Exam Flashcards
Ectotherm
Relies on external environment for heat
Endotherm
Make their own heat
What is the most important physiological variable for ectotherms?
Temperature
Temperature Tolerance Range
Range of temperatures between the boundaries of too hot and too cold
What do zebra-tailed lizards when the substrate is hot?
Curl up their toes and tails
Zone of Intolerance
Animal cannot survive and does not exist in this zone
Law of Tolerance Curve
Zone of intolerance at ends beyond the curve, survival zone at the ends of the curve, then growth, then greatest fitness in the centre (survival, growth, and reproduction)
Water and Salt Balance
Constant gradient/diffusion of salt and water in the body. Makes it more difficult to maintain internal balance
Why is a stable internal environment required for cells?
For metabolic processes
Water Flux
Water moves in an out of cells and bodies in a variety of ways
Why does water exchange differ between reptiles an amphibians?
Because their skin types differ
Routes of Water Transfer
Drinking (reptiles only), from food, across skin (amphibians mostly), metabolism, through highly vascularized tissues in the lining of the cloaca or esophagus
Uptake of Water by Amphibians
Across skin by osmosis and diffusion
Morphological Modifications of Amphibian Skin for Water Uptake
Smooth ventral skin in aquatic species and granular ventral skin of terrestrial species
Granular Ventral Skin
Dark spot on belly of terrestrial amphibians, made up of highly vascularized tissue for water uptake
Smooth Ventral Skin
Smooth, slippery skin of aquatic amphibians to help take up water
Granular Skin
Highly vascularized to enhance water absorption
Purpose of Costal Grooves on Salamanders
Channel water from underside to back
Uptake of Water by Reptiles
Drinking, methods vary by species. May drink from puddles, condensation drops in caves, or use body to channel water to mouth.
How do reptiles drink from condensation?
The water that evaporates in the desert is collected on the ceilings of caves, and the reptile drinks those drops.
How do reptiles use their body posture to drink?
Arch back and stretch out front arms to channel water down to their mouth
Rain Harvesting in Agamid Lizard
Honeycomb-shaped microstructures cover the surface of dorsal scales. There is a complex capillary system involved with the scale hinges. Water flow in these hinges is directed towards the mouth.
How do herps prevent water loss?
Must adjust behaviours and most would not last more than a day without them. Adjust daily/seasonal activity patterns. Seek humid retreats when inactive.
Anuran Burrowing and Water Retention
Burrow into the soil when it is moist and hunker down into a ball so there is less surface area for water loss. The soil is wet, they are protected by the wind, and the ground insulates them.
How does a Plains Spadefoot burrow?
Backwards, using horny/sharp/wedge-shaped feet that have a tubercle “spade” on them
How do Sandhill Frogs and Turtle Frogs burrow?
Frontwards, head-first, with small heads and strong arms
Aestivation
A dormancy period during seasonal drought and heat, like summer hibernation. Inactivity and metabolic depression help to prevent water loss.
Cocoon Formation in Anurans and Sirens
Make a cocoon of shedded skin layers around themselves, forming an impermeable sac with only their nostrils exposed, to reduce water loss during aestivation. When it finally rains after several weeks or months, they eat it.
How do anurans and sirens build their cocoons?
With a protective layer of skin cells. They shed and form a sheet around the body, and keep layering, and eventually form a thick opaque cocoon.
Measuring the Influence of Anuran Cocoons
Put frogs on wet and dry substrates to measure water flux. Cocooned frogs did not exchange significant amounts of water at either high or low substrate water potentials. The cocoon acts as a physical barrier to water exchange, not just to prevent evaporative water loss.
Aestivating Freshwater Crocodiles in Australia
Spend 3-4 months inactive, underground with no access to water
Aestivation in Turtles
Initially use water stored in bladder to osmoregulate. Blood chemistry parameters eventually increase. No metabolic depression other than regular responses to starvation.
Aestivation in Northern Spotted Turtles
Hyp: Avoid overheating and desiccation by aestivating when environmental temperatures increase.
Pred: Turtle body temp should be lower than ambient air and water temps during inactivity. Should choose aquatic sites for inactivity to avoid desiccation.
Conclusion: Avoidance of high summer temps and desiccation were not the reasons for aestivation behaviour, so may not really be aestivation.
Measuring Aestivation in Northern Spotted Turtles
Glued radiotransmitters on shell. Each has a different station. Should be representative of shell temperature. Faster beeps means hotter temperature of transmitter and therefore the shell (louder beep means the turtle is closer).
