Biology ETDs

Publication Date



Island ecosystems are commonly thought to be more vulnerable to the effects of invasive species than mainland systems. In recent decades, the number of exotic plants known to be present in the Galapagos archipelago has increased exponentially. Several of these plants are aggressive invaders that pose a threat to the biodiversity of the islands. Two of these plant species, Passiflora edulis Sims and Psidium guajava L. were introduced to Santa Cruz Island during the 20th century. Both pose a threat to the floristic diversity of the National Park land on Santa Cruz Island.

This paper explores the role played by the endemic Galapagos tortoise (Geochelone elephantopus) in the dispersal of P. edulis and P. guajava. Tortoises are able to spread viable seed of both species; germination percentages for P. edulis indicate that passage through an animal’s gut promotes seed germination. The germination percentages for P. guajava decrease after ingestion, but ingested seeds still germinate readily. Native animals can be an important factor in the spread of exotic plant species and should be taken into account when designing eradication and control strategies.



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Department Name

UNM Biology Department

First Committee Member (Chair)

Diane L. Marshall

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Biology Commons