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Lookup NU author(s): Dr Evelyn Jensen
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2022, The Author(s). The Galapagos Archipelago is recognized as a natural laboratory for studying evolutionary processes. San Cristóbal was one of the first islands colonized by tortoises, which radiated from there across the archipelago to inhabit 10 islands. Here, we sequenced the mitochondrial control region from six historical giant tortoises from San Cristóbal (five long deceased individuals found in a cave and one found alive during an expedition in 1906) and discovered that the five from the cave are from a clade that is distinct among known Galapagos giant tortoises but closely related to the species from Española and Pinta Islands. The haplotype of the individual collected alive in 1906 is in the same clade as the haplotype in the contemporary population. To search for traces of a second lineage in the contemporary population on San Cristóbal, we closely examined the population by sequencing the mitochondrial control region for 129 individuals and genotyping 70 of these for both 21 microsatellite loci and >12,000 genome-wide single nucleotide polymorphisms [SNPs]. Only a single mitochondrial haplotype was found, with no evidence to suggest substructure based on the nuclear markers. Given the geographic and temporal proximity of the two deeply divergent mitochondrial lineages in the historical samples, they were likely sympatric, raising the possibility that the lineages coexisted. Without the museum samples, this important discovery of an additional lineage of Galapagos giant tortoise would not have been possible, underscoring the value of such collections and providing insights into the early evolution of this iconic radiation.
Author(s): Jensen EL, Quinzin MC, Miller JM, Russello MA, Garrick RC, Edwards DL, Glaberman S, Chiari Y, Poulakakis N, Tapia W, Gibbs JP, Caccone A
Publication type: Article
Publication status: Published
Journal: Heredity
Year: 2022
Volume: 128
Issue: 4
Pages: 261-270
Print publication date: 01/04/2022
Online publication date: 25/02/2022
Acceptance date: 03/02/2022
Date deposited: 23/06/2022
ISSN (print): 0018-067X
ISSN (electronic): 1365-2540
Publisher: Springer Nature
URL: https://doi.org/10.1038/s41437-022-00510-8
DOI: 10.1038/s41437-022-00510-8
PubMed id: 35217806
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