DOCSLIB.ORG

The Circadian Clock of the Mexican Blind Cavefish, Astyanax Mexicanus

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Circadian Clock of the Mexican Blind Cavefish, Astyanax Mexicanus THE CIRCADIAN CLOCK OF THE MEXICAN BLIND CAVEFISH, ASTYANAX MEXICANUS Andrew David Beale University College London Thesis submitted For the FulFilment oF the requirements For the degree of Doctor of Philosophy. 2013 I, Andrew David Beale, conFirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the thesis. 2 ABSTRACT The prevalence oF circadian clocks in most, iF not all, organisms on the planet implies they are an adaptive trait. However, only a Few studies provide evidence to support this. To address this issue directly, we examined circadian clock Function in the Mexican caveFish, Astyanax mexicanus. This species has spent a signiFicant period oF its evolutionary history in constant darkness, away from the daily cycles of the surface environment. Many caveFish populations have adapted For liFe in the dark by reducing eyes and pigmentation and enhancing sensory processes relevant in darkness, such as mechanosensation. Have caveFish retained the circadian clock architecture in the absence oF the primary entraining cue, light? This thesis presents evidence For: i. The presence oF a light-entrainable molecular circadian clock in Astyanax caveFish. Robust circadian rhythms oF per1 expression are exhibited in cavefish, but with reduced amplitude and altered phase relative to their surFace Fish ancestors. ii. Alterations in the light input pathway, especially the raised expression oF a putative clock repressor, per2b. We propose that this dampens the amplitude oF core clock gene expression rhythms observed in cavefish. iii. Absence oF circadian rhythmicity in wild caveFish. iv. A developmental delay in the appearance oF light-detection in caveFish embryos v. Upregulation oF two DNA repair genes, CPD phr and ddb2, in caveFish. This eFFect is accentuated in the wild, leading us to propose that dampening of the circadian clock in caveFish may be a by-product oF selection For raised expression oF DNA repair Family genes and light-induced genes. 3 By examining multiple aspects oF the circadian biology oF A. mexicanus surface and caveFish, the data presented in this thesis supports the hypothesis that the clock gives a fitness advantage through the provision of internal temporal order but suggests the clock may be partially reduced in aperiodic environments. 4 TABLE OF CONTENTS List of Figures ......................................................................................................................................................... 12 List of tables ........................................................................................................................................................... 15 Acknowledgements ............................................................................................................................................ 16 1 General introduction .................................................................................................................................. 18 1.1 General introduction to the circadian clock ............................................................................ 20 1.2 Circadian clock organisation .......................................................................................................... 22 1.3 The molecular circadian clock ....................................................................................................... 22 1.4 Zebrafish and the circadian clock ................................................................................................ 25 1.4.1 The molecular clock oF zebraFish ......................................................................................... 27 1.5 Light input to the zebrafish circadian clock ............................................................................ 30 1.5.1 Detection oF light by the zebraFish clock .......................................................................... 30 1.5.2 Transduction oF light ................................................................................................................ 32 1.5.3 Development oF the light input pathway and circadian clock ................................ 35 1.6 Cave animals ......................................................................................................................................... 37 1.6.1 Clocks in cave animals and the adaptive value of clocks .......................................... 39 1.6.2 Astyanax caveFish as a model system ................................................................................. 42 1.7 Thesis aims ............................................................................................................................................ 46 2 Materials and Methods .............................................................................................................................. 47 5 2.1 Biological materials ........................................................................................................................... 48 2.1.1 Animal husbandry ...................................................................................................................... 48 2.1.2 Embryo collection ...................................................................................................................... 48 2.1.3 Astyanax cell lines ...................................................................................................................... 49 2.1.4 TransFection oF cells .................................................................................................................. 49 2.2 Field studies .......................................................................................................................................... 50 2.3 Laboratory experiments .................................................................................................................. 51 2.3.1 Adult Fish ........................................................................................................................................ 51 2.3.2 Embryo experiments ................................................................................................................ 52 2.3.3 Cell lines ......................................................................................................................................... 53 2.4 RNA extraction and cDNA synthesis ........................................................................................... 53 2.5 Cloning Astyanax genes .................................................................................................................... 