title: Evolutionary history of Cuban crocodiles Crocodylus rhombifer and Crocodylus acutus inferred from multilocus markers.
abstract: Among crocodilians, Crocodylus rhombifer is one of the world's most endangered species with the smallest natural distribution. In Cuba, this endemic species coexists with the American crocodile (Crocodylus acutus). Hybridization between these two species is well known in captivity and might occur in the wild, but has never been demonstrated genetically. Here, we combined molecular data with environmental, geographic, and fossil data to infer the evolutionary history of Crocodylus in the Cuban Archipelago, and to evaluate genealogical support for species boundaries. We analyzed seven microsatellite loci plus DNA sequence data from nuclear (RAG-1) and mitochondrial (cytochrome b and cytochrome oxidase I) genes from 89 wild-caught individuals in Cuba, Grand Cayman Island, Jamaica, and Central America, and two samples from zoo collections. Microsatellites showed evidence of introgression, suggesting potential hybridization among Cuban groups. In Cuba, C. acutus contained one mitochondrial DNA (mtDNA) haplotype, whereas C. rhombifer contained two haplotypes. MtDNA data showed that C. acutus is paraphyletic with respect to C. rhombifer, revealing 1% sequence divergence between species within Cuba vs. 8% divergence between Cuban forms and mainland C. acutus. We suggest that hybridization has been a historical as well as a current phenomenon between C. acutus and C. rhombifer. These findings suggest that long-term conservation of crocodiles in Cuba will require identification of genetically pure and hybrid individuals, and a decrease in anthropogenic activities. We also recommend more extensive morphological and genetic analyses of Cuban population to establish clear boundaries of the hybrid zone between C. acutus and C. rhombifer.
authors.affiliation: Universidad de La Habana, Ciudad Habana, Cuba.
authors.forename: Yoamel
authors.initials: Y
authors.lastname: Milián-García
authors.forename: Miryam
authors.initials: M
authors.lastname: Venegas-Anaya
authors.forename: Roberto
authors.initials: R
authors.lastname: Frias-Soler
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Crawford
authors.forename: Roberto
authors.initials: R
authors.lastname: Ramos-Targarona
authors.forename: Roberto
authors.initials: R
authors.lastname: Rodríguez-Soberón
authors.forename: Manuel
authors.initials: M
authors.lastname: Alonso-Tabet
authors.forename: John
authors.initials: J
authors.lastname: Thorbjarnarson
authors.forename: Oris I
authors.initials: OI
authors.lastname: Sanjur
authors.forename: Georgina
authors.initials: G
authors.lastname: Espinosa-López
authors.forename: Eldredge
authors.initials: E
authors.lastname: Bermingham
mesh_terms: D000483:Alleles; D000489:Alligators and Crocodiles / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D016000:Cluster Analysis; D003247:Conservation of Natural Resources; D003462:Cuba; D045303:Cytochromes b / Q000737:chemistry / Q000235:genetics; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics; D003576:Electron Transport Complex IV / Q000737:chemistry / Q000235:genetics; D019143:Evolution, Molecular; D014644:Genetic Variation; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics; D006824:Hybridization, Genetic; D018895:Microsatellite Repeats / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000662:veterinary; D016415:Sequence Alignment
chemical_list: D004272:DNA, Mitochondrial; D018398:Homeodomain Proteins; C064658:RAG-1 protein; D045303:Cytochromes b; D003576:Electron Transport Complex IV