A Journal of Integrative Biology
Hybridization Between Crocodylus acutus and Crocodylus moreletii in the Yucatan Peninsula: I. Evidence From Mitochondrial DNA and Morphology
´ ´ ˜ JOSE ROGELIO CEDENO-VAZQUEZ1Ã, DAVID RODRIGUEZ2, ´ 1, JAMES PERRAN ROSS3, LLEWELLYN D. DENSMORE III2, SOPHIE CALME 4 AND JOHN B. THORBJARNARSON 1 El Colegio de laFrontera Sur, Unidad Chetumal, Chetumal, Quintana Roo, Mexico 2 Department of Biological Sciences, Texas Tech University, Lubbock, Texas 3 Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida 4 Wildlife Conservation Society, Gainesville, Florida
The American crocodile (Crocodylus acutus) and the Morelet’s crocodile (C. moreletii) are broadly sympatric inBelize and Mexico. The presence of morphologically anomalous individuals in the overlapping range area suggests possible hybridization between these species. Analysis of 477 base pairs of the mitochondrial tRNAPro-tRNAPhe-Dloop region revealed the presence of pure C. acutus (N 5 43) and C. moreletii (N 5 56), as well as a high proportion of interspeciﬁc hybrids (N 5 17, 14.6%) in the YucatanPeninsula, Mexico. Although all individuals could be assigned to one species or other based on phenotypic characters, some had been characterized as potential hybrids in the ﬁeld by anomalous scale counts. The hybridization zone lies along the area of sympatry between C. acutus and C. moreletii investigated in this study, but extends further inland if hybrid localities from Belize are included.Hybridization in the Yucatan Peninsula is bidirectional, which indicates considerably more genetic contact between these species than previously recognized, and is probably more detrimental to the genetic integrity of smaller C. acutus populations. A more intensive study of the pattern of hybridization is warranted and supports continued classiﬁcation of C. acutus as a critically threatened species inthe Yucatan Peninsula. r 2008 Wiley-Liss, Inc. J. Exp. Zool. 309A:661–673, 2008. ´ ´ ˜ How to cite this article: Cedeno-Vazquez JR, Rodriguez D, Calme S, Ross JP, Densmore III LD, Thorbjarnarson JB. 2008. Hybridization between Crocodylus acutus and Crocodylus moreletii in the Yucatan Peninsula: I. evidence from mitochondrial DNA and morphology. J. Exp. Zool. 309A:661–673.
Effectiveprograms for conserving endangered species require the identiﬁcation of unambiguous management units that reﬂect evolutionarily important lineages (Avise, 2004) or speciﬁc evolutionarily signiﬁcant units (ESUs) (Waples, ’95), and the elucidation of threats affecting those units. Crocodilians represent unique evolutionary lineages that are valued ecologically as keystone members of the faunalcommunity (Hekkala, 2004). The crocodile specialist group has emphasized the need for information on population status and population genetic studies of threatened crocodilian species (Ross, ’98) like the
r 2008 WILEY-LISS, INC.
American crocodile (Crocodylus acutus) and Morelet’s crocodile (C. moreletii). The American crocodile occurs on the Atlantic and Paciﬁc coasts from Mexico to northern South´ Grant sponsors: Consejo Nacional de Ciencia y Tecnologıa (CONACYT Fellowship No. 192178); WWF-Education for Nature Program (Russell E. Train Fellowship, Grant Agreement No. RM37); Texas Tech University Graduate School. ÃCorrespondence to: J. Rogelio Cedeno Vazquez, El Colegio de la ´ ˜ Frontera Sur, Av. Centenario Km 5.5, 77014 Chetumal, Q. Roo, Mexico. E-mail:firstname.lastname@example.org,email@example.com Received 13 July 2007; Revised 12 May 2008; Accepted 17 May 2008 Published online 14 July 2008 in Wiley InterScience (www. interscience.wiley.com). DOI: 10.1002/jez.473
´ ˜ CEDENO-VAZQUEZ ET AL.
America, as well as in Cuba, Jamaica, Hispaniola (Haiti), and the southern tip of Florida, USA (Thorbjarnarson, ’89). Morelet’s crocodile occurs in the Atlantic and Caribbean...