Northern Spotted Turtle Activity Cycle
Mating late April to mid June, nesting last 2 weeks of June, aestivation July to August in the hottest part of the summer, hibernation September to April in the winter
Waterproofed Frogs
Secretion of lipids/wax from skin glands, and the frog uses its hands to spread the lipids over the body surface to cover themselves in this wax to reduce water loss. Iridiphores are several layers thick and increase in number during dry season.
Iridiphores
Iridescent cells in skin of waterproofed frogs that reflect and send sunlight (and radiation) away to avoid overheating and stay cool
Water-Conserving Postures
Dehydrated or resting amphibians flatten their ventral surface close to the substrate (lay flat on belly) and fold arms and legs tightly underneath their body to minimize the amount of skin exposed to the air to prevent water loss.
Homeostasis
Maintenance of a relatively constant internal environment relative to variable external conditions. Requires some means of regulating body temperature, water balance, pH, and amount of salts in fluids and tissues.
Osmoregulation
Control of water and salt balance
Hypo-Osmotic Relative to Environment
On land and in salt water, the animal has more water/less salt than its surroundings, so water moves out of their body, potentially causing severe dehydration so they need to regulate it
Hyper-Osmotic Relative to Environment
In fresh water, the animal has less water/more salt than its surroundings, so water moves inward, potentially causing cells to burst so they need to regulate it
Reptiles in Saline Environments
Salt glands (nasal glands/lacrimal glands) aid in the removal of salt. Marine iguanas sneeze salt. Sea turtles/snakes shed salt through tears. Some reptiles move away for a bit when a saltwater tide comes in.
Anhomeostasis of Desert Tortoise
Concentrations of solutes in body increase with increasing dehydration. Huge bladder acts as a reservoir to draw from until they are iso-osmotic to their environment to maintain homeostasis. Once they can no longer keep up, they let the solute concentration in their body go wild, drink like crazy, and flush it all out. When it rains, they drink a whole bunch again to store up their bladder for next time.
Anhomeostasis of Ctenophorus ornatus
Eat ants that have high sodium content, but the only way to secrete sodium is with urine, requiring a substantial loss of water. During dry spells, these lizards allow sodium to accumulate (2x) in their extracellular fluids, then they drink a bunch and flush it out when water becomes available.
Respiration
Process by which animals acquire oxygen. CO2 and H2O are produced as byproducts and must be eliminated.
Respiratory Surfaces
Heavily vascularized surfaces of one or a few cell layers between capillaries and exchange medium (air or water)
Respiratory Surfaces of Amphibians
Skin, gills in larvae, lungs in adults, buccopharyngeal cavity, cloaca. Most use more than one, switching or using 2 at once. Skin, cloaca, and buccopharyngeal cavity can be used in both air and water.
Respiratory Surfaces in Reptiles
Lungs, cloaca. Cutaneous respiration is rare and limited.
Which herps have gills?
Amphibian larvae and some aquatic salamanders (neotenic)
Gills as Respiratory Surfaces
Used for breathing in water. Highly branched to increase surface area, but lack of skeletal support means that they can only be supported in aquatic medium. Water allows them to spread out for more surface area exposure.
Gill Size/Structure
Long and feathery in pond types, medium in stream types, short and less filamentous in mountain brook types. Stagnant waters have less O2 and less water moving over the gills, so they need more surface area exposure. Long gills will also get ripped off in fast moving waters.
Buccal Cavity and Pharynx as Respiratory Surfaces
Membranes of mouth and throat are permeable to O2 and CO2. Important for species submerged in water for long periods, like turtle hibernation.
Skin as a Respiratory Surface
Skin folds increase surface area for gas exchange
Theories for Growth of “Hairs”
Help males sustain high activity associated with breeding. Greater surface area for gas exchange to allow males to stay with their eggs in underwater nests. Hairs release oxygen to aerate eggs during embryogenesis. Hairs serve as mechanical protection from claws in aggressive male-male interactions.
Lungs in Amphibians
Positive-pressure buccal pump. Floor of mouth is dropped and raised. When dropped, nostrils are open and air is taken into buccopharyngeal cavity and stored. Floor of mouth is elevated, and nostrils close and glottis is opened, expelling deoxygenated air from the lungs and forging oxygenated air into them.
Lungs in Reptiles
Negative-pressure thoracic aspiration. Elongate forms gave loss or reduction of a lung.
Lungs in Lizards
Use ribs and intercostal muscles to ventilate lungs. Sedentary lizards have few divisions in lungs, active lizards have complex lungs with many chambers to maximize surface area.
