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Complex Genetic Patterns (complex + genetic_pattern)
Selected AbstractsComplex phylogeographical patterns, introgression and cryptic species in a lineage of Malagasy dung beetles (Coleoptera: Scarabaeidae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009H. WIRTA Many taxa, including dung beetles, exhibit small-scale microendemism in Madagascar, which has contributed to the high level of species' diversity on the island. Species in the genus Nanos are numerically dominant in the dung beetle communities in rainforests in eastern Madagascar, but typically just one species occurs in any one locality. The two northern species, N. clypeatus and N. dubitatus, cannot be distinguished by either a mitochondrial or a nuclear genetic marker (cytochrome oxidase subunit I and internal transcription spacer 2). One population of the southern N. viettei is genetically highly divergent, although morphologically indistinguishable. Genetic data indicate that introgression occurred from N. dubitatus to N. viettei 1,2 Mya, and these species may continue to hybridize. Complex genetic patterns have mostly evolved within the last 2 Myr. During this time, the glacial cycles in the northern hemisphere were reflected in the oscillating climatic conditions in Africa, which repeatedly fragmented and re-united the rainforests in eastern Madagascar, possibly leading to the observed complex phylogeographical patterns in Nanos. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 942,955. [source] Population structure and paternal admixture landscape on present-day Mexican-Mestizos revealed by Y-STR haplotypesAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2010J. Salazar-Flores Mestizos currently represent most of the Mexican population (>90%); they are defined as individuals born in the country having a Spanish-derived last name, with family antecedents of Mexican ancestors back at least to the third generation. Mestizos are result of 500 years of admixture mainly among Spaniards, Amerindians, and African slaves. Consequently, a complex genetic pattern has been generated throughout the country that has been scarcely studied from the paternal point of view. This fact is important, taking into account that gene flow toward the New World comprised largely males. We analyzed the population structure and paternal admixture of present-day Mexican-Mestizo populations based on Y-STRs. We genotyped at least 12 Y-STRs in DNA samples of 986 males from five states: Aguascalientes (n = 293); Jalisco (n = 185); Guanajuato (n = 168); Chiapas (n = 170); and Yucatán (n = 170). AmpF,STR Y-filer and Powerplex-Y® kits were used. Inclusion of North and Central Y-STR databases in the analyses allowed obtaining a Y-STR variability landscape from Mexico. Results confirmed the population differentiation gradient previously noted in Mestizos with SNPs and autosomal STRs throughout the Mexican territory: European ancestry increments to the Northwest and, correspondingly, Amerindian ancestry increments to the Center and Southeast. In addition, SAMOVA test and Autocorrelation Index for DNA Analysis autocorrelogram plot suggested preferential gene flow of males with neighboring populations in agreement with the isolation-by-distance model. Results are important for disease-risk studies (principally male-related) and for human identification purposes, because Y-STR databases are not available on the majority of Mexican-Mestizo populations. Am. J. Hum. Biol., 2010. © 2009 Wiley-Liss, Inc. [source] Patterns of population genetic diversity in riparian and aquatic plant species along riversJOURNAL OF BIOGEOGRAPHY, Issue 9 2010Olivier Honnay Abstract Aim, The downstream hydrochoric spread of seeds of aquatic and riparian plant species, without upstream compensation, can be expected to result in downstream accumulation of population genetic diversity. This idea has been termed the ,unidirectional dispersal hypothesis' and is the genetic equivalent of the more generally known ,drift paradox'. Our aim was to test this unidirectional diversity hypothesis, and to present a general synthesis of the patterns of population genetic variation across different riparian and aquatic plant species along rivers. Location, The Meuse River (Belgium) and rivers world-wide. Methods, First, we used amplified fragment length polymorphism markers to compare patterns of within- and between-population genetic diversity among three riparian plant species (Sisymbrium austriacum, Erysimum cheiranthoides and Rorippa sylvestris), typically occurring in different habitats along a gradient perpendicular to the Meuse River. Second, we performed a meta-analysis on studies reporting on the population genetic structure of riparian and aquatic plant species along rivers. Results, Along the Meuse River, we found significant genetic differentiation among populations of all three riparian species, and significant isolation by distance for one of them (R. sylvestris). There was no clear association between the typical habitat of a species and its population genetic structure. None of the three species provided evidence for the unidirectional dispersal hypothesis. The meta-analysis, based on 21 data records, did not support the unidirectional dispersal hypothesis either. Average weighted population genetic differentiation across species was significant. Main conclusions, Important mechanisms of upstream seed dispersal, probably through zoochory, together with higher seed recruitment opportunities in upstream habitats due to density dependence of recruitment, may explain the absence of downstream accumulation of genetic diversity. Also, it seems difficult to find consistent patterns in genetic variation in species from aquatic and riparian habitats. We argue that this is due to the recurrent extinctions and colonizations characteristic of these habitats, resulting in complex genetic patterns. Our results strongly support previous suggestions that stream ecology should consistently embrace metapopulation theory to be able to understand patterns of genetic diversity, as well as species diversity. [source] Deep, hierarchical divergence of mitochondrial DNA in Amplirhagada land snails (Gastropoda: Camaenidae) from the Bonaparte Archipelago, Western AustraliaBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2010MICHAEL S. JOHNSON Continental islands have experienced cycles of isolation and connection. Although complex genetic patterns have been described for mainland species affected by glacial cycles of isolation, island biotas have received little attention. We examined mitochondrial DNA in Amplirhagada land snails from 16 islands and two adjacent mainland areas of the Bonaparte Archipelago, in the Kimberley region of northern Western Australia. Four major clades, with sequence divergence of 16,27% in the 16S ribosomal RNA gene, correspond to the major geographic groupings, separated by 10,160 km. Distinct lineages also characterize islands that are only a few kilometres apart. The large differences indicate that the lineages are much older than the islands themselves, and show no evidence of geologically recent connection. Three of the major clades match the morphological description of Amplirhagada alta. Either this named species comprises several morphologically cryptic species, or it is a single, genetically very diverse species, distributed over much of the Bonaparte Archipelago. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 141,153. [source] | ||||||||||