BIO2242 Lecture Notes - Lecture 24: Autotomy, Intraspecific Competition, Skink
Lecture 24 – Life History Case Study and Exam Prep
Case Study: Tail Loss in Lizards
• Tail detaches → tail thrashes around back and forth
o Detract attention from predators away from lizard (distracts)
• Why do lizards shed their tails?
o Escape predator’s grasp
o Tail distracts predator
o Makes a gateway
o Last-ditch strategy
• This is last strategy
o First: try to run away or camaflouge
• Caudal autotomy
o Caudal – tail
o Autotomy – voluntary shedding of body parts (self-amputation)
▪ Ancestral state
▪ 30 families of 38 lizard families that lose their tails
• Frequency is substantial: 3-82%
o Efficient predators leave no trace (0 tail loss
frequency as predator always gets prey)
o If predator is inefficient – lizards escape
regularly
• Autotomary occurs in several animal taxa
o Craps, starfish, octopus, spiders
• Emphasize tail
o Tail colouration
▪ E.g. Fire tail skink – long red tail l
▪ Older – past size threshold → less predators
▪ Juveniles more at risk
o Tail waving
▪ Velvet gecko
• Predatory attack to tail → higher chance of surviving
o Expendable
o Rarely survive attacks directed to the head or body
• Tail loss result of intraspecific competition
o Males bite base of competing males tail → competitive advantage
against that individual
• How do lizards lose their tails?
o Fracture plains in caudal vertebrae
▪ Occur in centre of vertebrae (3 lines of weakness where it
breaks)
▪ Muscles, blood vessels, nerves
▪ Valves, sphincters close to limit blood loss
o Under neural control – muscle contraction
▪ Doesn’t need to be touched
o Not in most proximal vertebrae (locomotor muscles)
o Inter-vertebrate: tail physically ripped off
• Consequences
o Absence of tail
find more resources at oneclass.com
find more resources at oneclass.com