54 2.6 Quantitative PCR ................................................................................................................................. 57 2.6.1 Assay ................................................................................................................................................ 57 2.6.2 Primer design and veriFication ............................................................................................. 57 2.6.3 Assay setup ................................................................................................................................... 58 2.6.4 Data analysis ................................................................................................................................. 60 2.7 Behavioural studies ........................................................................................................................... 60 2.8 Whole mount in situ hybridisation ............................................................................................. 60 2.9 DNA repair assays ............................................................................................................................... 62 6 2.9.1 Quantitation of repair of UV-induced DNA damage by ELISA ................................ 62 2.10 Overexpression oF CPD phr in zebrafish cells ...................................................................... 63 2.10.1 Tol2 system recombination (Kwan et al., 2007) ........................................................ 63 2.10.2 TransFection oF zebraFish cells ........................................................................................... 64 3 Examination oF the circadian system oF Astyanax mexicanus in the laboratory .............. 65 3.1 Introduction .......................................................................................................................................... 66 3.2 Methods ................................................................................................................................................... 68 3.2.1 Biological materials ................................................................................................................... 68 3.2.2 Cloning of Astyanax mexicanus clock genes .................................................................... 68 3.2.3 Quantitative PCR ......................................................................................................................... 69 3.2.4 Behavioural studies ................................................................................................................... 69 3.3 Results ..................................................................................................................................................... 70 3.3.1 Analysis oF Astyanax surface and caveFish clock
Load more

Recommended publications
  • The Origins and Evolution of Sleep Alex C
    © 2018. Published by The Company of Biologists Ltd | Journal of Experimental Biology (2018) 221, jeb159533. doi:10.1242/jeb.159533 REVIEW The origins and evolution of sleep Alex C. Keene1,2,* and Erik R. Duboue1,3,* ABSTRACT times vary widely, ranging from less than 5 h to 10 h or more (Webb Sleep is nearly ubiquitous throughout the animal kingdom, yet little is and Agnew, 1970; Kronholm et al., 2006). Despite a widespread known about how ecological factors or perturbations to the appreciation for the diversity in sleep duration between and within environment shape the duration and timing of sleep. In diverse species, surprisingly little is known about the relationship between ’ animal taxa, poor sleep negatively impacts development, cognitive sleep and an animal s ecological and evolutionary history. abilities and longevity. In addition to mammals, sleep has been Large differences in sleep duration and timing among humans characterized in genetic model organisms, ranging from the suggests that existing genetic variation among individuals potently nematode worm to zebrafish, and, more recently, in emergent affects sleep (Hartmann, 1973; Kronholm et al., 2006; He et al., models with simplified nervous systems such as Aplysia and 2009). While many laboratory studies investigating the molecular jellyfish. In addition, evolutionary models ranging from fruit flies to mechanisms of sleep regulation have relied on highly inbred model cavefish have leveraged natural genetic variation to investigate the systems including mice, zebrafish and fruit flies, the study of sleep relationship between ecology and sleep. Here, we describe the in outbred populations has revealed that geographical location, contributions of classical and emergent genetic model systems to evolutionary history and naturally occurring genetic variation investigate mechanisms underlying sleep regulation.
    [Show full text]
  • Investigating the Genetic Basis of Altered Activity Profiles in the Blind
    Investigating the genetic basis of altered activity profiles in the blind Mexican cavefish, Astyanax mexicanus A dissertation submitted to the Graduate School of the University of Cincinnati in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Biological Sciences of the McMicken College of Arts and Sciences by by Brian M. Carlson B.S. Biology, Xavier University, May 2010 Committee Chair: Dr. Joshua B. Gross June 2015 ABSTRACT Organisms that have evolved to exploit extreme ecological niches may alter or abandon survival strategies that no longer provide a benefit, or may even impose a cost, in the environment to which they have adapted. Cave environments are characterized by perpetual darkness, isolation and relatively constant temperature and humidity. Accordingly, cave-adapted species tend to converge on a suite of regressive and constructive morphological, physiological and behavioral alterations, including loss or reduction of eyes and pigmentation, increased locomotor activity and reduction or alteration of behavioral rhythmicity. The cave environment and the associated changes in locomotor behavior make species of cavefish prime natural models in which to examine the complex genetic architecture underlying these behavioral phenotypes. The principal goal of this dissertation was to investigate the genetic basis of altered locomotor activity patterns in the blind Mexican tetra, Astyanax mexicanus. Initially, a custom locomotor assay rig and experimental protocols were developed to assess, characterize and compare activity patterns in surface and Pachón cavefish. The results of these assays clarified differences between the morphotypes, provided evidence that Pachón cavefish retain a weakly-entrainable circadian oscillator with limited capacity to self-sustain entrained rhythms and suggested that patterns in spatial “tank usage” data may be the result of a positive masking effect in response to light stimulus in both morphotypes.
