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Neighboring Populations (neighboring + population)
Selected AbstractsInterpopulation differences in the mandible size of the coastal tiger beetle Lophyridia angulata associated with different sympatric speciesENTOMOLOGICAL SCIENCE, Issue 3 2004Aya SATOH Abstract The coastal tiger beetle Lophyridia angulata (Fabricius) co-occurs with one or two tiger beetle species at any one locality (in a sandy beach habitat) along the Japan Sea coast of Honshu, from eastern to southern Kyushu, and on Tanega-shima, an island south of Kyushu, in Japan. Lophyridia angulata displays sexual dimorphism in mandible length (the mandible is longer in females), and shows large interpopulation differences in mandible size. We analyzed variation in mandible length between L. angulata populations associated with three different sympatric species, and examined morphological differences that may have resulted from interaction with these other species. Lophyridia angulata showed a significant size shift towards larger mandibles in a population that co-occurred with Cicindela lewisii, which has a similar mandible length to that of L. angulata, as compared to a neighboring population of L. angulata that co-occurred with another species. This pattern may be interpreted as a type of character displacement associated with food resource competition. Males in L. angulata populations co-occurring with Chaetodera laetescripta showed little variation in mandible length, as compared to other populations. These males may experience some pressure from C. laetescripta and from conspecific females. We found no significant changes in mandible length or in size variation of L. angulata before and 20 years after the extinction of Abroscelis anchoralis at one site historically co-inhabited by both species; that is, we did not detect a character release over the 20 years. [source] GEOGRAPHIC GENETIC STRUCTURE IN THE FRANCISCANA DOLPHIN (PONTOPORIA BLAINVILLEI)MARINE MAMMAL SCIENCE, Issue 2 2004Marila Lázaro Abstract The franciscana, Pontoporia blainvillei, is endemic to the South Atlantic coast of South America. The species is of conservation concern because it suffers elevated mortality rates due to incidental captures in fishing nets, and perhaps it is one of the most threatened small cetaceans in this region. Previous morphological and genetic studies have suggested the existence of at least two distinct stocks to the north and south of Santa Catarina Island in Brazil. Fixed differences were found between a sample from Rio de Janeiro and one from Rio Grande do Sul, in southern Brazil. Using 94 sequences of the control region of mitochondrial DNA, we examined the genetic structure of the species. We found no shared haplotypes between Rio de Janeiro and samples from the southern range of the species distribution. However, a phylogenetic analysis suggests that the former population is diphyletic with respect to the southern samples. This suggests that the populations have not been isolated long enough to reach reciprocal monophyly. Furthermore, genetic differentiation is broadly consistent with a simple model of isolation by distance, that therefore appears as an alternative to a model of strict isolation of two stocks. The estimated levels of gene flow are higher among neighboring populations, and decrease as more distant localities are compared. Finally, the molecular data suggest that franciscanas have expanded in Rio de Janeiro. [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] Metric and nonmetric dental variation and the population structure of the AinuAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 2 2010Tsunehiko Hanihara Gene flow and genetic drift are important factors affecting geographic variations in human phenotypic traits. In the present study, the effects of gene flow from an outside source on the pattern of within- and among-group variation of the Ainu from Sakhalin Island and three local groups of Hokkaido are examined by applying an R-matrix approach to metric and nonmetric dental data. The comparative samples consist of their ancestral and neighboring populations, such as the Neolithic Jomon, the subsequent Epi-Jomon/Satsumon, the Okhotsk culture people who migrated from Northeast Asia to the northeastern part of Hokkaido during a period 1600,900 years B.P., and modern non-Ainu Japanese. The results obtained by using the census population sizes of the regional groups of the Ainu as an estimate of relative effective population size suggest the possibility of an admixture between the Okhotsk culture people and the indigenous inhabitants in Hokkaido, at least in the coastal region along the Sea of Okhotsk. Such gene flow from Northeast Asian continent may have exerted an effect on the genetic structure of the contemporary Ainu. The present findings indicate that the population structure, as represented by genetic drift and gene flow, tend to be obscured in the results obtained by standard statistical methods such as Mahalanobis' generalized distance and Smith's MMDs. The present extension of the R-matrix approach to metric and nonmetric dental data provide results that can be interpreted in terms of a genetically, archaeologically, and prehistorically suggested pattern of gene flow and isolation. Am. J. Hum. Biol., 2010. © 2009 Wiley-Liss, Inc. [source] Coalescent simulations of Yakut mtDNA variation suggest small founding populationAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009Mark Zlojutro Abstract The Yakuts are a Turkic-speaking population from northeastern Siberia who are believed to have originated from ancient Turkic populations in South Siberia, based on archaeological and ethnohistorical evidence. In order to better understand Yakut origins, we modeled 25 demographic scenarios and tested by coalescent simulation whether any are consistent with the patterns of mtDNA diversity observed in present-day Yakuts. The models consist of either two simulated demes that represent Yakuts and a South Siberian ancestral population, or three demes that also include a regional Northeast Siberian population that served as a source of local gene flow into the Yakut deme. The model that produced the best fit to the observed data defined a founder group with an effective female population size of only 150 individuals that migrated northwards approximately 1,000 years BP and who experienced significant admixture with neighboring populations in Northeastern Siberia. These simulation results indicate a pronounced founder effect that was primarily kin-structured and reconcile reported discrepancies between Yakut mtDNA and Y chromosome diversity levels. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||