Lungs in Crocodiles
Liver acts as a plunger and presses against lungs
Lungs in Turtles
Lungs and viscera in a single cavity in a hard shell. Skin and muscle at the anterior and posterior openings of shell provide the flexibility needed to change the volume of lungs to draw air in and out (can’t expand ribs). Breathing is partially facilitated by moving legs in and out of shell.
Lungs in Amphisbaenians
Right lung is absent
Lungs in Snakes
Left lung is reduced. 2 regions in right lung-vascular lung in anterior part of body vascularized for gas exchange, and saccular lung posterior to vascular lung to regulate air flow.
Lungs in Tadpoles
Play a role in buoyancy regulation, like a swim bladder
Gas Exchange by Eggs in Water
Gelatinous material around eggs is a barrier to oxygen diffusion, but channels between eggs allow convective flow of O2-rich water so they are in loose clusters.
Gas Exchange by Eggs/Tadpoles in Foam Nests
Volume of foam decreases as water evaporates, decreasing O2 concentration, which may trigger tadpoles to drop from nest to water.
Gas Exchange by Eggs on Land
Pores extend through crystalline layer of rigid eggs. Gaps between fibres in flexible eggs.
SMR
Standard metabolic rate
Standard Metabolic Rate
Minimum energy consumption an animal needs to remain alive
RMR
Resting metabolic rate
Resting Metabolic Rate
Metabolic rate of a resting but active animal
RMR vs SMR
RMR is usually ~10% higher than SMR
Factors Affecting Metabolic Rate
Temperature, body size, phylogeny, ecology, endogenous rhythms, health/body condition, physiological state, sex
Temperature Affecting Metabolic Rate
MR increases as temp increases
Body Size Affecting Metabolic Rate
As mass increases, total oxygen consumption and carbon dioxide production increase, but consumption rate decreases.
Aerobic vs Anaerobic Metabolism
An animal’s normal activities are fuelled by energy from aerobic metabolism, which requires oxygen. Energy can also be obtained by anaerobic metabolism when oxygen is not available.
Aerobic Metabolism
Oxidative metabolism and cellular respiration
Anaerobic Metabolism
Glycolysis and anaerobiosis
Benefits of Anaerobic Metabolism
Rapid conversion of muscle glycogen to glucose. Releases energy quickly for a rapid burst of activity. Allows survival in anoxic events. Temperature independent. Some muscles are specialized for it.
Costs of Anaerobic Metabolism
Energetically costly. Prolonged use is debilitating. Inefficient (needs 10x the food for equivalent work). Rapidly depletes energy stores.
Problem with Anaerobic Metabolism
Buildup of lactic acid in muscles, causing fatigue, lethargy, and vulnerability
Turtles and Lactic Acid
Some species with robust shells can mobilize calcium from shell to buffer acid buildup
Anoxia
Low oxygen
Anoxia Intolerant Turtle Species
Spiny softshell, map turtle, stinkpot, wood turtle
Anoxia Tolerant Turtle Species
Painted turtle, snapping turtle, spotted turtle, Blanding’s turtle
Factors Involved in Energetics
Biophysical environment, resource environment, social interactions, predation environments. The connection between energetics, metabolism, and respiration.
Components of Ecological Energy Budgets
Maintenance 40-80% (basic maintenance, activity, digestion) and production 20-60% (growth, reproduction, and storage). Must to maintenance first and production after maintenance is done.
FMR
Field metabolic rate
Field Metabolic Rate
Integrates cost of all activities and provides estimates of daily and annual costs of living
Energetic Costs of Locomotion
Salamanders use less energy to walk than Anurans use to walk or hop. Lizards move in bursts and pauses to save energy. Snakes have several types of movement.
Energetic Costs of Vocalization
Most energy is put into singing, reducing the energy used for other things
Toad vs Lizard Weather Behaviour in the Same Locality
Toads emerge when it rains and retreat when the sun comes out. Lizards bask in the sun and retreat when it rains.
Home Range
Area over which an animal normally travels in pursuit of its routine activities. The entire area it needs to go to get what it needs.
Territory vs Home Range
Territory is defended, HR is not
Techniques that Aid in Estimating Home Range Size
Individual marking and individual tracking. Need to follow the same animal to determine that animal’s HR.
Examples of Individual Marking
Shell notching in turtles, toe clipping in anurans and salamanders, PIT tagging in snakes
Shell Notching in Turtles
Make notches in the marginal scoots of the shell with a steel file (it doesn’t hurt). Different markings are given to each individual.
Toe Clipping in Anurans and Salamanders
Different combinations of toes are chopped off in different individuals. This hurts and the toes could grow back.
