WILD 3580 1st EditionExam# 2 Study Guide Lectures: 14-26Lecture 14 (February 11)Introduction to Amphibians I. Amphibian Evolution - Rhipidistians fishes: subclass Osteolepimorphio 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 eraII.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 gramsi. Minimizing overlap with other larger species between nichesii. Tendency to lose energy ectothermic iii. Smaller endothermic species have higher metabolic ratesb. Largest amphibian is the giant salamander (~5 feet) 3. Double lifea. 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 skinb. However, water can also be lost in drier environments 5. Toes lack claws or nailsIII. Ecological Roles - Mostly active at night no sun, higher humidity, maintain water (near water)o Hard to observe during the day timeo Easily to underestimate their importance 1. Invertebrate Predatora. Primary vertebrate predator in some areasb. Adult amphibians are carnivorous- feed on invertebrates c. Efficient at converting food to body mass  don’t have to maintainmetabolism, can convert food energy into growth and development 2. Plant “Predators”a. Larval amphibians feed on plants 3. Energy transfera. Between invertebrates and plants in higher tropic levelsb. Amphibians are the link between lower trophic levels to higher levelsIV. Skin- Water permeable- Functions: o Barrier between external and internal environments protection from pathogens and abrasionso Respirationo Absorption and release of water o Secretions to keep the skin moist o Protection through toxic secretions o Coloration- concealment or warning - Structureo Epidermis (outer layer) is divided into 3 sublayers  Stratum corneum- outer most layer-Dead cells that shed that are filled with keratino 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 -StructuralLesson 15(February 16)GlandsI. Pigments and Coloration- Chromatophores: cells containing pigmentso Usually in the stratum spongiosum- Structural Colorso Browns, blacks, greysMelanophore cells Eumelanin pigmentso 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 Iridophoreso Green- no pigments “zip-lock” effect Iridophores refract light that passes through the Xanthophores (yellow pigments)II. Skin Glands- Functions1. Mucous glandsa. Produce secretions to keep the skin moistb. Gases can cross the membrane c. Mostly on the dorsal surface 2. Poison Glandsa. More common in terrestrial speciesb. Defense mechanismc. More concentrated on the dorsal surface (head, back, and tail) areas that are most likely to affect predatorsd. Toxic could be distasteful or cause gag reflexes (foaming)i. F. Dendrobatidae- Poison Dart Frogs e. Sources to produce toxins come from foodf. Aposematic Coloration Warning colors- Predators learn to avoid that bright coloration- Leads to mimicry from other specieso 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 patterns3. Breeding Glandsa. Secretions that increase receptivity in femalesi. 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 drynessb. Adaptation from moving from an aquatic to a terrestrial environmentIII. 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 OrdersLesson 17 (February 20)Anuran ReproductionI. Frog calls - Make anurans expend a large amount of energy for callso Most energetic  amount increases with the rate of productiono 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