    [Show full text]
  • 1 Immunocytochemical Identification and Ontogeny of Adenohypophyseal Cells in a Cave Fish
    Manuscript_Grandi et al 2016 1 Immunocytochemical identification and ontogeny of adenohypophyseal cells in a cave fish, 2 Phreatichthys andruzzii (Cypriniformes: Cyprinidae) 3 4 5 G. Grandi, M. Pezzi, M. G. Marchetti, M. Chicca 6 7 8 Department of Life Sciences and Biotechnology, University of Ferrara, via L. Borsari 46, 44100 9 Ferrara, Italy 10 11 12 13 Running title: Pituitary cell types in P. andruzzii 14 15 16 17 Author to whom correspondence should be addressed: 18 19 Gilberto Grandi 20 Department of Life Sciences and Biotechnology, University of Ferrara, via L. Borsari 46, 44100 21 Ferrara, Italy 22 Phone: ++39 532 455741 23 Fax: ++39 532 249761 24 Email: [email protected] 25 1 26 ABSTRACT 27 The morphogenesis of the pituitary gland and the chronological appearance of adenohypophyseal 28 cells were investigated for the first time in a blind cave fish, Phreatichthys andruzzii, by 29 immunocytochemistry. The adult adenohypophysis contained: a rostral pars distalis, with prolactin 30 (PRL) cells arranged in follicles and adrenocorticotropic (ACTH) cells; a proximal pars distalis 31 with somatotropic (GH), β-thyrotropic (TSH), β-gonadotropic type I (GtH I) and type II (GtH II) 32 cells; and a pars intermedia with α-somatolactin (SL), α-melanotropic (MSH) and β-endorphin 33 (END) cells. All regions were deeply penetrated by neurohypophyseal branches. At hatching (24 34 hours post-fertilization) the pituitary was an oval cell mass, close to the ventral margin of 35 diencephalon. The first immunoreactive cells appeared as follows: PRL at 0.5 days after hatching 36 (dah), GH and SL at 1.5 dah, END at 2 dah, TSH, ACTH and MSH at 2.5 dah, GtH I at 28 dah, GtH 37 II at 90 dah.
    [Show full text]
  • Variation in Cephalic Neuromasts Surface and Cave-Dwelling Fishes of the Family Amblyopsidae (Teleostei: Percopsiformes)
    Daphne Soares and Matthew L. Niemiller. Variation in cephalic neuromasts surface and cave-dwelling fishes of the family amblyopsidae (teleostei: percopsiformes). Journal of Cave and Karst Studies, v. 82, no. 3, p. 198-209. DOI:10.4311/2019LSC0115 VARIATION IN CEPHALIC NEUROMASTS SURFACE AND CAVE-DWELLING FISHES OF THE FAMILY AMBLYOPSIDAE (TELEOSTEI: PERCOPSIFORMES) Daphne Soares1,C and Matthew L. Niemiller2 Abstract Cave adaptation has led to unique sensory specializations to compensate for the lack of visual cues in aphotic sub- terranean habitats. As the role of vision is reduced or disappears, other sensory modalities become hypertrophied, allowing cave-adapted organisms to successfully detect and interact with their surrounding environment. The array of aquatic subterranean habitats, from fast-flowing streams and waterfalls, to quiet phreatic pools, presents a diverse palette to examine what possible sensory solutions have evolved against a backdrop of complete darkness. Mecha- nosensation is enhanced in many subterranean animals to such an extent that a longer appendage is recognized as a prominent troglomorphic adaptation in many metazoans. Fishes, however, not only interact with the environment using their fins, but also with specialized sensory organs to detect hydrodynamic events. We hypothesize that subterranean adaptation drives the hypertrophy of the mechanosensory lateral line, but that other environmental forces dictate the specific neuromast phenotype. To this end, we studied differences in the cephalic lateral line of the fishes in the North American family Amblyopsidae, which includes surface, cave-facultative, and cave-obligate species. None of the taxa we examined possessed canal neuromasts on the head. Primarily surface-dwelling species, Chologaster cornuta and Forbesichthys agassizii, possessed receded neuromasts throughout most of the head, with a few on papillae located in front of the nostrils and on ventral grooves on each side of the mouth.