PIT Tagging in Snakes
Passive Integrated Transponder, or a microchip tracker. Injected with a needle and doesn’t hurt. No visual difference. Each has its own barcode and needs to be read with a sensor.
Examples of Individual Tracking
Radio telemetry, GPS satellite tracking, fluorescent powder, thread spooling
Radio Telemetry
Need to be in the area and hear the beeping, doesn’t show all movements, just the spots you find them.
GPS Satellite Tracking
Don’t need to be there and shows all movements. Widely used.
Fluorescent Powder for Individual Tracking
Can track with black light. Only short term.
Thread Spooling for Individual Tracking
Bobbin tied to animal and end of thread tied to something. You can follow the thread to track the animal and see all of its movements. May become interwoven in nests and you can see how they make their nests.
MCP Method
Most common method to determine home range size. Take all the points that the animal was recorded at and connect the outermost points (no angle over 180 degrees) to create a polygon.
MCP
Minimum Convex Polygon
Problems with the MCP Method
Overestimate the area, as some of the area is not actually used. More points give a bigger area so you need to know how many are needed to represent the home range.
Kernel Analysis Density Estimates
Spots of darker colours show areas that are used more frequently. Accounts for frequency of use, making it more useful to show home ranges.
GF
Gravid (pregnant) females
Home Range and Turtle Sexes
Mean home range size of pregnant females is ~3x the size, much bigger
Home Range and Lizard Sexes
Males always have a bigger home range than females because they travel to find mates
Variation in Home Range of the Same Species
Varies with age, sex, reproductive status, and time of year
Home Range Size and Population
Higher pop = smaller home range
Home Range of Sceloporus merriami
Males always more than females. Move less in extreme dry and heat.
Home Range of Abalone mutica
Shift the home range up river later in the summer
Home Range Size and Age
Larvae don’t really move but adult amphibians travel pretty far. Younger lizards hang out on lower and smaller ranges.
Home Range Size and Predation Style
Ambush predators don’t use home ranges in the typical sense. They are more nomadic and move away when resources are used up.
Territory
Portion of home range that is actively defended against intruders
Why are territories defended?
Usually because the resources of that area are better than those in adjacent areas. Defense results in exclusive use of territory by the resident. Some males defend a female’s territory as well.
Territoriality in Amphibians
Occurs most often in frogs with extended breeding seasons or extended parental care. Explosive breeders have no need to establish a territory.
Territoriality of L. catesbeianus
Males defend the best oviposition sites, which increases reproductive success and therefore fitness as well.
Territoriality of Plethodon cinereous (Red-Backed Sal)
Uses pheromones to chemically mark territories. “Dear enemy” recognition. Don’t always have to be fighting the neighbour that is always there, saving tail and energy.
“Dear Enemy” Regognition
Less aggressive to known/recognized enemies, and more aggressive towards unfamiliar intruders. You stay there and I’ll stay here so there is no need to always be fighting the neighbour guy that’s always there.
Territoriality of Rana dalmatina (Agile Frog)
“Dear enemy”. Call for a lot longer when someone unfamiliar is there. Not much of a difference between calls when alone and calls when a known enemy is near.
Territoriality in Reptiles
Species that feed on patchily distributed resources usually do not defend territories. Their home ranges tend to be large and overlapping when resources are patchy. Larger home ranges are harder to defend and the cost of sharing is a lot less than the cost of defending a large area.
Territoriality in Lizards
Defense by direct contact (fighting), threats (puff up and aggressive communication), and avoidance (chemical signals). Ancestral behaviour, reduction throughout evolution, currently more defence in sit-and-wait lizards.
Why would an animal move outside its home range?
When resources are depleted or there are catastrophes that destroy their home range. They say breeding or overwintering, but these should happen in the home range because they are essential to life.
Benefit Gained by Moving for Feeding
Growth, lipid, storage
Benefit Gained by Moving for Basking
Increased mobility due to increase in mean body temp, reduction of parasites, enhanced digestion
Benefit Gained by Moving for Courtship and Mating
Reproductive success
Benefit Gained by Moving for Hiding or Dormancy
Escape/safety from predators and environmental extremes
Intrapopulational Species
Short range
Purposes of Movement in Intrapopulational (Short Range) Species
Feeding, basking, courtship/mating, hiding/dormancy
Interpopulational Species
Long range
Purposes of Movement in Interpopulational (Long Range) Species
Food, nesting (females), mate seeking (males), migration/hibernation/aestivation, juveniles traveling from nests, departure from unsuitable habitat
Benefit Gained by Moving for Nesting (Females) or Mate Seeking (Males)
Direct increase in reproductive success/fitness
Benefit Gained by Moving for Migration/Hibernation/Aestivation
Survival
Benefit Gained by Moving for Juveniles Leaving the Nest
Initiation of Growth
Benefit Gained by Moving for Departure from Unsuitable Habitat
Survival
Reproductive Strategies Hypothesis and Findings in Spotted Turtles
Males have greater activity and movements than females during mating season. Females do during nesting season. Found that males only move more in fall and winter, and females do move more during nesting season but also at other times. Just not supported.
