Description of Calliactis tigris sp. nov.: reconciling taxonomy and phylogeny in hermit-crab symbiotic anemones (Cnidaria: Actiniaria: Hormathiidae)

Luciana C. Gusmão, E. Rodríguez, Marymegan Daly, M. Org Divers Evol (2019). https://doi.org/10.1007/s13127-019-00414-2

Abstract

The symbiosis between sea anemones and hermit crabs is ubiquitous in the marine environment (except in the poles), occurring from shallow to deep waters; it involves one or more anemones living on a shell inhabited by a hermit crab. The anemone-crab partnership is a mutualism in which hermit crabs provide a hard substrate, increased access to oxygenated waters and food supply, in exchange for defense by the anemone. The vast majority of the sea anemone partners belong to three genera in family Hormathiidae: Adamsia, Calliactis, Paracalliactis. Given the remarkable nature of the symbiosis, hormathiid partners have been hypothesized to represent a monophyletic group. This has been rejected by Gusmão and Daly et al. (2010) and confirmed by our phylogenetic analysis using molecular markers (12S, 16S, 18S, 28S, COIII). We expand the results of Gusmão and Daly et al. (2010) by finding a monophyletic Paracalliactis, which was left untested in their analyses. Thus, characters of taxonomic significance associated to the symbiotic habit are interpreted as functional rather than phylogenetic. We reconcile taxonomy and the present evolutionary framework to avoid defining taxonomic groups based on characters prone to convergence. We formalize the synonymy of Adamsia and Calliactis and provide updated diagnoses for the valid genera Calliactis and Paracalliactis to bring more stability to the group. Under this new framework, we describe Calliactis tigris sp. nov. from Australia based on 21 specimens collected off the coast of New South Wales and Queensland and differentiate it from congeners and other hermit crab symbionts recorded in the Pacific Ocean.

The influence of larval growth rate on juvenile recruitment in Lake Erie walleye (Sander vitreus)

Cassandra J. May, Stuart A. Ludsin, David C. Glover, Elizabeth A. Marschall. 2019. Canadian Journal of Fisheries and Aquatic Sciences. https://doi.org/10.1139/cjfas-2019-0059

Abstract

Growth-selective mortality as larvae can influence recruitment in marine fishes. Its importance in freshwater fishes, however, remains speculative. We quantified growth trajectories within annual cohorts (2011-2013) of Lake Erie walleye (Sander vitreus) and its relationship with recruitment. We hypothesized that selection against slow or fast growth would be associated with high mortality and poor recruitment, whereas weak or nonexistent growth-selective mortality co-occurring with fast growth would be associated with good recruitment. We used otoliths to reconstruct growth rates during the first 15 days of life from larvae collected during spring and juvenile recruits (survivors) collected during late summer. We documented growth-selective mortality during 2011 and 2013, which exhibited poor recruitment as expected. During 2012, growth-selection was absent, but growth was slow when compared to historical averages, resulting in poor recruitment. Growth was also considered slow in 2011 and 2013, due to multiple interacting conditions. Our study indicates that the relationship among larval growth, mortality, and future recruitment is complex, highlighting the need for continued research into how larval processes affect recruitment dynamics in freshwater fishes.

Use Of Hypertonic Medium To Cryopreserve Sauger (Sander canadensis) Spermatozoa

Bryan Blawut  Barbara Wolfe  Christa R. Moraes  Stuart A. Ludsin  Marco A. Coutinho da Silva. 2019. North American Journal of Aquaculture. https://doi.org/10.1002/naaq.10125

Abstract

The objective of this study was to determine the effects of extender osmolality on post‐thaw sperm quality and fertility in Sauger (Sander canadensis). Fresh milt from 10 male Sauger was diluted using base extenders with osmolalities of 350, 500, or 750 mOsm/kg (E350, E500 and E750, respectively) containing 10% DMSO, frozen in LN2 vapor, and stored. Sperm parameters (total motility, progressive motility, velocity, and viability) were assessed at different steps of the cryopreservation process (extended, equilibrated, and post‐thaw) Fertilization was compared between fresh and frozen sperm, and at two sperm‐to‐egg ratios. All parameters measured, except progressive motility, were reduced by cryopreservation. Extender 500 yielded the highest post‐thaw progressive motility (32.20 ± 3.86%) and velocity (84.97 ± 16.82 µm/s) whereas both E350 and E500 displayed the highest total motility (65.30 ± 4.24 and 68.70 ± 6.46%) and viability (80.60 ± 4.84 and 78.80 ± 3.91%), respectively. By contrast E750 yielded the lowest post‐thaw velocity, viability, total, and progressive motility. Despite the increase in motility parameters, fertilization was approximately two fold higher in E350 (13.93 %) compared to E500 (6.58 %), although not statistically different. In conclusion, traditional isosmotic base extenders (E350) were found to be superior to hypertonic base extenders in the preservation of Sauger milt. These results serve as a starting point for future investigation of cryopreservation potential for Sauger spermatozoa to develop a freezing protocol more suitable for large‐scale application.

