Genetic structure of Mediterranean populations revealed by Y-chromosome haplotype analysis

The allelic variability at six Y-chromosome-specific polymorphisms (YAP, DYS19, DYS389-I, DYS390, DYS391, and DYS392) was used to generate male-specific haplotypes in 333 males representing 12 population samples from the region around the Mediterranean sea. Extreme interindividual variation was observed, as more than 160 distinct Y-chromosome variants could be defined as six-locus haplotypes. Concomitant with this high variability, low levels of population genetic structure were observed. In particular, a "core" of populations directly facing the north and the east of the Mediterranean basin, from the Middle East to the Italian Peninsula, was found to be genetically undifferentiated. This observation, supported by a reanalysis of Y-specific binary polymorphisms in the same populations, suggests that at least part of the male-specific gene pools of these populations has either a very recent common origin (that could be related with the Neolithic demic diffusion hypothesis), and/or that gene flow has played a significant role in shaping the patterns of genetic variability in this region. In agreement with both hypotheses, we found that the spatial distribution of DYS392 alleles revealed a marked differentiation between the East and the West of the Mediterranean area. Through the analysis of microsatellite variation, the time to the most recent common ancestor (TMRCA) of the YAP(+) sublineage 4 has been estimated. The estimations, based on two different data sets, turn out to be quite recent (7,000-11,000 YBP), suggesting that this lineage may have been first introduced into Southern Europe through Neolithic migrations from the Middle East.     

Satyrinae butterflies from Sardinia and Corsica show a kaleidoscopic intraspecific biogeography (Lepidoptera,Nymphlidae)

The Mediterranean islands of Sardinia and Corsica are known for their multitude of endemics. Butterflies in particular have received much attention. However, no comprehensive studies aiming to compare populations of butterflies from Sardinia and Corsica with those from the neighbouring mainland and Sicily have been carried out. In the present study, the eleven Satyrinae species inhabiting Sardinia and Corsica islands were examined and compared with continental and Sicilian populations by means of geometric morphometrics of male genitalia. Relative warp computation, discriminant analyses, hierarchical clustering, and cross‐validation tests were used to identify coherent distributional patterns including both islands and mainland populations. The eleven species showed multifaceted distributional patterns, although three main conclusions can be drawn: (1) populations from North Africa and Spain are generally different from those belonging to the Italian Peninsula; (2) populations from Sardinia and Sicily often resemble the North Africa/Spain ones; Corsica shows transitional populations similar to those from France; and (3) sea barriers represent filters to dispersal, although their efficacy appears to be unrelated to their extension. Indeed, the short sea straits between Sardinia and Corsica and between Sicily and the Italian Peninsula revealed a strong effectiveness with respect to preventing faunal exchanges; populations giving onto sea channels between Corsica and Northern Italy and between Sicily and Tunisia showed a higher similarity. A comparison of island and mainland distributions of the eleven taxa have helped to unravel the complex co‐occurrence of historical factors, refugial dynamics, and recent (post‐glacial) dispersal with respect to shaping the populations of Mediterranean island butterflies. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100 , 195–212.     

Genetic data on Alghero population (Sardinia): Contrast between biological and cultural evidence

Data on 20 genetic polymorphisms (61 alleles) in the Algehero population on the northwestern coast of Sardinia are presented and discussed in relation to its linguistic peculiarity inside the island. Since the Aragonese (Spain) conquest of Sardinia in the 13th century, the Catalan language, the same as that spoken in Northeastern Spain and certain districts of Southern France, has been used in Alghero even until today. Analysis for heterogeneity of gene frequency distributions indicates that the genetic information obtained on Alghero is adequate to discriminate Sardinians from other neighbouring populations. Genetic variation between populations measured through genetic distances and principal-component analysis shows that the present-day population of Alghero is much closer genetically to Sardinians than to Catalonians. Our genetic results do not support any interpretation of the linguistic affinities between Alghero and Catalonia at present as indicative of biological kinship. © 1994 Wiley-Liss, Inc.     

