Evolution of Host Associations in Symbiotic Zoanthidea

Symbioses are pervasive in life and confer novel adaptive capabilities that enable ecological expansion into unexplored niches. Evolutionary transitions in symbiosis (terminations, origins, host shifts, or changes in relationship outcomes) can therefore have dramatic effects on the fitness, life history, and distribution of organisms. Because symbiotic interactions require coordination among traits that control recognition, colonization, and maintenance of symbiosis, transitions in symbiosis should generally be rare and conserved across evolutionary time. Cnidarians in the order Zoanthidea (class Anthozoa) are symbionts of taxa representing at least five invertebrate phyla and occur in most major benthic habitats from the intertidal to the deep sea. The Zoanthidea exhibit a startling array of evolutionary transitions in symbioses, and host associations and relationship outcomes appear to be highly homoplasious. To better understand these transitions and the effects of symbioses on Zoanthidea, I use a multifaceted approach that combines molecular phylogenetics and morphology with manipulative field experiments and surveys to clarify species delimitations, diversity and specificity of host associations, context-dependent relationship outcomes, and the evolution of symbioses. The results of this research indicate that our current understanding of symbiosis evolution in Zoanthidea is confounded by incomplete data on associations and relationships, and systematics that do not reflect evolutionary relationships; the data presented here indicate that host associations are largely conserved across evolutionary time

Molecular Parataxonomy as Taxon Description: Examples from Recently Named Zoanthidea (Cnidaria: Anthozoa) with Revision Based on Serial Histology of Microanatomy.

Current taxonomic practices require corroboration from multiple lines of evidence to provide sufficient rigor for species discovery and description. However, many recently named taxa (species–families) are defined by nucleotide sequence with little or no description of the features that traditionally define higher taxa and link nucleotide-based information to the existing taxonomic system. Without knowledge of form, it may be impossible to identify conspecifics, congeners, and confamiliars of new taxa among the hundreds of specimens and described species for which nucleotide sequencing is not now, and may never be, available. Additionally, some nucleotide sequences are invariant or inconsistently differentiated between congeners; severely limiting the utility of nucleotide-based taxon definitions. Here we use serial histology of paratypes to reveal the microanatomy of internal structures and revise the definitions of the Zoanthidea taxa Corallizoanthus tsukaharai Reimer, Antipathozoanthus hickmani Reimer & Fujii, Parazoanthus darwini Reimer & Fujii, Terrazoanthus onoi Reimer & Fujii, Terrazoanthus sinnigeri Reimer & Fujii, Microzoanthus kagerou Fujii & Reimer, and Zoanthus kuroshio Reimer & Ono; examination of Mesozoanthus lilkweminensis Reimer & Sinniger failed to produce interpretable sections. The results described here, with individual measurements documented in Morphbank (collection 829724) and Encyclopedia of Life (by taxon name), indicate a notably rich diversity of form for an order that is often characterized as depauperate in morphological diversity. One prominent example is a novel marginal muscle structure (cyclically transitional) that is not observable without serial sections. These findings may renew interest in morphological characters and provide the foundation for revision of Zoanthidea higher taxa, particularly now that phylogenetic relationships for these taxa can be inferred

LANGUAGE LEARNING UNDER CLASSROOM CONDITIONS DURING THE TRANSITION TO HYBRID INSTRUCTION: A CASE-STUDY OF STUDENT PERFORMANCE DURING THE IMPLEMENTATION OF INSTRUCTIONAL TECHNOLOGY

