Characterising a genetic stronghold amidst pervasive admixture: Morelet’s crocodiles ( Crocodylus moreletii ) in central Yucatan

Barão-Nóbrega, José António L; González-Jáuregui, Mauricio; Padilla-Paz, Sergio; Maher, Kathryn H; Martínez-Arce, Arely; Cedeño-Vázquez, José Rogelio; Jehle, Robert

Abstract

When backcrosses are fertile, interbreeding between endangered taxa can lead to the admixture of gene pools under threat. One such case pertains to the Mesoamerican crocodile Crocodylus moreletii, a species which shows strong signatures of both recent hybridisation and historic intogression with the American crocodile C. acutus across large parts of its range. In the present paper, we use RAD-seq derived SNPs (4980 nuclear and seven mtDNA loci) to demonstrate that C. moreletii populations inhabiting the region of Calakmul in central Yucatan (Mexico) are rather unaffected by hybridization, despite being surrounded by coastal areas where pervasive admixture has previously been documented. All (based on fastSTRUCTURE) and 96% (based on NGSadmix) of 84 genotyped individuals from 18 sampled waterbodies (locally termed aguadas) were free from nuclear introgression of C. acutus DNA at at threshold of 0.95. Seven individuals (8%) possessed a C. acutus mtDNA haplotype, five of which were derived from two adjacent, rather peripheral aguadas. Spatial inferences based on a DAPC and fineRADstructure further showed that the region of Calakmul is inhabited by three genetic clusters spanning across a set of distinct aguadas each. Taken together, our findings reveal that central Yucatan contains the currently largest documented stronghold of C. moreletii populations only marginally affected by introgression, which has major implications for the conservation management of this important flagship species.

Citation

Barão-Nóbrega, J. A. L., González-Jáuregui, M., Padilla-Paz, S., Maher, K. H., Martínez-Arce, A., Cedeño-Vázquez, J. R., & Jehle, R. (2023). Characterising a genetic stronghold amidst pervasive admixture: Morelet’s crocodiles ( Crocodylus moreletii ) in central Yucatan. Conservation Genetics, 24(6), 893-903. https://doi.org/10.1007/s10592-023-01544-z

• Journal Article Type: Article
• Acceptance Date: Jun 30, 2023
• Online Publication Date: Jul 22, 2023
• Publication Date: Dec 1, 2023
• Deposit Date: Jul 24, 2023
• Publicly Available Date: Jul 25, 2023
• Journal: Conservation Genetics
• Print ISSN: 1566-0621
• Electronic ISSN: 1572-9737
• Publisher: Springer Verlag
• Peer Reviewed: Peer Reviewed
• Volume: 24
• Issue: 6
• Pages: 893-903
• DOI: https://doi.org/10.1007/s10592-023-01544-z
• Keywords: Crocodiles, Conservation, Population genetics, Genetic swamping, Hybridisation
• Additional Information: Received: 17 June 2022; Accepted: 30 June 2023; First Online: 22 July 2023; : ; : The authors declare that they have no conflict of interest nor have relevant financial or non-financial interests to disclose.; : All applicable international, national, and/or institutional guidelines for the care and use of animals were followed.