WILD 3580 1st Edition Exam 2 Study Guide Lectures 14 26 Lecture 14 February 11 Introduction to Amphibians I Amphibian Evolution Rhipidistians fishes subclass Osteolepimorphi o Gave rise to amphibians terrestrial tetrapods Choanae internal nares connection between nasal cavity and respiratory system Maximum diversity during Carboniferous period Age of Amphibians in the Paleozoic era II Classification 3 Orders Anura frogs and toads most diverse 4700 species Caudata salamanders 475 species and Gymnophiona Caecilians 170 species 1 Ectothermic variable temperature body temperature depended on environment a Energetically inexpensive 2 Small body size a 90 of frogs and salamander species weigh less than 20 grams i Minimizing overlap with other larger species between niches ii Tendency to lose energy ectothermic iii Smaller endothermic species have higher metabolic rates b Largest amphibian is the giant salamander 5 feet 3 Double life a Many amphibians have a larval stage and an adult stage i Larvae Metamorphosis Adult 4 Skin lacks scales and is permeable to water a Some breath through their skins and absorb water through the skin b However water can also be lost in drier environments 5 Toes lack claws or nails III Ecological Roles Mostly active at night no sun higher humidity maintain water near water o Hard to observe during the day time o Easily to underestimate their importance 1 Invertebrate Predator a Primary vertebrate predator in some areas b Adult amphibians are carnivorous feed on invertebrates c Efficient at converting food to body mass don t have to maintain IV metabolism can convert food energy into growth and development 2 Plant Predators a Larval amphibians feed on plants 3 Energy transfer a Between invertebrates and plants in higher tropic levels b Amphibians are the link between lower trophic levels to higher levels Skin Water permeable Functions o Barrier between external and internal environments protection from pathogens and abrasions o Respiration o Absorption and release of water o Secretions to keep the skin moist o Protection through toxic secretions o Coloration concealment or warning Structure o Epidermis outer layer is divided into 3 sublayers Stratum corneum outer most layer Dead cells that shed that are filled with keratin o Keratin a dense fibrous structural protein Alpha keratin makes up softer structures hair skin nails ect amphibians only have this Beta keratin make up harder structures shells beaks scales ect Relatively thin layer compared to other vertebrates Ecdysis periodic shedding of skin o Amphibians eat the skin recycle nutrients o How often they shed depends on many factors Stratum granulosum middle layer where cells go to die Living cells die and are filled with keratin Keratin replaces the cytoplasm of the cells Stratum germinativum basal bottom innermost layer Cells that undergo mitosis o Dermis Stratum spongiosum Just below the epidermis Blood vessels glands and pigments Stratum compactum Binds the skin to the connective tissue and muscles Structural Lesson 15 February 16 Glands I Pigments and Coloration Chromatophores cells containing pigments o Usually in the stratum spongiosum Structural Colors o Browns blacks greys Melanophore cells Eumelanin pigments o Yellow oranges and red Xanthophore cells Pteridine pigments o White silver Iridophore cells no pigments Reflect light through guanine platelets o Blue no pigments Produced by refracting light on Iridophores o Green no pigments II zip lock effect Iridophores refract light that passes through the Xanthophores yellow pigments Skin Glands Functions 1 Mucous glands a Produce secretions to keep the skin moist b Gases can cross the membrane c Mostly on the dorsal surface 2 Poison Glands a More common in terrestrial species b Defense mechanism c More concentrated on the dorsal surface head back and tail areas that are most likely to affect predators d Toxic could be distasteful or cause gag reflexes foaming i F Dendrobatidae Poison Dart Frogs e Sources to produce toxins come from food f Aposematic Coloration Warning colors Predators learn to avoid that bright coloration Leads to mimicry from other species o Mimicry other species mimic the colors of a toxic species in order to reduce the risk of death Batesian Mimicry resemblance of a nontoxic mimic to a toxic model Model toxic species Mimic nontoxic species Ex Coral and Scarlet snakes Mullerian Mimicry resemblance of a toxic species to another toxic species Ex Monarch and Vicerory butterflies More opportunities for predators to learn Some come in patterns 3 Breeding Glands a Secretions that increase receptivity in females i Ex Tubular glands in Anurans and mental glands in Plethodontidae on chins ii Ex Genial glands in newts 4 Harderian Glands a Located in the corner of the eye that secretes a lubricant to prevent dryness b Adaptation from moving from an aquatic to a terrestrial environment III Breathing and Respiration Buccal pumping movements of the throat that creates a flow of water or air across the respiratory surface Positive pressure ventilation air is forced into the lung or across gills by raising the pressure in the buccal region Lesson 16 February 18 Amphibian Orders Lesson 17 February 20 Anuran Reproduction I Frog calls Make anurans expend a large amount of energy for calls o Most energetic amount increases with the rate of production o Lose weight and heart rate increases when producing calls o Reproduction success is relevant to the rate of production payoff Types of Calls o Advertisement call mating for advertise reproductive state sex and location of an individual species specific both sexes are toned in for these calls attracts females and warns other males to establish territorial boundaries many species use the same area breeding site is species specific commonly pool dry seasonally no fish evolve divergent sounds characteristics prevent sounds from getting swamped and acts as a premate isolation mechanism differ in pitch timber pulse frequencies durations and cadence volumes Typical breeding sequence males gather at breeding site and begin a chorus calling group attracting other males first and then females Females may go to a male directly to mate or they can choose a specific male o Courtship calls Becomes softer when female approaches Encourages females and cannot be heard by other males o Release call Non receptive females Males jump on non calling frog mistaking species and sex Similar species make similar release calls