Y-chromosome diversity in Native Mexicans reveals continental transition of genetic structure in the Americas

The genetic characterization of Native Mexicans is important to understand multiethnic based features influencing the medical genetics of present Mexican populations, as well as to the reconstruct the peopling of the Americas. We describe the Y-chromosome genetic diversity of 197 Native Mexicans from 11 populations and 1,044 individuals from 44 Native American populations after combining with publicly available data. We found extensive heterogeneity among Native Mexican populations and ample segregation of Q-M242* (46%) and Q-M3 (54%) haplogroups within Mexico. The northernmost sampled populations falling outside Mesoamerica (Pima and Tarahumara) showed a clear differentiation with respect to the other populations, which is in agreement with previous results from mtDNA lineages. However, our results point toward a complex genetic makeup of Native Mexicans whose maternal and paternal lineages reveal different narratives of their population history, with sex-biased continental contributions and different admixture proportions. At a continental scale, we found that Arctic populations and the northernmost groups from North America cluster together, but we did not find a clear differentiation within Mesoamerica and the rest of the continent, which coupled with the fact that the majority of individuals from Central and South American samples are restricted to the Q-M3 branch, supports the notion that most Native Americans from Mesoamerica southwards are descendants from a single wave of migration. This observation is compatible with the idea that present day Mexico might have constituted an area of transition in the diversification of paternal lineages during the colonization of the Americas.     

No signature of Y chromosomal resemblance between possible descendants of the Cimbri in Denmark and Northern Italy

Two European populations are believed to be related to the ancient Germanic tribe Cimbri: one living in Northern Italy, the other living in Jutland, Denmark. The people called Cimbri are documented in the ancient Roman historical record. Arriving from the far north their movements can be tracked from successive battles with the Romans. The Cimbri finally entered Italy from the northeast and were defeated at Vercellae (present day Vercelli) in 101 BC by Gaius Marius and his professional legions. Classical sources from the first centuries AD relate the homeland of the Cimbri to the coasts around the Elb estuary (northern Germany) or specifically towards the north (Himmerland in northern Jutland). In the alpine parts of Veneto, northeast of the historical battlefield, local traditions dating back to late medieval time, identify a local population as Cimbri living in Terra dei Cimbri. They are considered the descendents of the Germanic combatants that fled the battlefield at Vercelli. As the defeated Cimbri that possibly fled to the mountains of Northern Italy most likely would have been male (warriors), the present study investigated the possible Y chromosomal diversity of the two present populations using microsatellite markers and single nucleotide polymorphisms. While Cimbri from Himmerland resembled their geographical neighbors from Denmark for the Y-chromosome markers, Cimbri from Italy were significantly differentiated both from Cimbri from Himmerland and from Danes. Therefore, we were not able to show any biological relationship for uniparentally transmitted markers.     

Y-chromosome variation among Sudanese: restricted gene flow, concordance with language, geography, and history

We study the major levels of Y-chromosome haplogroup variation in 15 Sudanese populations by typing major Y-haplogroups in 445 unrelated males representing the three linguistic families in Sudan. Our analysis shows Sudanese populations fall into haplogroups A, B, E, F, I, J, K, and R in frequencies of 16.9, 7.9, 34.4, 3.1, 1.3, 22.5, 0.9, and 13% respectively. Haplogroups A, B, and E occur mainly in Nilo-Saharan speaking groups including Nilotics, Fur, Borgu, and Masalit; whereas haplogroups F, I, J, K, and R are more frequent among Afro-Asiatic speaking groups including Arabs, Beja, Copts, and Hausa, and Niger-Congo speakers from the Fulani ethnic group. Mantel tests reveal a strong correlation between genetic and linguistic structures (r = 0.31, P = 0.007), and a similar correlation between genetic and geographic distances (r = 0.29, P = 0.025) that appears after removing nomadic pastoralists of no known geographic locality from the analysis. The bulk of genetic diversity appears to be a consequence of recent migrations and demographic events mainly from Asia and Europe, evident in a higher migration rate for speakers of Afro-Asiatic as compared with the Nilo-Saharan family of languages, and a generally higher effective population size for the former. The data provide insights not only into the history of the Nile Valley, but also in part to the history of Africa and the area of the Sahel.     

