Bio of Vertebrates - Final Exam

Chapters 15, 16, 17, 19/21, and 22/23

Lepidosauria

-Tuataras and squamates
-Dry skin covered by keratinaceous scales (relatively impermeable and resistant to desiccation)
-Respiration via lungs, typically no cutaneous respiration.
-Excrete nitrogenous waste primarily as uric acid (semi-solid), minimizing water loss, successful in arid regions.
-Terrestrial fossorial, arboreal, saxicolous, aquatic, or marine.
-Herbivorous, carnivorous, or omnivorous (eat plant and animal foods)
-All have internal fertilization; paired hemipenises of males extend/evert from inverted position in base of tail.
-All have amniotic eggs
-Typically ectothermic and poikilothermic.
-Many squamates thermoregulate very precisely, often maintaining body temperatures very different from surroundings.

Tuataras

Sphenodontidae… one species on small New Zealand islands.

Squamata - lizards

-Lizards
-Not a monophyletic group.
-All squamates except snakes and amphisbaenians
-Most have 4 well-developed legs.
-Limb reduction and loss has occurred in several lineages.
-Have external ears.
-Terrestrial, fossorial, arboreal, and saxicolous species
-Most are carnivorous, but some larger species are herbivorous
-Most (~80%) species are <20g as adults and insectivorous
-Some species are venomous.
-Temperature-dependent sx determination in several families.
-Oviparous or viviparous
-Placentotrophy in one clade of lizards

Squamata

-Lizards, snakes, and amphisbaenians
-Most have four well-developed limbs
-Oviparous or viviparous
-Viviparous taxa are lecithotrophic to matrotrophic (placentotrophic)
-Placenta: union of extraembryonic membranes and maternal tissue for physiological exchange
-Eggs have hard, calcareous shells or soft, flexible shells
-Most have no parental care after oviposition/birth, but some guard or brood eggs
-Periodically shed outer layer of the epidermis, ecdysis.

Squamata - amphisbaenians

-Amphisbaenians, fossorial, limbless lizards
-Lack limbs entirely or have only forelimbs
-Highly fossorial
-Scales for annuli (rings) around body
-Skin mostly free of connections to trunk of body, body slides forward and backward inside “tube” of skin.
-Accordion like extension and contraction to move through tunnels.
-Longitudinal muscles in skin contract annuli lengthwise, causing an increase in diameter, anchoring in tunnel.

Squamata - snakes

-Serpentes, monophyletic lineage of snakes
-Just one clade of limbless squamates
-Lack limbs entirely or have vestigial hindlimbs
-Lack external ears, no tympana, mandible picks up seismic vibrations.
-All are carnivorous and swallow prey whole.
-Forked tongue delivers stimuli to paired vomeronasal organs
-Terrestrial, fossorial, arboreal, aquatic, and marine species
-Kill prey by constriction or venom, or eat it alive.
-Extensive cranial kinesis; left and right halves of jaws move independently
-Oviparous or viviparous
-Viviparous species are lecithotrophic.

Lateral Undulation

General terrestrial and swimming locomotion
-Undulatory waves pass along body length.
-Curves of body push backward against surface irregularities.

Rectilinear

Slow, straight-line movement
-Alternating segments of venter are raised, moved forward, planted, and then drawn backward.
-Stalking by heavy-bodied snakes.
-Climbing straight up broad surfaces (tree trunks)

Concertina

Burrows and other tight passages.
-Curves of body extend outward to wedge/anchor
-Rest of body is push/pulled along.

Sidewindling

Shifting desert sands
-Loops of body raised and swung forward
-Only 2 or 3 anchor points on ground.
-Minimal lateral force, mostly downward.

Aglyphous

Dentition, no enlarged fangs.
-Maxillary teeth all essentially the same.
-Non-venomous snakes

Opisthoglyphous

Dentition, enlarged rear fangs.
-Fangs solid, but some with lengthwise groove for venom delivery.
-Fangs fixed in position.
-Venom but delivered effectively

Proteroglyphous

Dentition, enlarged anterior fangs.
-Fangs hollow, for more effective and rapid venom delivery.
-Fangs are relatively short and fixed in position.

Solenoglyphous

Enlarged anterior fangs.
-Fangs hollow, for more effective and rapid venom delivery.
-Fangs relatively long, for deeper venom injection.
-Fangs moveable, fold against roof of mouth when the jaw is closed.

Foraging modes of Squamates

-Continuum with correlated differences in morphology, physiology, behavior, and life-history.