We examined the unmanipulated performance of students under real classroom conditions in order to assess the effect of a technology-enhanced hybrid learning approach to second language, (L2) instruction on beginning and advanced Spanish language learners. This research focused on the transition period of technology implementation when the entire section of Spanish of a modern language department of a liberal arts university transitioned from traditional face-to-face instruction, to a technology-enhanced hybrid learning approach with concurrent reduction in face-to-face classroom hours. This implementation provided an opportunity to compare the performance of students prior to and during the transition to hybrid model of instruction across multiple language proficiency levels. This research is designed to critically evaluate the performance of students under real classroom conditions in order to examine the effectiveness of a hybrid approach during its implementation such that the performance of students participating in the methodological transition can be understood in light of the performance of students in the previous quarters. The results indicate that introductory students did not realize the full potential benefits of hybrid instruction in the transition period, but that the performance of advanced students was improved, suggesting that a phased-in approach to hybrid instruction implementation, where advanced students are the first to transition to hybrid instruction, may supplement training experiences for instructors and support staff and improve overall student success during technology implementation.   Article visualizations

LANGUAGE LEARNING UNDER CLASSROOM CONDITIONS DURING THE TRANSITION TO HYBRID INSTRUCTION: A CASE-STUDY OF STUDENT PERFORMANCE DURING THE IMPLEMENTATION OF INSTRUCTIONAL TECHNOLOGY

We examined the unmanipulated performance of students under real classroom conditions in order to assess the effect of a technology-enhanced hybrid learning approach to second language, (L2) instruction on beginning and advanced Spanish language learners. This research focused on the transition period of technology implementation when the entire section of Spanish of a modern language department of a liberal arts university transitioned from traditional face-to-face instruction, to a technology-enhanced hybrid learning approach with concurrent reduction in face-to-face classroom hours. This implementation provided an opportunity to compare the performance of students prior to and during the transition to hybrid model of instruction across multiple language proficiency levels. This research is designed to critically evaluate the performance of students under real classroom conditions in order to examine the effectiveness of a hybrid approach during its implementation such that the performance of students participating in the methodological transition can be understood in light of the performance of students in the previous quarters. The results indicate that introductory students did not realize the full potential benefits of hybrid instruction in the transition period, but that the performance of advanced students was improved, suggesting that a phased-in approach to hybrid instruction implementation, where advanced students are the first to transition to hybrid instruction, may supplement training experiences for instructors and support staff and improve overall student success during technology implementation.   Article visualizations

Structural rRNA Characters Support Monophyly of Raptorial Limbs and Paraphyly of Limb Specialization in Water Fleas

The evolutionary success of arthropods has been attributed partly to the diversity of their limb morphologies. Large morphological diversity and increased specialization are observed in water flea (Cladocera) limbs, but it is unclear whether the increased limb specialization in different cladoceran orders is the result of shared ancestry or parallel evolution. We inferred a robust among–order cladoceran phylogeny using small–subunit and large–subunit rRNA nuclear gene sequences, signature sequence regions, novel stem–loops and secondary structure morphometrics to assess the phylogenetic distribution of limb specialization. The sequence–based and structural rRNA morphometric phylogenies were congruent and suggested monophyly of orders with raptorial limbs, but paraphyly of orders with reduced numbers of specialized limbs. These results highlight the utility of complex molecular structural characters in resolving ancient rapid radiations

Sponges of Navassa

This photographic guide was compiled from data collected during the 2004 NOAA survey of the coral reefs of Navassa and does not represent a comprehensive list of all Porifera in Navassa. Specifically missing are taxa that inhabit caves, overhangs, vertical walls; species that live in the interstices of the reef framework; and species found at depths greater than 50 meters. Specimens were identified by Janie Wulff and Timothy Swain of Florida State University using a combination of digital photography, field observations, and microscopic examination of siliceous spicules. Genera are organized into higher taxa according to Systema Porifera, Hooper & van Soest (ed.) 2002. We have purposefully erred on the side of splitting similar taxa for which a species designation could not be definitively assigned, in order to demonstrate the range of forms observed in this survey. Some species are shown with symbiotic zoanthids on the surface of the sponge, but zoanthids are not always present and should not be relied on for identification of the sponge taxa

Use of Fluorescence Microscopy in an Assay of Sperm Density for the Gorgonian Coral, Plexaura kuna

