Iguanas in Fiji

GS 1 – Environment

Context:

A recent study suggests that iguanas colonized Fiji by surviving an 8,000-kilometer oceanic journey—the longest known migration of any land-dwelling vertebrate.

About Iguanas

Iguanas are terrestrial reptiles, yet they are found on distant Pacific islands such as Fiji, Tonga, and the Galápagos, raising the question: How did they get there?

  • Recent Study Findings:
    • Genomic analysis reveals that the ancestors of the Fijian Banded Iguana (Brachylophus fasciatus) rafted from North America about 30 million years ago.
    • The study suggests floating vegetation (downed trees, broken branches) carried the iguanas across vast oceanic distances.
    • The South Equatorial Current likely facilitated their drift across the Pacific.
Evidence Supporting the Theory
  1. Genetic Links:
    • Fijian iguanas share their closest genetic relatives with Dipsosaurus, a genus of desert iguanas found in the American Southwest and Mexico.
    • The evolutionary split between these species dates back 30–34 million years, coinciding with the formation of the Fijian archipelago.
  2. Proven Rafting Events:
    • In 1995, hurricanes washed green iguanas from Central America to the Caribbean using floating logs, proving that such long-distance dispersal is possible.
About Fiji
  • Location: Tropical archipelago in the South Pacific Ocean.
  • Number of Islands: Around 300 (100 inhabited).
  • Capital: Suva (located on Viti Levu, the largest island).
  • Independence: Gained from British rule in October 1970.
  • Government: Parliamentary democracy.
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