Mammalogy Lecture Exam 2

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Ambulatory
Movement by walking
Cursorial
Movement by running
Richochetal
Movement by jumping on two hind limbs
Saltatorial
Movement by hopping/jumping with four limbs
Fossorial
Movement by digging
Brachiation
Movement by swinging
Glissant
Movement by gliding
Volant
Movement by flying
Natatorial
Movement by swimming
Summation of independent velocities
If different muscles move different joints in the same direction, the total motion is greater.
Total velocity is then the sum of the independent velocities.
Digger equation at equilibrium
FoLo=FiLi
Adaptations for diggers
Extension of scapula for large muscles pulling leg back to dig
Large scapular spine for muscles moving arm out
Stout clavicle
Short, strong bones
Short hand with large claws
Enlarged olecranon process
Larger calcaneus
Cursorial equation at equilibrium
ViLo=VoLi
Adaptations for runners
Scapular spine- reduced muscles to lift arm outwards
Clavicle lost
Ulna reduced (no twisting or rotation of hand)
Constrained wrist joint
Long hand bones, short finger digits
Limb element lengthened and often fused
Increasing stride length- walk on toes, sometimes include scapula as part of the limb, flexing the spine, muscles inserted close to joints
Reduction in number of digits
What are ways in which runners can increase their stride length?
Walk on toes (unguligrade)
Include scapula as part of the limb
Flexing the spine
Muscles inserted close to joints to move the joint through a wider angle
Jump height equation
2sa/g
s=distance of the flexed and extended hindlimb
a=acceleration
g=gravity
Low aspect ratio
Short, broad wings
High aspect ratio
Long, narrow wings
Laminar vs. Turbulent flow
Using the equation, how can you maximize digging?
Fo=FiLi/Lo
Increase Fi: larger muscles
Increase Li: smaller limbs, stocky bones
Decrease Lo
Speed =
rate of stride * length of stride
Using the equation, how can you maximize running?
Vo=ViLo/Li
Increase Vi
Increase Lo: make legs longer away from body, distal levers longer as opposed to proximal levers
Decrease Li
Paraxonic
Weight supported between two digits
Elongation and Fusion
Artiodactyla
Mesaxonic
Weight supported below one digit
Elongation and reduction
Perissodactyla
What is the common goal of paraxonic and mesaxonic foot symmetry?
All have the goal of increasing distal elements of limb
Adaptations for jumpers
Elongation of hindlimbs (tibia as much as 1.5x as long as femur)
Long neural spines, more muscle mass for launching and tail
Fused cervical vertebrae: compress center of mass, provide rigidity
What's an adaptation of Tarsiers?
Very long tarsal bones, rather than metatarsals as in kangaroos, because they're arboreal
What's an adaptation of Jerboas?
Elongate and fused metatarsals, convergent evolution to Artiodactyla
Examples of glissant mammals
13 or so sciurids have evolved gliding
Also, colugo (Cynocephalidae) and scaly-tailed squirrels (Anomaluridae)
Airfoil
Any plane directed in an airstream
What is required for powered flight?
A cambered (curved) airfoil
Fewer molecules of air on the dorsal aspect than the ventral aspect
Lift raises airfoil, gravity pulls it down, propulsion moves it forward, drag caused by friction
Factors that increase lift
1. Increase camber
2. Increase surface area of airfoil
3. Increase angle of attack
4. Increase air speed
Wing load =
mass/wing area, unit mass per square centimeter of wing, g/cm^2
Bat 1: 59.6g/380.4cm^2=0.18g/cm^2
Bat 2: 9.99g/101.74cm^2=0.098g/cm^2
Who has the lower wing load?
Who has the higher lift?
Bat 2 has the lower wing load and therefore higher lift
Aspect ratio
wingspan^2/wing area, ratio of length of the wing to the width
How do bats change their camber?
Bats shift the shape of their camber with their fifth digit and hind foot
Dactylopatagium contracts
Adaptations of swimmers
Fusiform
Minimal hair/short hair
Partially fused cervical vertebrae
Paddlelike structure for locomotion
Skin that promotes laminar flow
Fusiform
Streamlined body
Relationship between volume or mass and area
As surface area increases, volume increases
Propulsion in whales comes from the...
