Hybridization and Speciation Among New-World Crocodilian Species

In this chapter is analyzed one characteristic of the reproductive behavior that is frequently found among crocodilian species: hybridization. Hybridization is defined as reproduction between members of genetically distinct populations, producing offspring of mixed ancestry. The phenomenon of hybridization and hybrid speciation has been a topic of extensive discussion because it questions the concept of biological species. These discussions include topics such as sexual compatibility between species, fertility or not of hybrid offspring, phenotypic or genotypic similarity of hybrids, hybrid vigor, and potential hybrid zones. Crocodiles are long-lived and ancient species, but their specimens are very promiscuous and sexually actives in their reproduction seasons. In this context, hybridization was and is a significant force in evolution to crocodilians. In this chapter, the different mechanisms that influence hybridization processes, the effects of hybridization at different evolutionary levels, species boundaries in hybrid zones, methodologies for the study of this phenomenon, main results of hybridization studies, and the conservation status of parental and hybrid species in New-World crocodile species are discussed.