Genetic structure of continental and island populations of the Mediterranean endemic Cyclamen balearicum (Primulaceae)

Cyclamen balearicum is a self-compatible perennial herb endemic to the western Mediterranean Basin. This species occurs in five geographically isolated terrestrial islands in southern France and on four Balearic islands. In this study, we compare genetic variability and differentiation within and among 11 terrestrial island populations and 17 true island populations. Of nine readable enzyme loci, five were polymorphic in both terrestrial and true islands. F statistics showed a significant heterozygote deficiency in all populations, probably due to high levels of autonomous selfing, restricted gene flow, and subsequent genetic drift. Genetic diversity was higher in terrestrial islands than on the Balearic islands, suggesting that the Balearic islands were colonized when they were in contact with the continent. Population differentiation was greater among terrestrial islands (Fst = 0.417 and Gst = 0.344) than among true islands (Fst = 0.112 and Gst = 0.093). Furthermore, differentiation among populations on the Basses Cévennes terrestrial island was greater (Fst = 0.254) than among populations on the true island of Mallorca (Fst = 0.163). The greater genetic differentiation among terrestrial islands could have been caused by genetic bottlenecks associated with changes in climate and human land use that may have reduced population sizes more severely in terrestrial islands in southern France than on the Balearic islands.     

Genetic structure among continental and island populations of gyrfalcons

Little is known about the possible influence that past glacial events have had on the phylogeography and population structure of avian predators in the Arctic and sub-Arctic. In this study, we use microsatellite and mitochondrial control region DNA variation to investigate the population genetic structure of gyrfalcons (Falco rusticolus) throughout a large portion of their circumpolar distribution. In most locations sampled, the mtDNA data revealed little geographic structure; however, five out of eight mtDNA haplotypes were unique to a particular geographic area (Greenland, Iceland, or Alaska) and the Iceland population differed from others based on haplotype frequency differences (F(ST)). With the microsatellite results, significant population structure (F(ST), principal components analysis, and cluster analysis) was observed identifying Greenland and Iceland as separate populations, while Norway, Alaska and Canada were identified as a single population consistent with contemporary gene flow across Russia. Within Greenland, differing levels of gene flow between western and eastern sampling locations was indicated with apparent asymmetric dispersal in western Greenland from north to south. This dispersal bias is in agreement with the distribution of plumage colour variants with white gyrfalcons in much higher proportion in northern Greenland. Lastly, because the mtDNA control region sequence differed by only one to four nucleotides from a common haplotype among all gyrfalcons, we infer that the observed microsatellite population genetic structure has developed since the last glacial maximum. This conclusion is further supported by our finding that a closely related species, the saker falcon (Falco cherrug), has greater genetic heterogeneity, including mtDNA haplotypes differing by 1-16 nucleotide substitutions from a common gyrfalcon haplotype. This is consistent with gyrfalcons having expanded rapidly from a single glacial-age refugium to their current circumpolar distribution. Additional sampling of gyrfalcons from Fennoscandia and Russia throughout Siberia is necessary to test putative gene flow between Norway and Alaska and Canada as suggested by this study.     

Vegetation dynamics in north-western Mediterranean regions: Instability of the Mediterranean bioclimate

Abstract

Pollen and plant macrofossil records from a selection of sites in Spain, France and Italy are used to explore the origin and the development of the Mediterranean vegetation. The role of evergreen and summergreen taxa is discussed. The expansion of sclerophyllous trees during the Pleistocene interglacials is well correlated with the orbital forcing. During the Holocene, the large number of data illustrates latitudinal and longitudinal differences in vegetation dynamics. Multidisciplinary studies identify short terms climatic fluctuations. The debate is still open between those who attribute an increase of sclerophyllous forests during the late Holocene to a trend toward aridity and those who consider this dynamic as human-induced.     

