Record Details

Buckley, Lawrence Joseph
Phylogeny and Evolution of the Genus Ctenosaura (Squamata: Iguanidae)
Southern Illinois University at Carbondale
Amblyrhynchus sp.;Brachylophus sp.;Conolophus sp.;Ctenosaura acanthura;Ctenosaura alfredschmidti;Ctenosaura bakeri;Ctenosaura clarki;Ctenosaura defensor;Ctenosaura flavidorsalis;Ctenosaura hemilopha macrolopha;Ctenosaura melanosterna;Ctenosaura oedirhina;Ctenosaura palearis;Ctenosaura pectinata;Ctenosaura quinquecarinata;Ctenosaura similis;Cyclura sp.;Dipsosaurus sp.;Iguana sp.;Sauromalus sp.
Morphological and molecular variation within Ctenosaura and among other iguanine genera are used to identify species boundaries, assess suitable systematic characters, identify evolutionary patterns in cytochrome b and reconstruct species and area relationships in Central America and Mexico. Variation in squamation characters distinguishes all known species of Ctenosaura with univariate and multivariate tests. Geographic boundaries are addressed with interpretations of unique populations of C. similis in Panama, C. bakeri in Utila Island, Honduras, and C. pectinata x C. hemilopha macrolopha in central Sinaloa, Mexico.The substitution biases of cytochrome b agree with those from other studies. Genetic distances among genera are large, indicating long and separate histories originating in the mid-Eocene to mid-Miocene. Sister relationships are indicated between the Galapagos iguanas and Ctenosaura, and also Iguana and Sauromalus. The position of Cyclura is equivocal as either the sister to Iguana and Sauromalus, or sister to these plus Ctenosaura and the Galapagos iguanas. A clade of all six genera is well supported. Both Brachylophus and Dipsosaurus are equally supported as the earliest branch of the subfamily. Phylogenetic analyses converge on two preferred hypotheses of relationships among four species groups in Ctenosaura. These groups exhibit late-Miocene and mid- Pliocene radiations. The first hypothesis posits an early split between the Ctenosaura similis and the remainder of the genus, followed by a split between the Pectinata group (C. pectinata, C. acanthura and C. hemilopha) and the Palearis-Quinquecarinata (C. palearis, C. melanosterna, C. bakeri and C. oedirhina, C. quinquecarinata and C. flavidorsalis) and Defensor (C. defensor, C. clarki and C. alfredschmidti) groups. The alternative hypothesis suggests the deepest split between the common ancestor of the Pectinata and Defensor groups and the common ancestor of C. similis and the Palearis- Quinquecarinata groups. An area cladogram of the first hypothesis suggests a mid-Miocene split of lower Central America from upper Central America and Mexico, and a late-Miocene to early-Pliocene split between the latter two. The alternative proposes a mid-Miocene split of Mexico and Central America, with late-Miocene to mid-Pliocene splits within each independently.