Flukes (tail)
Upstroke "spring" (blubber) compressed
Downstroke "spring" (muscles) relaxed
Diving adaptations in cetaceans
Double capillary, alveoli (3x as much oxygen as humans)
2x red blood cell count
9x myoglobin
Bradycardia - heart rate slows
Blood shunted to those most critical (brain, circulatory system)
High lactic acid respiration
Adaptations of pinnipeds (Odoriidae)
External pinna
Steer with hind flippers, rotate flippers to allow them to walk on all fours on land
Fewer RBC's, greater blood volume
Similar deep water adaptations to whales
Adductors
Close jaw
Chew food to increase the surface area in order to make digestion easier
Muscles evolved with the jaw, specific condyloid process
Temporalis
Important muscle for closing the jaw (adductors)
Vertical action of chewing
Masseters
Muscle that moves jaw side to side (adductor)
Originates on zygomatic arch (either directly or more forward on rostrum)
Inserts on mandible
Pterygoids
Grinding
Medial inserts on inside of coronoid process
Lateral inserts on outside of coronoid process
Abductor
Opens jaw
Relies on digastric muscle
Digastric
Muscle that helps open the jaw
Inserts on point of mandible, lies below the body of mandible
Shape of condyloid process in herbivores
More rounded, moves in rotary fashion
Shorter, in-level on herbivores
Shape of condyloid process in carnivores
More transverse (cylindrical), moves side to side
Long, in-level on carnivores to increase bite force
Herbivore toothrows
Parallel toothrows
Fore and aft grinding
Carnivore toothrows
Convergent toothrows
transverse grinding
Ruminant herbivore digestive system
Four chambered stomach with large rumen
Small and large intestine is long
Large cecum
Carnivore digestive system
Shorter intestine and colon
Small cecum
Non-ruminant herbivore digestive system
Simple stomach
Large cecum
Insectivore digestive system
Short intestine
No cecum
Vampire bat adaptations
Sanguivorous
Stomach is long reservoir that fills with blood (can consume up to 40% of its body weight per night)
No colon
Have an anticoagulant in their saliva
Small grooves bordering their tongue, peristalsis
Because they increase their wing load by half, they urinate all over prey while feeding
Kidneys remove NH4
Hindgut fermenters
Fermentation vact is posterior to the small intestine
Ex. rodents, perissodactyls
Cecum fermenters
< 5lbs
Coprophagy
Ex. rabbits, hamster, koala, hyrax, guinea pig
Coprophagy
Consume their shit to gain extra nutrients not absorbed the first time
Colon fermenters
> 50lbs
Consume mass quantities of low quality vegetation
Ex. pony
Foregut fermentation
Abomasum is the true stomach
Omasum, reticulum, and rumen are all part of the esophagus
Higher quality forage, consume less
Ex. Ruminantia
Balaenidae feeding
Skim the ocean surface for plankton
Balaenopteridae feeding
Humpbacks create a bubble net
Eschrichtiidae feeding
Feed on the bottom, kick up mud, coarsest baleen
Endotherms
Organisms that can "trap" the heat of metabolism
Homeotherms
Physiologically control body temperature
Heterotherms
Parts of body are different temperatures than others
Pros and cons of endothermy
Pros:
Can live in a wider range of habitats
Can be more active
Cons:
Expensive metabolically, have to eat more
Less efficient at converting what they eat into biomass
What percentage do endotherms convert what they eat into biomass compared to exotherms?
Endotherms (1-10%)
Exotherms (30-90%)
Thermoneutral zone
Range of ambient temperatures over which an endotherm doesn't have to expend any additional energy to maintain a constant body temperature
Upper critical temperature
Temperature above which an endotherm has to expend energy to maintain a constant body temperature
Lower critical temperature
Temperature below which an endotherm has to expend energy to maintain a constant body temperature
Is there more variability in the lower or upper critical temperature among mammal species?
