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Although guanacos (Lama guanicoe) are widely distributed throughout much of their historic range, they are often restricted to small, isolated populations that are at risk of inbreeding and loss of genetic diversity. Here we document and interpret baseline patterns of genetic variation in a guanaco population inhabiting in the Bolivian Chaco that is threatened by hunting and habitat degradation. The region, once open grasslands, is dominated by dense shrubs, the result of livestock grazing. The most-recent census identified only 74 individuals and is designated as at 'risk of extinction' by the Bolivian government. We assessed the population's genetic health and uniqueness from the genetic patterns of 16 microsatellite loci, the Hyper-variable Domain I of the mitochondrial Control Region and SRY gene with 29 fecal samples. We identified 19 male and 10 female unique individuals. Microsatellite variation (Ho = 0.64) was similar to larger, less-isolated populations. However, the estimated effective population size was low and consistent with the continuing loss of allelic variation. The two observed mtDNA haplotypes are common in other L. g. guanicoe populations. Although we documented moderate genetic diversity, gene flow among Bolivian and Paraguayan guanaco Chaco populations should be assessed and integrated into explicit conservation management plans. [ABSTRACT FROM AUTHOR]

Eight traditional subspecies of tiger (Panthera tigris), of which three recently became extinct, are commonly recognized on the basis of geographic isolation and morphological characteristics. To investigate the species' evolutionary history and to establish objective methods for subspecies recognition, voucher specimens of blood, skin, hair, and/or skin biopsies from 134 tigers with verified geographic origins or heritage across the whole distribution range were examined for three molecular markers: (1) 4.0 kb of mitochondrial DNA (mtDNA) sequence; (2) allele variation in the nuclear major histocompatibility complex class II DRB gene; and (3) composite nuclear microsatellite genotypes based on 30 loci. Relatively low genetic variation with mtDNA, DRB, and microsatellite loci was found, but significant population subdivision was nonetheless apparent among five living subspecies. In addition, a distinct partition of the Indochinese subspecies P. t. corbetti into northern Indochinese and Malayan Peninsula populations was discovered. Population genetic structure would suggest recognition of six taxonomic units or subspecies: (1) Amur tiger P. t. altaica; (2) northern Indochinese tiger P. t. corbetti; (3) South China tiger P. t. amoyensis; (4) Malayan tiger P. t. jacksoni, named for the tiger conservationist Peter Jackson; (5) Sumatran tiger P. t. sumatrae; and (6) Bengal tiger P. t. tigris. The proposed South China tiger lineage is tentative due to limited sampling. The age of the most recent common ancestor for tiger mtDNA was estimated to be 72,000–108,000 y, relatively younger than some other Panthera species. A combination of population expansions, reduced gene flow, and genetic drift following the last genetic diminution, and the recent anthropogenic range contraction, have led to the distinct genetic partitions. These results provide an explicit basis for subspecies recognition and will lead to the improved management and conservation of these recently isolated but distinct geographic populations of tigers. Genetic analysis provides the basis for subspecies recognition among tigers, and will lead to improved conservation strategies for these endangered animals. [ABSTRACT FROM AUTHOR]