Herpetology Exam 2

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Amphibian/Reptile Physiology: What are the three ways of water gain?

Liquid Water, Performed Water, and metabolic water

Liquid water

performed via drinking

Performed water

Acquired via eating

Metabolic water

Acquired via productivity: size dependent

Why can't carnivores just get all water from their prey?

Lose water to excretion/respiration, can lead to water deficit, and small organisms produce more metabolically

Amphibian Physiology/Reptile: What are the three routes for water loss?

Evaporation, Respiratory, excretion/gestation

Evaporation

Loss via skin

Respiratory

Loss via opening to respiratory tract

Excretion/gestation

Loss to urine and feces

When are most amphibians active during the day and why might that be?

Dusk and Dawn - because it eliminates evaporation and temperature

Two modes exhibit by amphibians:

Ammonia and Urea

Ammonia

High solubility, High toxicity, Low water, and site of excretion is in the skin, gills, and cloaca

Urea

High solubility, low toxicity, mild water, and site of excretion in cloaca

What is a way to minimize water loss?

Posture - Laying flat, standing upright

Behavior:

Burrowing, astevation/cacooning, and wiping

Energy Balance for amphibian or reptile:

H gain = Qabs + M +- R+-C+-LE+-G

Energy exchange is

Bi-directional

Qabs

Absorbed radiation by surface of animal

M =

Positive metabolic heat reduction

C =

Heat gain or loss via convection

R =

In-fared radiation received or emitted by organism

Le =

Heat gained by condensation or loss via evaporation

G =

Heat gained or lost via conduction or direct contact with an animal

What about the equation for Qabs?

Qabs = SAVFS*a

S =

intensity of solar radiation

A =

surface area of animal

vfs =

proportion of exposed surface of animal to the sun

a =

absorvity - proportion of solar radiation that is absorbed by the animal

What are two temperature avenues?

Reduce absorvity and behavior to regulate conduction

The three Mechanisms of thermoregulation:

Heliotherm, Thirothermy, and thermoconformers

Heliotherm

Rely on solar radiation

Trigothermy

Rely on conduction

Thermoconformers

Do not regulate temperatures

Most amphibians are limited in ability to use behavioral thermoregulation, Why? Why is it beneficial?

Because surface area and breath rate are increased

Some Frogs waterproof their skin to minimize water loss, but can lead to overheating. How do they counteract?

Dissolve waxy coating of higher temperatures, open eyes help combat warm enviornments

Trouble with Temperature Long term physiological effects?

Evidence from species in the Appalachian mountains support the shrinking hypothisis

Mode exhibit by reptiles?

Uric acid

Uric acid

Is insoluble, low toxicity, low water usage, and site of excretion is in the cloaca

Reptiles

Reduce Qabs, not much in variation, and heat transfers from hotter to cooler surfaces

Reptiles depend on taxa:

Influences infrared absorption or emission and uses metamorphosis pigments for color

Endothermy hypothesis (Endothermy in ectotherms):

1. Aerobic capacity model - evolved as a means to facilitate aerobic capacity (adaption)

2. Parental care model - enhances metabolic activity during reproduction (ex-adaption)

Ecothermy in ectotherms:

Ecotherm metabolism should be low, rarely exceeds Ta by 1 degree Celsius, Needs more thermogenisis to do greater

H pit evolution

H1 evolved for prey aquisition, H2 evolved for other use of thermoregulation (Pits must appeared once in evolutionary history)

Amphibian: Reproduction is a process of intersection of ecology and evolution and why is it important?

It relates directly to fitness (environmentally influenced, whole organism trait syndrome, morphological, physiological, and behavior components)

Amphibian: Interacts with life cycles/Life history

Hormonal function, breeding season, variation in reproductive output, favors evolution of mating systems

Two types of reproduction:

Sexual - requires male and female gametes

Asexual - requires female gametes

Hybridogenisis:

Female hybrids produce gametes of only one parental species, female breeds with male parental species to main hybrid genotypes

Gynogenisis:

Females need the males sperm, rejects, and creates a fertilized egg.

Parthogenisis:

All female, can back cross to parental species and create new species

What type of fertilization do most amphibians have?

External

Adaptations for sperm transfer:

Anura: (Amplexus) Brings male and female cloaca as close as possible

Cuadata: spermatophore allows females to internalize male sperm

Cecilians: phallodium

What are the two reproductions for sex determination?

Genetic Sex Determination and Temperature Sex Determination

Genetic Sex Determination

One sex is hetero gametic and exhibits by most animals

Temperature Sex Dependent

Incubation temperature determines sex (males at intermediate temp and males at low temp - adaptive)

Who exhibits Genetic Sex Determination

All Amphibians

Parental Care

Survival - takes a lot of energy to invest

Form nests, clustering eggs in vegetation, and water sources

Gymnophionia (Naked snakes)

Females provide nutrients in a form of shed skin and directly maintain eggs. They keep eggs moist and bacterial fungus free. (Increased disease, drying out, etc.

Cuadata

Nest site selections - females choose protective areas to lay eggs.

Describe one key distinction between gynogenisis and parthenogenisis?

Gynogenisis requires rejected sperm and parthenogenisis only requires female

What non-amphibian family is well known for its use of parthenogenisis?

Teiidae (Whiptail/tegus)

Nest site construction

Storage of eggs in mucous bag like structures

Egg guarding

Females directly guard eggs and protects them from bacteria/fungi

Deamognathus fuscus

Mothers carry eggs to new areas (on their back)

Salamandridae atra

Mothers keeps eggs in Uterus and liberates young once they completely metamophisize

Importance of nest site selection:

Needs proper temperature and moisture, lack of predators and competitors, and timing with necessary environmental conditions

Reproduction of life histories (amphibians):

Gymnophiona: Larvae looks like adults, have gills, eyes, lack tentacles

Cudata: Larvae looks like adults, have gills, carnivorous

Anurans: Looks different, spend over 1 year as tadpole

When is reproduction most common?

