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Stephen L Zegura

Publications and source records attributed to Stephen L Zegura.

4 recordsLinked to original sources
PubMed2003

High-resolution SNPs and microsatellite haplotypes point to a single, recent entry of Native American Y chromosomes into the Americas.

A total of 63 binary polymorphisms and 10 short tandem repeats (STRs) were genotyped on a sample of 2,344 Y chromosomes from 18 Native American, 28 Asian, and 5 European populations to investigate the origin(s) of Native American paternal lineages. All three of Greenberg's major linguistic divisions (including 342 Amerind speakers, 186 Na-Dene speakers, and 60 Aleut-Eskimo speakers) were represented in our sample of 588 Native Americans. Single-nucleotide polymorphism (SNP) analysis indicated that three major haplogroups, denoted as C, Q, and R, accounted for nearly 96% of Native American Y chromosomes. Haplogroups C and Q were deemed to represent early Native American founding Y chromosome lineages; however, most haplogroup R lineages present in Native Americans most likely came from recent admixture with Europeans. Although different phylogeographic and STR diversity patterns for the two major founding haplogroups previously led to the inference that they were carried from Asia to the Americas separately, the hypothesis of a single migration of a polymorphic founding population better fits our expanded database. Phylogenetic analyses of STR variation within haplogroups C and Q traced both lineages to a probable ancestral homeland in the vicinity of the Altai Mountains in Southwest Siberia. Divergence dates between the Altai plus North Asians versus the Native American population system ranged from 10,100 to 17,200 years for all lineages, precluding a very early entry into the Americas.

Analysis of Variance↗
PubMed2002

High levels of Y-chromosome differentiation among native Siberian populations and the genetic signature of a boreal hunter-gatherer way of life.

We examined genetic variation on the nonrecombining portion of the Y chromosome (NRY) to investigate the paternal population structure of indigenous Siberian groups and to reconstruct the historical events leading to the peopling of Siberia. A set of 62 biallelic markers on the NRY were genotyped in 1432 males representing 18 Siberian populations, as well as nine populations from Central and East Asia and one from European Russia. A subset of these markers defines the 18 major NRY haplogroups (A-R) recently described by the Y Chromosome Consortium (YCC 2002). While only four of these 18 major NRY haplogroups accounted for -95% of Siberian Y-chromosome variation, native Siberian populations differed greatly in their haplogroup composition and exhibited the highest phiST value for any region of the world. When we divided our Siberian sample into four geographic regions versus five major linguistic groupings, analyses of molecular variance (AMOVA) indicated higher phiST and phiCT values for linguistic groups than for geographic groups. Mantel tests also supported the existence of NRY genetic patterns that were correlated with language, indicating that language affiliation might be a better predictor of the genetic affinity among Siberians than their present geographic position. The combined results, including those from a nested cladistic analysis, underscored the important role of directed dispersals, range expansions, and long-distance colonizations bound by common ethnic and linguistic affiliation in shaping the genetic landscape of Siberia. The Siberian pattern of reduced haplogroup diversity within populations combined with high levels of differentiation among populations may be a general feature characteristic of indigenous groups that have small effective population sizes and that have been isolated for long periods of time.

Chromosomes, Human, Y↗
PubMed2001

High levels of Y-chromosome nucleotide diversity in the genus Pan.

Although some mitochondrial, X chromosome, and autosomal sequence diversity data are available for our closest relatives, Pan troglodytes and Pan paniscus, data from the nonrecombining portion of the Y chromosome (NRY) are more limited. We examined approximately 3 kb of NRY DNA from 101 chimpanzees, seven bonobos, and 42 humans to investigate: (i) relative levels of intraspecific diversity; (ii) the degree of paternal lineage sorting among species and subspecies of the genus Pan; and (iii) the date of the chimpanzee/bonobo divergence. We identified 10 informative sequence-tagged sites associated with 23 polymorphisms on the NRY from the genus Pan. Nucleotide diversity was significantly higher on the NRY of chimpanzees and bonobos than on the human NRY. Similar to mtDNA, but unlike X-linked and autosomal loci, lineages defined by mutations on the NRY were not shared among subspecies of P. troglodytes. Comparisons with mtDNA ND2 sequences from some of the same individuals revealed a larger female versus male effective population size for chimpanzees. The NRY-based divergence time between chimpanzees and bonobos was estimated at approximately 1.8 million years ago. In contrast to human populations who appear to have had a low effective size and a recent origin with subsequent population growth, some taxa within the genus Pan may be characterized by large populations of relatively constant size, more ancient origins, and high levels of subdivision.

Animals↗