title: Should I stay or should I go? Dispersal and population structure in small, isolated desert populations of West African crocodiles.
abstract: The maintenance of both spatial and genetic connectivity is paramount to the long-term persistence of small, isolated populations living in environments with extreme climates. We aim to identify the distribution of genetic diversity and assess population sub-structuring and dispersal across dwarfed desert populations of Crocodylus suchus, which occur in isolated groups, usually less than five individuals, along the mountains of Mauritania (West Africa). We used both invasive and non-invasive sampling methods and a combination of mitochondrial DNA (12 S and ND4) and microsatellite markers (32 loci and a subset of 12 loci). Our results showed high genetic differentiation and geographic structure in Mauritanian populations of C. suchus. We identified a metapopulation system acting within four river sub-basins (high gene flow and absence of genetic structure) and considerable genetic differentiation between sub-basins (FST range: 0.12-0.24) with rare dispersal events. Effective population sizes tend to be low within sub-basins while genetic diversity is maintained. Our study suggests that hydrographic networks (temporal connections along seasonal rivers during rainy periods) allow C. suchus to disperse and maintain metapopulation dynamics within sub-basins, which attenuate the loss of genetic diversity and the risk of extinction. We highlight the need of hydrographic conservation to protect vulnerable crocodiles isolated in small water bodies. We propose C. suchus as an umbrella species in Mauritania based on ecological affinities shared with other water-dependent species in desert environments.
authors.affiliation: CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos da Universidade do Porto, Instituto de Ciências Agrárias de Vairão, Vairão, Portugal.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Velo-Antón
authors.affiliation: CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos da Universidade do Porto, Instituto de Ciências Agrárias de Vairão, Vairão, Portugal.
authors.forename: Raquel
authors.initials: R
authors.lastname: Godinho
authors.affiliation: CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos da Universidade do Porto, Instituto de Ciências Agrárias de Vairão, Vairão, Portugal.
authors.forename: João Carlos
authors.initials: JC
authors.lastname: Campos
authors.affiliation: CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos da Universidade do Porto, Instituto de Ciências Agrárias de Vairão, Vairão, Portugal; Departamento de Biología da Faculdade de Ciências da Universidade do Porto, Porto, Portugal.
authors.forename: José Carlos
authors.initials: JC
authors.lastname: Brito
mesh_terms: D000489:Alligators and Crocodiles / Q000145:classification / Q000235:genetics* / Q000254:growth & development; D000818:Animals; D001483:Base Sequence; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics*; D003889:Desert Climate; D051456:Gene Flow; D014644:Genetic Variation; D005843:Geography; D008435:Mauritania; D018895:Microsatellite Repeats / Q000235:genetics*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011156:Population Density; D011157:Population Dynamics; D045483:Rivers; D017422:Sequence Analysis, DNA
chemical_list: D004272:DNA, Mitochondrial
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