    [Show full text]
  • Article Contrasted Gene Decay in Subterranean Vertebrates
    bioRxiv preprint doi: https://doi.org/10.1101/2020.03.05.978213; this version posted March 6, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 1 Article 2 3 Contrasted gene decay in subterranean vertebrates: insights from 4 cavefishes and fossorial mammals 5 6 Maxime Policarpo1, Julien Fumey‡,1, Philippe Lafargeas1, Delphine Naquin2, Claude 7 Thermes2, Magali Naville3, Corentin Dechaud3, Jean-Nicolas Volff3, Cedric Cabau4, 8 Christophe Klopp5, Peter Rask Møller6, Louis Bernatchez7, Erik García-Machado7,8, Sylvie 9 Rétaux*,9 and Didier Casane*,1,10 10 11 1 Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et 12 Écologie, 91198, Gif-sur-Yvette, France. 13 2 Institute for Integrative Biology of the Cell, UMR9198, FRC3115, CEA, CNRS, Université 14 Paris-Sud, 91198 Gif-sur-Yvette, France. 15 3 Institut de Génomique Fonctionnelle de Lyon, Univ Lyon, CNRS UMR 5242, Ecole 16 Normale Supérieure de Lyon, Université Claude Bernard Lyon 1, Lyon, France. 17 4 SIGENAE, GenPhySE, Université de Toulouse, INRAE, ENVT, F-31326, Castanet Tolosan, 18 France. 19 5 INRAE, SIGENAE, MIAT UR875, F-31326, Castanet Tolosan, France. 20 6 Natural History Museum of Denmark, University of Copenhagen, Universitetsparken 15, 21 DK-2100 Copenhagen Ø, Denmark. 22 7 Department of Biology, Institut de Biologie Intégrative et des Systèmes, Université Laval, 23 1030 Avenue de la Médecine, Québec City, Québec G1V 0A6, Canada. 24 8 Centro de Investigaciones Marinas, Universidad de La Habana, Calle 16, No. 114 entre 1ra e 25 3ra, Miramar, Playa, La Habana 11300, Cuba.
    [Show full text]
  • SOMALIA National Biodiversity Strategy and Action Plan (NBSAP)
    FEDERAL REPUBLIC OF SOMALIA National Biodiversity Strategy and Action Plan (NBSAP) December, 2015 The designations employed and the presentation of material in this document do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations and the SWALIM Project concerning the legal status of any country, territory, city or area of its authorities, or concerning the delimitation of its frontiers or boundaries. This document should be cited as follows: Ullah, Saleem and Gadain, Hussein 2016. National Biodiversity Strategy and Action Plan (NBSAP) of Somalia, FAO-Somalia. Contents Executive Summary .................................................................................................................... 6 CHAPTER 1: INTRODUCTION ............................................................................................. 12 1.1. Background to the National Biodiversity Strategy and Action Plan: ............................. 12 1.2. Overview of the NBSAP development process in Somalia ........................................... 12 1.3. Structure of the National Biodiversity Strategy and Action Plan .................................. 16 1.4. Understanding biodiversity ............................................................................................ 17 1.5. Importance of biodiversity ............................................................................................. 17 1.6. Generic Profile of Somalia ............................................................................................
    [Show full text]
  • National Biodiversity Strategy and Action Plan
    FEDERAL REPUBLIC OF SOMALIA National Biodiversity Strategy and Action Plan (NBSAP) April, 2015 (Draft) 1 2 Executive Summary The context setting for this NBSAP was done with the two fold objective of creating a shared understanding of biodiversity among the stakeholders at the national and regional level in Somalia; and aligning their understanding as well as commitment to biodiversity conservation with the overall CBD strategic framework 2011-2020. The CBD definition of biodiversity, “the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes which they are part; this includes diversity within species, between species and of ecosystems” is adopted. The importance of biodiversity is encapsulated at Ecosystem Goods and Services (EGS) level, commencing from the provisional services to life supporting systems such as watersheds, etc. The link of overall Somali economy with biodiversity is explained as the direct and indirect contribution of biodiversity towards the economy goes beyond 80%. This can be justified while looking at the watershed and nutrient cycles support to agriculture and livestock sectors. The EGS also feed the energy requirements through elements such as charcoal, etc. Another contribution of the biodiversity is enhancing resilience on the face of disasters – natural and man made. The status of biodiversity of Somalia was assessed in the context of two larger biodiversity hotspots, predominantly Horn of Africa and a southern encroachment Coastal Forests of Eastern Africa Hotspot. This was further elaborated on the basis of six eco-regions of the country, five terrestrial regions and one aquatic/coastal region.