-Sit-and-wait (ambush) to widely foraging.
-Heavy-bodied to slender
-Inactive to active
-Few, large prey to many, small prey.
-Low endurance to high endurance
-Fast sprint to slow sprint
-Low to high daily energy intake and expenditure
-Small, defended to large, undefended area.
-High to low reproductive output.

Life histories of Squamata

-Short to long-lived.
-Early to late maturity
-Frequent to infrequent reproduction

Overall, very variable.

Social Behavior and Courtship of Squamata

-Social systems more complex in lizards than snakes
-Visual, chemical, tactile and vocal communication used in courtship and aggressive/dominance interactions.
-Many lizards are territorial, male and often females defend females.
-Visual displays (often brightly colored) and olfactory markers common in territorial defense.
-Male lizards and snakes often compete/fight for access to mates.
-Male-male combat is highly ritualized, series of discrete threat behaviors that lead up to actual combat.

Predator Defense in Squamates

-Many are highly cryptic (especially ambush foragers)
-Usually have planned escape routes within their home range.
-Tail autotomy tail breaks off (at fracture planes in vertebrae) when seized by predator, then wiggles while animal escapes.
-Autotomizing tails are often brightly colored and displayed.
-Venom of snakes for prey acquisition, but readily used for defense.
-Venomous species often aposematically colored, or have warning behavior.

Sexual versus Asexual Reprod. in Squamates

-Most species reproduce sxually (males and females)
-Parthenogensis is asexual reprod. with unfertilized egg develops into clone of mother.
-Parthenogenetic (all female) species; males do not exist.
-Facultative parthenogensis occurs in some normally sexual snake species.

Parthenogensis

Aseuxal reprod. with unfertilized egg develops into clone of mother.

Parthenogenetic

All female species; males do not exist.

Sex Determination in Squamates

-Some have Genotypic Sex Determination (GSD); sex chromosomes (both male and female heterogamety)
-Many have Environmental Sex Determination (ESD); temperature during middle third of incubation determines offspring sex (also know as TSD)

Parental Care in Squamates

-Most exhibit no parental care after oviposition or birth
-Egg attendance, egg guarding, egg brooding (pythons)
-Some remain with young after birth.

Testudines

-Turtles
-Body enclosed in a rigid bony shell, carapace dorsally and plastron ventrally.
-Shell usually overlain by scutes; large, thick keratinaceous scales.
-Dry skin covered by keratinaceous scales; relatively impermeable and resistant to desiccation.
-Respiration via lungs; usually no cutaneous respiration.
-Terrestrial, aquatic, or marine
-Herbivorous, carnivorous, or omnivorous (eat plant and animal foods)
-All have internal fertilization
-Penis of males extends/everts from the cloaca.
-All are oviparous
-Females dig nest and bury eggs in soil/sand
-Aquatic/marine species go ashore to nest.
-Eggs have hard, calcareous shells or soft, flexible shells.
-No parental care after oviposition
-4 well-developed limbs; legs or flippers.
-Locomotion via walking or swimming with limbs, no flexing/undulation of axial skeleton.
-Anapsid (Parareptile) or Diapsid (Eureptile) debated.

Turtles in Parareptilia

-Long thought, due to anapsid skulls
-Positions turtles as the sister group other “reptiles”

Diapsid origin, sister group to Lepidosauria

-Anapsid skull secondarily derived, from diapsid
-Supported by some DNA evidence

Diapsid origin, sister group to Archosauria

-Anapsid skull secondarily derived, from diapsid.
-Also supported by some DNA evidence.

Carapace

Dorsal shell

Plastron

Ventral shell

Bridges

Connect carapace and plastron mid-laterally

Turtle shell

Carapace and plastron are formed from plates of dermal bone fused with parts of axial skeleton. Carapace dermal bones fused with trunk vertebrae and ribs. Pectoral and pelvic girdles are entirely within the shell; interior to the ribs. Unlike other amniotes, can not use ribs to ventilate lungs, muscle pump anterior and posterior viscera in/out to ventilate. Plastron sometimes has one or two hinges that allow closing of shell.

Turtle heart

-Intermediate; between single and double circuit.
-Atrium is totally divided; right and left.
-Ventricle is partially divided
-Pulmonary circuit; blood pumped from heart to lungs to heart.
-Systematic circuit; blood pumped from heart to body to heart.
-Blood flow through heart is facultative; can be changed to suit the turtle’s respiratory state.

