Exam 2 Flashcards
Amphibians in freshwater
- hyperosmotic
- actively sequester ions via gills and skin
Amphibians in brackish water
- Hypo-osmotic
- most amphibians would dehydrate in ocean water
How do spadefoots survive by being underground for 9 months a year
- start with a full bladder of dilute urine
- for first 7 months, their plasma and urine conc dont change
- for las 2-3 months, soil dries, toads ramp up their plasma osmolality and continue to extract moisture from soil
Cutaneous drinking
- dermal absorption of water
- primarily through the seat patch or pelvic patch or venter
- amphibians
Salamander grooves and annuli
- Costal grooves
- grooves and wrinkles on ventrum draw water from a wet surface up onto animal through capillary action
Water gains
- liquid water
- performed water
- metabolic water
Water loss
- evaporation
- urine and feces
- salt glands
Ammonotelic
-in aquatic env
Ureotelic
-in moist terrestrial env
Uricotelic
-in arid env
Aestivation
-dormancy and cocoon formation of dead epidermis or encapsulating dried mucous
Biogeography
-past and present distribution of animals
What is preformed water
-water that is derived from dietary components like starch, fat, protein
Metabolic rate in reptiles and amphibians
-generally low
O2 consumption rate in herps
-10-20% of similarly sized endothermic animals
Why do herps require much less energy overall
-lower resting rates and not at active temps much of the time
rank the metabolic rate of anurans, salamanders, and reptiles
salamanders < anurans < reptiles
-carnivores > herbivores
benefits of lower energy requirements
- lizards and snakes can go months without food between nesting seasons of birds
- geckos can store 9 months worth of food in 4 days of feeding
- spadefoot toads are active during summer and can spend 9 months underground
- lower energy requirements allow dependence on temporally clumped resources
Less oxygen required allows….
- animals to survive longer in anoxic env
- iguanas can escape predators by jumping into water and staying submerged for more than 30 min
red or dark meat
-muscles that rely primarily on oxidative respiration
Aerobic pathway: Cellular respiration/Oxidative metabolism
- break down of food into cellular energy
- oxygen and glucose must be transported thorough body
- efficient production of ATP per unit glycogen
- slow response time
Anaerobic: glycosis
- conversts cellular glycogen into lactic acid and ATP without the need for oxygen
- very fast at making small amounts of ATP
- build up of lactic acid
- temperature independent white muscle (light meat)
Variation in aerobic scope
- sit and wait predators have lower aerobic scopes than pursuit predators
- Anuran jumbers have a higher aerobic scope than hoppers (Rana vs Bufo)
What is the aerobic scope
-the difference between resting and peak metabolic rates
Costs of anaerobiosis
- animal is quickly depleted (often after 2-3 min)
- recovery via breakdown or conversion of lactic acid can last hours to days
How do gases cross moist cell membranes
-gases can only cross cell membranes when they are dissolved in water or an aqueous solution
Gas exchange
- all amphibians and some reptiles can use both air and water as a respiratory medium
- requires a moist membrane
- drying of membranes is always a problem
Sites of gas exchange
- lungs (pulmonary) all reptiles, many amph
- surface of skin, pharynx, cloaca (nonpulmonary)
lungs and respiratory movements of turtles (pulmonary)
- negative pressure ventilation
- involves increasing volume of thoracic cavity to create negative pressure
- leads to a passive influx of air
Buccal pump (pulmonary)
- positive pressure ventilation
- used by amphibians with lungs
- involves the glottis, expanding and contracting of buccal cavity, and lungs
Snake pulmonary respiration (pulmonary)
- no diaphragm
- narrow rib cage to push air out and then widening it again
- apnea occurs after each breathing cycle
- mostly right lung
Gas exchange in aquatic species
- running water carries CO2 away and brings oxygenated water in contact with skin
- skin folds are used as gas-exchange structures
Skin appendages
- external lung hair-like filaments
- appear during mating season when oxygen demands are high
- can be used to supply eggs guarded by male
cutaneous respiration in reptiles
- up to 30% total gas exchange
- via scale hinge-interscaler spaces in lizards, snakes, turtles
- all gas exchange in seasnakes is cutaneous
Buccopharynx
- minor surface for normal respiration
- vital for long term submergence in some species like hibernation
Cloaca
-used in some turtles for gas exchange when submerged
Sites of gas exchange (pulmonary vs nonpulmonary)
- Pulmonary: lungs, negative-pressure ventilation
