lect 2 - limblessness

Question 1

limb reduction in squamates

Answer 1

evolutionary process where limbs are reduced or lost, occurring multiple times in separate lineages

Question 2

2 types of limb reduction lineages

Answer 2

1. whole lineages
   (eg. serpentes, amphisbaenia)
2. independent within lineage
   (eg. anguidae, scincidae)

Question 3

lifestyle associated with limb reduction

Answer 3

fossorial (burrowing)

Question 4

evolution of limbless elongated body forms

Answer 4

• evolved 25 times independently
• associated with changes in movement + locomotion
• can lose limbs and re-evolve

Question 5

limb reduction leads to 2 ecomorphs

Answer 5

1. long-tailed surface dwellers (~5)
   eg. anguidae, pygopodidae
   - larger + occupy wide range of habit
2. short-tailed borrowers (~20)
   eg. dibamidae, serpentes, amphisbaenia
   - smaller + dependent on particular habitats

Question 6

bachia

Answer 6

particular lineage has hind limbs reduced before forelimbs
- revolved digits (not full limbs)

Question 7

lerista

Answer 7

particular lineage has forelimb reduction without hindlimb reduction

Question 8

functionality of body elongation

Answer 8

• more flexibility (not faster)
• advantageous in less open habitats
• irreversible evolution

Question 9

transitional forms

Answer 9

partial limb reduction maintained for a long period of time can be stable