amphibian biology 2014

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Diapositias sobre la biologia de anfibios del curso de Ecotoxicología de la Universidad de Aveiro 2014

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  • 07/04/2014

    1

    AmphibiansBiology, ecology and conservation topics

    and their applications in ecotoxicology

    Ecotoxicology of amphibians and reptiles: from theory to practice. Aveiro, April 2014

    Manuel Ortiz SantaliestraInstitute for Environmental Sciences University of Koblenz-Landau (Germany)

    ortiz@uni-landau.de

    Outline

    INTRODUCTION

    Origin and evolution

    Diversity

    LIFE HISTORY

    Breeding migrations

    Mating, fecundation and oviposition

    Eggs and embryonic development

    Larval development

    Metamorphosis

    Sexual determination

    Maturation and adulthood

    ENVIRONMENTAL PHYSIOLOGY

    Thermoregulation and water balance

    Excretory physiology

    Overwintering and aestivation

    Gaseous exchange

    ECOLOGY

    Habitat

    Feeding ecology

    Antipredatory strategies

    CONSERVATION

    Global decline

    Threats

    Outline

    INTRODUCTION

    Origin and evolution

    Diversity

    LIFE HISTORY

    Breeding migrations

    Mating, fecundation and oviposition

    Eggs and embryonic development

    Larval development

    Metamorphosis

    Sexual determination

    Maturation and adulthood

    ENVIRONMENTAL PHYSIOLOGY

    Thermoregulation and water balance

    Excretory physiology

    Overwintering and aestivation

    Gaseous exchange

    ECOLOGY

    Habitat

    Feeding ecology

    Antipredatory strategies

    CONSERVATION

    Global decline

    Threats

    Origin and evolution

    Geoff Simpson

    Dan Nedrelo

    Heidi & Hans-Jrgen Koch

    Dan L. Perman

    An uncompleted step towards the independence from water

    Amphibians = two lives Reptiles

    Origin and evolution Current diversity of amphibians

    Order Gymnophiona (Caecilians)

    200 species (all from Neotropic)

    Order Caudata (newts and salamanders)

    660 species (10 in the Iberian Peninsula)

    Chris Harrison

    Order Anura (frogs and toads)

    6396 species (19 in the Iberian Peninsula)

    http://amphibiaweb.org/ (updated on April 6th 2014)

  • 07/04/2014

    2

    Overview of Iberian amphibians

    African species crossing the Strait ofGibraltar during the Messinian period(5.5 million years b.p.)

    Eurosiberian species searching fromrefuge during Pleistocene glaciations(80,000 years b.p.)

    The cosmopolite Iberian batrachofauna (African, Eurosiberian and endemic species)

    Rana temporaria

    Pleurodeles waltl

    Iberian endemism originated byisolation, area reduction or habitatlimitation Chioglossa

    lusitanica

    Outline

    INTRODUCTION

    Origin and evolution

    Diversity

    LIFE HISTORY

    Breeding migrations

    Mating, fecundation and oviposition

    Eggs and embryonic development

    Larval development

    Metamorphosis

    Sexual determination

    Maturation and adulthood

    ENVIRONMENTAL PHYSIOLOGY

    Thermoregulation and water balance

    Excretory physiology

    Overwintering and aestivation

    Gaseous exchange

    ECOLOGY

    Habitat

    Feeding ecology

    Antipredatory strategies

    CONSERVATION

    Global decline

    Threats

    Reproductive modes variability: A key for successThe common reproductive strategy:

    Terrestrial adults

    Aquatic breeding, eggs and larvae

    Breeding migrations

    0

    50

    100

    150

    200

    25 40 55 70 85

    Ammonium nitrate dose (kg N / Ha)

    Tim

    e of

    ano

    mal

    ous

    effe

    cts

    (s)

    Adults migrate from winter refuges to breeding ponds

    Orientation by magnetic fields, firmament, chemical cues and conspecific or heterospecific calls.

    Risks:

    Road mortality

    Pollution in fields crossed during migrations

    2=23.204; N=28; p=0.001

    Ortiz-Santaliestra et al. (2005) Bull Environ Contam Toxicol 75, 662-669

    Impact of terrestrial ammonium nitrate application on Iberian newt

    Recommended level of application

    Mating and fecundation in AnuraMales arrive first. Two strategies depending on size (male quality):

    Bigger males attract females (deeper calls). They wait for females within the ponds territorialism

    Smaller males do not attract females. They wait for females outside the water to couplebefore their entering the ponds

    Amplexus (coupling). External fecundation

    Some exceptions:Internal fecundation

    (Ascaphus)

    Terrestrial amplexa (e.g., Alytes)

    Brad Moon Daniel Phillips

    Inguinal

    Axilar

    Cephalic

    Wells (2007) The Ecology and Behavior of Amphibians. Chicago University Press

    Mating and fecundation in Caudata

    Males arrive first and wait for females within the water

    Mating after courtships which end with spermatophore deposition (internal fecundation)

    Spermatophore deposition and pick up in a terrestrial courtship

    Oregon State University

    Some exceptions:

  • 07/04/2014

    3

    OvipositionAlthough most species are oviparous, there are ovoviviparous and viviparous species

    Alytes(~40 eggs)

    Bottom: low predation, high asphyxia

    Surface: high predation, low asphyxiaVegetation: low predation, high eutrophication

    Bufo(~3000-5000 eggs)

    Clutch size

    Where to lay?

