Bryan L. Stuart

Repeated evolution of limblessness and digging heads in worm lizards revealed by DNA from old bones

The evolutionary relationships of the burrowing amphisbaenians (‘worm lizards’) have long been controversial for several reasons: the rarity of museum specimens available for study, highly derived morphological conditions that can confound comparative studies and difficulty in obtaining tissues for molecular phylogenetic studies because of their secretive habits in the wild. We present a phylogenetic analysis of two nuclear genes obtained from both fresh tissues and museum specimens of worm lizards. We achieved sufficient taxonomic sampling for analysis by extracting DNA from museum specimens using a modified forensics protocol. Results show the limbless Rhineuridae to be the most basal lineage, whereas the limbed Bipedidae occupy a more derived position as the sister–taxon to a Trogonophidae–Amphisbaenidae clade. This pattern of relationships indicates widespread morphological convergence within the group, including three independent incidences of limb loss. Convergence in skull shape and scalation is also prevalent. Mosaic evolution in the skull versus postcranial skeleton parallels that seen in snake evolution.

Recent hybrid origin of three rare chinese turtles

Three rare geoemydid turtles described from Chinese trade specimens in the early 1990s, Ocadia glyphistoma, O. philippeni, and Sacalia pseudocellata, are suspected to be hybrids because they are known only from their original descriptions and because they have morphologies intermediate between other, better-known species. We cloned the alleles of a bi-parentally inherited nuclear intron from samples of these three species. The two aligned parental alleles of O. glyphistoma, O. philippeni, and S. pseudocellata have 5–11.5 times more heterozygous positions than do 13 other geoemydid species. Phylogenetic analysis shows that the two alleles from each turtle are strongly paraphyletic, but correctly match sequences of other species that were hypothesized from morphology to be their parental species. We conclude that these rare turtles represent recent hybrids rather than valid species. Specifically, “O. glyphistoma” is a hybrid of Mauremys sinensis and M.␣cf. annamensis, “O.␣philippeni” is a hybrid of M. sinensis and Cuora trifasciata, and “S. pseudocellata” is a hybrid of C. trifasciata and S. quadriocellata. Conservation resources are better directed toward finding and protecting populations of other rare Southeast Asian turtles that do represent distinct evolutionary lineages.

Evolutionary distinctiveness of the extinct Yunnan box turtle (Cuora yunnanensis) revealed by DNA from an old museum specimen

Cuora yunnanensis is an extinct turtle known from 12 specimens collected from Yunnan, China, before 1908. We used ancient DNA methods to sequence 1723 base pairs of mitochondrial DNA from a museum specimen of C. yunnanensis. Unlike some rare ‘species’ recently described from the pet trade, C. yunnanensis represents a lineage that is distinct from other known turtles. Besides C. yunnanensis, two other valid species (C. mccordi, C. zhoui) are unknown in the wild but are supposedly from Yunnan. Intensive field surveys for surviving wild populations of these critically endangered species are urgently needed.

Extraction of nuclear DNA from bone of skeletonized and fluid‐preserved museum specimens

Abstract Obtaining DNA sequences, particularly nuclear DNA, from museum specimens is challenging. We sequenced nuclear DNA from small bone fragments of skeletonized and fluid‐fixed museum specimens of squamate reptiles by using a forensic protocol developed for isolating DNA from human bones. The method yielded high quality nuclear DNA sequences from bones taken from 11 of 21 (52.4%) skeletonized or desiccated specimens, the oldest of which dated back to 1938, and 1 of 9 (11.1%) fluid‐preserved specimens, which was collected in 1957.