Extensive mitochondrial diversity within a single Amerindian tribe.
- R. Ward, B. Frazier, K. Dew-Jager, S. Pääbo
- BiologyProceedings of the National Academy of Sciences…
- 1 October 1991
Data do not support the concept of a dramatic founder effect during the peopling of the Americas and suggest that a single Amerindian tribe can contain such extensive molecular diversity, it is unnecessary to presume that substantial genetic bottlenecks occurred during the formation of contemporary ethnic groups.
The retrieval of ancient human DNA sequences.
These results show that more experimental work than is often applied is necessary to ensure that DNA sequences amplified from ancient human remains are authentic and quantitation of the numbers of amplifiable molecules is a useful tool to determine the role of contaminating contemporary molecules and PCR errors in amplifications from ancient DNA.
mtDNA sequences suggest a recent evolutionary divergence for Beringian and northern North American populations.
The similarity of sequences found among the geographically dispersed Circumarctic groups, plus the small values of mean pairwise sequence differences withincircumarctic populations, suggest a recent and rapid evolutionary radiation of these populations.
Reduced mtDNA diversity in the Ngöbé Amerinds of Panamá.
- C. Kolman, E. Bermingham, R. Cooke, R. Ward, T. D. Arias, F. Guionneau-Sinclair
- 1 May 1995
It is posited that the Ngöbé passed through a population bottleneck caused by ethnogenesis from a small founding population and/or European conquest and colonization, and exhibits the lowest mtDNA control region sequence diversity yet reported for an Amerind group.
Genetic and linguistic differentiation in the Americas.
- R. Ward, A. Redd, D. Valencia, B. Frazier, S. Pääbo
- Linguistics, BiologyProceedings of the National Academy of Sciences…
- 15 November 1993
In the New World, rates of linguistic differentiation appear to be markedly faster than rates of biological differentiation, with little congruence between linguistic hierarchy and the pattern of evolutionary relationships.
mtDNA variation in the Chibcha Amerindian Huetar from Costa Rica.
- M. Santos, R. Ward, R. Barrantes
- BiologyHuman Biology: The Official Publication of the…
- 1 December 1994
The genetic variation in a Chibcha-speaking Amerindian tribe from lower Central America, the Huetar, was analyzed using nucleotide sequences of the hypervariable segments of the mitochondrial DNA…
Mitochondrial DNA polymorphism in three Brazilian Indian tribes
- R. Ward, F. Salzano, S. Bonatto, M. Hutz, C. E. Coimbra, R. Santos
- BiologyAmerican Journal of Human Biology
Nucleotide diversity, as evaluated by three indices, are not much different from those observed in Indians from Central and North America, despite the fact that the Xavante consistently show lower numbers, and the need for additional studies in this system is stressed.
Rapid radiation events in the family Ursidae indicated by likelihood phylogenetic estimation from multiple fragments of mtDNA.
- L. Waits, J. Sullivan, S. O’Brien, R. Ward
- BiologyMolecular Phylogenetics and Evolution
- 1 October 1999
It is suggested that the difficulties surrounding the resolution of the evolutionary relationships of the Ursidae are linked to the existence of sequential rapid radiation events in bear evolution, and unresolved branching orders during these time periods may represent an accurate representation of the evolved history of bear species.
Molecular systematics of short-horned lizards: biogeography and taxonomy of a widespread species complex.
High levels of genetic variation found in population comparisons are in accord with high levels of morphological variation in this species group; however, only in the Pacific Northwest region is there spatial congruence between these phylogenetic results and subspecific ranges based on previous morphological studies.
Multiple sclerosis: updated risks for relatives.
Age-specific MS risks were calculated for first-, second-, and third-degree relatives of probands and are presented in an easy-reference format and in general, first- Degree relatives of Probands have a risk that is 30-50 times greater than the 0.1% risk for the general population.