from perched water in different plateaus of the Cleaverville Formation, combining morphological and molecular data from mitochondrial and nuclear genes. We described two new species and genera (Anguillanella callawaensis gen. et sp. nov. and Muccanella cundalinensis gen. et sp. nov.), and two additional taxa are recognised using morphology and/or Automatic Barcode Gap Discovery and Poisson Tree Processes species delimitation methods. New genera and species result restricted to isolate perched aquifers on single plateaus and their distributions, phylogenetic relationships, and divergence time estimates support multiple vicariant events and ancient allopatric speciation.
Maliheh Pirayesh Shirazinejad, Mansour Aliabadian and Omid Mirshamsi
The white wagtail (Motacilla alba) species complex with its distinctive plumage in separate geographical areas can serve as a model to test evolutionary hypotheses. Its extensive variety in plumage, despite the genetic similarity between taxa, and the evolutionary events connected to this variety are poorly understood. Therefore we sampled in the breeding range of the white wagtail: 338 individuals were analyzed from 74 areas in the Palearctic and Mediterranean. We studied the white wagtail complex based on two mitochondrial DNA markers to make inferences about the evolutionary history. Our phylogenetic trees highlight mtDNA sequences (ND2, CR), and one nuclear marker (CHD1Z), which partly correspond to earlier described clades: the northern Palearctic (clade N); eastern and central Asia (clade SE); south-western Asia west to the British Isles (clade SW); and Morocco (clade M). The divergence of all clades occurred during the Pleistocene. We also used ecological niche modelling for three genetic lineages (excluding clade M); results showed congruence between niche and phylogenetic divergence in these clades. The results of the white wagtail ancestral area reconstruction showed the influence of dispersal on the distribution and divergence of this complex species. The most important vicariance event for the white wagtail complex may have been caused by the Gobi and Taklamakan deserts. We conclude that the ancestral area of the white wagtail complex was probably in the Mediterranean, with its geography having a considerable effect on speciation processes.
Miguel A. Meca, Pilar Drake and Daniel Martin
The polychaete Oxydromus okupa lives in association with the bivalves Scrobicularia plana and Macomopsis pellucida in the intertidal of Río San Pedro (CI = Cádiz Intertidal) and adjacent to CHipiona (CH) harbour, and in the subtidal of the Bay of Cádiz (CS = Cádiz Subtidal). We analyse these populations morphometrically, ecologically (including infestation characteristics) and genetically (intertidal populations, 16S and ITS-1 genes). We consider “host”, “environment” and the combined “host and environment” as possible factors of interpopulation variability. Morphometry revealed three well-defined clusters for CI, CH and CS, showing intergroup phenotypic differences ranging from 35 to 50%. Hosts shell lengths ranged between 26 and 36 mm for S. plana and 20 and 28 mm for M. pellucida. The infestation of small M. pellucida by juvenile O. okupa suggests they show an active size segregation behaviour. The intertidal seems to be less favourable (infestation rate <25% vs. up to 65% in the subtidal), and did not show recent bottleneck events. Overall, CI and CH were genetically homogeneous, but showed a significant divergence (one dominant haplotype in each host species), suggesting host shift as being a soft barrier to gene flow. Most characters related with host-entering varied among populations, suggesting symbiotic behaviour to play a key role in reducing panmixia and leading to the initial phases of a speciation process in sympatric symbiotic populations. Polyxeny and symbiotic behaviour in O. okupa seem thus to be underlying mechanisms contributing to its great phenotypic variety, marked ecological differences, and genetic divergence.
Giacinta Angela Stocchino, Ronald Sluys, Abdel Halim Harrath, Lamjed Mansour and Renata Manconi
Invasions of alien species form one of the major threats to global biodiversity. Among planarian flatworms many species are known to be invasive, in several cases strongly affecting local ecosystems. Therefore, a detailed knowledge on the biology of an invasive species is of utmost importance for understanding the process of invasion, the cause of its success, and the subsequent ecological impact on native species. This paper provides new information on the biology of introduced populations of the freshwater flatworm Girardia tigrina (Girard, 1850) from Europe. This species is a native of the Nearctic Region that was accidentally introduced into Europe in the 1920s. Since then, numerous records across the European continent bear witness of the invasiveness of this species, although only a few studies focused on the biology of the introduced populations. We report on the morphology of sexualized individuals from a fissiparous Italian population, representing the second record of spontaneous sexualization of fissiparous individuals in this species. A detailed morphological account of the reproductive apparatus of these ex-fissiparous animals is presented. Our results increased the number of morphological groups previously recognized for European populations of G. tigrina, thus corroborating the hypothesis on multiple independent introductions to this continent. Karyological results obtained from our fissiparous Italian individuals revealed a constant diploid chromosome complement of sixteen chromosomes. Further, we document the marked intraspecific variation in several morphological features of this species.
Cessa Rauch, Bert W. Hoeksema, Bambang Hermanto and Charles H.J.M. Fransen
Most marine palaemonid shrimp species live in symbiosis with invertebrates of various phyla. These associations range from weak epibiosis to obligatory endosymbiosis and from restricted commensalism to semi-parasitism. On coral reefs, such symbiotic shrimps can contribute to the associated biodiversity of reef corals. Among the host taxa, mushroom corals (Cnidaria: Anthozoa: Fungiidae) are known to harbour various groups of symbionts, including shrimps. Some but not all of these associated species are host-specific. Because data on the host specificity of shrimps on mushroom corals are scarce, shrimp species of the genus Periclimenes were collected from mushroom corals during fieldwork in Lembeh Strait, North Sulawesi, Indonesia. Using molecular (COI barcoding gene) and morphological methods, three species of Periclimenes were identified: P. diversipes, P. watamuae and a species new to science, P. subcorallum sp. nov., described herein. Their host specificity was variable, with eight, three and two fungiid host records, respectively. It is concluded that shrimp species of the genus Periclimenes show much overlap in their host choice and that particular morphological traits in the host species appear to play a more important role than phylogenetic affinities within the host group.