Insights into Iberian population origins through the construction of highly informative Y-chromosome haplotypes using biallelic markers,STRs, and the MSY1 minisatellite

To investigate the diversity of Y chromosomes in the Iberian Peninsula and the North African population of Maghreb, we constructed superhaplotypes on the basis of 10 biallelic markers, 7 microsatellites, and 1 minisatellite located in the nonrecombining portion of the human Y chromosome. The analysis of extremely high MSY1 variability was performed by reducing the MVR-codes to modular structures. Y-STRs and MSY1 data provide information about the relationship between closely related populations such as those of Iberia. Analysis of biallelic markers allowed us to identify 7 of 12 haplogroups defined by those polymorphisms. The haplogroup background showed clear differences between Iberian populations and the North African one. The use of differently mutating Y-chromosome markers allowed us to infer different population events at different time scales: the Paleolithic background of the Iberian Peninsula, the Neolithic fingerprint on Y-chromosome lineages, and the Iron Age influence in the populations of Iberia. Implications of our results for the highly debated origin of Basques are also discussed.     

Long-term comparison of algal assemblages dominated by Cystoseira crinita (Fucales,Heterokontophyta) from Cap Corse (Corsica,North Western Mediterranean)

Species composition and abundance of present rocky shore assemblages at Cap Corse (Corsica, North Western Mediterranean) dominated by the fucalean alga Cystoseira crinita are compared with similar data obtained almost 50 years ago. Fifteen sites at five different localities where dense C. crinita assemblages were present in the past were revisited in June 2007. Possible differences between the two sampling times were investigated, applying various multivariate analysis techniques available in the statistical package PRIMER v.6. Dense assemblages dominated by C. crinita were found at 14 out of the 15 surveyed sites, showing a similar structure and composition to the assemblages studied in the past. PERMANOVA indicated slight differences in species composition and abundances between old and new surveys. These differences can be summarized as a higher abundance of encrusting species (up to 3?times greater cover), and more sciaphilic turf-forming species (3 to 60-fold greater, depending on the species) and Cladophora spp. (20?times greater) in the present study than in the old study. Furthermore, the present assemblages showed a lower abundance of photophilic turf-forming species. These differences could be due to different taxonomic competence between observers, seasonal fluctuations or long-term changes. Assemblages dominated by Cystoseira crinita in Cap Corse were confirmed to be common, as they were found and sampled at 22 new sites around the island.     

mtDNA and Y-chromosome variation in the Talysh of Iran and Azerbaijan

The Northern Talysh from Azerbaijan and the Southern Talysh from Iran self‐identify as one ethnic group and speak a Northwestern Iranian language. However, the Northern and Southern Talysh dialects are so different that they may actually be separate languages. Does this linguistic differentiation reflect internal change due to isolation, or could contact‐induced change have played a role? We analyzed mtDNA HVI sequences, 11 Y‐chromosome bi‐allelic markers, and 9 Y‐STR loci in Northern and Southern Talysh and compared them with their neighboring groups. The mtDNA data show a close relatedness of both groups with each other and with neighboring groups, whereas the Northern Talysh Y‐chromosome variation differs from that of neighboring groups, probably as a result of genetic drift. This genetic drift most likely reflects a founder event in the male gene pool of Northern Talysh: either fewer males than females migrated to Azerbaijan, or there was a higher degree of relatedness among the male migrants. Since we find no evidence of substantial genetic contact between either Northern or Southern Talysh and neighboring groups, we conclude that internal change, rather than contact‐induced change, most likely explains the linguistic differentiation between Northern and Southern Talysh. Am J Phys Anthropol, 2009. © 2008 Wiley‐Liss, Inc.     

