Marine iguanas

• Amblyrhynchus

  monospecific lineage, forming a clade native to the Galapagos

  • including Amblyrhynchus + 3 species of galapagos land iguana
• Galapagos

  • volcanic island chain in a zone where warm and cold ocean currents meet
  • diverse biodiversity
  • whaling was previously developed
  • not a huge amount of vegetation -> lack of terrestrial iguanas
• How were within-island speciation and between-island hybridisation explored

  • groups of marine iguana
• How could speciation and hybridization of marine iguanas arise

  • strong swimmers -> movement between neighbouring islands
  • high levels of island-specific genetic diversity appear recently and may be linked to volcanic events
• Examples of lizards adapting to feeding pressures

  • columbia -> intertidal feeding, feeding on crustacea
  • madagascar -> feeding on insects, crustacea and fish
• How have marine iguana adapted for foraging

  -> from land-based cousins around 4 mya

  • long claws -> hanging onto rocks
  • laterally compressed tail -> swimming + diving
  • salt gland -> nostril
  • feed on red and green algae
  • tricuspid teeth
  • dark skin -> UV Protection + warming
• Thermoregulation in marine iguanas

  • bask in sun
  • black skin -> absorbs heat quickly
  • smaller and thinner iguana (young) = low thermal capacity, can only feed intertidally
• Climate effects on marine iguanas

  • el nino -> loss of green and red algae
  • brown algae is indigestible -> starvation, skeleton shrinkage + death
• invasive species on marine iguanas

  • grape weed
  • marine iguanas cannot eat it