Seasonal

Pond larvae

Ambystomatidae, Salamandridae

High body profile, broad tail fin, front legs at hatching, plume like gills

Stream larvae

Plethonidae

Depressed body profile, narrow tail fin, curvy gills, and 4 legs present at hatching

Caudata life histories: Salamandridae

Reproduce in ponds during spring and summer, metamorphisize 4 months, sexual maturation 4 years, 25 year life span

Ambyostomidae:

Reproduce in ponds, timing varies, metamorphisis in 2 years, maturation 5 years, life span 10 years

Plethonidae:

Reproduce in ponds or land, metamorphisis varies, 4 years to reach maturity, 10 year life span

Anuran life histories: Microhylidae

Aquatic tadpoles, reproduce without amplexus

Pelobatidae:

metamorphosis in 1 month, reproduce in permenant or ephemeral waters, maturity 1-2 years, lifespan 15 years

Bufonidae:

Reproduce in permanent or ephemeral waters early spring, metamorphosis 1-2 months, maturation 4-6 years, life span 15 years

Hylidae:

Reproduce in ponds early spring, metamorphisis 2 months, sexual maturation 1-2 years, lifespan unknown

Ranidae:

Reproduce in permanent waters early spring, 3-4 months to metamorphosis, 2-4 years maturation, life span 10 years

Reptile Reproduction:

Nest site selection: moist rotting logs, soil, humus, under rocks, mound nesting by crocidilians (most crocodiles defend aggressively)

Shivering Thermogenisis:

Production of heat increases metabolism of muscles

Nest site selection is very critical in GSD because:

it affects incubation time and development rate

Nest Site selection: Overwintering

Challenge is to gain enough energy to overwinter, most reptiles lay eggs in spring or summer, to give their hatchings about 2 months to store energy and grow and survive

Nest Site Overwintering (NSD)

Condition dependent, high resource abundance, lower predation risk (needs cover)

Operational sex ratio (OSR)

The ratio of males ready to mate with females. Theory predicts that if there is a shortage of breeding males females should produce more males.

What are the reproduction types of reptiles?

Sexual, asexual that can arise via hybridogenisis like amphibians

Life History Variation in major clades: Crocidilians and Testuidnes

Late maturing and long lived, clutch size 6-60, some females guard nest

Squamata:

Time for maturity varies from less than 9 months to less than 70 months

Evolution of TSD

Phylogenetic analyses suggest frequent transitions to TSD. Suggests high degrees of convergence and complex stories

Charnov Bull Hypothisis:

Tsd evolved as an adaptation to control OSR

Locomotion: Limbed locomotion

Most amphibians and many reptiles

Stout sprawling limbs and lateral undulations, bodies pressed against ground at rest, rise during motion

Lizard Locomotion

Four metatursals fused, fifth toe is a leverage and presses forward, allows for rapid acceleration and direction changes

Bipedal Locomotion

Only some lizards are able to, but only while running, used to escape predators, fringed toes create an air pocket while they run, tail holds as a counterweight, and support due to feet striking water and expanding air cavities

Turtle Locomotion

Locomative problems due to sternum, vertebrae, and ribs. Limb movements confined to shell opening.

On land: Raised up body, support on three feet, slowly one foot at a time to move forward

Anuran Locomotion:

Hind limbs enlarged, short, rigid vertebrae, Urostyle: fused internal tail and Illia flex strong site for muscle attachment

Jumping requires

Landing - The pectoral girdle helps support forelimbs and also acts as a shock absorber

1. Long high limbs - Jumpers and swimmers

2. short hind limbs - walkers, hopper,s runners

3. Both limbs short - walkers and burrowers

4. Long forelimb - climbers

Climbing Locomotion (Amphibians and reptiles Lizards and Frogs)

Amphibian toe pads - Stick via adhesion typically wetsurface, mucus produced by cells

Lizard toe pads - Adhesion is based on molecular attraction, requires close contact with surface,

Ariel locomotion

Anurans can parachute and the mechanism of webbing between toes allows this. (Spread out webbing, fore and hind limbs enlarged, able to adjust landing sites.

Squamata: Mechanism = skin extensions (Flattened body, extend skin, and can glide and direct landing)

Burrowing Locomotion:

Limb reduction and slender body form

Anurans - Limbs present but hind limbs modified for digging, throw soil upwards while burrowing

Squamates: Pointed, reinforced skulls, scales modified for digging

Aquatic locomotion:

Water provides support against gravity, density makes propulsion possible

1. Undulatory - produces waves of motion along the body

2. Oscillatory - moves limbs or fins back and forth, creates lift and thrust

3. Propulsive - kicked high limbs back in jumping motion

Limbless Locomotion:

Lateral Undulation - each curve of the body pushes against a rough surface, requires wide space and smooth surface

Sidewinding - Involves acute angles rewards along lagitudional body axis (most common in viperidae). Section by section is shifted from one axis to a parralel surface.

Rectilinear - Creep forward linearly, fixes certain segments while extending while drawing others in (best for heavy-bodied snakes)

Concerntina - Involves piling body up on one spot and extending or drawing rest forward and repeated. (energetically expensive)

From locomotion to spatial ecology

Within a species, individuals move in a set area, not defended from other individuals, typically encompasses 90-100 percent of resources. This is called a home range