Turtle Normal Function/Breathing

-Oxygenated and deoxygenated blood mix very little.
-Deoxygenated blood enters right atrium and flows out to pulmonary circuit, is oxygenated, then flows back to heart (left atrium)
-Oxygenated blood enters left atrium and flows out ot systemic circuit, is deoxygenated, then flows back to heart (right atrium)
-Functions essentially as two separate circuits.

Turtle Modified Function/not breathing

-Vessels of pulmonary circuit constrict, increasing resistance to flow.
-Deoxygenated blood (from systemic circuit) enters right atrium, but much of it flows out via the left ventricle, to the systemic circuit.
-Pulmonary circuit is bypassed, saving effort of pumping blood through capillary beds of lungs.

Ecology of turtles

-Long-lived and late-maturing.
-Sxually mature at 7-15 years old
-Life spans 14-80 yrs
-Larger species live longer, mature later.

Turtles Thermoregulation

Ectothermic and Poikilothermic.
-Bask in sun to warm
-Move to water or shade to cool
-Orient body surfaces to maximize or minimize solar heating
-Larger tortoises and marine turtles have great thermal inertia, low surface area to volume ratio.
-Larger marine turtles are partially endothermic; heat generated by metabolic activity elevates body temperature.

Behavioral Thermoregulation

Move between warm and cool microhabitats to maintain preferred body temperature.

Testudines Social Behavior and Courtship

-Visual, tactile, chemical, and vocal communication used in social interactions.
-Courtship, males use visual displays (swim in front of female, elevate/bob head), tacile stimulation (vibrate claws against cheek of female), grunts, and pheromones.
-Male/male combat - males fight over dominance/territory and mates, biting, ramming, hooking/flipping.

Testudines Migration and Navigation

-Pond and terrestrial turtles limit activity to a restricted home range; use landmarks and sun for orientation/navigation.
-Sea turtles often migrate thousands of kilometers from freeding to nesting habitats, without visible landmarks.
-Homing behavior; sea turtles return to their natal beach to nest (years after hatching) and to the same location year after year.
-Sea turtles use magnetic sense (to determine direction and latitude), wave/current direction, light, and olfaction to navigate and home.

Testudines Conservation

-Many are threatened with extinction worldwide.
-Harvest for food and traditional medicine is largely unregulated and unrestricted.
-Habitat loss has impacted terrestrial, aquatic, and marine turtles.
-Aquatic turtles affected by hydrological changes (dams, levees, canals) that limit access to or alter nesting habitat and by water pollution.
-Introduced predators and artificially high predator numbers lead to much nest/hatchling predation.

Seasonal Migration and Navigation by Green Turtles

-Feeding areas along coast of Brazil
-Use currents, olfactory cues, and magnetic sense to navigate.
-Magnetic field allows them to determine compass heading and latitude
-Satellite tracking showed precise navigation between feeding and breeding areas.

Sex Determination in Turtles

-Some turtles have genetic (chromosomal) sex determination.
-Most turtles have environmental (temperature-dependent) sex determination- ESD or TSD.

Temperature-dependent sex determination in Testudines

-Sex of offspring is determined by temperatures experienced by embryos during middle one-third of development.
-High temp produce females, low temp produce males in turtles.
-Crocodilians, tuataras, and some lizards have TSD, but high temperatures produce males.
-Offspring sex or sex ratio affected by nest location (shade, cover, aspect, slope, elevation), depth, time of year, and position of eggs in nest.
-Most natural nests produce predominantly or totally one sex.
-Conservation implications are inappropriate artificial incubation and/or changes in available nesting habitat can alter population sex ratios.

Crocodylia

-Wordwide in tropical, subtropical, and temperate habitats.

-Alligatoridae, crocodylidae, and gavialidae
-Semiaquatic; marine, estaurine, and freshwater
-Laterally compressed tail used for swimming
-Dry skin covered by keratinaceous scales; relatively impermeable and resistant to desiccation.
-Respiration via lungs, no cutaneous respiration.
-Dorsal armor of osteoderms
-Carnivorous
-All have internal fertilization
-Males = intromittent organ (single pen)
-All are oviparous
-Nest on land.
-Temperature-dependent sex determination. Females at low, males at high.
-Parental care shown by most or all; attend nest, assist hatching, transport hatchling to water, guard juveniles
-Ectothermic and poikilothermic but thermoregulate behaviorally and physiologically.

Archosauria

Dinosaurs, pterosaurs, crocodylia, and birds.

