# Tracing Genetic Divergence and Phylogeographic Patterns of Gekko gecko Linnaeus, 1758 (Squamata: Gekkonidae) Across Southeast Asia Using RAG1 Sequence

## TL;DR

The study reveals genetic diversity in tokay geckos across Southeast Asia, suggesting multiple hidden species within what was thought to be one.

## Contribution

The study identifies three distinct genetic lineages in Gekko gecko using RAG1 sequences, supporting the need for integrative taxonomy.

## Key findings

- Analysis of RAG1 sequences revealed 20 haplotypes and strong regional genetic structuring in Gekko gecko.
- Three distinct evolutionary lineages (A–C) were identified, supported by species delimitation tests.
- Color morphs (red- and black-spotted) do not correspond to genetic differentiation at the RAG1 locus.

## Abstract

The tokay gecko (Gekko gecko) is a colorful lizard found in Southeast Asia and is widely used in traditional medicine. In this study, we analyzed DNA from tokay geckos in Thailand, Laos, and Cambodia to understand their genetic differences. We found clear genetic variation between populations and discovered three main genetic lineages. These results suggest that what is thought to be one species may include hidden, distinct groups. This information is important for protecting the species and managing its trade.

The tokay gecko (Gekko gecko) is a widely distributed lizard species in Southeast Asia, with significant importance in traditional medicine and the pet trade. Previous studies using mitochondrial DNA sequences revealed extensive genetic variation across its range, indicating the presence of distinct evolutionary lineages. In this study, we assessed the nuclear genetic variation and phylogenetic pattern of G. gecko using the recombination activating gene 1 (RAG1). We analyzed 105 RAG1 sequences from 16 localities across Thailand, Laos, and Cambodia, along with additional sequences from GenBank. Sequence analysis revealed 20 variable sites and 20 haplotypes (TgR1–TgR20). Haplotype network and phylogenetic analyses revealed strong regional structuring and at least three distinct evolutionary lineages (A–C), supported by the species delimitation test (PTP). Both red- and black-spotted morphs were present in different clades, indicating that external coloration does not correspond to genetic differentiation at this locus. Our results support the presence of distinct evolutionary lineages in G. gecko and emphasize the importance of integrative taxonomy for accurate species delimitation. These findings have implications for conservation, sustainable management, and regulation of international trade in this commercially exploited species.