Sicilian Populations Research Articles

Genetic relationships between Sicilian wild populations of Brassica analysed with RAPD markers

Abstract Brassica comprises very variable species, both morphologically and genetically. Among these species, the Sicilian populations of Brassica sect. Brassica, species related to kale crops form a complex group. The genetic relationships among 15 populations occurring in Sicily and one from Calabria, representing the existing diversity, have been investigated using random amplified polymorphic DNA (RAPD) markers. This assay, carried out with 22 arbitrary primers, generated 236 polymorphic fragments, 21 of which were specific for single populations (mainly Brassica insularis, Brassica incana and Brassica macro‐carpa). Jaccard's genetic distances were computed and the phylogenic tree was established using the UPGMA algorithm. The dendrogram obtained showed four branches grouping: (1) B. incana populations; (2) B. insularis and B. macrocarpa, occurring in small islands around Sicily; (3) B. rupestris populations; and (4) B. villosa populations. Within B. rupestris, only B. rupestris subsp. brevisiliqua was clustered in the B. villosa group. The classification obtained is discussed with regard to the morphological, ecological and geographical data.

A molecular approach to the study of the ancient populations of southern Italy

The peopling of southern Italy must be traced back to the first expansion of the early forms of our species because of the geographical location of this area in the middle of the Mediterranean basin. Since then, the area was the site of a complex network of migration of different peoples, mainly from Phoenicia, Greece, Arabia, the Balkans, the Middle and Near East and north Africa, resulting in a heterogeneous pattern of both cultural and genetic interactions. In order to test the extent of the genetic impact of these various populations upon the peoples of southern Italy, a mitochondrial-DNA (mtDNA)-based research program was undertaken. This would help trace the geographic origin and past history of these populations. Previous detailed and extensive investigations on the distribution of traditional marker allele frequencies in the Sicilian and Apulian extant populations, could only clearly detect the presence of the more recent gene flow from north Africa and the Middle East, superimposed on a predominant Greek genetic substratum. No traces of the ancient groups who peopled Italy in pre-Roman times were detected. Other authors still claim that it is possible to determine the existence of such ancient traces in southern Italy, stressing the difficulties connected to the reconstruction of human evolution based uniquely on the present structure of the genes. Until recently, population genetic studies have heavily relied upon indirect evidence from the genetics of extant populations as well as information gained from cultural, historical and anthropological sources. The possibility to recover DNA from ancient soft tissue, bone and teeth, and the development of sensitive molecular techniques, such as PCR, have enabled us to directly compare genetic diversity between extinct populations and their extant counterparts. This has also provided a temporal dimension to the study of molecular evolution. These comparisons will generate independent data to address archaeological issues concerning migration, population replacement, lineage extinction, inbreeding, and the genetic relationships of ancient human populations. DNA from bone and tooth samples obtained from the necropoles of Rifriscolaro (6th century BC) and Ticchiara (Bronze age), and DNA of extant populations from various Mediterranean areas, were extracted and analysed for mtDNA polymorphisms (region V, D-loop I and II). Moreover, in order to identify the remains of the family of the Prince Branciforte (a Sicilian maecenas and benefactor who lived between 16th and 17th centuries), molecular sex identification and mitochondrial DNA (mtDNA) analyses were used. a-DNA were extracted from the ribs of two adult and three young individuals. NJ and ML phylogenetic reconstructions, performed to verify the reliability of the identified ancient lineages, confirmed the clustering of the Mediterranean mtDNAs into distinct lineage groups, each defined by a set of associated polymorphisms. The joint analysis of D-loop I and II allowed the identification of at least three distinct lineages within the previously identified aplogroup 1 (or H).

Genetic diversity in some species of hydropsyche (trichoptera, hydropsychidae) in central and southern Italy

The genetic differences in 32 populations of Hydropsyche belonging to nine species distributed in Sicily, and central and southern Italy were assayed by horizontal starch gel electrophoresis. Larval specimens were examined. Twelve enzyme loci were assayed and allele frequencies, variability parameters, and Nei's genetic distance were calculated. The percentage of polymorphic loci ranged from 8.3 to 50.0%, the mean number of alleles per locus from 1.1 to 1.8, and the mean observed heterozygosity from 0.009 to 0.123. Nei's genetic distances values between conspecific populations ranged from 0 to 0.096; in the comparison between populations from Sicily and Calabria, H. doehleri had the highest values. Only for H. spiritoi there were differences among the Sicilian populations. From genetic distance data, a dendrogram was obtained. At interspecific level, the values of genetic distance between conspecific populations ranged from 0.201 {H. spiritoi ‐ H. gereckei) to 1.135 (H. dinarica ‐ H. klefbecki). Genetic data were in agreement with morphological data.