Contrasting patterns of sexually selected traits in Mediterranean and continental populations of European mouflon

The expression of sexually selected traits in highly dimorphic ungulates may be influenced by environmental quality. Variations in habitat conditions can impose different constraints on the allocation of energy resources to male life‐history traits, and possibly alter the female preferences for specific features. Here, we compared the horn growth patterns in male European mouflon Ovis aries musimon living in different habitats (Mediterranean vs. continental) but sharing a common genetic origin. We hypothesized that the expression of sexually selected traits such as horn development should be promoted in more favorable habitat conditions (i.e., Mediterranean). Using linear mixed models on data retrieved from individuals harvested under the same hunting regime, we found longer horns and greater individual variance in horn segment length in the Mediterranean population than in the continental one. Furthermore, Mediterranean rams showed no evidence of compensatory horn growth, as opposed to the continental rams. Unexpectedly, horn base circumference was greater in the continental habitat than in the Mediterranean one. The overall results suggest different patterns of investment in horns in the two populations, with seemingly stronger pressure and consequences of sexual selection on mouflon rams living in more favorable environments. Although the role of hunters' selectivity cannot be excluded a priori, our data suggest that the differences in the expression of sexually selected traits in our study populations may be influenced by environmental conditions. Because sexual selection can impose substantial fitness costs on individuals, further investigations on the trade‐offs between reproduction and survival would improve our understanding of the dynamics of mouflon populations living in different environmental conditions.     

Vicariance and marine migration in continental island populations of a frog endemic to the Atlantic Coastal forest

The theory of island biogeography is most often studied in the context of oceanic islands where all island inhabitants are descendants from founding events involving migration from mainland source populations. Far fewer studies have considered predictions of island biogeography in the case of continental islands, where island formation typically splits continuous populations and thus vicariance also contributes to the diversity of island populations. We examined one such case on continental islands in southeastern Brazil, to determine how classic island biogeography predictions and past vicariance explain the population genetic diversity of Thoropa taophora, a frog endemic to the Atlantic Coastal Forest. We used nuclear microsatellite markers to examine the genetic diversity of coastal and island populations of this species. We found that island isolation has a role in shaping the genetic diversity of continental island species, with island populations being significantly less diverse than coastal populations. However, area of the island and distance from coast had no significant effect on genetic diversity. We also found no significant differences between migration among coastal populations and migration to and from islands. We discuss how vicariance and the effects of continued migration between coastal and island populations interact to shape evolutionary patterns on continental islands.     

Tail autotomy and extinction in Mediterranean lizards. A preliminary study of continental and insular populations

Tail autotomy is one of the main anti-predator mechanisms of lacertid lizards, but it has been predicted that it is only retained in its full capacity when its benefits exceed its costs (Arnold, 1988). To test this hypothesis, ease of tail shedding was examined in a number of continental and insular lacertid lizard populations, each of which showed a different shedding capacity. Tails are shed more easily in those continental and insular populations where there is a greater probability of predation. In insular populations not subjected to strong predation, the tail tends to be retained. The relationship of these findings to insular Mediterranean lizard populations and to the extinction of the Balearic lizard, Podarcis lilfordi are discussed.     

Isonymy, consanguinity and repeated pairs of surnames in Aromun populations

The Aromuns represent a small and almost unknown people that live scattered over the Balkan Peninsula. Due to their language, that is very similar to classical Latin, they are in a special position. The Aromuns settled only in more recent times. Until now they lived as shepherds, as caravan guides and merchants and lead a semi-nomadic life. We are currently carrying out studies to determine the genetic structure of this population. To facilitate the interpretation of these data, we are also trying to obtain other important parameters that pertain to migration processes and the genealogical structure of this populations. The data arise from three areas in Albania, the Republic of Macedonia and Romania. The inbreeding coefficient and the proportion of repeated pairs of surnames was calculated through the use of genealogies and the isonymy method. The difference between these three populations are due primarily to confounding by selection of mates and family composition.     

Genetic differentiation of continental and island populations of Bombus terrestris (Hymenoptera: Apidae) in Europe

Ten microsatellite loci and a partial sequence of the COII mitochondrial gene were used to investigate genetic differentiation in B. terrestris, a bumble bee of interest for its high-value crop pollination. The analysis included eight populations from the European continent, five from Mediterranean islands (six subspecies altogether) and one from Tenerife (initially described as a colour form of B. terrestris but recently considered as a separate species, B. canariensis). Eight of the 10 microsatellite loci displayed high levels of polymorphism in most populations. In B. terrestris populations, the total number of alleles detected per polymorphic locus ranged from 3 to 16, with observed allelic diversity from 3.8 ± 0.5 to 6.5 ± 1.4 and average calculated heterozygosities from 0.41 ± 0.09 to 0.65 ± 0.07. B. canariensis showed a significantly lower average calculated heterozygosity (0.12 ± 0.08) and observed allelic diversity (1.5 ± 0.04) as compared to both continental and island populations of B. terrestris. No significant differentiation was found among populations of B. terrestris from the European continent. In contrast, island populations were all significantly and most of them strongly differentiated from continental populations. B. terrestris mitochondrial DNA is characterized by a low nucleotide diversity: 0.18%± 0.07%, 0.20%± 0.04% and 0.27%± 0.04% for the continental populations, the island populations and all populations together, respectively. The only haplotype found in the Tenerife population differs by a single nucleotide substitution from the most common continental haplotype of B. terrestris. This situation, identical to that of Tyrrhenian islands populations and quite different from that of B. lucorum (15 substitutions between terrestris and lucorum mtDNA) casts doubts on the species status of B. canariensis. The large genetic distance between the Tenerife and B. terrestris populations estimated from microsatellite data result, most probably, from a severe bottleneck in the Canary island population. Microsatellite and mitochondrial DNA data call for the protection of the island populations of B. terrestris against importation of bumble bees of foreign origin which are used as crop pollinators.     

