Lepidosaurs: Tuatara + lizards (+snakes)

Question 1

How big is the group “lepidosaurs”?

Answer 1

Largest group of non-avian reptiles (big)

Question 2

What types of organisms make up the lepidosaurs?

Answer 2

Predominantly terrestrial tetrapods, with some aquatic species

Question 3

What are the main characteristics of lepidosaurs?

Answer 3

Scaly skin, impermeable to water. Outer layer of epidermis shed at intervals. Transverse cloacal slit (unlike other tetrapods).

Question 4

The group tuatara is also called sphenodontids- what does this mean?

Answer 4

“spine on back”

Question 5

Where does tuatara reside?

Answer 5

New Zealand and its islands

Question 6

What are the main characteristics of tuatara?

Answer 6

Nocturnal (lower body temp than most lizards)

• bask during day
• feed on seabirds at night (and inverts)

Question 7

How does the tuatara jaw work?

Answer 7

Shearing motion: 2 rows of teeth on upper jaw, 1 row on lower jaw fits between these. Lower jaw closes then slides forward to shear

Question 8

What is the most significant derived feature of squamates?

Answer 8

Determinate growth- grow to certain size then stop. Allows them to be insect eaters their whole life

Question 9

Where does growth occur in squamates and how does it stop?

Answer 9

Growth occurs at epiphysial plates (the cartilage growth plates at ends of long bones)
- it stops when epiphyses have fused to shaft of bone

Question 10

Do turtles and crocodilians stop growing like this too?

Answer 10

No- they grow throughout their lives

Question 11

What type of diet do most large lizards have?

Answer 11

Herbivores

Question 12

What group of lizards are the exception to herbivory? Why?

Answer 12

Large monitor lizards (varanids).

- Positive pressure throat allows them to sustain activity long enough to hunt

Question 13

What do Komodo dragons hunt?

Answer 13

Water buffalo, goats, deer

Question 14

How do Komodo dragons eat?

Answer 14

Relies on slashing motion and venom containing enzymes which result in rapid drop of blood pressure of prey (bc they have a low bite force)

Question 15

What are legless lizards called?

Answer 15

Amphisbaenians

Question 16

What adaptations do amphisbaenians have to burrow?

Answer 16

Rigid skulls

Question 17

What is a derived feature of squamates that assists with foraging and feeding?

Answer 17

They have a high degree of mobility/flexibility in skull, and stronger jaw muscles

Question 18

What is a lizard with an extremely sedentary lifestyle?

Answer 18

Tropidurid lizard: remains motionless for 99% of the day, with short dashes less than 2 seconds to capture prey

Question 19

What is a lizard with a very active lifestyle?

Answer 19

Teiid lizards: move 70% of the time, average 1 body length every 2-5 seconds

Question 20

What body type do sit-and-wait predators have?

Answer 20

Stout-bodied, short-tailed, cryptically coloured (dorsal blotches of colour that obscure body outline)

Question 21

What body type do “widely-foraging” species have?

Answer 21

Slender, elongate, long-tailed with stripes patterns that produce optical illusions as they move

Question 22

What is the “tail-break” mechanism?

Answer 22

Autotomy- tail can fall off to avoid predation

Question 23

What kind of metabolism do “sit-and-wait” predators use?

Answer 23

Anaerobic metabolism of glycogen stored in muscles. This allows quick synthesis of ATP and no oxygen is required. This means they have high sprint speed but no endurance.

Question 24

What kind of metabolism do “wide-ranging” predators use?

Answer 24

Aerobic metabolism of glucose in blood stream. Low sprint speed, high endurance. (also have larger hearts)

Question 25

What is the gist of squamate social behaviour?

Answer 25

• many species show dominance hierarchies or territoriality (=relatively limited social behaviour)

Question 26

What level of parental attendance or care is given by squamates?

Answer 26

Parental attendance at nest during egg incubation occurs in some, but extended parental care of young is rare

Question 27

What is the gular fan and what is it used for? (In the male alone lizard)

Answer 27

It is the skin beneath the chin that can be distended for visual displays (also displays push-ups and head bobs)

Question 28

How do territorial male lizards respond towards intruding males? Intruding females?

Answer 28

Respond aggressively towards males. Initiate courtship behaviour toward intruding females.

Question 29

What are the 3 styles of western side-blotched lizard?

Answer 29

Blue, orange, or yellow throat. Throat colour is determined by testosterone levels in male, fixed early in development

Question 30

What does a blue throat western side-blotched lizard mean?

Answer 30

This lizard maintains territory overlapping with one or more females

Question 31

What does an orange throat western side-blotched lizard mean?

Answer 31

More aggressive than blue throat, but do not maintain their own territory. Instead, they displace blue throats and mate with females on territory

Question 32

What does a yellow throat western side-blotched lizard mean?

Answer 32

They sneak onto blue throat territory to mate with a female before being chased off

Question 33

What does the fitness of any one morph of throat colour male depend on?

Answer 33

The distribution and relative abundance of morphs

Question 34

What are the benefits and costs of viviparity?

Answer 34

• allows female to use her own thermoreg. to regulate temp. of developing young
• may lower repro output
• agility of female is reduced when carrying young

Question 35

What does having a parthenogenetic species mean?

Answer 35

All female species. Found in at least 6 lizard and 1 snake family

Question 36

How do parthenogenic squamates arise?

Answer 36

From hybridization of 2 sexually reproducing species, resulting in duplication of chromosomes. Cross over happens between sister chromatids.

Question 37

Why can pathenogenesis be better than normal reproduction?

Answer 37

Every individual is capable of reproducing (which is twice the reproductive capacity of normal repro)- If disaster hits, these groups can repopulate faster

Question 38

What is a form of temperature dependent sex determination in lizards?

Answer 38

Female can regulate body temp to determine sex of offspring

Question 39

How does the Australian three-lined skink override genetic sex determination?

Answer 39

Low temperature can override genetic sex determination- producing XX males

Question 40

What are the behavioural mechanisms lizards use to control body temp?

Answer 40

• movement between sun and shade
• orientation toward sun
• body contour (change area exposed)
• colour of skin (moving pigment to make darker or lighter)

Question 41

How are melanophores shaped and how does this work?

Answer 41

Melanophores are mushroom shaped. When melanin granules are in the broad section, it appears dark. When melanin is in the stalk (away from skin surface), skin appears light

Question 42

What is the activity temperature range of most lizards?

Answer 42

33-38 degrees

Question 43

What is the physiological mechanism to determine temperature?

Answer 43

• dilate or restrict blood vessels to facilitate rapid heating or slow cooling