Isolation and biodiversity in Cytisus villosus Pourret (Fabaceae, Genisteae): enzyme polymorphism in disjunct populations

ABSTRACT The genetic diversity of isolated populations of Cytisus villosus has been studied by means of enzyme polymorphism analysis. Two types of isolated populations were studied: “terrestrial islands” in Sicily, and “true islands” in the Aeolian archipelago. In the populations of “true islands” the number of alleles and the heterozygosity are lower than in “terrestrial islands”. Isolation amongst Sicilian populations seems to be more recent than isolation of the Aeolian populations, and may be attributed to climatic changes which occurred during the Holocene and/or to human activities. The disjunction of the Aeolian populations seems much more recent than the origin of the isles themselves; the colonization of the archipelago is attributed to a single, recent dispersal event not followed by local evolution. In view of the biological structure of the Aeolian populations, C. villosus must be regarded as a locally endangered species.

Genetic variation and differentiation in the lizard, Podarcis wagleriana (Reptilia: Lacertidae)

Abstract The electrophoretic variation at 26 presumptive gene loci was investigated in populations of Podarcis wagleriana from Sicily, the Aegadian Islands, and the Aeolian Islands. For interspecific comparison, samples of the closely related lizard P. sicula from the same geographic area were also used. Population heterogeneity analyses carried out by the estimation of F -statistics and Nei's standard genetic distance, showed a high genetic homogeneity within P. sicula , but a noticeable genetic differentiation within P. wagleriana . In the latter species, Nei's D ranged from 0 to 0.212, and this is because the Aeolian populations were quite distinct from those inhabiting Sicily and the Aegadian Islands. Fixed differences identified at three loci ( Ck, Ada, Gp-4 ) contributed to a relatively high value of Nei's standard genetic distance between the two population groups ( D = 0.147). This value is very similar to those found comparing pairs of well-recognized biological species included in the genera Podarcis and Lacerta . Estimation of the time of evolutionary divergence shows that the Aeolian and Sicilian populations of P. wagleriana have been isolated geographically for a long time (0.7 Myr according to Nei's formula; 2 Myr according to Sarich's calibration), indicating evolutionary divergence at the species level. Based on genetic and biogeographic data, it is suggested the recognition of full specific status for the Aeolian populations, for which the name P. raffonei comb. nova (Aeolian wall lizard) is proposed. Electrophoretic data and comparative species distributions suggest that (1) Podarcis sicula recently colonized the Aeolian Islands, and (2) it has competed successfully with P. raffonei in this area, greatly reducing the range of the latter and causing the extinction of most of its populations. In fact, P. sicula is widespread in the Aeolian Archipelago, while P. raffonei is confined at present to one large island (Vulcano) and three tiny islands (Strombolicchio, Scoglio Faraglione, La Canna). This can be considered a classic example of competitive exclusion of a native form ( P. raffonei ) by a species accidentally introduced by man ( P. sicula ).

Genetic variation and differentiation in the lizard, Podarcis wagleriana (Reptilia: Lacertidae)

The electrophoretic variation at 26 presumptive gene loci was investigated in populations of Podarcis wagleriana from Sicily, the Aegadian Islands, and the Aeolian Islands. For interspecific comparison, samples of the closely related lizard P. sicula from the same geographic area were also used. Population heterogeneity analyses carried out by the estimation of F -statistics and Nei's standard genetic distance, showed a high genetic homogeneity within P. sicula, but a noticeable genetic differentiation within P. wagleriana. In the latter species, Nei's D ranged from 0 to 0.212, and this is because the Aeolian populations were quite distinct from those inhabiting Sicily and the Aegadian Islands. Fixed differences identified at three loci (Ck, Ada, Gp-4) contributed to a relatively high value of Nei's standard genetic distance between the two population groups (D = 0.147). This value is very similar to those found comparing pairs of well-recognized biological species included in the genera Podarcis and Lacerta. Estimation of the time of evolutionary divergence shows that the Aeolian and Sicilian populations of P. wagleriana have been isolated geographically for a long time (0.7 Myr according to Nei's formula; 2 Myr according to Sarich's calibration), indicating evolutionary divergence at the species level. Based on genetic and biogeographic data, it is suggested the recognition of full specific status for the Aeolian populations, for which the name P. raffonei comb. nova (Aeolian wall lizard) is proposed. Electrophoretic data and comparative species distributions suggest that (1) Podarcis sicula recently colonized the Aeolian Islands, and (2) it has competed successfully with P. raffonei in this area, greatly reducing the range of the latter and causing the extinction of most of its populations. In fact, P. sicula is widespread in the Aeolian Archipelago, while P. raffonei is confined at present to one large island (Vulcano) and three tiny islands (Strombolicchio, Scoglio Faraglione, La Canna). This can be considered a classic example of competitive exclusion of a native form (P. raffonei) by a species accidentally introduced by man (P. sicula).

