Mitochondrial‐Dna Analyses And The Origin And Relative Age Of Parthenogenetic Lizards (Genus Cnemidophorus). Ii. C. Neomexicanus And The C. Tesselatus Complex

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137490/1/evo02541.pd

Mitochondrial‐Dna Analyses And The Origin And Relative Age Of Parthenogenetic Lizards (Genus Cnemidophorus). Iv. Nine Sexlineatus‐Group Unisexuals

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137512/1/evo02543.pd

Low levels of nucleotide diversity in Crocodylus moreletii and evidence of hybridization with C. acutus

Examinations of both population genetic structure and the processes that lead to such structure in crocodilians have been initiated in several species in response to a call by the IUCN Crocodile Specialist Group. A recent study used microsatellite markers to characterize Morelet\u27s crocodile (Crocodylus moreletii) populations in north-central Belize and presented evidence for isolation by distance. To further investigate this hypothesis, we sequenced a portion of the mitochondrial control region for representative animals after including samples from additional locales in Belize, Guatemala and Mexico. While there is limited evidence of subdivision involving other locales, we found that most of the differentiation among populations of C. moreletii can be attributed to animals collected from a single locale in Belize, Banana Bank Lagoon. Furthermore, mitochondrial DNA sequence analysis showed that animals from this and certain other locales display a haplotype characteristic of the American crocodile, C. acutus, rather than C. moreletii. We interpret this as evidence of hybridization between the two species and comment on how these new data have influenced our interpretation of previous findings. We also find very low levels of nucleotide diversity in C. moreletii haplotypes and provide evidence for a low rate of substitution in the crocodilian mitochondrial control region. Finally, the conservation implications of these findings are discussed

A New Horned Crocodile from the Plio-Pleistocene Hominid Sites at Olduvai Gorge, Tanzania

BACKGROUND: The fossil record reveals surprising crocodile diversity in the Neogene of Africa, but relationships with their living relatives and the biogeographic origins of the modern African crocodylian fauna are poorly understood. A Plio-Pleistocene crocodile from Olduvai Gorge, Tanzania, represents a new extinct species and shows that high crocodylian diversity in Africa persisted after the Miocene. It had prominent triangular "horns" over the ears and a relatively deep snout, these resemble those of the recently extinct Malagasy crocodile Voay robustus, but the new species lacks features found among osteolaemines and shares derived similarities with living species of Crocodylus. METHODOLOGY/PRINCIPAL FINDINGS: The holotype consists of a partial skull and skeleton and was collected on the surface between two tuffs dated to approximately 1.84 million years (Ma), in the same interval near the type localities for the hominids Homo habilis and Australopithecus boisei. It was compared with previously-collected material from Olduvai Gorge referable to the same species. Phylogenetic analysis places the new form within or adjacent to crown Crocodylus. CONCLUSIONS/SIGNIFICANCE: The new crocodile species was the largest predator encountered by our ancestors at Olduvai Gorge, as indicated by hominid specimens preserving crocodile bite marks from these sites. The new species also reinforces the emerging view of high crocodylian diversity throughout the Neogene, and it represents one of the few extinct species referable to crown genus Crocodylus

Sequencing three crocodilian genomes to illuminate the evolution of archosaurs and amniotes

The International Crocodilian Genomes Working Group (ICGWG) will sequence and assemble the American alligator (Alligator mississippiensis), saltwater crocodile (Crocodylus porosus) and Indian gharial (Gavialis gangeticus) genomes. The status of these projects and our planned analyses are described

Morphologic and allozymic analysis of microgeographic variation in the isopod Sphaeroma Quadridentatum

The intertidal marine isopod Sphaeroma quadridentatum was scored for polymorphisms of color, carapace pattern and enzyme systems. Samples were collected at six sites in Galveston County, Texas, during three collection periods: August, 1976; December, 1976 and February, 1977. Possible microgeographic variation and population subdivision were evaluated by spatial and temporal analysis. Data for the morphologic characters and one allozyme locus were analyzed using GH tests and a non-parametric analysis of variance. Also, allozyme frequencies were used to calculate genetic measures of subdivision. Spatial analysis revealed no significant deviations from homogeneity either morphologically or allozymically. Temporal variation was not distinguishable allozymically, however, morphological analysis revealed an increase of the red and grey color classes. This change may be related to seasonality, however further work is necessary to make any definitive statement.Biology and Biochemistry, Department o