Inverted patterns of genetic diversity in continental and island populations of the heather Erica scoparia s.l.

Aim Using the heather Erica scoparia s.l. as a model, this paper aims to test theoretical predictions that island populations are genetically less diverse than continental ones and to determine the extent to which island and continental populations are connected by pollen‐ and seed‐mediated gene flow. Location Macaronesia, Mediterranean, Atlantic fringe of Europe. Methods Patterns of genetic diversity are described based on variation at two chloroplast DNA (cpDNA) loci and one nuclear DNA (nDNA) locus for 109 accessions across the entire distribution range of the species. Global patterns of genetic differentiation were investigated using principal coordinates analysis. Genetic differentiation between island and continental areas, estimations of pollen‐ and seed‐mediated gene flow, and the presence of phylogeographical signal were assessed by means of F_st /N_ST (continental scale) and F_ij/N_ij (local scale). Extant and past distribution ranges of the species were inferred from niche modelling using layers describing present and Last Glacial Maximum (LGM) macroclimatic conditions. Results The Azores exhibited a significantly higher genetic diversity than the continent. The lowest levels of genetic differentiation were observed between the Azores and the western Mediterranean, and the diversity observed in the Azores resulted from at least two colonization waves. Within the Azores, kinship coefficients showed a significant and much steeper decrease with geographical distance in the cpDNA than in the nDNA. The distribution predicted by LGM models was markedly different from the current potential distribution, particularly in western Europe, where no suitable areas were predicted by LGM models, and along the Atlantic coast of the African continent, where LGM models predicted highly suitable climatic conditions. Main conclusions The higher diversity observed in Azorean than in continental populations is inconsistent with MacArthur and Wilson’s equilibrium model and derived theoretical population genetic expectations. This inverted pattern may be the result of extinction on the continent coupled with multiple island colonization events and subsequent allopatric diversification and lineage hybridization in the Azores. The results highlight the role of allopatric diversification in explaining diversification on islands and suggest that this process has played a much more significant role in shaping Azorean biodiversity than previously thought.     

Chromosomal polymorphism of populations of Anopheles arabiensis (Diptera: Culicidae) from Reunion island and cross-fertility among continental African populations

Cytological examination of a sample of Anopheles gambiae complex mosquitoes from Reunion island revealed the presence of An. arabiensis only. Chromosomal polymorphisms were observed only for inversion 3Ra, the standard homozygote form being predominant. Cross-mating experiments with laboratory specimens originating from continental Africa produced viable and fertile offspring with no chromosomal asynapsis observed in the F1 female progeny. There was no evidence for speciation of the Reunion island populations. The results are discussed with regard to the behaviour of the vector and its influence on the vectorial capacity of this species, and the history of malaria and malaria control in the South-West islands of the Indian Ocean and on Reunion island in particular.     

Body size structure in north-western Mediterranean Plio-Pleistocene mammalian faunas

