Biodiversity Data Journal :
Research Article
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Corresponding author: Maria de Lourdes Torres (ltorres@usfq.edu.ec)
Academic editor: Katharina Wollenberg Valero
Received: 27 Sep 2023 | Accepted: 01 Nov 2023 | Published: 16 Nov 2023
© 2023 Lía Altamirano-Ponce, Mateo Dávila-Játiva, Gabriela Pozo, María José Pozo, Martín Terán-Velástegui, Carlos Daniel Cadena, Diego Cisneros-Heredia, Maria de Lourdes Torres
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Altamirano-Ponce L, Dávila-Játiva M, Pozo G, Pozo MJ, Terán-Velástegui M, Cadena CD, Cisneros-Heredia DF, Torres ML (2023) First genetic insights of Gonatodes caudiscutatus (Reptilia, Gekkota) in the Galapagos Islands and mainland Ecuador. Biodiversity Data Journal 11: e113396. https://doi.org/10.3897/BDJ.11.e113396
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Studies on genetic variability amongst native and introduced species contribute to a better understanding of the genetic diversity of species along their autochthonous distribution and identify possible routes of introduction. Gonatodes caudiscutatus is a gecko native to western Ecuador and introduced to the Galapagos Islands. Despite being a successful species in human-modified habitats along its native and non-native ranges, neither the colonisation process nor the genetic diversity of this gecko is known. In this study, we analysed 55 individuals from 14 localities in western Ecuador and six localities in San Cristobal Island, Galapagos — the only island with a large, self-sustaining population. We amplified and analysed the genetic variability of two nuclear genes (Cmos and Rag2) and one mitochondrial gene (16S). Cmos and Rag2 sequences presented little to none genetic variability, while 16S allowed us to build a haplotype network. We identified nine haplotypes across mainland Ecuador, two of which are also present in Galapagos. Low genetic diversity between insular and continental populations suggests that the introduction of G. caudiscutatus on the Islands is relatively recent. Due to the widespread geographical distribution of mainland haplotypes, it was not possible to determine the source population of the introduction. This study represents the first exploration of the genetic diversity of Gonatodes caudiscutatus, utilising genetic tools to gain insights into its invasion history in the Galapagos.
introduced species, genetic variability, haplotype, gecko, Gonatodes caudiscutatus, Galapagos Islands, Ecuador
Human-mediated introductions of non-native species are a common and well-documented phenomenon, exponentially increasing in our globalised world (
Geckos (infraorder Gekkota) are some of the most successful colonisers of novel areas amongst terrestrial vertebrate taxa. Many species in this group have established thriving non-native populations on oceanic islands (
Gonatodes is a genus of small neotropical sphaerodactylid geckos with strong sexual dimorphism (
There are no studies about the colonisation process of G. caudiscutatus in the Galapagos Islands and, in general, little is known about the species beyond its general morphology and distribution (
Across the globe, most species of introduced herpetofauna are understudied (Kraus 2009a) and genetic data for such species in the Galapagos are limited (
We surveyed 34 localities across the native range of G. caudiscutatus in mainland Ecuador and 12 localities in San Cristóbal Island, Galapagos Archipelago (Suppl. material
Fieldwork was carried out in June–July 2019 in Galapagos and August- September 2019 in mainland Ecuador. Two researchers exhaustively searched for geckos at each locality for approximately 3 hours during the daytime, carefully looking under rocks, logs, rubble and other debris. Geckos were captured by hand and euthanised with benzocaine. Tail muscle samples were preserved in 90% ethanol and stored at −20°C until used and analysed at the Plant Biotechnology Lab of Universidad San Francisco de Quito USFQ. Voucher specimens were fixed in formalin and preserved in ethanol 70%. Specimens are deposited in the Zoology Museum at Universidad San Francisco de Quito, Quito, Ecuador (ZSFQ) under collection codes specified in Suppl. material
Cell lysis was performed following the protocol described by
Sequence cleaning and aligning were performed using Geneious Prime 2020.0.5 software under default parameters. In order to assess genetic differentiation and genealogical relationships amongst G. caudiscutatus populations from San Cristóbal Island and mainland Ecuador, we built two trees using the three concatenated genes. The first tree was built using the Bayesian Inference (BI9 model under the default parameters in the Geneious Tree Builder option using Geneious Prime 2020.0.5 software (
The GenBank accession numbers for the new sequences are MZ434825-MZ434876 for 16S sequences and MZ594479-MZ594565 for Cmos and Rag2.
We found individuals in 32 out of the 46 sampled sites and obtained sequence data of Rag2 for 40 individuals, of Cmos for 47 individuals and of 16S for 52 individuals. 16S sequences varied considerably (overall mean genetic distance of 24.31), but there were few differences in Cmos (overall mean genetic distance of 0.41) and no variation in Rag2 (overall mean genetic distance of 0). The results of the overall mean genetic distance for each gene and the genetic pairwise distances between all individuals for each gene can be found in Suppl. material
16S sequences showed 21 variable sites in the 403 base-pair region (Fig.
