Caecilians and Salamanders: Characteristics, Families, and Phylogeny, Study notes of Animal Biology

Download Caecilians and Salamanders: Characteristics, Families, and Phylogeny and more Study notes Animal Biology in PDF only on Docsity! 1 The diversity and evolution of Amphibia: What are they and where did they come from? Lecture goal To familiarize students with characteristics of the Class Amphibia, the diversity of extant amphibians, and the fossil record of amphibians. Reading assignments: Wells: pp. 1-15, 41-58, 65-74, 77-80 Supplemental readings on amphibian taxa: Wells: pp. 16-41, 59-65, 75-77 Lecture roadmap Extant amphibian orders Amphibian fossil record and evolution Characteristics of amphibian orders and diversity Characteristics of amphibians 2 What are amphibians? These foul and loathsome animals are abhorrent because of their cold body, pale color, cartilaginous skeleton, filthy skin, fierce aspect, calculating eye, offensive smell, harsh voice, squalid habitation, and terrible venom; and so their Creator has not exerted his powers to make many of them. Carl von Linne (Linnaeus) Systema Naturae (1758) What are amphibians? Ectothermic tetrapods that have a biphasic life cycle consisting of anamniotic eggs (often aquatic) and a terrestrial adult stage. Orders: •Anura (frogs) •Caudata (salamanders) •Gymnophiona (caecilians) Kingdom: Animalia Class: Amphibia Phylum: Chordata Subphylum: Vertebrata Subclass: Lissamphibia (amphibios: “double life”) Amphibia characteristics 1) Cutaneous respiration 2) Skin glands Oxygen and CO2 Transfer Family Plethodontidae Gills (larvae, few adult salamanders), 2 Lungs (adults) Mucous glands Granular glands Plethodon dorsalis 5 Caecilian families 3) Typhlonectidae (Aquatic Caecilians) •14 species (8%) •Primary annuli •No true tail •Strongly aquatic •Zygokrotaphic skull Chthonerpeton indistinctum •Viviparous Chthonerpeton indistinctum Typhlonectes compressicauda Caecilian families 4) Rhinatrematidae (Beaked Caecilians) •9 species (5%) •Primary annuli with secondary & tertiary annuli •True tail •Oviparous •Zygokrotaphic skull •Primitive family Epicrionops bicolor Rhinatrema bivittatum Epicrionops bicolor Caecilian families 5) Scolecomorphidae (Tropical Caecilians) •6 species (4%) •Primary annuli •No true tail •Some are viviparous •Zygokrotaphic skull 6) Uraeotyphlidae (Indian Caecilians) •5 species (3%) •Primary annuli with secondary annuli •True tail •Stegokrotaphic skull •Calcified spines on phallodea Scolecomorphus vittatus Uraeotyphlus 6 Caecilian phylogeny Rhinatrematidae Ichthyophidae Uraeotyphlidae Scolecomorphidae Caecilidae Typhlonectidae Primitive Derived 1 Loss of tail Loss of secondary annuli Viviparous/Direct Development Stegokrotaphic skull 2 4 4 3 Caecilian morphology and ecology Some other topics to explore on your own 1. Modes of locomotion 2. Burrowing 3. Sensory systems Caudata (Salamanders) Characteristics: •Tails and superficially segmented bodies •Well-developed limbs (except aquatic) •Internal fertilization (most) •Pheromones (mucous glands) •Larval development external (most) •Lack tympanum & middle ear Mostly Temperate Distribution 10 Families •Regenerate lost limbs 7 Salamander families 1) Plethodontidae (Lungless salamanders) •378 species (68%) •Found in the US and New World Tropics •Cutaneous respiration •Nasolabial groove (chemoreception) •Reduced skull •Eggs usually guarded Bolitoglossa adspersa Hydromantes supramontis Oedipina gracilis Thorius papaloae Pseudoeurycea bellii Movie Salamander families 2) Salamandridae (True salamanders) •74 species (13%) •Found in the US and SE Asia •Lungs •Toxic skin with bright coloration •Free-swimming larvae in most species Triturus pygmaeus Tylototriton shanjing Neurergus crocatus Neurergus kaiseri Triturus dobrogicus Salamander families 3) Hynobiidae (Asian salamanders) •51 species (9%) •Found in Asia •External fertilization •Reduced lungs in most species •Teeth are in patches Salamandrella keyserlingii Ranodon sibiricus Pachyhynobius shangchengensis Onychodactylus japonicus Hynobius tsuensis Batrachuperus pinchonii 10 Anura (Frogs and Toad) Characteristics: Global Distribution 29 Families •Shortened presacral vertebrate (usually 8) •Ribs are reduced or absent (2nd or 4th) •Presacral vertebrae firmly articulated •External fertilization (usually) •Large hind limbs, no tail (except 1 family) •Flat heads and large mouths (usually) •Vocal sacs in males (usually) Saltatorial 2-10X BL Video Anuran families 1) Leptodactylidae (Southern Frogs) •1283 species (24%) •Found in the New World Tropics •Males brood eggs •Foam nests •Varied life history (tadpoles, direct dev., viviparous) •Eggs usually guarded Lithodytes lineatus Eleutherodactylus coqui Leptodactylus mystacinus Pleurodema thaul Ceratophrys ornata Telmatobius culeus Anuran families 2) Hylidae (Tree Frogs) •835 species (15%) •Global distribution •Toe discs •Good climbers and jumpers •Free swimming tadpoles (most) Anotheca spinosa Cruziohyla calcarifer Dendropsophus berthalutzae Hylomantis lemur Pachymedusa dacnicolor Triprion petasatus Scinax garbei 11 Anuran families 3) Ranidae (True Frogs) •799 species (14.7%) •Global distribution (Africa and Asia most) •Well-developed legs and webbed feet •Free swimming tadpoles (most) Ceratobatrachus guentheri Micrixalus saxicola Tomopterna tuberculosaStaurois natator Rana warszewitschii Pyxicephalus adspersus Platymantis vitiensis Anuran families 4) Bufonidae (True Toads) •493 species (9%) •Global distribution •Cutaneous glands •Teeth nearly absent •Bidder’s organ Nectophrynoides asperginis Atelopus crucigerPedostibes hosii Melanophryniscus stelzneri Crepidophryne chompipe Bufo superciliaris Anuran families 5) Microhylidae (Narrow-mouthed Frogs) •449 species (8%) •Mostly tropical and subtropical •2-3 palatal folds •Stout hind legs, short snouts, and globose bodies •Breviceps - males produce secretions to stick to females Scaphiophryne madagascariensis Rhombophryne testudo Relictivomer pearsei Phrynomantis bifasciatus Myersiella microps 12 Anuran families 6) Rhacophoridae (Asian Tree Frogs) •288 species (5%) •Africa, India, SE Asia •Hanging foam nests •“Flying Frogs” •Flash coloration on inner thigh Polypedates cruciger Polypedates otilophus Rhacophorus reinwardtii Theloderma corticale Nyctixalus pictus Specimen Anuran families 7) Hyperoliidae (African Tree Frogs) •261 species (4.8%) •Africa, Madagascar, Seychelles •Pupil vertically elliptical •Toe discs •Brightly colored Afrixalus fornasini Heterixalus tricolor Hyperolius marmoratus Kassina kuvangensis Leptopelis vermiculatus Anuran families 8) Dendrobatidae (Poison Arrow Frogs) •252 species (4.7%) •Found in Central and South America •Brightly colored and toxic skin •Most very small (<1 inch) •Males wrestle for dominance •Tadpole ride on males back Dendrobates tinctorius Video Dendrobates imitator 9) Mantellidae (Mantellas) •164 species (3%) •Madagascar only •Brightly colored and toxic skin •Most very small (<1 inch) •Some convergent with Dendrobatidae Mantella madagascariensis Tsingymantis antitra Laliostoma labrosum 15 Anuran families 27) Allophrynidae (Ruthven’s Frog) •1 species (<0.1%) Allophryne ruthveni •NE South America •Little known about its ecology •Centrolenidae (related?; foot muscle morphology) 28) Nasikabatrachidae (Purple Frog)•1 species (<0.1%) Nasikabatrachus sahyadrensis •India (discovered 2003) •Fossorial •Explosive breeders •Little known 29) Rhinophrynidae (Mexican Burrowing Toad) •1 species (<0.1%) •Costa Rica to Rio Grande •Fossorial •Explosive breeders •Termite and ant specialists •No teeth Rhinophrynus dorsalis Anuran phylogeny Primitive Derived Anuran morphology and ecology Some other topics to explore on your own 1. Habitat associations of adult anurans 2. Body size and ecology of adult anurans 3. Adaptations for different life styles 16 Evolutionary history of Amphibia Events in Geologic History Fish to Tetrapods Tetrapods to Amphibians Geologic history Alfred Wegener Continental drift Events in geologic history (Mississippian) 350 MYA First Amphibians Modern Amphibians (late Permian) 250 MYA Carboniferous 17 Ecological history First tetrapods appeared in the Devonian (400 MYA) What were the conditions at this time? • Tropical/subtropical latitudes - relatively warm and stable • Primitive plants and arthropods Pangaea Fish to tetrapod transition Sarcopterygian (lobe-finned fishes) Panderichthys -Long snout -Dorsal eyes -Reduced median fins -Flattened bodies Tiktaalik -More developed limbs with wrist and finger bones (body postures) -Robust rib cage -Lungs and gills -Neck separated from body Eusthenopteron -Pelagic -Internal nostrils -Distinct humerus, ulna, and radius and femur, tibia, and fibula Fish to tetrapod transition Ichthyostega 1 m Acanthostega 0.6 m Greenland •Piscivorous •Limbs likely used for navigating •Lungs •Tail for balance •Skeletal structure forelimbs •Piscivorous •Fish-like •Limbs likely used for paddling Elbow could not bend •Skeletal structure •Gills and Lungs •8 digits