Aim We investigated the patterns of body‐size changes of the north‐western Mediterranean Plio‐Pleistocene large mammal faunas (excluding rodents, bats, lagomorphs and insectivores) in order to identify the tempo and mode of the major shifts in body size distribution, and to put them in the context of Plio‐Pleistocene environmental changes and the development of the Mediterranean climate. Location We analysed fossil faunas of Spain, France and Italy. A set of recent regional faunas from several macroclimatic regions was selected to serve as elements for comparison of the size distribution of past faunas, consisting of: Spain, France and Italy together, Florida, California, Central Chile, Indochina, India, Korea‐Manchuria, Malawi, The Cape, North Africa, Turkey and Australia. Methods Mammal species were grouped into five body size categories for carnivores and four categories for noncarnivore species. The number of species in each size category was computed and the resulting matrix of body weight classes × regions and time intervals was used as an input matrix in a Correspondence Analysis. Results Recent and fossil faunas strongly differ in body size structure. The distribution of recent faunas within the CA seems to reflect both ecological and historic factors, intertwined in a complex fashion. No clear relationship has been observed between body size structure and environmental factors. During the late Pliocene to early Pleistocene there were only minor changes in the pattern of size distribution, although plant communities were in a transition process from subtropical forests to Mediterranean woodlands and steppes. The major change in body size structure of the north‐western Mediterranean fauna occurred at the Galerian, around 1 Ma ago. This marked the beginning of the modern fauna, and a general trend towards a larger body size, reduction in the number of medium sized herbivores, and an increase of large herbivores and megaherbivores. Main conclusions The Plio‐Pleistocene faunas lack modern analogues. The body size structure of mammalian regional faunas appears to be strongly dependent on historical factors. The only major shift in body size distribution occurred during the Plio‐Pleistocene, in the late Villafranchian‐Galerian transition, coincident with the onset of the Pleistocene high intensity glacial cycles.     

Floral trimorphism and monomorphism in continental and island populations of Eichhornia paniculata (Spreng.) Solms. (Pontederiaceae)

Eichhornia paniculata (Spreng.) Solms. (Pontederiaceae) is a short-lived perennial or annual of marshes, seasonal pools and ditches of lowland tropical South America, primarily NE Brazil, and the Caribbean islands of Cuba and Jamaica. Comparisons, made under uniform glasshouse conditions, of populations originating from seed collected in the two regions revealed striking differences in their floral biology and breeding systems. The majority of populations sampled in NE Brazil are tristylous. Floral trimorphism is associated with pollen trimorphism and minor differences in anther size and pollen production among the three stamen levels. Unlike the majority of heterostylous plants the floral morphs of E. paniculata are highly self-fertile. Populations sampled on the island of Jamaica are composed exclusively of self-pollinating, semi-homostylous, mid-styled forms. Flowers from these populations are smaller and less showy, with reduced pollen heteromorphism and significantly fewer pollen grains and ovules per flower, in comparison with trimorphic populations from Brazil. Individual genotypes from Jamaican populations display considerable developmental instability in floral expression, particularly with respect to filament elongation of the lower stamen level. It is proposed that self-pollinating populations of E. paniculata are evolutionarily derived from tristylous ancestors and that the shift in breeding system is favoured at low density, following population bottlenecks, where pollinator service is unreliable.     

Bathymetric distribution and growth patterns of Bathypterois mediterraneus from the north-western Mediterranean Sea

Bathypterois mediterraneus was collected on 148 bottom trawls between 147 and 2251 m depth in the north-western Mediterranean. The species appeared below 700 m, its relative abundance and biomass increased progressively and reached its maximum at 2100-2300 m. A total of 1913 specimens were measured, ranging from 4 to 20 cm standard length ( L _s). The size composition with depth did not show any specific trend, and no modal progression could be distinguished in the length frequency distribution by cruise, with dominance of large fish (13-15 cm L _s) and a unimodal size pattern. The otoliths of 173 specimens were examined and showed the ring pattern common to teleost fishes. The age ranged between 0 and 15 years, although specimens of 4-12 years old were the most abundant. The growth parameters and the growth curve obtained from the interpretation of the growth rings in otoliths showed a low growth rate.     

Nutritional value of some algae from the north-western Mediterranean coast of Egypt