    [Show full text]
  • Università Degli Studi Di Ferrara
    Università degli Studi di Ferrara DOTTORATO DI RICERCA IN BIOLOGIA EVOLUZIONISTICA E AMBIENTALE CICLO XXVII COORDINATORE Prof. GUIDO BARBUJANI Molecular and Bioinformatic Analysis of the Circadian Clock in Phreatichthys andruzzii Settore Scientifico Disciplinare BIO/05 Dottorando Tutore Dott. NEGRINI PIETRO Prof. BERTOLUCCI CRISTIANO Anni 2012/2014 2 TABLE OF CONTENTS Page Abstract (English)...…………………………………………………............................7 Abstract (Italiano)...........................................................................................................9 I. Introduction………………………………………………....................................11 1.1 General aspects of the circadian clock……………………………………….13 1.1.1 Circadian pacemakers………………………..........................................................13 1.1.2 Molecular clock mechanism…………………………………………………….…15 1.1.3 Light input pathways……………………………………………………...…….…19 1.1.4 Temperature input pathway………………………………………...……………..21 1.1.5 Output pathways…………………………………………………………………...22 1.2 Zebrafish as a circadian clock model system……………...………………22 1.2.1 Zebrafish circadian clock genes…………………………………………….……..24 1.2.2 Zebrafish light input pathway……………………………………………………..24 1.2.3 Zebrafish temperature input pathway…………..…………………………..……27 1.2.4 The role of the SCN and pineal gland in zebrafish…….…………………..…….27 1.2.5 Circadian clock outputs in zebrafish………………………………………….…..28 1.3 Cavefish as a new circadian clock model system………………..…….….29 1.3.1 Life in the darkness: special features of cave inhabitants………………….…....29
    [Show full text]
  • Evolution of Eye Development in the Darkness of Caves: Adaptation, Drift, Or Both? Sylvie Rétaux1* and Didier Casane2
    Rétaux and Casane EvoDevo 2013, 4:26 http://www.evodevojournal.com/content/4/1/26 REVIEW Open Access Evolution of eye development in the darkness of caves: adaptation, drift, or both? Sylvie Rétaux1* and Didier Casane2 Abstract Animals inhabiting the darkness of caves are generally blind and de-pigmented, regardless of the phylum they belong to. Survival in this environment is an enormous challenge, the most obvious being to find food and mates without the help of vision, and the loss of eyes in cave animals is often accompanied by an enhancement of other sensory apparatuses. Here we review the recent literature describing developmental biology and molecular evolution studies in order to discuss the evolutionary mechanisms underlying adaptation to life in the dark. We conclude that both genetic drift (neutral hypothesis) and direct and indirect selection (selective hypothesis) occurred together during the loss of eyes in cave animals. We also identify some future directions of research to better understand adaptation to total darkness, for which integrative analyses relying on evo-devo approaches associated with thorough ecological and population genomic studies should shed some light. Keywords: Astyanax, lens, retina, transcriptome, population biology Review Nevertheless the amplitude of variation of many environ- The cave environment mental parameters, in particular temperature, is much less Water- and air-filled cavities are abundant in all conti- than that of the surface habitats [2]. nents but Antarctica. North America and Eurasia are es- pecially rich in cave-bearing rocks. Actually, more than 94% of the world’s unfrozen freshwater is stored under- The diversity of cave animals ground.
    [Show full text]
  • Reproduction, Development, Asymmetry
    A peer-reviewed open-access journal Subterranean Biology 38: 91–112 (2021) doi: 10.3897/subtbiol.31.60691 RESEARCH ARTICLE Subterranean Published by https://subtbiol.pensoft.net The International Society Biology for Subterranean Biology Reproduction, development, asymmetry and late eye regression in the Brazilian cave catfish Ituglanis passensis (Siluriformes, Trichomycteridae): evidence contributing to the neutral mutation theory Sandro Secutti1, Eleonora Trajano2 1 Núcleo da Floresta – Núcleo de Pesquisa e Extensão em Fauna e Flora. Av. Marcos Penteado de Ulhôa Rod- rigues, 4446 – CEP. 06543-001, Santana de Parnaíba-SP, Brazil 2 Instituto de Biociências da Universidade e São Paulo. Rua Nobre Vieira 364 – CEP 05587-180, de São Paulo, Brazil Corresponding author: Eleonora Trajano ([email protected]) Academic editor: Horst Wilkens | Received 12 November 2020 | Accepted 4 March 2021 | Published 19 April 2021 http://zoobank.org/A5132226-180C-42A7-96F5-A769212D7090 Citation: Secutti S, Trajano E (2021) Reproduction, development, asymmetry and late eye regression in the Brazilian cave catfish Ituglanis passensis (Siluriformes, Trichomycteridae): evidence contributing to the neutral mutation theory. Subterranean Biology 38: 91–112. https://doi.org/10.3897/subtbiol.31.60691 Abstract The troglobitic (exclusively subterranean source population) catfishItuglanis passensis (Siluriformes, Tricho- mycteridae) is endemic to the Passa Três Cave, São Domingos karst area, Rio Tocantins basin, Central Bra- zil. This unique population presents variably reduced eyes and melanic pigmentation. We describe repro- duction and early development in this species based on a spontaneous (non-induced) reproductive-event that occurred in the laboratory in January–February, 2009, while simultaneously comparing with data from the cave-habitat and a previous reproductive event.