Aves

-Birds
-Lineage of dinosaurs that evolved flight
-Worldwide; virtually every habitat
-Feathers cover skin, except lower hind legs
-Forelimbs modified as wings
-Flight secondarily lost in some
-No teeth in extant forms
-Keratinaceous bill on rostrum, shape varies with diet.
-Respiration via very efficient lungs; unidirectional air flow
-Have internal fertilization
-Intromittent organ varies from minimal (cloaca together)
-All are oviparous
-Eggs are incubated and tended
-Endothermic and homeothermic
-Smaller species in cold climates go into torpor overnight; body temperature (and metabolic rate) allowed to fall lower
-Many aquatic and land birds migrate seasonally.

Feathers and Flight

-Feathers function as thermal insulation and as airfoils for flight
-Wing functions as an airfoil (generate lift) and as a propeller when flapped
-Air flow over inner wing (secondary feathers) produces lift
-Twisting/opening movement of outer wing (primary feathers) generates forward thrust, propeller-like.
-Wing shape varies with flight habits, from rapid flapping flight to soaring/gliding.

Avian Lungs and Air Sacs

-Lungs are semi-rigid and do not expand and contract
-Air sacs expand and contract, pumping air through respiratory tissues of parabronchial lungs.
-Air flow through most of lung is unidirectional, making gas exchange more efficient.
-Efficiency of lung allow for higher altitudes.

Digestive Tract of Aves

-Crop expansion of the esophagus for food storage
-Stomach has two chambers
-Proventriculus: digestive chamber of stomach (secretes acid and enzymes)
-Gizzard (ventriculus) muscular chamber of stomach
-Grit (sand, small stones) swallowed to help grind hard foods in gizzard
-Gizzard used for storage of food in carnivorous birds
-Some (owls and water birds) sort undigestible parts of prey into gizzard, then regurgitate as a pellet later.

Beaks/bills of Aves

-Keratinaceous (horny) bill or beak serves role of teeth
-Beak/bill morphology varies with diet and foraging technique
-Beak/bill used to grab, tear, crush, crack, probe, scoop, strain, sift, etc.
-Tongue also specialized for feeding in woodpeckers and nectar feeding birds

Life history of Aves

-Short to long-lived and early to late-maturing
-Most reproduce seasonally
-All reproduce sexually

Reproduction in Aves

-All are oviparous
-Have extensive parental care of eggs and young after they hatch
-Developmental state and independence of young at hatching varies (precocial vs altricial)
-One or both parents, and sometimes older siblings, feed and care for young until and even after fledging
-Young remain with parent (s) for extended periods, during which much behavior is learned.

Precocial

Independent; well-developed at birth.

Altricial

Totally dependent, undeveloped at birth

Senses and Social Communication in Aves

-Rely most heavily on vision and hearing for predator/food detection and social communication.
-Birds have excellent color vision and acute hearing
-Brightly colored plumage and display behaviors common in social (territorial, defense, courtship) communication
-Song important in social communication
-Olfaction poor in most, except soil probers and carrion feeders
-Some can sense small changes in air pressure - predict weather
-Sun’s position (and time of day) used as a compass
-Polarized light, landmarks, infrasound, and olfactory cues also used for navigation and finding water.
-Magnetic sense also present in some migratory birds

Vertebrate Mating Systems

Most vertebrates reproduce sexually, but some Osteichthyes, Lissamphibia, and Lepidosauria reproduce asexually.

Parental Investment in Aves

-Sxual reproduction requires mating of a female and a male, but the parental investment differs among the sexes.
-Males generally have a lower investment in offspring (sperm are cheap to produce) can maximize their reproductive output by mating with multiple females.
-Females generally have a higher investment in offspring (eggs are expensive to produce, and burden female until oviposition/birth), can maximize their reproductive output by making the male invest more (than just gametes) into reproduction.
-This conflict between the sexes has been resolved in many ways, with many varieties of mating strategies or mating systems.

Monogamy

Pair bond between one male and one female
-Each mates with only one individual
-Pair bond may last part or all of a breeding season, over multiple seasons, or for a lifetime
-Even among monogamous species, “cheating” is common, by both sexes.

Polygamy

An individual has more than one mate per breeding season. Includes polygyny, polyandry, and promiscuity

Polygyny

One male mates with more than one female.
-Exhibited by many amphibians, reptiles, mammals, and some birds
-Female usually provides all parental care

Resource Defense Polygyny

Male gains access to multiple mates by defending a valuable resource (payoff to females), such as nest sites, food, etc.
-Territoriality is common; males defend terriorities that contain resources that attract females.

