Related Experiment Video
Updated: May 12, 2026
13:18
Data Collection on Marine Litter Ingestion in Sea Turtles and Thresholds for Good Environmental Status
Published on: May 18, 2019
One extinct turtle species less: Pelusios seychellensis is not extinct, it never existed
Heiko Stuckas1, Richard Gemel, Uwe Fritz
1Museum of Zoology, Senckenberg Dresden, Dresden, Germany.
Plos One
|April 11, 2013
Summary
The extinct Seychelles freshwater turtle, Pelusios seychellensis, is actually the widespread West African Pelusios castaneus. This finding removes P. seychellensis from extinction lists and Seychelles fauna.
Area of Science:
- Herpetology
- Molecular Phylogenetics
- Conservation Biology
Background:
- Pelusios seychellensis, a freshwater turtle, was believed endemic to Mahé, Seychelles.
- Only three 19th-century specimens exist, and extensive searches failed to relocate it.
- Consequently, it was listed as extinct by the IUCN, the only known extinct freshwater turtle.
Purpose of the Study:
- To investigate the taxonomic status of Pelusios seychellensis using molecular data.
- To resolve the identity of the type specimen and its implications for conservation status.
Main Methods:
- DNA sequencing of three mitochondrial genes from the historical type specimen.
- Phylogenetic analyses incorporating all Pelusios species.
Main Results:
- Phylogenetic analyses revealed the type specimen of P. seychellensis is identical to Pelusios castaneus.
- P. castaneus is a widely distributed West African species, not endemic to Seychelles.
Conclusions:
- Pelusios seychellensis is synonymized with Pelusios castaneus.
- P. seychellensis is removed from the list of extinct species and the Seychelles fauna.
- Re-evaluation of taxonomic status impacts conservation assessments.
Related Concept Videos
02:56The Fossil Record
The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...
02:04Conservation of Small Populations
Small population sizes put a species at extreme risk of extinction due to a lack of variation, and a consequent decrease in adaptability. This weakens the chances of survival under pressures such as climate change, competition from other species, or new diseases. Large populations are more likely to survive pressures such as these, as such populations are more likely to harbor individuals that have genetic variants that are adaptive under new stresses. Small populations are much less likely to...
02:07Conservation of Declining Populations
Conservation of declining population focuses on ways of detecting, diagnosing, and halting a population decline. The approach uses methods to prevent populations from going extinct.
01:39Keystone Species
Measures of species biodiversity, such as richness (i.e., the number of species present) and evenness (i.e., their relative abundance), describe an ecological community’s structure. Many factors affect community structure, including abiotic factors (e.g., sunlight and nutrients), disturbances (e.g., fire or flood), species interactions (e.g., predation or competition), and chance events (e.g., foreign species invasion). Certain species—such as keystone species—also play a pivotal role in the...
02:26Non-vascular Seedless Plants
The diverse plant life on Earth—consisting of nearly 400,000 species—can be divided into three broad categories based on biological characteristics: nonvascular, seedless vascular, and seed plants.
01:17What is a Species?
Overview