title: Integrating molecular, phenotypic and environmental data to elucidate patterns of crocodile hybridization in Belize.
abstract: The genus Crocodylus comprises 12 currently recognized species, many of which can be difficult to differentiate phenotypically. Interspecific hybridization among crocodiles is known to occur in captivity and has been documented between some species in the wild. The identification of hybrid individuals is of importance for management and monitoring of crocodilians, many of which are Convention on International Trade in Endangered Species (CITES) listed. In this study, both mitochondrial and nuclear DNA markers were evaluated for their use in confirming a suspected hybrid zone between American crocodile (Crocodylus acutus) and Morelet's crocodile (Crocodylus moreletii) populations in southern Belize where individuals and nests exhibiting atypical phenotypic features had previously been observed. Patterns observed in both phenotypic and molecular data indicate possible behavioural and ecological characteristics associated with hybridization events. The results of the combined analyses found that the majority of suspected hybrid samples represent crosses between female C. acutus and male C. moreletii. Phenotypic data could statistically identify hybrids, although morphological overlap between hybrids and C. moreletii reduced reliability of identification based solely on field characters. Ecologically, C. acutus was exclusively found in saline waters, whereas hybrids and C. moreletii were largely absent in these conditions. A hypothesized correlation between unidirectional hybridization and destruction of C. acutus breeding habitats warrants additional research.
authors.affiliation: Department Biological Sciences , Fordham University , New York, NY 10458, USA ; Sackler Institute for Comparative Genomics, American Museum of Natural History , New York, NY 10024, USA.
authors.forename: Evon R
authors.initials: ER
authors.lastname: Hekkala
authors.affiliation: Wildlife Conservation Society , 2300 Southern Boulevard, Bronx, NY 10460, USA.
authors.forename: Steven G
authors.initials: SG
authors.lastname: Platt
authors.affiliation: Wildlife Conservation Society , 2300 Southern Boulevard, Bronx, NY 10460, USA.
authors.forename: John B
authors.initials: JB
authors.lastname: Thorbjarnarson
authors.affiliation: Baruch Institute of Coastal Ecology and Forest Science, Clemson University , PO Box 596, Georgetown, SC 29440, USA.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Rainwater
authors.affiliation: Sackler Institute for Comparative Genomics, American Museum of Natural History , New York, NY 10024, USA ; Richard Gilder Graduate School, American Museum of Natural History , New York, NY 10024, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Tessler
authors.affiliation: Department Biological Sciences , Fordham University , New York, NY 10458, USA.
authors.forename: Seth W
authors.initials: SW
authors.lastname: Cunningham
authors.affiliation: C2Me Engineering, 2744 Santa Claus Drive , South Lake Tahoe, CA 96150, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Twomey
authors.affiliation: Sackler Institute for Comparative Genomics, American Museum of Natural History , New York, NY 10024, USA.
authors.forename: George
authors.initials: G
authors.lastname: Amato
keywords: American crocodile; Belize; Morelet’s crocodile; hybrid zone; hybridization; species' boundaries