Abundance and geographical distribution of haplotypes found in this study. Locality data are available in Suppl. material
Haplotypes |
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Province |
Locality |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
Esmeraldas |
Acantilado |
2 |
||||||||
Esmeraldas City |
3 |
1 |
||||||||
Bolivar |
Caluma |
1 |
2 |
|||||||
Guayas |
Cerro Blanco |
5 |
||||||||
Bucay |
1 |
|||||||||
Pantanal Zoo |
1 |
1 |
2 |
|||||||
Manabí |
Agua Blanca |
4 |
||||||||
Pto. Lopez |
2 |
|||||||||
Sto. Domingo |
Santo Domingo City |
3 |
2 |
1 |
||||||
Los Ríos |
Quevedo |
1 |
1 |
|||||||
San Cristobal |
Highlands |
3 |
8 |
|||||||
San Cristobal |
Lowlands |
2 |
6 |
|||||||
Total |
12 |
4 |
1 |
22 |
2 |
2 |
1 |
1 |
7 |
Haplotypes 1 and 4 were found widely throughout mainland Ecuador and are the only haplotypes found in the samples of San Cristóbal (Fig.
Genetic variation in surveyed populations of G. caudiscutatus. Pie chart colours correspond to haplotypes found in each locality. Numbers correspond to haplotypes detailed in Table
This study presents the first insights into the genetic diversity of native and introduced populations of G caudiscutatus in mainland and insular Ecuador. A total of nine haplotypes were found along the native range of G. caudiscutatus in western Ecuador. We found low nucleotide diversity values in mainland sites, with minor differences amongst populations. However, haplotype diversity was high; six haplotypes were unique to specific sampling locations, but their distribution did not correspond to any discernible biogeographic pattern. High haplotype diversity values have been reported for other Gonatodes that inhabit complex geographic ranges (
Two haplotypes were found on San Cristóbal Island, but none is exclusive to Galapagos and represent a small portion of the haplotype diversity from the mainland. Our analyses could not provide concrete evidence about the origin of the introduced populations of G. caudiscutatus in the Galapagos because there was no discernible genetic structure in the mainland: both island haplotypes were scattered throughout western Ecuador (Fig.
Loss of genetic variation in introduced population due to bottlenecks during introductions has been reported to compromise the ability of populations to adapt to novel areas and limit their viability (
Extra-range records of G. caudiscutatus are recurrently reported in mainland Ecuador and Galapagos, suggesting that the species may eventually hold a larger potential for colonisation of different lowland ecosystems (
We thank Camila Piñeiros for her support during fieldwork; Emilia Peñaherrera for her help with the map; Giovanny Sarigu who allowed us to carry out field research at Hacienda La Tranquila; Carlos Mena, Diego Quiroga, Steve Walsh, Sofía Tacle, Cecibel Narváez, Anita Carrión, Sylvia and Jessenia Sotamba, Cristina Vintimilla, Máximo and Marlene Ochoa and all the personnel from the Galapagos Science Center GSC (Universidad San Francisco de Quito USFQ and University of North Carolina at Chapel-Hill UNC) and Universidad San Francisco de Quito, Galapagos extension — GAIAS for their constant support and help; the Galapagos National Park Directorate, including all authorities and park rangers of the Galapagos National Park for their valuable comments during project proposal reviews and support with logistics and transportation to the sampling sites; Carolina Reyes-Puig, David Brito, Catalina Palacios, Fabian Salgado-Roa, Julian Peña and all members of the USFQ Plant Biotechnology Laboratory, USFQ Terrestrial Zoology Laboratory and the Laboratorio de Biología Evolutiva de Vertebrados, Departamento de Ciencias Biológicas of Universidad de los Andes (Bogotá, Colombia) for their technical assistance, guidance, support and access to equipment, labs and other facilities; and the members of the Lab of Life in San Cristóbal, Comunidad Agua Blanca in Manabí and Bosque Protector Río Blanco in Guayaquil, Villa Colombia hostel in Manabi for allowing us to do research in their territories. Our work was possible thanks to Galapagos POA Grants provided by the GSC, COCIBA Grants provided by the Colegio de Ciencias Biológicas y Ambientales COCIBA–USFQ, Fondos Semilla grant provided by the Facultad de Ciencias at Universidad de los Andes Colombia and all the supporters of the Experiment.com crowdfunding campaign (experiment.com/geckos). Research permits (PC-59-19, 019-2018-IC-FAU-DNB/MAE) and framework contracts for access to genetic resources (MAE-DNB-CM-2018-0106) were issued by the Galapagos National Park Directorate, Ministry of Environment of Ecuador. All applicable international and national guidelines for the care and use of animals were followed in accordance with the Ministry of Environment of Ecuador permit 019-2018-IC-FAU-DNB/MAE.
Nomenclature, province and coordinates for each continental locality visited during this research along with the date at which the fieldwork was conducted there.
This document contains geographical information for the Gonatodes caudiscutatus tissue samples used on this study, including codes, waypoints, provinces on mainland Ecuador and the Galapagos Islands and sex of the specimen.
List of the sequencing primers and their respective PCR conditions (initial heating step, denaturation, annealing, extension and number of corresponding cycles) used for this work.
Estimates of overall genetic diversity for each gene sequence (Cmos, Rag2 and 16S) and estimates of pairwise genetic diversity between all individuals for each gene (Cmos, Rag2 and 16S).
A detail of the sequences obtained for the 16S that conform to each of the nine haplotypes we found.
This is a list of the collection codes of the specimens used for this research project.