Fourteen taxa from Chlorophyta, Rhodophyta and Phaeophyta were collected from seven stations at different depths, along the north-western Mediterranean coast of Egypt during winter and summer 2006. Total carbohydrates (TCH), total protein (TPr), total lipids (TL), chlorophyll a, β-carotene, minerals and trace metals were determined in a total of 50 specimens. The concentrations of these components varied significantly with respect to the algal taxa and showed different patterns of distribution in the three classes. The content of TCH ranged from 5 to 20.9?%, being much higher for Cystoseira spinosa (20.9?%), TPr 3.86 to 27.65?% where Gelidium corneum showed the maximum value and TL content displayed wide variation (2.34 to 48.95?%), with Sargassum hornschuchii having the highest values. A minor component was β-carotene in all samples (1.80?2.50?×?10^?3 mg (100 g)^?1) which was much lower than in vegetables, in contrast to chlorophyll a concentrations which have attained high values (6.70?94.20 mg (100 g)^?1) and were lower than in vegetables. Mineral content was abundant in all samples and was higher than in common food and vegetables, whereas the measured trace metals all exceeded the permissible doses and were far from the accepted concentrations in the regulations of many countries. This limits their use in food consumption, except copper which recorded acceptable concentrations in the study. The maximum values of phosphorus (3,305 mg (100 g^?1), potassium (930 mg (100 g^?1) and calcium (3,070 mg (100 g^?1) were recorded in members of Chlorophyceae: Codium bursa, Udotea sp. and Udotea petiolata, whereas the red alga Rhodymenia ardissonei had the lowest concentrations in iodine (80 ppm) and sodium (1,450 mg (100 g)^?1) and the highest concentrations in the trace metals copper (3.89 ppm), nickel (13.14 ppm), zinc (38.87 ppm) and a relatively large amount of lead (41.60 ppm).     

Genetic diversity of oceanic island Lasaea (Mollusca: Bivalvia) lineages exceeds that of continental populations in the northwestern Atlantic

Direct-developing lineages of the intertidal marine bivalve Lasaea have colonized both upstream mainland (southeastern Florida) and downstream oceanic island (Bermuda) locations in the western North Atlantic. Replicate samples from these two regional populations, separated by about 1500 km of open ocean, were sequenced for a 655-nucleotide portion of the mitochondrial (mt) cytochrome oxidase subunit I gene. Twelve haplotypes (2 Floridian and 10 Bermudan) were obtained that differed by a maximum of four substitutions among pairwise comparisons. Phylogenetic analysis yielded a parsimony network within which the mainland lineages clustered in one of the terminal branches; a mirror image of a priori expectations based on regional surface-current polarity. It is difficult, however, to envisage a plausible countercurrent dispersal mechanism. This tree topology may stem from divergent demographic processes operating on these two evolutionarily recent regional populations. The starlike phylogenetic pattern of Bermudan lineages is consistent with a history of rapid population growth. The restricted genetic repertoire and relative ecological scarcity of Floridian lineages imply either a recent founder event by unstudied Caribbean source populations or else a history of pronounced bottlenecks in population size. Bermuda's impoverished Caribbean marine biota may allow western North Atlantic Lasaea lineages to escape severe competitive interactions impacting other parts of their geographic range.     

Factors affecting bird communities in fragments ofsecondary pine forests in the north-western Mediterranean basin

We assessed the influence of size, extent of isolation and vegetation structure of secondary forest fragments on the richness and species composition of breeding bird communities in a sample of pine forest fragments surrounded by an agricultural matrix in the north-western Mediterranean basin. Fragment size was the main predictor of bird’s occurrence, since it accounted for 70 % of the model variation. Isolation was also a valuable predictor of species occurrence, especially for forest specialists. Finally, subarboreal vegetation such as holm oak and a well-developed tree layer of large pines favoured forest species occurrence. Therefore, in spite of the long history of human impact, forest birds in Mediterranean mosaics are sensitive to both habitat loss and isolation of remnant patches in a similar manner to the patterns found in other temperate fragmented landscapes where human impact is more recent.     

Extreme mtDNA homogeneity in continental Asian populations

Mitochondrial DNA (mtDNA) variation in continental Asia has not been well-studied. Here, we report mtDNA HV1 sequences for 84 Xi'an and 82 Changsha Han Chinese, 89 Honshu Japanese, and 35 Vietnamese. Comparison of these sequences with other Asian mtDNA sequences reveals high variability within populations, but extremely low differentiation among Asian populations. Correlations between genetic distance and geographic distance, based on mtDNA and Y chromosome variation, indicate a higher migration rate in females than in males. This may reflect patrilocality, as suggested previously, but another plausible hypothesis is that the demographic expansion associated with the spread of agriculture in Asia may be responsible for the extreme genetic homogeneity in Asia.     

Pattern intensity in the Mediterranean area

The distribution of the Pattern Intensity (PI) index in the mediterranean populations shows an increase of the PI from west to east. Mean and standard deviation of some mediterranean groups are also presented. Partially supported by M.P.I. 60%, 1983.     