The Antarctic mite, Alaskozetes antarcticus, shares bacterial microbiome community membership but not abundance between adults and tritonymphs

Christopher J. Holmes, Emily C. Jennings, J. D. Gantz, Drew Spacht, Austin A. Spangler, David L. Denlinger, Richard E. Lee Jr., Trinity L. Hamilton, Joshua B. Benoit. 2019. Polar Biol. https://doi.org/10.1007/s00300-019-02582-5

Abstract

The Antarctic mite (Alaskozetes antarcticus) is widely distributed on sub-Antarctic islands and throughout the Antarctic Peninsula, making it one of the most abundant terrestrial arthropods in the region. Despite the impressive ability of A. antarcticus to thrive in harsh Antarctic conditions, little is known about the biology of this species. In this study, we performed 16S rRNA gene sequencing to examine the microbiome of the final immature instar (tritonymph) and both male and female adults. The microbiome included a limited number of microbial classes and genera, with few differences in community membership noted among the different stages. However, the abundances of taxa that composed the microbial community differed between adults and tritonymphs. Five classes—Actinobacteria, Flavobacteriia, Sphingobacteriia, Gammaproteobacteria, and Betaproteobacteria—comprised ~ 82.0% of the microbial composition, and five (identified) genera—Dermacoccus, Pedobacter, Chryseobacterium, Pseudomonas, and Flavobacterium—accounted for ~ 68.0% of the total composition. The core microbiome present in all surveyed A. antarcticus was dominated by the families Flavobacteriaceae, Comamonadaceae, Sphingobacteriaceae, Chitinophagaceae and Cytophagaceae, but the majority of the core consisted of operational taxonomic units of low abundance. This comprehensive analysis reveals a diverse microbiome among individuals of different stages, with overlap likely due to their shared habitat and common feeding preferences as herbivores and detritivores. The microbiome of the Antarctic mite shows considerably more diversity than observed in mite species from lower latitudes.

Defining a spectrum of integrative trait‐based vegetation canopy structural types

Robert T. Fahey, Jeff W. Atkins, Christopher M. Gough, Brady S. Hardiman, Lucas E. Nave, Jason M. Tallant, Knute J. Nadehoffer, Christoph Vogel, Cynthia M. Scheuermann,  Ellen Stuart‐Haëntjens, Lisa T. Haber, Alexander T. Fotis, Raleigh Ricart, Peter S. Curtis. 2019. Ecology Letters. https://doi.org/10.1111/ele.13388

Abstract

Vegetation canopy structure is a fundamental characteristic of terrestrial ecosystems that defines vegetation types and drives ecosystem functioning. We use the multivariate structural trait composition of vegetation canopies to classify ecosystems within a global canopy structure spectrum. Across the temperate forest sub‐set of this spectrum, we assess gradients in canopy structural traits, characterise canopy structural types (CST) and evaluate drivers and functional consequences of canopy structural variation. We derive CSTs from multivariate canopy structure data, illustrating variation along three primary structural axes and resolution into six largely distinct and functionally relevant CSTs. Our results illustrate that within‐ecosystem successional processes and disturbance legacies can produce variation in canopy structure similar to that associated with sub‐continental variation in forest types and eco‐climatic zones. The potential to classify ecosystems into CSTs based on suites of structural traits represents an important advance in understanding and modelling structure–function relationships in vegetated ecosystems.

The emerging field of venom-microbiomics for exploring venom as a microenvironment, and the corresponding Initiative for Venom Associated Microbes and Parasites (iVAMP)

Sabah Ul-Hasan, Eduardo Rodríguez-Román, Adam M.Reitzel, Rachelle M.M.Adams, Volker Herzig, Steven A.Trim, Anthony J.Saviola, Clarissa J.Nobile, Erin E. Stiers, Sterghios A.Moschos, Carl N. Keiser, Daniel Petras, Yehu Moran, Timothy J. Colston. 2019. Toxicon: X. https://doi.org/10.1016/j.toxcx.2019.100016

Abstract

Venom is a known source of novel antimicrobial natural products. The substantial, increasing number of these discoveries have unintentionally culminated in the misconception that venom and venom-producing glands are largely sterile environments. Culture-dependent and -independent studies on the microbial communities in venom microenvironments reveal the presence of archaea, algae, bacteria, endoparasites, fungi, protozoa, and viruses. Venom-centric microbiome studies are relatively sparse to date and the adaptive advantages that venom-associated microbes might offer to their hosts, or that hosts might provide to venom-associated microbes, remain unknown. We highlight the potential for the discovery of venom-microbiomes within the adaptive landscape of venom systems. The considerable number of known, convergently evolved venomous animals juxtaposed with the comparatively few studies to identify microbial communities in venom provides new possibilities for both biodiversity and therapeutic discoveries. We present an evidence-based argument for integrating microbiology as part of venomics to which we refer to as venom-microbiomics. We also introduce iVAMP, the Initiative for Venom Associated Microbes and Parasites (https://ivamp-consortium.github.io/), as a growing consortium for interested parties to contribute and collaborate within this subdiscipline. Our consortium seeks to support diversity, inclusion and scientific collaboration among all researchers interested in this subdiscipline.