The density of sperm in the water column during the broadcast spawning events of marine invertebrates is often undetermined or reported in terms of fertilization potential. The density of sperm during such events can be determined by directly counting numbers of spermatozoa using a modification of the acridine orange direct count (AODC) technique for enumerating bacteria. A number of variables in the handling and processing of samples may bias estimates. Sample collection in glass and rapid fixation and filtration are necessary for reproducible estimates. Once filtered, samples are stable for many months, and counts on filters that were poorly stained in the field can be enhanced by additional staining with 4\u276-diamidino-2-phynlindole (DAPI). The AODC technique was employed to examine the effects of distance from a male colony on density of sperm for the gorgonian coral Plexaura kuna. In situ sperm densities ranged from 0 to 1,000 sperm/ml. Sperm densities in 18 l aquaria containing 20 cm long P. kuna explants reached 100,000 sperm/ml

Towards Integrative Systematics of Anthozoa (Cnidaria): Evolution of Form in the Order Zoanthidea

A decade of research inferring evolutionary relationships from nucleotide sequences has demonstrated a fundamental misconception of the evolution of form in Zoanthidea. Morphological features that define current taxa are plesiomorphic or homoplastic and do not circumscribe clades of species delineated by ecological and molecular characters. Although molecular data have been critical in exposing this deficiency, their parataxonomic application to Zoanthidea has created a barrier to comprehensive revision within the order. Species descriptions and higher taxon definitions based on nucleotide sequences isolate new taxa from the existing taxonomic system and restrict the application of novel systematics hypotheses to a fraction of the known diversity of taxa. This creates competing taxonomic systems that do not benefit from the knowledge contained in the opposing system. To enable the integration of modern molecular data with more than a century of morphological research, characters that can simultaneously span the parataxonomy barrier, existing taxonomic system and historical record must be identified. Here, we test the utility of morphological characters for integrative systematics by reviewing commonly described and novel morphological characters, assessing independence of character components and analysing character homoplasy and ancestral states on the most comprehensive molecular phylogeny available. The results indicate a rich diversity of form that span the full range of homoplasy values, including more than a dozen independent characters useful to systematics or differentiating closely related species. The least homoplasious characters include traditionally targeted (fifth mesenteries, marginal muscle arrangement, encircling sinus) and novel (fissure morphology, basal canals of the mesenteries) features. These analyses represent a first step in identifying characters necessary for reunification and revision of Zoanthidea systematics

Structural rRNA characters support monophyly of raptorial limbs and paraphyly of limb specialization in water fleas

The evolutionary success of arthropods has been attributed partly to the diversity of their limb morphologies. Large morphological diversity and increased specialization are observed in water flea (Cladocera) limbs, but it is unclear whether the increased limb specialization in different cladoceran orders is the result of shared ancestry or parallel evolution. We inferred a robust among-order cladoceran phylogeny using small-subunit and large-subunit rRNA nuclear gene sequences, signature sequence regions, novel stemloops and secondary structure morphometrics to assess the phylogenetic distribution of limb specialization. The sequence-based and structural rRNA morphometric phylogenies were congruent and suggested monophyly of orders with raptorial limbs, but paraphyly of orders with reduced numbers of specialized limbs. These results highlight the utility of complex molecular structural characters in resolving ancient rapid radiations

Bleaching Response of Coral Species in the Context of Assemblage Response

Caribbean coral reefs are declining due to a mosaic of local and global stresses, including climate change-induced thermal stress. Species and assemblage responses differ due to factors that are not easily identifiable or quantifiable. We calculated a novel species-specific metric of coral bleaching response, taxon-α and -β, which relates the response of a species to that of its assemblages for 16 species over 18 assemblages. By contextualizing species responses within the response of their assemblages, the effects of environmental factors are removed and intrinsic differences among taxa are revealed. Most corals experience either a saturation response, overly sensitive to weak stress (α \u3e 0) but under-responsive compared to assemblage bleaching (β \u3c 1), or a threshold response, insensitive to weak stress (α \u3c 0) but over-responsive compared to assemblage bleaching (β \u3e 1). This metric may help reveal key factors of bleaching susceptibility and identify species as targets for conservation