    [Show full text]
  • Effets Des Informations Chimiques Provenant D'un Milieu Habitã© Par
    Int. J. Speleol. 12 (1982) pp. 103.117 Effets des informations chimiques provenant d'un milieu habite par des congeneres sur I'orientation topographique du poisson cavernicole Phreatichthys andruzzii Vinciguerra (Pisces, Cyprinidae).* R. Berti•• , G. Thines••• et B. Lefevre." SUMMARY Two series of experiments were performed on the oriented locomotor reo sponses of 27 specimens of the blind cave fish Phreatichthys andruzzii from Somalia using a three-compartment choice apparatus. The oriented re- sponses were observed individually from the central compartment towards either of the extreme ones. In one of them, 500 ml water were introduced from either the tank in which the test fish had previously resided with con- specifics (1st series, 46 experiments) or from another tank occupied by un- known conspecifics, the other compartment receiving an equivalent volume of pure water. The two series were peI'formed in random blocks of 6 expe. riments, the momentary position of the test fish ,being noted every 30 seconds after an adaptation period of at least 4 hours. Results, analyzed in 9 blocks of 5 minutes show a definite preferential orientation of the fishes for the compartment containing chemical information from both known or unknown conspecifics. This effect is discussed in relation to the ecological conditions in which the species rmder study lives. INTRODUCTION Le role des stimulations sensorielles susceptibles de determi- ner l'orientation de la locomotion chez les poissons cavernico- les a ete principalement etudie, a l'origine, sous Ie rapport de la stimulation photique et, secondairement, sous Ie rapport de Recherche effectuee a~ec l'aide du Centro di Studio per la Faunistica ed Ecologi'a Tropicali del Consiglio Nazionale delle 'Ricerche (nil'.
    [Show full text]
  • Behavioural and Morphological Changes Caused by Light Conditions in Deep-Sea and Shallow-Water Habitats Introduction
    ZOBODAT - www.zobodat.at Zoologisch-Botanische Datenbank/Zoological-Botanical Database Digitale Literatur/Digital Literature Zeitschrift/Journal: Biosystematics and Ecology Jahr/Year: 1996 Band/Volume: 11 Autor(en)/Author(s): Parzefall Jakob Artikel/Article: I. Light. Behavioural and morphological changes caused by light conditions in deep-sea and shallow-water habitats. In: Deep Sea and Extreme Shallow-water Habitats: Affinities and Adaptations. 91-122 Uiblein, F., Ott, J.,©Akademie Stachowitsch, d. Wissenschaften M. (Eds): Wien; downloadDeep-sea unter and www.biologiezentrum.at extreme shallow-water habitats: affinities and adaptions. - Biosystematics and Ecology Series 11:91-122. Behavioural and morphological changes caused by light conditions in deep-sea and shallow-water habitats J. PARZEFALL Abstract: Animals living permanently in the total darkness of caves and those living in the ocean at depths below 1200 m seem likely to share morphological and behavioural specializations due to the lack of light. Both these habitats can in general be characterized as old, climatically stable, and non-rigorous. But there are also differences: the presence of luminous organs and drumming organs is restricted to deep-sea animals only. Cave dwellers - except inhabitants of phreatic waters - do not have to live under high hydrostatic pressure. Deep-sea species, unlike the cave-living ones, are not isolated in smaller habitats. These facts will be used to compare morphological reductions of visual organs and pigmentation in fish and invertebrates as well as the progressive traits in other sensory systems. Besides these changes, the behaviour of various characters also differs compared with epigean relatives. These include phototactic behaviour, locomotory activity, food and feeding, reproduction, aggression, dorsal light reaction, and circadian clock.
    [Show full text]