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The occurrence of two individuals of Zu cristatus at 2 m depth in coastal waters of the Gulf of Castellamare (Tyrrhenian Sea, Italy) together with records of this rare pan-Oceanic mesopelagic species is reported. Analyses of two mitochondrial genes (12 s and 16 s; 936 bp) revealed a 2.6% sequence divergence between Mediterranean and Pacific (Japanese) samples of the species.
The population status of the harbour porpoise (Phocoena phocoena) in the Baltic area has been a continuous matter of debate. Here we present the by far most comprehensive genetic population structure assessment to date for this region, both with regard to geographic coverage and sample size: 497 porpoise samples from North Sea, Skagerrak, Kattegat, Belt Sea, and Inner Baltic Sea were sequenced at the mitochondrial Control Region and 305 of these specimens were typed at 15 polymorphic microsatellite loci. Samples were stratified according to sample type (stranding vs. by- caught), sex, and season (breeding vs. non-breeding season). Our data provide ample evidence for a population split between the Skagerrak and the Belt Sea, with a transition zone in the Kattegat area. Among other measures, this was particularly visible in significant frequency shifts of the most abundant mitochondrial haplotypes. A particular haplotype almost absent in the North Sea was the most abundant in Belt Sea and Inner Baltic Sea. Microsatellites yielded a similar pattern (i.e., turnover in occurrence of clusters identified by STRUCTURE). Moreover, a highly significant association between microsatellite assignment and unlinked mitochondrial haplotypes further indicates a split between North Sea and Baltic porpoises. For the Inner Baltic Sea, we consistently recovered a small, but significant separation from the Belt Sea population. Despite recent arguments that separation should exceed a predefined threshold before populations shall be managed separately, we argue in favour of precautionary acknowledging the Inner Baltic porpoises as a separate management unit, which should receive particular attention, as it is threatened by various factors, in particular local fishery measures.
Sequence variation of a fragment of the mitochondrial DNA encoding for the cytochrome b gene was used to reconstruct the phylogeography of the two species of bleaks occurring in Italy: the alborella Alburnus arborella in northern Italy and the vulturino Alburnus albidus in southern Italy. The study includes four populations of the alborella and 14 populations of the vulturino. A total of 57 haplotypes were identified; these could not be sorted into two reciprocally monophyletic clusters. Multiple phylogenetic methods and nested clade phylogeographical analysis consistently retrieved three well-supported clades, two of which contained both Northern and Southern Italian haplotypes. A third clade is limited to southern Italy. This clade is tentatively assigned to the vulturino. The placement in the same clade of northern and southern Italian haplotypes is explained in light of the introductions of fishes operated from northern to central and southern Italy. The origin of the vulturino dates back to the last two million years. This divergence time estimate identifies the Pleistocene confluences between adjacent river basins along the Adriatic slope of the Italian peninsula and their subsequent isolation as the cause that triggered the diversification of the genus in the area. The existence of a clade endemic to southern Italy supports the recognition of the area as a new peri-Mediterranean ichthyogeographic district, the borders of which correspond to the northern and southern edges of the vulturino range.
Contrasting signals from multiple markers illuminate population connectivity in a marine fish
(2009)
Recent advances in molecular biology and bioinformatics have helped to unveil striking and previously unrecognized patterns of geographic genetic structure in marine populations. Largely driven by the pressing needs of fisheries management and conservation, studies on marine fish populations have played a pivotal role in testing the efficiency of a range of approaches to explore connectivity and dispersal at sea. Here, we employed nuclear and mitochondrial DNA markers and parasitic infestations to examine the nature and patterns of population structure in a warm-temperate coastal marine teleost across major putative biogeographic barriers in the Mediterranean Sea and Eastern Atlantic Ocean. We detected deep genetic divergence between mitochondrial lineages, likely caused by dramatic climatic and geological transformations before and during the Pleistocene. Such long-diverged lineages later came into secondary contact and can now be found in sympatry. More importantly, microsatellite data revealed that these lineages, after millions of years of independent evolution, now interbreed extensively. By combining genetic and parasite data, we were able to identify at least five independent demographic units. While the different genetic and parasite-based methods produce notably contrasting signals and may complicate the reconstruction of connectivity dynamics, we show that by tailoring the correct interpretation to each of the descriptors used, it is possible to achieve a deeper understanding of the micro-evolutionary process and, consequently, resolve population structure.
Chirocephalus ruffoi is a fairy shrimp endemic to the Italian peninsula, where it is known only from thirteen high mountain locations. Twelve of these are in the Northern Apennines while the thirteenth is about 700 km away in the Calabrian Apennines (Southern Italy). We quantified degree of genetic divergence within the species by sequencing a fragment of the mitochondrial DNA encoding for Cytochrome Oxidase I. We then combined genetic data with the re-analysis of two different datasets on the morphometrics of the resting eggs (cysts) produced by the species as an adaptation to survive seasonal droughts. Genetic data revealed profound divergence; we identified four clusters of haplotypes within the species phylogeography, three in the Northern Apennines and one in the Calabrian Apennines with most of the genetic variation (a parts per thousand 70%) being apportioned among haplogroups. We found high variability in cyst morphometrics, especially in cyst size and height of the spines ornamenting the surface. Genetic and morphometric data are decoupled suggesting that cyst morphology is either under selection or a plastic trait. We, therefore, caution against using cyst morphology for taxonomic purposes in anostracans.