Allelic diversity at the Mhc-DQA locus of woodmouse populations (Apodemus sylvaticus) present in the islands and mainland of the northern Mediterranean

Aim Polymorphism at neutral markers and at MHC loci in rodent populations living on islands is generally low. The main genetic factors that may contribute to a reduced level of genetic variability are genetic drift, reduced gene flow and founder events. We investigated the pattern of polymorphism at the second exon of the Mhc‐DQA gene in island populations of Apodemus sylvaticus and in their mainland counterparts to investigate the pattern of MHC polymorphism in a phylogeographical context and to assess the impact of insularity on diversity at this locus. Location Eight north Mediterranean populations of Apodemus sylvaticus were studied, including five island populations (Majorca, Minorca, Porquerolles, Port‐Cros and Sicily) and three mainland populations. Methods cDNA sequencing and nucleotide sequences analyses. Synonymous and non‐synonymous substitutions were examined at the PBR and non‐PBR sites. The DQA allelic distribution in populations was compared with the woodmouse phylogeography. Results This study presents novel DQA alleles. High polymorphism of the DQA locus is recorded in natural populations of A. sylvaticus with 13 alleles being widely distributed irrespective of the geographical origin and palaeoclimatic history of populations. The DQA locus does not show the expected pattern for non‐synonymous substitutions at the PBR sites. However, island populations show a weak loss of polymorphism in comparison with their mainland counterparts. Main conclusions The DQA locus in the woodmouse seems to be subject to weak selection and does not allow resolution of phylogeographical relationships among European woodmouse populations. The presence of at least three alleles in island populations and the maintenance of five alleles between the two European lineages over 1.5 Myr suggest that balancing selection may act within populations, and more precisely within island populations, to maintain genetic variability. This study shows that phylogeographical studies are a prerequisite for any genetic investigation of selected genes in natural populations.     

Genetic structure of Tunisian ethnic groups revealed by paternal lineages

Tunisia has experienced a variety of human migrations that have modeled the myriad cultural groups inhabiting the area. Both Arabic and Berber-speaking populations live in Tunisia. Berbers are commonly considered as in situ descendants of peoples who settled roughly in Palaeolithic times, and posterior demographic events such as the arrival of the Neolithic, the Arab migrations, and the expulsion of the "Moors" from Spain, had a strong cultural influence. Nonetheless, the genetic structure and the population relationships of the ethnic groups living in Tunisia have been poorly assessed. In order to gain insight into the paternal genetic landscape and population structure, more than 40 Y-chromosome single nucleotide polymorphisms and 17 short tandem repeats were analyzed in five Tunisian ethnic groups (three Berber-speaking isolates, one Andalusian, and one Cosmopolitan Arab). The most common lineage was the North African haplogroup E-M81 (71%), being fixed in two Berber samples (Chenini-Douiret and Jradou), suggesting isolation and genetic drift. Differential levels of paternal gene flow from the Near East were detected in the Tunisian samples (J-M267 lineage over 30%); however, no major sub-Saharan African or European influence was found. This result contrasts with the high amount of sub-Saharan and Eurasian maternal lineages previously described in Tunisia. Overall, our results reveal a certain genetic inter-population diversity, especially among Berber groups, and sexual asymmetry, paternal lineages being mostly of autochthonous origin. In addition, Andalusians, who are supposed to be migrants from southern Spain, do not exhibit any substantial contribution of European lineages, suggesting a North African origin for this ethnic group.     

Distribution pattern and genetic structure of Aedes zammitii (Diptera: Culicidae) along the Mediterranean and Aegean coasts of Turkey

The Mariae species complex, consisting of Aedes mariae, Aedes phoeniciae, and Aedes zammitii, has a limited distribution worldwide. All three species are found in rocky habitats on the coastal areas of Mediterranean countries. Aedes phoeniciae and Ae. zammitii are two members of the Mariae complex that exist in Turkey. The aim of this study was to determine the distribution pattern and genetic structure of Ae. zammitii along the Mediterranean and Aegean regions. For this purpose, larval and adult samples of Ae. zammitii were collected from 19 different rocky habitats along the coastal regions of Antalya, Mu?la, Ayd?n, ?zmir, Bal?kesir, and Çanakkale provinces. DNA isolation was performed primarily from collected samples, and mitochondrial NADH dehydrogenase 4 (ND4) gene was amplified by polymerase chain reaction. Based on ND4 sequence analyses, 21 haplotypes were detected along the distribution range of the species. Analyses of molecular variance (AMOVA) and spatial analyses of molecular variance (SAMOVA) indicated six groups, and most of the variation was among groups, demonstrating the population structuring at group level. Isolation by distance analyses (IBD) showed a correlation between geographic and genetic distances.     