    Streams: attached to stones, adapted to high O2 and water currents

    Terrestrial eggs

    Thomas Reich

    Oviposition

    Isolated masses

    Individual (newts)

    How to lay?

    Communal

    Andy Fion

    Henk.Wallays from Flickr

    Jenny Gitlitz

    Parental care of the eggs

    Foam nests (Chiromantis)

    Wrapped by plants (Triturus)

    Under stones or in cavities (Chioglossa)

    Attached to the plants (Hyla)Shallow water

    Direct parental protection

    Carrying out (Alytes)

    Covered by skin (Gastrotheca)

    Gastric brooding (Rheobatrachus)

    Jack Goldfarb

    Merike Linammgi

    Louise Mentjies

    Luis Bravo

    Kevin Johnson

    Egg protection beyond parental care

    Jelly coatFormed after absorptionof water once eggs havebeen laid

    UnpalatabilityCamouflage

    Dark top to camouflage against the bottom

    Bright bottom to camouflage against the surface

    Embryonic development

    Gosner (1960) Herpetologica 16, 183-190

    Risk of pollution during egg andembryonic stage:

    Removal of laying substrates

    Alteration of parental behaviours(oviposition, site selection, egg protection)

    Uptake of chemicals by jelly coat

    Maternal transfer of pollutants throughjelly coat

    Egg rotation

    Direct effects on embryonic development

    The frog embryo teratogenesis assay - Xenopus

    Standardized protocol to test teratogenesisStatic system

    Freshly deposited embryos of Xenopus laevis

    25 embryos per glass in 140 ml + g soil

    4 replicates (total 100 embryos)

    Environment: FETAX solution

    20-25 tadpoles per tank in 10-12.5 liters

    Duration: 96 hours

    Phase 1) Screening test: control + 100% sample

    Responses are expressed as percent effect

    Phase 2) Final test

    LC50

    EC50

    Description of abnormalities

    ASTM (2004) Report # E1439-98; Bantle et al. (1991) Atlas of Abnormalities: A Guide for the Performance of FETAX. OSU Press

  • 07/04/2014

    4

    Larval development

    Gosner (1960) Herpetologica 16, 183-190

    Anura

    Caudata

    Larval morphological adaptations

    Duelllman & Trueb (1994) Biology of Amphibians. John Hopkins University Press

    Mouth morphology and position

    Spiracle

    Pond (low O2) Stream (high O2)

    CAUDATA

    Pond, benthonic

    Pond, pelagic

    Stream

    ANURA

    Larval development

    Longer times(bigger tadpoles)

    Shorter times(smaller tadpoles)

    Juvenile survival

    Reproductive quality

    Avoid desiccation

    Avoid predation

    ? Avoid pollution ?

    Viviparity (S. salamandra)

    Duration: from hours to years

    Camouflage Unpalatability

    Parental care

    Exceptions:

    Direct development

    Protection Tom Ray

    Dendrobatidae Rhinoderma darwinii

    Fogdenphotos.com

    Eleutherodactylus sp.

    Grow or survive?

    Advantages of phenotypicplasticity

    Metamorphosis in Anura

    Changes:

    Respiratory system

    Digestive track

    Cranium and jaws

    Pelvic girdle

    Skin keratinization

    Vision organs (cones rods)

    Immunological modifications

    Gosner (1960) Herpetologica 16, 183-190

    Ecotoxicological interest:

    Mobilization of reserves

    Transport of accumulative chemicals from aquatic to terrestrial environment

    Metamorphosis. Hormonal control

    Amphibian metamorphosis assay for evaluation of EDCs:

    Flow-through system

    Water filtered and UV-treated

    20-25 tadpoles per tank in 10-12.5 liters

    Food: Sera Micron

    Duration: 14-21 days

    Endpoints:

    -Periodical monitoring of developmental stage and snout-vent length

    -Histological examination of thyroid gland at the end of the exposure

    Duellman & Trueb (1994) Biology of Amphibians. John Hopkins University Press; OECD (2004) Report #ENV/JM/MONO(2004)17

    Amphibian metamorphosis depends on thyroid hormones (major effects) and pituitary hormones

    Metamorphosis. Immunological overview

    -Development of adult immune system components +

    Maternal antibodies

    Larval immune system

    Developing adult immune system

    Developed adult immune system

    Rearrangement of immune defenses

    Destruction of some components of the larval immune system

    Thyroid hormones

    Glucocorticoids

    PerchlorateMalathion*Atrazine*

    *Known immunoto