Talitrids are the only family within the order Amphipoda to have colonised supralittoral and terrestrial environments. They live in a variety of settings, from sandy to rocky and pebble beaches, to river and lake banks, and to leaf litter and caves. A common feature is the absence of a planktonic larval stage to facilitate passive dispersal over long-distances. However, some species have broad distributions. Genetic studies over the past 25 years have tried to explain this apparent contradiction by assessing patterns of species genetic structuring on different geographical scales. Here, we review the molecular studies available to date and focus on the population genetics of talitrids. Most of these studies considered populations in the Mediterranean area, but also along the Atlantic coast and in Canary Island caves. From this review, the group emerges as a potential model to understand processes of dispersal and divergence in non-highly-vagile supralittoral organisms. At the same time, studies on these issues are still too restricted geographically: a worldwide scale including different regions would provide us with a better perspective on these problems.
The land snail genus Solatopupa consists of six species and has a peri-Tyrrhenian distribution; most of the species have a very narrow range and all of them except one (Solatopupa cianensis, which inhabits porphyritic rocks) are strictly bound to calcareous substrates. One species (Solatopupa gidoni) is limited to Sardinia, Corsica, and Elba Island. Because the potential for dispersal of these snails is low, the insular range of this species has been traditionally related to the Oligocenic detachment of the Sardinia-Corsica microplate from the Iberian plate and its subsequent rotation towards the Italian peninsula. In this Study, we used sequences of three mitochondrial and one nuclear gene to reconstruct the evolutionary history of the genus. Our phylogenetic results are consistent with the genetic relationships found using allozymes, but contrast with the phylogenetic hypotheses based on karyology and morphology. Molecular clock estimates indicate that the main cladogenetic events in the genus occurred between the middle Miocene and the middle-late Pliocene. Patterns of phylogenetic relationships and geological considerations suggest that the cladogenesis of the genus can be explained by vicariant (tectonic) processes. Our datings do not support a causal relation between the split of S. guidoni from its continental sister taxon and the initial phases of the detachment of the Corsica-Sardinia microplate from the mainland. On the contrary, time estimates coincide with the very last phase of detachment of the microplate (from 5 to 3 Myrs ago). Overall, our molecular clock estimates are in good agreement with the latest geological views on the tectonic evolution of the peri-Tyrrhenian area.
By combining morphology, ecology, biology, and biogeography with the available molecular (sequence variation of the entire mitochondrial cytochrome b gene; cyt-b) and karyology data, the taxonomy of several species of the Rutilus complex inhabiting southern Europe is revised. Rutilus stoumboudae, new species, is described from Lake Volvi, Greece. It differs from Rutilus rutilus in possessing more total GR and less branched rays in both dorsal and anal fins and in its placement in the cyt-b based phylogeny of the genus. The resurrected genus Leucos Heckel, 1843 (type species Leucos aula, Bonaparte, 1841), which according to molecular data diverged from Rutilus more than 5 million years ago, during the Messinian salinity crisis, includes five species of small size, without spinous tubercles on scales and head in reproductive males, pharyngeal teeth formula 5-5, and all show a preference for still waters. Leucos aula is the Italian species endemic in the Padany-Venetian district: L. basak is widespread in Croatia, Albania, Montenegro and former Yugoslav Republic of Macedonia (FYROM); L. albus, recently described from Lake Skadar, Montenegro, is also found in rivers Moraca and Zeta (Montenegro). L. albus differs from L. basak, its closest relative, in having more scales on the LL and less anal-fin rays; L. panosi is endemic to the western-Greece district, and L. ylikiensis is endemic to lakes Yliki and Paralimni in eastern Greece (introduced in Lake Volvi). Among the nominal species examined, Rutilus karamani, R. ohridanus, R. prespensis and R. prespensis vukovici are all junior synonyms of Leucos basak. Rutilus vegariticus is definitively regarded as junior synonym for R. rutilus. Sarmarutilus n.gen. is a monotypic genus, with Sarmarutilus rubilio as the type species. According to phylogenetic data, Sarmarutilus rubilio is basal to a cluster of species that includes Leucos basak, L. albus, L. aula, L. panosi and L. ylikiensis. Sarmarutilus possibly evolved in pre-Messinian time, in the Lago Mare, entered the Mediterranean area during the Messinian Lago Mare phase of the Mediterranean Sea and survived only in the Tuscany-Latium district. This genus differs from Leucos in having large pearl organs on the central part of head and body scales in mature males and for the habitat preference, being a riverine-adapted species. It differs from Rutilus in pharyngeal teeth formula (5-5 in Sarmarutilus and 6-5 in Rutilus), size (small in Sarmarutilus and large in Rutilus) and for the preferential habitat (riverine vs. still water). Finally, lectotypes for Leucos basak, Leucos aula, and Sarmarutilus rubilio are designated.