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Poleward range expansions are observed for an increasing number of species, which may be an effect of global warming during the past decades. However, it is still not clear in how far these expansions reflect simple geographical shifts of species ranges, or whether new genetic adaptations play a role as well. Here, we analyse the expansion of the wasp spider Argiope bruennichi into Northern Europe during the last century. We have used a range-wide sampling of contemporary populations and historical specimens from museums to trace the phylogeography and genetic changes associated with the range shift. Based on the analysis of mitochondrial, microsatellite and SNP markers, we observe a higher level of genetic diversity in the expanding populations, apparently due to admixture of formerly isolated lineages. Using reciprocal transplant experiments for testing overwintering tolerance, as well as temperature preference and tolerance tests in the laboratory, we find that the invading spiders have possibly shifted their temperature niche. This may be a key adaptation for survival in Northern latitudes. The museum samples allow a reconstruction of the invasion's genetic history. A first, small-scale range shift started around 1930, in parallel with the onset of global warming. A more massive invasion of Northern Europe associated with genetic admixture and morphological changes occurred in later decades. We suggest that the latter range expansion into far Northern latitudes may be a consequence of the admixture that provided the genetic material for adaptations to new environmental regimes. Hence, global warming could have facilitated the initial admixture of populations and this resulted in genetic lineages with new habitat preferences., (© 2013 Blackwell Publishing Ltd.)

North African populations are distinct from sub-Saharan Africans based on cultural, linguistic, and phenotypic attributes; however, the time and the extent of genetic divergence between populations north and south of the Sahara remain poorly understood. Here, we interrogate the multilayered history of North Africa by characterizing the effect of hypothesized migrations from the Near East, Europe, and sub-Saharan Africa on current genetic diversity. We present dense, genome-wide SNP genotyping array data (730,000 sites) from seven North African populations, spanning from Egypt to Morocco, and one Spanish population. We identify a gradient of likely autochthonous Maghrebi ancestry that increases from east to west across northern Africa; this ancestry is likely derived from "back-to-Africa" gene flow more than 12,000 years ago (ya), prior to the Holocene. The indigenous North African ancestry is more frequent in populations with historical Berber ethnicity. In most North African populations we also see substantial shared ancestry with the Near East, and to a lesser extent sub-Saharan Africa and Europe. To estimate the time of migration from sub-Saharan populations into North Africa, we implement a maximum likelihood dating method based on the distribution of migrant tracts. In order to first identify migrant tracts, we assign local ancestry to haplotypes using a novel, principal component-based analysis of three ancestral populations. We estimate that a migration of western African origin into Morocco began about 40 generations ago (approximately 1,200 ya); a migration of individuals with Nilotic ancestry into Egypt occurred about 25 generations ago (approximately 750 ya). Our genomic data reveal an extraordinarily complex history of migrations, involving at least five ancestral populations, into North Africa., Competing Interests: The authors have declared that no competing interests exist.

The author reviews the major demographic trends of the twentieth century in Bulgaria. "The results from the analysis show that the demographic development of Bulgaria especially in the years after 1950 differs very little from the developed, urbanized and industrialized countries. The common features are: development towards [replacement] fertility, [lower mortality rates], zero natural growth [leading] to an increasing life expectancy at birth, [and] population ageing...." (SUMMARY IN ENG AND RUS), (excerpt)

"The study contains...statements of the...sixteenth report of the Government Population Commission on 'Poland's demographic situation'.... The 1990 Report presents for the first time a thorough analysis of mortality caused by...circulatory and respiratory system diseases, malignant neoplasms, injuries and poisonings, [for] basic administrative units (towns and gminas). Moreover, the 1990 Report presents an analysis of changes in the structures of: the socio-demographic situation of households and families, disability, and the external migration of Poland's population in the years 1978-1988. The Report also contains an analysis of the [sociological] changes in Polish family life over the postwar period....", (excerpt)

This article deals with relationships and childbearing as observed in the 1983 survey of the well-being of the population (WBP'83), a survey in which a sample of Dutch citizens aged 18 years and over was interviewed. The demographic part of the survey can be considered as a continuation of the Netherlands Fertility Surveys 1977 and 1982 (NFS'77 and NFS'82) as well as the 1980 survey on the well-being of the population (WBP'80). As the fertility surveys consist of interviews with women of reproductive ages, only the well-being surveys are of particular interest as they also consist of interviews with older women and with men. As cohabitation is on the increase and many youngsters expect ever to cohabit, one could wonder whether these phenomena will result in a continuing decrease of marriages or in a delay of marriages until older ages. The latter hypothesis would seem to make more sense, since the majority of the interviewed persons, even among the youngest, is already married or expects to do so. After the sharp decreases in the average number of children per person, a more stable pattern can be observed in the youngest generations. The expected ultimate numbers of children to persons born in the 1950s and early 1960s are, on average, just below the level of replacement. However, a somewhat lower level can even be expected, as research on the reliability of fertility expectations shows that many women, expecially (still) childless women, overestimate their future number of births. The fertility expectations of men and women show remarkable agreement. However, men do not know the future number of children they expect to have in more cases than women. This implies that the men's answers are less suitable for quantitative calculations.