Ryan mentioned this rather interesting study from a year ago on IBD trans-Mediterranean affinities of Europeans.
Laura R. Botigué et al., Gene flow from North Africa contributes to differential human genetic diversity in southern Europe. PNAS 2013. Freely accessible by now → LINK [doi:10.1073/pnas.1306223110]
Human genetic diversity in southern Europe is higher than in other regions of the continent. This difference has been attributed to postglacial expansions, the demic diffusion of agriculture from the Near East, and gene flow from Africa. Using SNP data from 2,099 individuals in 43 populations, we show that estimates of recent shared ancestry between Europe and Africa are substantially increased when gene flow from North Africans, rather than Sub-Saharan Africans, is considered. The gradient of North African ancestry accounts for previous observations of low levels of sharing with Sub-Saharan Africa and is independent of recent gene flow from the Near East. The source of genetic diversity in southern Europe has important biomedical implications; we find that most disease risk alleles from genome-wide association studies follow expected patterns of divergence between Europe and North Africa, with the principal exception of multiple sclerosis.
The most interesting section is surely the one titled Long identical-by-descent haplotypes. Here the authors use long IBD readings to estimate "recent" genetic flows. However they cannot discern the direction of these flows, i.e. flows from Europe to West Asia and North Africa will look exactly the same as the reverse ones.
It seems obvious that North African affinity is concentrated in Iberia, especially in the Western half, what is consistent with previous data, and that West Asian affinity is concentrated in SE Europe. The Iberian extension of this one may be partly related to North African affinity (or not), as North Africans also have some clear West Asian affinity (as should be apparent from the Canarian inset).
I insist that directionality of this affinity is not clear. In the case of West Asian one, it seems plausible that most of it is caused by Neolithic inflows into Europe but in the case of the North African affinity cline, it probably represents bidirectional flows, because previous mtDNA and autosomal data show also quite apparent Iberian influx into North Africa, although the reverse flow is also real.
I find interesting the low levels of West Asian IBD affinity among Basques when compared with estimates of ancestry by early European farmers (EEF, partly West Asian themselves). In the map above Basques score just like other Atlantic populations in this element, yet in the Lazaridis study (see also here and here), Basques score quite high in EEF ancestry, much like the French, which in this graph are clearly higher in "recent" West Asian affinity. That makes me suspect that confounding factors may be at play and reinforces the notion of taking autosomal DNA statistical analyses with some care and try to contrast different approaches before reaching to conclusions.
Also interesting is fig. 3, which pinpoints the specific North African (or Arabian) regions which may show the strongest IBD affinities for the various European regions:
As expected, NW Africa is the most common source-or-destination of Iberian long IBD affinities, instead Qatar or Egypt are most outstanding regarding Italy and SE Europe, what underlines that (North) African genetics in Europe arrived mostly via West Asia (Neolithic), with the notorious Iberian exception.