Comparing and combining distance-based and character-based approaches for barcoding turtles.

Area of Science:

• Conservation Genetics
• Molecular Ecology
• Wildlife Forensics

Background:

• Illegal wildlife trade threatens many turtle species (Order Testudines).
• Molecular barcoding is a valuable tool for species identification and conservation efforts.
• Previous barcoding efforts for turtles were limited in scope.

Purpose of the Study:

• To create a comprehensive molecular barcode dataset for turtles.
• To evaluate the effectiveness of DNA barcoding for turtle species identification.
• To develop tools for aiding in turtle conservation and combating illegal trade.

Main Methods:

• Generated 650 bp cytochrome oxidase subunit one (COI) sequences for 174 turtle species.
• Combined new sequences with 50 publicly available sequences.
• Assessed genetic variability and evaluated distance-based and character-based identification methods.

Main Results:

• Analyzed a dataset representing a broad diversity of the turtle order.
• Found average intraspecific divergence of 1.3% and interspecific divergence of 6.4% between genera.
• Identified 15 species with high intraspecific divergence and 49 species with low interspecific divergence (<2%) from congeners.
• Character-based methods improved species resolution where distance-based methods failed.

Conclusions:

• Molecular barcoding is effective for turtle identification and conservation, despite challenges like high intraspecific and low interspecific divergence.
• High intraspecific divergence may indicate cryptic species or complex population structures.
• Low interspecific divergence suggests recent evolutionary radiations or slow mtDNA evolution in turtles.
• An online identification engine was developed to support conservation and forensic applications.