SIBLING SPECIES OF ARTEMIA: A LIGHT AND ELECTRON MICROSCOPIC SURVEY OF THE MORPHOLOGY OF THE FRONTAL KNOBS. PART II

In this note the frontal knob morphology of a number of Italian populations of Artemia from Sardinia and Central Italy is analyzed and discussed. All of the samples examined showed a subconical shape of the knobs, almost identical to the description formerly given for the Artemia from San Bartolomeo salterns (Cagliari), once named A. salina (Barigozzi, 1974; Piccinelli and Prosdocimi, 1968), and subsequently named A. tunisiana (Bowen et al., 1978; Barigozzi, 1980; Clark and Bowen, 1976). As already pointed out by Mura et al. (1989), all the Mediterranean samples we examined exhibited a common pattern in frontal knob morphology. According to a recent investigation (Baratelli et al., 1988), all the samples from Sardinia, even though characterized by heteroploidy to some extent, seem to correspond in respect to morphological characters to the typical morphology of A. salina sensu Barigozzi (1974), and hence to the morphology of A. tunisiana, as the first Sardinian Artemia observed was subsequently named (Bowen, 1965; Bowen et al., 1978). Nonetheless, the problem concerning to which species of the genus should these populations be ascribed needs further investigation, particularly considering recent data on north African and Sicilian populations (Rodinò et al., 1987). Therefore, we prefer here to use only the generic name (Barigozzi, 1980; Barigozzi and Baratelli-Zambruni, 1982; Bowen et al., 1980).

SIBLING SPECIES OF ARTEMIA: A LIGHT AND ELECTRON MICROSCOPIC SURVEY OF THE MORPHOLOGY OF THE FRONTAL KNOBS. PART I

ABSTRACT In this note the frontal knob morphology of a number of Italian populations of Artemia from Sardinia and Central Italy is analyzed and discussed. All of the samples examined showed a subconical shape of the knobs, almost identical to the description formerly given for the Artemia from San Bartolomeo salterns (Cagliari), once named A. salina (Barigozzi, 1974; Piccinelli and Prosdocimi, 1968), and subsequently named A. tunisiana (Bowen et al., 1978; Barigozzi, 1980; Clark and Bowen, 1976). As already pointed out by Mura et al. (1989), all the Mediterranean samples we examined exhibited a common pattern in frontal knob morphology. According to a recent investigation (Baratelli et al., 1988), all the samples from Sardinia, even though characterized by heteroploidy to some extent, seem to correspond in respect to morphological characters to the typical morphology of A. salina sensu Barigozzi (1974), and hence to the morphology of A. tunisiana, as the first Sardinian Artemia observed was subsequently named (Bowen, 1965; Bowen et al., 1978). Nonetheless, the problem concerning to which species of the genus should these populations be ascribed needs further investigation, particularly considering recent data on north African and Sicilian populations (Rodino et al., 1987). Therefore, we prefer here to use only the generic name (Barigozzi, 1980; Barigozzi and Baratelli-Zambruni, 1982; Bowen et al., 1980).

Relationships among wing length, wing shape and migration in BlackcapSylvia atricapillapopulations

Wing length was measured and wing formula recorded for 182 male Blackcaps. These two characters were closely related; frequencies of the three different wing formulae vary in relation to wing length, so that the pointed wing is mostly recorded for longer wings, while the rounded one has a higher frequency among birds with shorter wings. It is suggested that wing formula and wing length are closely related to the migratory tendency of each Blackcap population. Southern populations have a shorter wing, and a rounded one; ringing data show them to be resident or only partially migrant. We suggest that the altitude of breeding areas has the same effect on the population morphology as latitude. In two Sicilian populations of Blackcaps, that breeding at 1700 m has a longer and more pointed wing than that breeding around sea level.

Blood group phenotypes and the origin of sickle cell hemoglobin in Sicilians.

As an approach to investigating the origin of sickle cell hemoglobin (hemoglobin S) in white persons of Sicilian ancestry, two groups of native Sicilians were tested for blood group evidence of African admixture. Among 100 unrelated Sicilians, the phenotypes cDe(Rho) and Fy(a-b-), and the antigens V(hrv) and Jsa, which are considered to be African genetic markers, were detected in 12 individuals. Among 64 individuals from 21 families with at least one known hemoglobin S carrier, African blood group markers were detected in 7 (11%). These findings indicate that hemoglobin S is only one of multiple African genes present in contemporary Sicilian populations. The occurrence of hemoglobin S in white persons of Sicilian ancestry is considered to be a manifestation of the continuing dissemination of the original African mutation.