WFC134 Terms

Monophyletic group

All the descendants of a common ancestor

Polyphyletic group

A group of organisms who do not arise from a common ancestor

Paraphyletic group

Some but not all groups who all descend from a common ancestor

Ectothermy

When an organism controls their internal body temperature with the external environment because they are incapable of producing their own heat, favorable with a big SA:V ratio, performance/activity depends on external temperature

Why are reptiles and amphibians studied together if they are a polyphyletic group?

Both groups are ectothermic tetrapods

Actinopterygii (ray-finned fish)

An extremely diverse outgroup of tetrapoda, their fins have extrinsic muscles

Extrinsic muscles

Muscles that attach to two different bones or systems

Actinistia

An outgroup of tetrapoda, contains an extant species — coelacanth — who is described as a living fossil since it is relatively unchanged for 300 million years, 3 lobed tail

Dipnoi (lungfishes)

An outgroup of tetrapoda, have homologous lungs to tetrapods, 3 extant genera

Sarcopterygii (lobe-finned fish)

A clade containing actinistia, dipnoi, and tetrapoda, fins/limbs are supported by bone with intrinsic muscle, have teeth with enamel

Intrinsic muscle

Muscles that span one specific body part, both ends attached to the same bone/system

Important shared (for the most part) features of tetrapoda

Ankle and wrist joints, pectoral girdle present and free from skull, discrete shaft of humerus, paired bones in distal part of limbs, digits at the end of limbs

Tiktaalik

An important transitional form in tetrapoda! they have a mobile neck, pectoral girdle detached from the skull, and retained gill arches

Evolutions for supporting weight/coping with gravity in the transition from land to water

Larger and more differentiated limbs, development of joints, pectoral girdle separated from head, limb girdles more closely attached to vertebrae

Evolutions for movement in the transition from land to water

More robust and differentiated limbs, intrinsic musculature on limbs

Evolutions for breathing air in the transition from land to water

Developed lungs, possibly to adapt to low oxygen water, ventilation powered by muscles of the rib cage, reduced reliance on cutaneous respiration

Evolutions for conserving water in the transition from land to water

Excreting uric acid instead of ammonia, mucous glands that limit evaporation from amphibian skin, behavioral changes

Evolutions for hearing in the transition from land to water

The hyomandibula bone of the 1st gill arch became the stapes (inner ear that connects to tympanum) which enhances sound conduction to inner ear, loss of lateral line system

Evolutions for feeding in the transition from land to water

Increased use of jaws and tongue

Amnion

The membrane of the amniotic egg that surrounds the embryo, does gas exchange and protects the embryo

Chorion

Forms the placenta in mammals, outermost membrane of amniotic egg (within the shell)

Allantois

The “waste basket” of the amniotic egg, forms umbilical cords, grows as it is filled

Yolk sac

The nutrient source of the amniotic egg, shrinks as it’s used

Shell

Forms the outside of the amniotic egg, created by the mother, participates in gas exchange

What is the major differentiation between the clade Amniota

The number of holes in the skull (Diapside, Synapsid, or Anapsid)

Temnospondylii

A subclass containing the modern and extant lineage of amphibians

The three orders of Lissamphibia

Gymnophonia, Anura, and Caudata

Which two orders of Lissamphibia are more closely related than the third

Caudata and Anura

Lissamphibia (“Living amphibians”)

The three orders of extant amphibians, generally considered a monophyletic group due to shared derived traits and modern molecular evidence (but there’s some controversy)

Characteristics UNQIUE to Lissamphibia

• Amphibian papilla - sensory region in the inner ear for low frequency sounds 

• Opercular bone - bone in the inner ear that transmits low frequency vibrations from legs to amphibian papilla, connected by muscle to pectoral girdle

• Green rods in retina - allow for night vision

  • NOT in caecilians

• Levator bulbi muscle that elevates eye, this increases their FOV and allows for more space in the mouth

• Fat stored in an organ associated with the gonads 

Heterochrony

Changes in timing and/or developmental rate of some traits

Paedomorphosis

Retention of juvenile characteristics despite sexual maturity

Neoteny

Delaying or slowing of somatic development relative to sexual development, which stays normal

Progenesis

Accelerating sexual development relative to somatic development, which stays normal

Facultative paedomorphosis

Individuals that are capable of metamorphosing but can also be paedomorphic, depends on environmental conditions

Obligate paedomorphosis

Individuals that are all paedomorphic, cannot metamorphosis

Direct development

When the larval stage is in the egg

Indirect development

When the embryo doesn’t fully develop in the mother/egg and results in free living larval stage

Three suborders of Caudata

Salamandroidea, Sirenoidea, and Cryptobranchoidea

What is the ancestral trait for fertilization and parental care in Caudata?