Lower critical temperature
Adaptations to cold
Very dense hairs (sea otters blow air into their fur)
Countercurrent heat exchange
Huddling
Subnivean zone
Foraging zones
Food hoarding
Torpor
Hibernation
Adaptive hypothermia
Shivering thermogenesis: energy expensive
Non-shivering thermogenesis
Countercurrent heat exchange
Small gradients are maintained
Rete Mirabile- arterial and venous capillaries are closely associated
Flowing in opposite directions
Designed to retain heat, ions, or gases in certain tissues or areas of the body
Concurrent heat exchange
Large gradients disappear quickly
Subnivean zone
Stays about 32 degrees as long as the snow is > 6 inches deep regardless of air temperature
More snow can be better than less snow for small mammals
Foraging zones
Zones which have a much higher temperature than the outside air, where mammals often forage
Scatter hoarder
Scatter food around, use scent or memory to find food
Ex. southern flying squirrel
Larder hoarder
Make one or few big stashes, need to protect
Ex. chickaree
Normal body temp vs. hibernating body temp
Normal= 38 degrees Celsius
Hibernating= 3-4 degrees
Adaptive hypothermia
Torpid by day, active by night
Non-shivering thermogenesis
Thermogenin protein in brown adipose fat tissue has mitochondria produce heat instead of ATP
Acts as miniature internal blanket that overlies parts of the vascular system and heats blood
Heat adaptations
Sweat
Panting
Very long loop of Henle
Saliva spreading (kangaroos)
Water in diet from succulents and body fluids of prey
Metabolic water
Nasal mucosa
Carotid rete
Estivation
Burrowing, using shade
Pros and cons of sweating and panting
Cons:
Lose water
Sweating loses electrolytes
Panting uses muscular activity and generates some heat
Pros:
Both promote evaporative heat loss
Panting combined with countercurrent exchange can help keep brain cool
Oryx diet
Feeds on certain plants only at night after that plant has absorbed most of its water
Camel adaptations to heat
Able to take on a lot of heat during day, lose heat at night
Hygroscopic mucus, recycles exhaled water
Dry urine and feces
Antelope ground squirrel adaptations to heat
Only spends minutes above ground at a time during heat of day
Poor thermal inertia, heats up quick
Uses tail as a parasol for shade
Returns to cool burrow to lower body temp
Carotid rete
Special counter-current system to cool brain
Lies between nasal sinus and brain
Cool venous blood from nasals runs along warm arterial blood entering from body via the carotid artery
After passing through the carotid rete, arterial blood is much cooler
Heat dissipated from arteries before it makes it to the brain
Blood from heart is relatively hot
Estivation
Period of dormancy in reaction to excessive heat
Animal more lethargic than torpid
Decreases body temp, reduces metabolic rate
Also a reaction to low food supply
Reproduction in monotremes
Only left ovary is functional
Mammary glands but no nipples
Eggs much larger than in viviparous mammals
Have a cloaca
No placenta, amniotic egg incubated in pouch around 10 days, sticky coating
Reproduction in marsupials
Cloaca for urine and reproductive stuff, separate rectum for digestive waste
Two vaginas: sperm travels up side vaginas, joey travels down middle vagina
Choriovitelline placenta
Offspring have short gestation, altricial, extended lactation
Choriovitelline placenta
Marsupials
Enlarged yolk sac
Chorion fuses with part of the yolk sac
Little surface where gas exchange occurs
Embryo sits in pocket of endrometrium, almost no erosion of uterine wall
No direct contact between fetal and maternal circulation
Nutrient transfer is relatively inefficient; nutrients diffuse from the uterine milk
Embryo can't get very big
No trophoblast, loss of antibody protection
Chorioallantoic placenta
Eutherians
Close contact between fetus and mother, erosion of endometrium
Villi extend deeply into uterus, increasing surface area for oxygen exchange between young and mother
Nutrient transport from maternal to fetal circulation takes place across the endometrium through the chorionic villi
Baculum
Penis bone
Male testes
Abdominal testes most of the year, only drop during reproductive season
Marsupial genitals
Bifurcated penis
Hairy vagina
Female fertilization takes place in the...
Filopian tube
Sperm produced in...