Genetic and morphometric differentiation among island populations of two Norops lizards (Reptilia: Sauria: Polychrotidae) on independently colonized islands of the Islas de Bahia (Honduras)

Aim Anole lizards (Reptilia: Sauria: Polychrotidae) display remarkable morphological and genetic differentiation between island populations. Morphological differences between islands are probably due to both adaptive (e.g. differential resource exploitation and intra‐ or interspecific competition) and non‐adaptive differentiation in allopatry. Anoles are well known for their extreme diversity and rapid adaptive speciation on islands. The main aim of this study was to use tests of morphological and genetic differentiation to investigate the population structure and colonization history of islands of the Islas de Bahia, off the coast of Honduras. Location Five populations of Norops bicaorum and Norops lemurinus were sampled, four from islands of the Islas de Bahia and one from the mainland of Honduras. Methods Body size and weight differentiation were measured in order to test for significant differences between sexes and populations. In addition, individuals were genotyped using the amplified fragment length polymorphism technique. Bayesian model‐based and assignment/exclusion methods were used to study genetic differentiation between island and mainland populations and to test colonization hypotheses. Results Assignment tests suggested migration from the mainland to the Cayos Cochinos, and from there independently to both Utila and Roatán, whereas migration between Utila and Roatán was lacking. Migration from the mainland to Utila was inferred, but was much less frequent. Morphologically, individuals from Utila appeared to be significantly different in comparison with all other localities. Significant differentiation between males of Roatán and the mainland was found in body size, whereas no significant difference was detected between the mainland and the Cayos Cochinos. Main conclusions Significant genetic and morphological differentiation was found among populations. A stepping‐stone model for colonization, in combination with an independent migration to Utila and Roatán, was suggested by assignment tests and was compatible with the observed morphological differentiation.     

Insights from 180 years of mitochondrial variability in the endangered Mediterranean monk seal (Monachus monachus)

Mediterranean monk seals (MMS) are among the most endangered marine mammals on Earth. We screened mitochondrial variability (control region [CR1] and mitogenomes) of the species through a 180‐yr timeframe and extended by 20% (n = 205) the number of samples from a previous investigation, including historical specimens from 1833 to 1975. Although we detected two new, rare CR1 haplotypes, genetic diversity remained extremely low. Fully resolved haplotype median network and rarefaction analysis both suggested low probability for further unscreened haplotypes. There was no clear phylogeographic structure across the 12 marine subdivisions covered by the species’ range. Haplotypes previously considered diagnostic of the extant North Atlantic and eastern Mediterranean populations had their distributions extended into the western Mediterranean and the North Atlantic, respectively, by both historical and recent samples. Our study suggests that MMS have been genetically depauperate since at least the mid‐19th century, and that the massive 1997 die‐off in Western Sahara (North Atlantic) could have caused local haplotype extinctions. Our results support the hypothesis of past metapopulation dynamics across the species range, where the current segregation into geographically distant and genetically depauperate breeding populations (i.e., North Atlantic and eastern Mediterranean Sea) derives from the combined effects of historical extinctions, genetic drift on small breeding groups, and persistently low levels of genetic diversity.     

Anthesis effects on Posidonia oceanica (L.) Delile phenology in the Bay of Calvi (Corsica,Mediterranean Sea)

In Posidonia oceanica (L.) Delile, anthesis induces a decrease in the number of juvenile leaves resulting in a significant reduction in the number of leaves on the flowering shoots. All the leaves of the flowering shoots are narrower than the leaves of nonflowering shoots. A modification of the leaf growth also appears in flowering shoots: the oldest leaves are longer and the leaves induced during or after anthesis are shorter. At 10 m depth, in the Bay of Calvi, anthesis lasts roughly 3 months and the flowering is induced 7 months before anthesis.