Palm wine harvesting by the Bassari threatens Borassus aethiopum populations in north-western Guinea

The use of the palm tree Borassus aethiopum Mart(Coryphoideae) by the Bassari ethnic group in the Republic of Guinea wasstudied. Ethnic groups have multiple uses for B. aethiopumthroughout its distribution in tropical Africa. The Bassari use this palm mostlyas a palm wine resource. As their harvesting technique leads to the death of thepalm, the populations of this species are highly endangered in the areapopulated by the Bassari. The fast decline of an important resource has recentlygained attention at governmental level. In order to conserve the populations ofthis palm, it is essential to understand whether the Bassari use a lethaltechnique because of socio-economic reasons or due to a lack of knowledge. Thepresent study aims to answer this question. We collected the data in thenorth-western part of the Republic of Guinea in May 1996 by field observationsand by using 'Rapid Rural Appraisal' tools consisting of interactiveinterviews with palm wine harvesters, collectors, carriers and sellers. Afterconstructing a woody ladder fixed to the stem the Bassari extract the sap bycutting a hole into the palm heart and by removing a small part of the palmheart two times per day. Individual trees produce on average 10 lper day. After 35–45 days the sap production ceases and thepalm dies. A harvester kills on average 56 individuals of B.aethiopum per year. As a consequence of this lethal techniqueexploiters have to constantly move through and between palm populations. Thereis no reforestation of the degraded areas. The palm wine extraction ofB. aethiopum is the main activity of the Bassari for 7months of the year. For harvesters, collectors, carriers andsellers, palm wine extraction provides one of the most important annual incomes.The harvester pays a monthly tax of USD 5 to the forestry administration.Despite its economic importance, the Bassari palm wine harvesters rangeB. aethiopum as the sixth most important plant species in the area. The paradoxical situation of acommunity that threatens a resource that it is highly dependent on may beexplained by the following circumstances. Firstly, the exploiters seek a maximumprofit on a short term basis. Secondly, the exploiters apparently do not takeinto consideration the total value of other potential products from theBorassus. Thirdly, the Bassari do not have an importanttradition for exploiting B. aethiopum so that there is noapparent cultural alliance between the Bassari and the palm. Finally, the rulesand regulations for harvesting Borassus products favourquick profit. The extinction of the palm population studied can be expectedwithin about 25 years if no protection measure is taken.     

Basin scale distribution of zooplankton in the Ligurian Sea (north-western Mediterranean) in late autumn

Mesozooplankton biomass and abundance were evaluated in epipelagic waters at 59 stations covering the Italian sector of the Ligurian Sea (north-western Mediterranean) in December 1990. This region is characterised by a cyclonic circulation which encloses a central divergence zone and is associated with a main thermohaline front offshore the western Ligurian coast. At the end of autumn, mesozooplankton biomass (range: 0.80–4.24 mg DW m⁻³) and the abundance (range: 83.8–932 ind. m⁻³) were lower in the divergence zone. On the contrary, in the Ligurian frontal zone at the periphery of the divergence and on the eastern continental shelf the greatest values of biomass and abundance were recorded. Copepods and appendicularians dominated the mesozooplankton community, the main taxa being the copepods Clausocalanus spp. (46% of total zooplankton) and Oithona spp. (15%) and the appendicularian Fritillaria spp. (12%). Three hydrological sub-regions, i.e. the divergence, the eastern continental shelf and the periphery of the divergence, were characterised by different zooplankton communities and characteristic species. Environmental differences between the three zones were mainly related to changes in bottom topography, sea surface temperatures and quantity of particulate organic matter. Vertical mesozooplankton abundance and taxa distribution from the surface to 1,900 m depth were also examined in one station. The results showed that the bulk of the community was concentrated in the upper 200 m, small copepods being dominant particularly in the upper 50 m. The copepod community was more diversified in sub-superficial waters, with a maximum observed in the 200–400 m layer. The distributions of main zooplankton taxa described in epipelagic waters in the eastern Ligurian Sea in autumn were compared with their distribution at surface in the north-western Mediterranean obtained by sampling performed with the Continuous Plankton Recorder in 1997–1999. The analysis of the zooplankton community in CPR samples confirms the dominance of small copepods (Paracalanus spp., Clausocalanus spp., Oithona spp.) and appendicularians in the north-western Mediterranean in late autumn-winter and shows that their distribution is mainly related to the main mesoscale hydrographic features characterising this basin. Guest editors: S. Souissi & G. A. Boxshall Copepoda in the Mediterranean: Papers from the 9th International Conference on Copepoda, Hammamet, Tunisia