Seminiferous tubules
Cowper's gland
Located below prostate
Affects acidity of semen and pH of vagina
Supplies nutrients
Estrous cycle
Period of female sexual receptivity to copulation
1. Low levels of estrogen from the ovary trigger release of FSH
2. Follicle begins to form and releases estrogen
3. Stimulates LH production and inhibits FSH production, stimulating the thickening of the endometrium
4. LH induces ovulation
5. Follicle bursts, egg released and may or may not be fertilized
6. LH triggers corpus luteum to form
7. Corpus luteum produces high levels of progesterone
8. Continued thickening of endometrium and growth of mammary glands
Progesterone in Eutherians
Provides a negative feedback loop that inhibits FSH and LH formation to prevent formation of new follicle when female is pregnant
Progesterone in Marsupials
Does not inhibit FSH production, so gestation must be shorter than the estrous cycle
Severely limits the length of in utero development in marsupials
Placenta
Complex of embryonic and maternal tissues
1. Anchors fetus to uterus
2. Transports nutrients to fetus
3. Collects metabolic wastes from fetus
4. Produces hormones regulating organs of both mother and fetus
5. Provides immune protection from maternal antibodies
Trophoblast
Prevents immune response by mother to embryo, chorion
Eutherians
Common sequence in female reproductive cycle
1. Ovulation: gametogenesis
2. Copulation: insemination
3. Fertilization: formation of diploid zygote
4. Implantation: attachment to endometrium
5. Gestation: intrauterine development
6. Parturition: birth
7. Lactation: nursing
Ovulation is usually...
spontaneous
Examples of induced ovulation
Cats, some mustelids, and rodents
Examples of delayed fertilization
Insectivorous bats
Examples of delayed implantation
Ursids, mustelids, phocids, armadillos, and many other groups
Embryonic diapause
Delayed implantation in marsupials (kangaroos)
Embryo development halted mid-way through development
Mother may mate again when joey is 6 months old
Suckling prevents development of 2nd joey
Female can have three young dependent on her at one time
Lactation
Production of milk by the mammary glands
Milk contains fats, proteins, lactose, vitamins, salts
1. Provides nutrients for growth of newborn
2. Transmits passive immunity (colostrum)
3. May support the growth of symbiotic intestinal flora
Colostrum
A protein-rich fluid containing antibodies that confer mother's immunity to various diseases to young
First released by mammary gland following birth
Six Superorders
1. Ameridelphia
2. Australodelphia
3. Afrotheria
4. Xenarthra
5. Euarchontoglires
6. Laurasiatheria
Two orders in S.O. Ameridelphia
1. Didelphimorphia - opossums
2. Paucituberculata - caenolestids
Five orders in S.O. Australodelphia
1. Microbiotheria - monito del monte
2. Peramelemorphia - bandicoots & bilbies
3. Notorycetemorphia - marsupial moles
4. Dasyuromorphia - Tasmanian devil & allies
5. Diprotodontia - kangaroos, koalas, wombats, etc.
Six orders in S.O. Afrotheria
1. Proboscidea - elephants
2. Hyracoidea - hyraxes
3. Sirenia - dugongs & manatees
4. Tubulidentata - aardvarks
5. Macroscelidea - elephant shrews
6. Tenrecoidea - tenrecs
Two orders in S.O. Xenarthra
1. Pilosa - sloths & anteaters
2. Cingulata - armadillos
Five orders in S.O. Euarchontoglires
1. Primates - monkeys & apes
2. Scandentia - tree shrews
3. Dermoptera - colugo
4. Lagomorpha - rabbits, hares, & pikas
5. Rodentia - rodents
Eight orders in S.O. Laurasiatheria
1. Pholidota - pangolins
2. Carnivora - carnivores
3. Perissodactyla - "odd-toed" ungulates
4. Artiodactyla - "even-toed" ungulates
5. Chiroptera - bats
6. Soricomorpha - shrews & moles
7. Erinaceomorpha - hedgehogs
8. Solenodonta - solenodons
Metabolic equation
C6H12O6 + 6O2 -> energy + 6H2O + 6CO2