Why are only gravid females looked at?
Not all females nest every year, and nesting is the reason for the movement
Mass Movements
Related to breeding events or overwintering
Terrestrial Drift Fences
Used to monitor movements around amphibian breeding ponds. Pitfalls on both sides of fence and can measure how many are migrating. Look at mass migration so usually only look at one side of the fence at a time. Cover the pits when not using them.
Dispersal
Undirected movement to locations unknown to the dispersing animal. Commonly refers to juveniles leaving home ranges of their parents to find a home of their own.
Primary Evolutionary Forces Causing Dispersal
Habitat instability, intraspecific competition, inbreeding depression
Migration vs Dispersal
Migration is a regular pattern and dispersal is random, one way, and no return
Costs of Dispersal
Increased predation risk associated with entering unknown habitats, potential difficulties finding resources, increased aggression from unfamiliar conspecifics
Benefits of Dispersal
Opportunities to discover better resources, increased likelihood of outbreeding, reduced local competition
Homing
Ability of displaced individuals to return to their original location. Animals must be able to sense the direction in which they are moving.
How do animals have a sense of direction?
Olfactory system, eyes and pineal complex, magneto reception, auditory system
How do animals use their olfactory system for orientation?
Pond odours and local odour patterns for mapping and piloting. Know the difference between home odours and unfamiliar odours. Couldn’t navigate without this ability.
How do animals use their eyes and pineal complex for orientation?
Sun, moon, stars, skylight polarization, and fixed landmarks to map, clock, compass, and pilot
How do animals use their magnetoreception for orientation?
Earth’s magnetic field to map and compass
How do animals use their auditory system for orientation?
Chorus of conspecifics to pilot
How do sea turtle hatchlings use waves for orientation?
Move perpendicular to waves to go out to sea.
How do sea turtles orient?
There are no landmarks in the ocean, so hatchlings orient to magnetic fields, waves, the moon’s reflection off the ocean and chemical cues.
Homing of Sea Turtles
Females come back to nest on the same beach she hatched from
Communication
Cooperative transfer of information from a signaller to a receiver
Human vs Amphibian Communication
Humans have a huge (55:1) brain:spinal cord weight ratio, but amphibians have a very small ratio (1:1), so they need good and clear communication because there is not much room for miscommunication
Why do herps communicate?
Social behaviour is an interaction with one or more conspecifics
Interactions
Reproduction, fighting, avoidance of predation
Sense Cues
Visual (colours, behavioural displays, etc.), chemical (pheromones), acoustic (sounds), tactile (touch)
Colourful Displays
Interspecific recognition, like aposematic colours when poisonous, or sex recognition, like colour change related to reproductive condition or sexual colour dimorphism
Behavioural Displays of Limbs
Toe trembling, hind foot lifting, arm waiving, limb shaking, wiping, leg stretching, foot flagging
Behavioural Displays of Stationary Body
Body lowering, upright posture, head bobbing, throat display, dewlap fanning, body raising, body inflation, two-legged pushups, body jerking, back raising
Behavioural Displays of Non-Stationary Body
Running, jumping display, circling
Acoustic Communication
Best known is anurans but also occurs in geckos, crocs, and turtles. Sing, scream, crocs slap body to make sound.
Chemical Communication
Odours. Volatile molecules (nasal) or surface-adherent molecules (vomeronasal) by placing scent on ground
Tactile Communication
When one individual rubs, presses, or hits a body part against another individual. Often happens after visual, acoustic, or chemical contact has been established. Like snakes that tangle to fight or painted turtle males that tickle females.
Salamander Communication
Courtship relies heavily on chemical signs, pheromones to distinguish between species/individuals/reproductive status, elaborate visual and tactile cues
Ambystoma talpoideum (Mole Salamander) Communication
Nose tapping to detect pheromones, glands on chin, caudal glands on tail. Males comes and nudges female’s face with his tail, she smells and checks out his genitals, and if she’s interested he drops the spermatophore and she picks it up.
Red-Spotted Newt Communication
Male amplexes the female and uses genial glands to make her receptive to breeding