- Non-pulmonary: skin, gills, pharynx, cloaca
External fertilization in salamanders
- eggs
- ancestral condition
- sirenidae, cryptobranchidae, hynobiidae
Internal fertilization in salamanders
- ~90% of sal spp
- most produce spermatophores
- males attempt to interests a female to pick up sperm packet with their cloaca
Pheromones in salamanders
- used for reproduction
- increase female receptivity
- scratching pheromone delivery by two lined sal
sperm storage by salamanders
- accomplished by females in specialized tubules
- leads to possibility of sperm competition
- flexibility in terms of female mate choice
- greater sexual selection may lead to evolution of courtship
Egg symbioses
- local phenomenon involving a unicellular green algae
- found in stagnant water and soils
- extremely abundant in inner envelope of eggs and gives egg masses a green hue
elements of egg symbioses
- -algae produces O2
- algae consume CO2 and N-rich waste produced by developing embryo
- increases fitness and protection against bacteria
Heterochrony
-the difference between timing of development between an ancestral form and a derived one
Cause of heterochrony
-delayed secretion of the thyroid hormone thyroxine delays metamorphosis
Neoteny
- the retention of juvenille features in the adult animal
- commonly in Notophthalmus and Amybstoma
When can neoteny become viable
-in populations inhabiting permanent aquatic habitats where fishes are rare or absent
All anurans have _____ fertilization
- external (amplexus)
- internal in only a few spp
secondary sexual characteristics in anurans
- changes in coloration
- nuptial pad (helps male grasp around female)
Prolonged breeders
- permanent habitats and social systems predicated on female choice
- Green frogs and bullfrogs
Explosive breeders
- ephemeral habitats and spp whose reproduction is strongly cued by environmental stimuli
- males may emit release calls when amplexed by another male
- wood frogs, spadefoots
Communal dumping
- wood frogs lay their eggs together
- suns rays increase egg temperatures 3-5 degrees C above the surrounding temp
- promotes tiny water currents through the egg masses increasing the availability of oxygen
anuran reproduction in tropics
- incredibly diverse
- trend towards terrestriality
- on leaves over water
- foam nests
Parental care in anurans
- female dorsal pouch (Gastrotheca spp)
- eggs embedded in back (pipa pipa)
- carried in male vocal sacs (Darwin’s frog)
Reproduction in caecilians
- internal fertilization via phallodeum
- can be viviparous (~75%) or oviparous
Parental care in caecillians
-Dermatophagy: in oviparous spp – young feed on mothers enriched skin cells
ALL reptiles have ____ fertilization
-internal
Hydraulic intromittent organs
-hemipenes in squamates
hemipenes
- paired evaginations in the wall of the cloaca that are everted to expose a complex surface
- one is used at a time
- has spines or hooks used as anchors
Sperm storage
- known in all reptile groups
- especially common among turtles
Oviparity
- egg laying
- al turtles and crocs
- some squamates
Viviparity
- live bearing
- only in squamates (snakes, lizards, and amphibaenids)
- has evolved independently at least 103 times
Reptile eggs
- huge size variation among species (300g to .1 g)
- has two layers
Reptile egg structure
- Embryo
- Amnion: cushion membrane
- Yolk sac: nutrition
- Allantois: waste sac
- Chorion: membrane immediately inside shell
- Albumin: egg white
- Shell: hard or leathery
Egg teeth
- assists in hatching by splitting the inner membrane and cracking the outer membrane of the egg
- it is not a true tooth and is resorbed
Cold env hypothesis for viviparity
-viviparity is increasingly common where the env is too cold or growing season is too short to allow normal development
Sex determination in reptiles
- genetic in most species
- mot turtles, crocs, tuatara, some squamates have temp sex determination
Type Ia TSD
-more femles than males are produced at higher temps
Type Ib TSD
-more males than females are produced at higher temps
Type II
Females are produced at low and high incubation tempes with males at intermediate temps
Female temp determination
- enzyme aromatase induced
- converts testosterone to estradiol which triggers more estrogen production
Male temp determination
- enzyme 5-reductase induced
- testosterone > dihydrotestosterone > testes development
Parental care
- nearly all crocs
- few squamates
- rare in turtles
Parthenogenesis
- reproduction without sex
- asexual
- desert grassland whiptail lizard
Pseudocopulation
- Aspidoscelis uniparens
- one female plays the role of the male
- increases gonadal activity
Flower pot snake
- Ramphotyphlops braminus
- invasiv
- a single female can start an entire new population
