title: Rigorous approaches to species delimitation have significant implications for African crocodilian systematics and conservation.
abstract: Accurate species delimitation is a central assumption of biology that, in groups such as the Crocodylia, is often hindered by highly conserved morphology and frequent introgression. In Africa, crocodilian systematics has been hampered by complex regional biogeography and confounded taxonomic history. We used rigorous molecular and morphological species delimitation methods to test the hypothesis that the slender-snouted crocodile (Mecistops cataphractus) is composed of multiple species corresponding to the Congolian and Guinean biogeographic zones. Speciation probability was assessed by using 11 mitochondrial and nuclear genes, and cranial morphology for over 100 specimens, representing the full geographical extent of the species distribution. Molecular Bayesian and phylogenetic species delimitation showed unanimous support for two Mecistops species isolated to the Upper Guinean and Congo (including Lower Guinean) biomes that were supported by 13 cranial characters capable of unambiguously diagnosing each species. Fossil-calibrated phylogenetic reconstruction estimated that the species split ± 6.5-7.5 Ma, which is congruent with intraspecies divergence within the sympatric crocodile genus Osteolaemus and the formation of the Cameroon Volcanic Line. Our results underscore the necessity of comprehensive phylogeographic analyses within currently recognized taxa to detect cryptic species within the Crocodylia. We recommend that the community of crocodilian researchers reconsider the conceptualization of crocodilian species especially in the light of the conservation ramifications for this economically and ecologically important group.
authors: Department of Wildlife Ecology and Conservation, University of Florida, , 110 Newins-Ziegler Hall, Gainesville, FL 32611, USA, SFM Safari Gabon, , BP 1107, Libreville, Gabon, Department of Biology, University of Florida, , 220 Bartram Hall, Gainesville, FL 32611, USA.
authors: Matthew H
authors: MH
authors: Shirley
authors: Kent A
authors: KA
authors: Vliet
authors: Amanda N
authors: AN
authors: Carr
authors: James D
authors: JD
authors: Austin
mesh_terms: D000350:Africa, Central; D000354:Africa, Western; D000489:Alligators and Crocodiles / Q000033:anatomy & histology* / Q000235:genetics* / Q000502:physiology; D063147:Animal Distribution; D000818:Animals; D001483:Base Sequence; D001499:Bayes Theorem; D002467:Cell Nucleus / Q000235:genetics; D002965:Classification / Q000379:methods*; D003247:Conservation of Natural Resources / Q000379:methods*; D004272:DNA, Mitochondrial / Q000235:genetics; D005580:Fossils; D008957:Models, Genetic; D008969:Molecular Sequence Data; D060885:Multiplex Polymerase Chain Reaction; D010802:Phylogeny; D058974:Phylogeography / Q000379:methods; D017422:Sequence Analysis, DNA; D012886:Skull / Q000033:anatomy & histology; D013045:Species Specificity
chemical_list: D004272:DNA, Mitochondrial
keywords: African biogeography; Mecistops; Osteolaemus; phylogeography; speciation probability