Male Dominance Polygyny

Males do not defend resources, but compete with one another to establish dominance or attract mates.
-Dominance established via male/male combat, or ritualized displays.
-Lek; multiple males simultaneously conduct courtship displays before an audience of potential mates

Polyandry

One female mates with more than one male.
-Uncommon occurs only when female controls access to some critical resource, that males must have to reproduce successfully
-Exhibited by some ground-nesting birds with high nest predation only females can produce a “replacement” clutch of eggs.
-Male usually provides all parental care.

Promiscuity

Both males and females mate with several individuals. Common among amphibians, reptiles, mammals, and some birds.

Mammalia

-Mammals
-Synapsid lineage of amniotes
-Hair; keratinaceous skin derivative… insulation
-Mammary glands secrete milk to nurse young
-Sebaceous glands secrete oils to condition skin and hair
-Sweat Glands secrete water for evaporative cooling
-Claws, nails, hooves, and horns are also keratinaceous skin derivatives
-Endothermic and homeothermic, but some hibernate or short torpor
-Terrestrial, arboreal, volant (flying) fossorial, aquatic.
-Herbivorous, carnivorous, or omnivorous
-All reproduce sexually
-All have internal fertilization
-All have genetic sex determination (sex chromosomes)
-Oviparous (only monotremes) or viviparous
-Viviparous taxa are matrotrophic-placentotrophic

Synapsid features

-Synapsid skull; single temporal opening per side
-Limbs beneath body, not splayed out to sides
-No lateral flexing/undulation of axial skeleton during locomotion
-Able to breathe and run at the same time without interference
-Heterodont dentition; different types of teeth in different parts of mouth; for different functions.
-Rearticulation of the jaw; stronger and more controlled bite force
-Chewing processes large or hard to digest foods into smaller pieces; easier to ingest/digest.
-Chewing is important for feeding on coarse plant matter
-Secondary palate allows for breathing and chewing at the same time.

Primary clades of extant mammals

-Prototheria (monotremes)
-Theria (Metatheria (marsupials) and Eutheria (placental))

Life History of Mammalia

-Short to long-lived and early to late-maturing
-From essentially annual species to 80 years plus
-Reproduce seasonally, cylically, or continously.

Reproduction and Parental Care in Mammalia

-Young are dependent at birth (or hatching)
-Female (and sometimes male) lactates to feed young
-Parental care often extended well beyond weaning (ending of nursing)
-Mother or both parents (sometimes other members of social group) protect and feed young
-Much behavior is learned from parents

Senses in Mammalia

-Adaptation to nocturnal life
-Rely more on hearing and olfaction than most other tetrapods
-Exceptionally sensitive and acute hearing
-4 ear ossicles transmit vibrations more efficiently
-Pinna (External ear concentrates/focuses sound onto tympanum and helps determine direction)
-Long, coiled cochlea in innear allows for more precise pitch discrimination
-Sensitive and acute olfactory and vomerolfactory senses, for airborne and surface odors
-Vision less acute than in birds, but more sensitive (night vision)
-Tapetum lucidum, reflective layer behind retina that reflects light back out over photoreceptors (reason for “eye shine”)
-Olfactory and hearing senses reduced, lost, or modified in marine mammals

Mammalia social communication and behavior

-Vocialization and visual displays common in social (territorial defense, courtship) communication
-Scent glands (pheromones) also used for territorial marking.
-Many live in social groups, with dominance hierarchies

Prototheria

-Monotremata (monotreme mammals)
-Only 5 species; platypus and echidnas
-Have a cloaca, single opening for digestive and reproductive tracts
-Oviparous typical amniotic egg
-Young nurse after hatching
-No teats (nipples) milk lapped from breast hair.
-Sister group to Theria/Theriiformes (metatherians and eutherians)

Metatheria

-Marsupial mammals
-Separate openings for digestive and reproductive tracts
-Viviparous but young are born small, undeveloped. Altricial.
-After birth, young crawl across mother to an external pouch (marsupium)
-Inside pouch, tiny young attach to a teat, feed on milk, and continue development/growth
-Young continue to ride in pouch even after they are physically independent.
-Advantage is that its easy to abort young if conditions become harsh or challenging
-Beneficial in unpredictable environments.

Eutheria/Placentalia

-Placental mammals
-Most diverse lineage of mammals
-Separate openings for digestive and reproductive tracts
-Viviparous, with young born larger and more well-developed
-Young still dependent at birth and are nursed
-Several lineages are aquatic
-Evolved and diversified on northern hemisphere continents
-Invaded southern landmasses when tectonic plates collided; Isthmus of Panama linking N & S America.