External fertilization, paternal care

Unken reflex

A trait prominent in salamanders, a way to show off coloration once crypsis fails

Reproductive mode

A combination of ovipositional, developmental, and parental care factors that characterize a species

Amplexus mating clasp

An embrace during mating that positions the male near a female to fertilize her eggs

Inguinal amplexus

The ancestral mating clasp in anura, females are grasped near the pelvis

Axillary amplexus

The advanced/derived mating clasp in anura, females are grasped around shoulders

Parental care

Any behavior exhibited by parent towards offspring that increase their chances of survival

Often associated with terrestrial eggs, direct development, and less + larger eggs

Arciferal girdle

The ancestral girdle condition in anura, contains spongy cartigenlous tissue

Firmisternal girdle

The dervied girdle condition in anura, sternum is firmly connected and lacks cartilege, acts a shock absorber when landing hops

Archaeobatrachia

Ancient frog suborder, families contain many ancestral traits

Neobatrachia

Contains bulk of the frog families, “new” or “advanced” frogs with advanced traits

Egg tooth

A keratinized tip of the nose that help offspring cut open egg once developed

Bidder’s organ

A rudimentary ovary retained in adult males, paedomorphic trait

Unique characteristics of caecilians (compared to other amphibians)

Retractable tentacle, phallodeum in males (copulatory organ), dermatophagy, compact skull, interhyoideus jaw muscle, dermal scales

Ancestral trait for caecilian jaw mechanism

Less reliance on interhyoideus muscle, use adductor mandibulae more

Derived trait of caecilian jaw mechanism

More reliance on interhyoideus muscle, less use of adductor mandibulae

Retractable tentacle

A sensory unique to JUST caecilians

Ancestral trait of retractable tentacle

Emerges from the eye socket

Derived trait of retractable tentacle

Emerges from evolved foramen opening

Dermatophagy

When young feed off of mother’s skin to live, mother regrows skin every few days

Acrodont

Tooth type where teeth are fused and arranged in a groove, present in agamidae lizards and sphenodontia

Pleurodont

Tooth type where the teeth are attached primarily to the inner side of the high labial wall, common in most snakes and lizards

Thecodont

Tooth type where the long cylindrical base is set in the deepy, bony socket, found in crocodilians

Ecdysis

The shedding of outer layer of dead skin cells

Stratum corneum

The outer layer of flat, dead keratinized skin cells

Stratum germinativum

The deepest layer of the epidermis that gives rise to the outer layer, aka the growing layer

Type 1A Temperature-dependent sex determination

Hot temperature lead to females, cool temperatures lead to males (hot girls, cool guys), found in turtles

Jacobson’s organ

Chemosensory organ that receives chemical cues from the tongue, secondarily lost in birds/mammals, important in tuatara, snakes, and lizards

Carapace

The dorsal side of a turtle’s shell (the “top”)

Plastron

The ventral side of a turtle’s shell (the “bottom”)

Bridge

Part of turtle’s shell that connects the carapace and plastron

Cervical scute

Thickened scale behind a turtle’s head that protects it when extended, helps distinguish between families

What are the three distinguishing factors between the two orders of Testudines?

Vertical vs lateral withdrawing of the neck

Whether the pelvis is or isn’t fused to the plastron

Northern and Southern hemisphere distribution or just southern

Hemipenes

Copulatory organ in squamata, two “half” penises

Type 1B Temperature-dependent sex determination

Males at warm temperatures, females at cooler temperatures, present in crocodylia, tuatara, and many lizards

Type 2 Temperature-dependent sex determination

Males at intermediate temperatures, females at extreme temperatures, rare presence in lizards

Parthenogenesis

Asexual reproduction through self-fertilization

What was the major split in the Iguania infraorder?

Pleurodonta vs Acrodonta (based on teeth and global distribution)

Lateral undulation/serpentine

Locomotion in snakes where they push off of pivot points, looks like a wave passing through the body, used for swimming and crawling

Concertina locomotion

Locomotion in snakes on low friction surfaces where they use a push/pull motion, used for climbing and going through confined spaces

Sidewinding

Locomotion in snakes on frictionless or shifting surfaces (like sand), most of the body stays in contact with the ground, moves in a sideways motion by throwing head forward and the rest of the body follows

Rectilinear locomotion

Locomotion in snakes where they “belly crawl” in a straight line using belly scales, similar to catepillar motion

Traits in an active foraging snake

Diurnal, thin and elongated body shape, smaller prey, more frequent feeding

Traits in an ambush predator

Nocturnal, thicker body shape, larger prey/can’t be picky about size, feed less frequently, use crypsis or bites as predator defense

Opisthoglyphs

Rear-fanged teeth, posterior pair of teeth on maxilla enlarged and often grooved, can be deadly but often ineffective because a good grip is needed to deliver, use duverroy’s gland, found in colubrids

Duverroy’s gland

Similar to a poison gland, highly concentrated saliva found in colubrids for venom delivery (in contrast to venom gland in vipers)

Solenoglyphs

Front-fanged venom delivery found in vipers, movable hollow fangs located on front of maxillae, highly mobile, swing forward and out

Proteroglyphs

Front-fanged venom delivery in elapids, grooved fangs partially or completely closed over, on front of maxillae and less kinetic

Aglyphous

Teeth in non-venomous species (MOST SNAKES), no specialized teeth, pleurodont dentition

Major split in serpentes

Scolecophidia (blind snakes, smaller) and Alethinophidia (true snakes, lots of diversity)

What is the major difference between crocodiles and alligators?

Snout shape (broad in alligators, narrow in crocs), teeth arrangement (teeth in lower jaw fit with alligators, fourth lower tooth outside in crocs), lingual salt glands (present in crocs)

Nictitating membrane

Trait in Crocodylia — transparent third eyelid that protects eye when underwater

Gastralia

Long bony plate of shields with accessory ribs found in tuatara

Parietal eye

Third eye developed, covered in scales after birth, unique trait of tuatara, helpful with circadian rhythm and thermoregulation