title: Morphometrics parallel genetics in a newly discovered and endangered taxon of Galápagos tortoise.
abstract: Galápagos tortoises represent the only surviving lineage of giant tortoises that exhibit two different types of shell morphology. The taxonomy of Galápagos tortoises was initially based mainly on diagnostic morphological characters of the shell, but has been clarified by molecular studies indicating that most islands harbor monophyletic lineages, with the exception of Isabela and Santa Cruz. On Santa Cruz there is strong genetic differentiation between the two tortoise populations (Cerro Fatal and La Reserva) exhibiting domed shell morphology. Here we integrate nuclear microsatellite and mitochondrial data with statistical analyses of shell shape morphology to evaluate whether the genetic distinction and variability of the two domed tortoise populations is paralleled by differences in shell shape. Based on our results, morphometric analyses support the genetic distinction of the two populations and also reveal that the level of genetic variation is associated with morphological shell shape variation in both populations. The Cerro Fatal population possesses lower levels of morphological and genetic variation compared to the La Reserva population. Because the turtle shell is a complex heritable trait, our results suggest that, for the Cerro Fatal population, non-neutral loci have probably experienced a parallel decrease in variability as that observed for the genetic data.
authors.affiliation: Department of Ecology and Evolutionary Biology and YIBS-Molecular Systematics and Conservation Genetics Lab, Yale University, New Haven, Connecticut, United States of America. yle@yleniachiari.it
authors.forename: Ylenia
authors.initials: Y
authors.lastname: Chiari
authors.forename: Chaz
authors.initials: C
authors.lastname: Hyseni
authors.forename: Tom H
authors.initials: TH
authors.lastname: Fritts
authors.forename: Scott
authors.initials: S
authors.lastname: Glaberman
authors.forename: Cruz
authors.initials: C
authors.lastname: Marquez
authors.forename: James P
authors.initials: JP
authors.lastname: Gibbs
authors.forename: Julien
authors.initials: J
authors.lastname: Claude
authors.forename: Adalgisa
authors.initials: A
authors.lastname: Caccone
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003247:Conservation of Natural Resources; D004272:DNA, Mitochondrial / Q000235:genetics; D004484:Ecuador; D005260:Female; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D010802:Phylogeny; D014426:Turtles / Q000145:classification / Q000235:genetics*
chemical_list: D004272:DNA, Mitochondrial