Phylogenetic Insights and Genetic Diversity of Testudinid Tortoises

Testudinid tortoises, comprising over fifty extant species of the family Testudinidae, exhibit deep evolutionary splits and varied genetic landscapes shaped by ancient geological events and more recent human influences. Phylogenetic reconstructions using both mitochondrial and nuclear markers have clarified interspecific relationships among Mediterranean, African, Asian and American lineages, revealing divergences from the late Eocene through the Pleistocene. Studies integrating morphometric data with genomic information have exposed cryptic diversity at subspecies and regional levels, while population-level analyses highlight variation in genetic diversity associated with habitat fragmentation, island isolation and conservation status. Together, these insights inform taxonomic revision, guide conservation management and underscore the global significance of genetic stewardship in tortoise lineages facing anthropogenic pressures.

Research from Nature Portfolio

Recent studies have combined mitogenomic sequencing and detailed morphological assessments to resolve key phylogenetic questions. Analysis of complete mitochondrial genomes from extinct Mascarene giant tortoises has demonstrated an ancient Eocene origin for this lineage, with Oligocene diversification preceding island emergence and long-distance dispersal via now-submerged seamounts. Complementary work on two subspecies of Testudo graeca across their contact zone has identified two primary monophyletic clades correlating with shell-shape differences, with divergence linked to Pliocene uplift of the Zagros Mountains; this research also delineated management units critical for conserving intraspecific evolutionary potential.

Phylogenetic Insights and Genetic Diversity of Testudinid Tortoises publication trend

The graph below shows the total number of articles in phylogenetic insights and genetic diversity of testudinid tortoises across all publications each year (not limited to Nature Index journals).

Technical terms

Clade: A group of organisms derived from a common ancestor.

Mitogenome: The entire mitochondrial DNA sequence of an organism.

Phylogeography: The study of how historical processes influence the geographic distribution of genetic lineages.

Monophyletic: A taxonomic group containing an ancestor and all its descendants.

Genetic diversity: The total number of genetic characteristics in the genetic makeup of a species.

Ecological niche modelling: A computational method to predict a species’ suitable habitat based on environmental parameters.

References

1. Population genomics of the endangered giant Galápagos tortoise. Genome Biology (2013).
2. Phylogeographic and phenotypic divergence between two subspecies of Testudo graeca (T. g. buxtoni and T. g. zarudnyi) across their contact zone in Iran. Scientific Reports (2022).
3. Ancient mitogenomics clarifies radiation of extinct Mascarene giant tortoises (Cylindraspis spp.). Scientific Reports (2019).
4. The desert tortoise trichotomy: Mexico hosts a third, new sister-species of tortoise in the Gopherus morafkai–G. agassizii group. ZooKeys (2016).
5. Mitochondrial DNA and Distribution Modelling Evidenced the Lost Genetic Diversity and Wild-Residence of Star Tortoise, Geochelone elegans (Testudines: Testudinidae) in India. Animals (2022).